Dog taxonomy is complicated and frequently rearranged due to genetic discoveries. The domestic dog is considered either a variant species/sub-species of Grey Wolf. The Dingo and several other primitive dogs that were once treated as separate species are now also considered to be a subspecies of domestic dog. The ability of these to interbreed and produce fertile offspring and for genes to flow in either direction means that genus Canis is quite a mish-mash.

The domestic dog (C. familiaris) has been crossed experimentally with numerous wild dog/wolf species, often to create new domestic breeds. Feral domestic dogs have also hybridised with local wild dog/wolf (sub)species e.g. the Indian Wolf, Red Wolf, Grey Wolf and Ethiopian Wolf. The hybrids are fertile and tend towards the wolf in type. Later generations of hybrids tend towards the backcross species in appearance and behaviour. Female sled-dogs were sometimes crossed to wolves to improve the sled dog hardiness and stamioa. The black-coloured wolves of North America gained the dark colouration from domestic dogs.

Many members of the dog family are also capable of interbreeding and producing fertile offspring. This depends on how closely they are related. Molecular analysis divides the dog family into 4 divisions:

1. Wolf-like canids including the domestic dog, dingo, grey wolf, coyote, and jackal
2. South American canids
3. Old and New World red-fox-like canids, e.g. red fox and kit fox
4. Monotypic species, e.g. bat-eared fox, raccoon dog

The wolf, coyote, jackal, and domestic dog (including the dingo) have 78 chromosomes arranged in 39 pairs. They are interfertile (unless size or behavioural differences obstruct mating) and produce fertile offspring. The wolf, coyote, and golden jackal diverged around 3 to 4 million years ago. The African Wild Dog also has 78 chromosomes, but is considered distinct enough (with different physical features) to be placed in its own genus. Other members of the dog family diverged 7 to 10 million years ago and are less closely related. These cannot hybridise with the wolf-like canids and they have different numbers of chromosomes: the yellow Jackal has 74 chromosomes, the red fox has 38 chromosomes, the raccoon dog has 42 chromosomes, the Fennec fox has 64 chromosomes. Differences in chromosome number are not always a barrier to producing viable hybrids; it depends on the gene combinations in the hybrid and whether these allow an embryo to develop. However, large differences in chromosome number make female hybrids poorly fertile and male hybrids sterile. In the case of dogs and foxes, it appears that viable embryos are not formed.

According to "Dogs In Britain, A Description of All native Breeds and Most Foreign Breeds in Britain" by Clifford LB Hubbard, 1948 "So also do we find that in the Americas the aboriginal dog stock has been slightly influenced by the coyote (Canis latrans),whilst in the east the blood of the jackal (Canis aureus) has to an appreciable extent pulled most of the semi-wild Pariah Dogs into a uniformity of shape noticeably apparent even to the most casual observer. It will be seen from these references to the wolf, jackal and coyote that cross-breeding is not only possible between these animals and the true dog but is, in fact, fairly frequent; less so to-day, of course, when dog breeding is so strongly controlled by man and his fancies for this or that shape, but originally quite common. All members of the genus Canis interbreed freely and their progeny are as a rule quite fertile, whereas dogs do not mate with such animals as hyaenas, African 'wild dogs,' foxes and the like. A few alleged fox-dog hybrids have been mentioned from time to time, but the details concerning the matings have not been authentic."

People wanting to improve domestic dogs have sometimes bred them back to wolves; as well as compensating for genetic problems in domestic dogs, the wolf-dog hybrids tend to be dominant and less domesticable. Grey wolves have been crossed with wolf-like dogs e.g. German Shepherds, Malamutes. Many become a problem in adulthood, usually because the owner expects them to act like a domestic dog and is not prepared for their more wolf-like behaviour. The Saarloos breed is derived from such crosses. Parts of Europe, the wolf naturally hybridises with stray domestic dogs resulting in mongrel populations. The Australian Dingo (a feral, rather than wild, species) also hybridises freely with domestic dogs. Harmsworth Natural History (1910, main authors R Lydekker, Sir H Johnston & Prof JR Ainsworth-Davis) notes The dingo breeds freely with the various European dogs introduced by the colonists and classes the dingo as a descendent of Asian domesticated dogs rather than a distinct species. Clifford LB Hubbard wrote in Dogs In Britain, A Description of All native Breeds and Most Foreign Breeds in Britain (1948): When early Scots settlers went to Australia some small working Sheepdogs (probably Welsh Sheepdogs or working Border Collies) were taken with them to help round up their then small flocks. The foundation stock appear to have been a British working Sheep-dog, of one or other of the above breeds, named Caesar and a cross-bred Dingo-Collie called 'Kelpie': of the resulting black-tan-and-red litter one bitch so resembled its dam that it was named 'Kelpie II'

According to the "Illustrated Natural History" by the Rev JG Wood (1853, 1874): When Wolves and dogs are domesticated in the same residence, a mutual attachment will often spring up between them, although they naturally bear the bitterest hatred to each other. A mixed offspring is sometimes the result of this curious friendship, and it is said that these half-bred animals are more powerful and courageous than the ordinary dog. Mr. Palliser possessed a remarkably fine animal of this kind, the father of which was a white wolf and the mother an ordinary Indian dog. Its fur was white, like that of its wolf-parent. When Ishmah as the dog was named, was first purchased from its Indian owners, he was so terrified at the white face of his new master, that he always ran away whenever he saw him, and could not be persuaded to come within two hundred yards. Ishmah was then tied up with a cord, but the moment that he was left to himself he held the cord to the ground with his paw, severed it in an instant with his sharp teeth, leaped out of the window, and dashed off to his former owners. After a while, however, he became reconciled to his white master, and proved to be a most faithful and useful ally; dragging a small sledge that contained the heavier necessaries of a hunter's life, and partaking with his master all the pleasures and privations of a nomad existence. On account of wolfish ancestry, he was rather apt to run off and play with the young wolves instead of attending to his duty, but was never induced to throw off his allegiance. On one occasion the dog saved the life of his master by lying close to him on a bitterly freezing night, and with his long warm fur preserving him from the terrible death by frost.

December 13th, 1901 (various): BOSTOCK ANIMALS FIGHT. Bears, Lions and Hybrid Wolves in a Scrap One Bear Killed. BOSTON, Dec. 12. A fierce combat took place at Bostock s animal arena today' between three black bears from India, two forest-bred lions and two hybrid wolves. As a result one bear is dead. Mr. Johnson, the menagerie superintendent, discovered the battle soon after it started, and called to his assistance Merman Weelon. Arthur Mullen and others, who entered the cage with hot irons and revolvers to quell the disturbance. Mullen was bitten in the calf of one leg, but his Injury is not dangerous. It was twelve minutes before the animals were separated. Then it was found that a 6-year-old bear, very valuable, had been bitten through the jugular vein. He died soon after. The hybrids are a cross between American bloodhounds and Siberian wolves and have been trained by Mme. Beaufort. They are very savage and probably they started the battle.There was great excitement during the combat, and Mr. Bostock regards it as fortunate that it occurred when no audience was present.

The following series of articles describe wolf hybrids born at the Wembley Exhibition. At the time there was a heated debate over the Alsatian (German Shepherd Dog) and whether it contained wolf ancestry. At the time Alsatians were often thought to have poor temperaments and untrustworthy (when I grew up in the 1960s and 1970s they still had a bad reputation) and this raised suspicions about their ancestry.

WOLF-DOG HYBRIDS AND OTHERS. A home dweller informs me that he possesses two wolf-dog hybrids, now about two years old. They were born at the Wembley Exhibition, the sire being a cross-bred White Siberian and a Canadian timber wolf, whilst the dam was a pure-bred Alsatian bitch. My correspondent thinks that these hybrids may be of some scientific value, and no doubt he is right. I hope to see these creatures shortly, and then I may be able to give my readers further and more personal details. The owner says they have bred quite true to type, and, as far as he himself is concerned, are reliable, affectionate and quite domesticated, but are hardly to be trusted with strangers. Some time back I went rather carefully into the question of the vulpine and canine cross. I was satisfied from the evidence with which I was furnished that such a cross did actually occur. Readers of the Sporting and Dramatic may remember the reproduction of a photo of the parents and offspring which appeared in the columns which I have the honour of "feeding." Moreover, it is safe to assume that these whelps were not the only ones that have been produced from time to time by such an extraneous cross, although it is certain that similar occurrences are very rare and that even where a fox has been successfully mated with a bitch the coition is generally sterile, because the fox, although one of the inclusive canine group, is not of the same sub-section as the dog. On the other hand, the lupine and canine varieties are far more closely allied in fact, the number of cases where there has been inter-breeding are, and always have been, of frequent occurrence. If my memory serves me aright, about two years ago at the London Zoo a dingo bitch produced a strong and healthy litter to a wolf of sorts, but whether of the timber or prairie variety I am unable to say off-hand. Then, again, there is no doubt but that the Huskies of the Far North are saturated with primitive lupine blood. Indeed, it was, and is, a well-recognised practice with dog team drivers to tether fecund bitches remote from the camp, ln order that they may attract the attentions of a wolfish mate, such an outcross being resorted to in order to counteract the degenerating effect of too close in-breeding in the respective teams.

And what about the German sheep dogs (the so-called Alsatians). Their protagonists may protest until Doomsday and produce pedigrees going back for many generations, hut nothing will persuade me to subscribe to their slogan that their favourites owe nothing of their type or temperament to lupine blood. Even a tyro in cynology cannot fail to trace the influence thereof. When in Germany, guards were first required for the flocks and herds half-breds or even pure wolves, probably were used for the purpose. This type was persevered with and bred to standard, so that nowadays we have plenty of thoroughly reliable Alsatians, which can be trusted as well as the individuals of any other breed of dogs. However it would be idle to overlook the fact that - in numerous cases - atavic influences result in the production of a certain number of Alsatians which are highly temperamental, and which display lupine characteristics, most markedly. Many of these remoter peculiarities have been successfully bred out, but the lope of the wolf persists, though the peculiar action is now, among the elect," euphemistically and technically termed gait," whilst lupine structure, balance and symmetry of outline is known as angulation." (Illustrated Sporting and Dramatic News, 28th August 1926)

MORE ABOUT WOLF HYBRIDS. IN my last article I dealt to some extent with the dog and wolf hybrids which were produced two years ago at the Wembley Exhibition. Two of these pups were purchased by Mr. J. Slattery, who very kindly drew my attention to them. As before stated, he thought that I would be interested in the fact of their production, and he was not mistaken. I have not yet had an opportunity of viewing these creatures in the flesh, as Mr. Slattery had to be absent from London at the only time when I could have seen them, but he has now provided me with details which I hope will be of interest to my readers. I cannot do better than quote that part of his letter which applies to the animals in question.

"I have proved conclusively that my dogs are not sterile, and consequently are not mules or hybrids in the sense that a goldfinch and canary, or a horse and donkey cross is a mule or hybrid. I bred one litter of three pups all dogs from my pedigree Alsatian bitch, a year ago, by one of the dog-wolves. Recently the same bitch was mated to the other one, but through playing with the dogs and over-exerting herself she had her pups prematurely, a fortnight before they were due, all dead. This was indeed a calamity from my point of view as experiments, as I had sold two of the first litter, whilst the third and best one died of distemper. I may here state the circumstances in which I became possessed of these animals. Wandering into the menagerie at Wembley Exhibition in July, 1924, I happened to ask the attendant if he ever attempted to breed from the big grey male wolf. Yes,' he replied, 'would you like to see some of the results? To my astonishment he took me round to the back of the cages and showed me six of the dearest little grey pups, with their Alsatian dam. I immediately bought two of the friendliest ones. They were barely a month old. By taking them so young I reckoned that they would become more attached to me than if I let them grow older and wilder. They were both males, for Mr. Tyrwhitt Drake, the owner of the menagerie, would not sell me the bitches. You probably know Mr. Tyrwhitt Drake, of Maidstone. He deserves all the credit for mating the wolf with the Alsatian, but I recognised at once the potential scientific value of such a cross, and that is why I bought two of the litter. I possess a certificate from Mr. Tyrwhitt Drake to the effect that the sire of my two dog-wolves was bred by him in his menagerie from a female grey Canadian timber wolf (obtained from the Lon don Zoo) by a light-coloured male Russian wolf. He (Mr. Drake) says that it is very difficult to get the male timber wolves to mate, as they are almost monogamous. [This is an interesting fact, quite new to me. H.C.] The dam of my two was an Alsatian with an excellent pedigree, which Mr. Tyrwhitt Drake got from Mrs. MacDougall-Porter, Pathway Kennels, Sevenoaks. My dogs, therefore, combine the blood of the Canadian timber wolf, the white Russian wolf (Siberian?), and the Alsatian, and are probably unique, except for the other four of the litter. Mr. Drake, however, has since bred some more. I obtained a bitch from him about five months ago, but she is a weakling and a curiosity. She is more like a chow, with a curly tail, which spoils her. She is evidently a throw-back. There is not the least doubt that my two dogs are the sons of the wolf, as the Alsatian bitch never left the cage during her heat, and the coition was witnessed by the keeper. My Alsatian bitch, also, never left my garden.

My observations of the two dogs in my garden, for over two years, are (1) They are one-man dogs, and are devoted to me. (They take flying leaps to kiss me when I come home.) (2) They can bark, but seldom do so it is usually a whine of joy when they, see me. (3) They have a marked antipathy to all dogs. A diabolical snarl and a warning chop of the teeth sends an inquisitive dog flying. (4) They have glorious teeth, and a chop is like the closing of a steel trap. (5) They play by the hour, hiding and stalking, and they will wrestle to order like two human beings. (6) They still retain the ear-splitting wolf- howl, much to the disgust of the neighbours A bugle blown, or an organ played, will set them off. (7) They become very suspicious and inclined to slink when I point the garden syringe at them. (8) They are also very suspicious over any strange food. They look at me with searching eyes seeming to ask, Is it poison? (9) They sometimes try to burrow holes in the garden, and do it in a sort of relay fashion one behind the other. (10) They occasionally quarrel and snarl, and raise their bristles, but I have never yet seen them fight. One places his paws on the other's back but the argument is soon over and they resume their play.

I always take them out singly, on a chain. I have had to surround the garden with special wire netting, or they would escape. They can chew through ordinary wire netting as if it were string. They are very intelligent and are too quick for me at times. One escaped into Kensington Gardens when six months old, and he was found by the police the same evening down a front area in Maida Vale giving the wolf-howl for all he was worth. It took four policemen to lasso him and send him in a van to the Dogs' Home, where the officials were glad to see the back of him. Both dogs escaped into the streets one day and raided a butcher's shop, but did not do much damage, though they killed an unfortunate mongrel terrier which ventured to bark at them. One came back, but the other reached Kensington Gardens, where we found him two days later. He was mightily pleased to see us and would not let any stranger approach him. They are most lovable dogs to me, but I simply dare not trust them with strangers. Some time ago a Mrs. Giffard (now in Rhodesia) bought one of the pups. She was Secretary of the Alsatian Police Dog Society." Mr. Slattery adds Now I think I have told you truthfully all I know about the dogs." (Illustrated Sporting and Dramatic News, 4th September 1926)

DOGS OF THE DAY. By Major Harding Cox. HYBRIDS. SINCE writing my two recent articles as published in the I. S. and D. News, I have had an opportunity of inspecting, in the flesh, one of the two wolf-Alsatian hybrids to which I alluded therein, and with which Mr. Slattery's interesting letter, which I printed in full, dealt. The owner was kind enough to bring the bigger of his two favourites to the Garrick Club for me to see. Wolf," as the animal is named, seemed timid. An unwonted journey in the Tube had evidently scared him stiff, but there was apparently no sign of savagery or even resentment in his demeanour. His glance was quite benevolent and rather appealing. He made no attempt to show his very strong and serviceable teeth. He is evidently devoted to his master, placing his paws upon Mr. Slattery's shoulder, laying back his lugs, and caressing that gentleman's face as might an affectionate Alsatian. On the other hand, his owner was obviously nervous about the handling of the beast by a stranger, lest, peradventure, the wolfish strain should assert itself and cause the hybrid to indulge in one of those quick and disastrous slashes which are typical of the lupine species. However, we three indulged in a little stroll up a sparsely frequented side street, where Mr. Wolf was persuaded to show his paces. His gait was perfect and would have done credit to an excellent Alsatian champion, while his angulation left little to be desired, though his couplings are too open to suit my fancy. His general appearance favours his sire (a wolf) rather than his dam (a pure-bred and handsome Alsatian). He is of lean habit, but evidently not from lack of sustenance, and he shows the rather narrow quarters and slack thighs and gaskins of his paternal forbears. The colouration is that of a timber wolf. It will be remembered that his paternal grandsire was of this species, which, being mated with a grey Russian (probably Siberian) wolf, the sire of the hybrid in question was the result. Wolf is bigger than the average Alsatian dog, but is of lighter build from stem to stern and has less bone. Otherwise he is well put together and well balanced. As previously stated, he is not sterile, having already, at two years of age, begotten a litter which, unfortunately, did not survive, so that lie is not a true mule," which goes far to prove that the wolf and the Alsatian are of the same species and are germane. It is probable that the crossing of a wolf with a bitch which is not of an analogous group, such as a foxhound or a spaniel although possibly fertile, would result in progeny which would prove sterile. Mr. Slattery's experiments might be carried much further, and, in the issue, might well prove the fallacy of the slogan of the Alsatian fans, that their favourites owe nothing of their physical peculiarities and dynamics or their temperamental idiosyncrasies to a lupine origin. (Illustrated Sporting and Dramatic News, 18th September 1926)

THE various articles and letters which I have contributed to The Illustrated Sporting and Dramatic News and its contemporaries on the subject of "The Alsatian Wolf dog," alias "The Alsatian," alias "The German Sheep-dog," alias "Le Berger Allemand," seem to have excited a very lively controversy, judging by the private correspondence which I have received on the subject. One of my correspondents writes that he cannot accept my statement as to the existence of a wolf-Alsatian hybrid. Whether he "accepts" it or not, the fact of such a cross is indisputable. The evidence in my possession and my personal inspection of a creature so produced leaves no shadow of doubt on the matter. I must admit that I have not myself indulged in experiments connected with the production of hybrids between wild animals and domestic dogs, but there are numerous practical scientists who have done so with results which prove that the lupine-canine mating is one which is easily contrived and almost invariably prolific. That such is the case is vouched for by Mr. Tyrwhitt Drake, mayor of Maidstone, who has a private Zoo; by Mr. Robert Leadbetter, late master of the O.B.H., who also kept a private menagerie in Bucks; and by Mr. H. C. Brooke, the last-named of whom has long been known as an expert eugenist and cynologist, whose practical experiments, conducted over a space of many years, show results which must prove of the greatest interest to physiologists and zoologists in general, and to those interested in the canine genus in particular, seeing that such results are vouched for by the weight of Mr. Brooke's undoubted authority. That gentleman has been kind enough to supply me with details, some of which I have now the pleasure of printing.

To begin with, Mr. Brooke questions my theory that hybrids between wolves and dogs are prolific only where the latter are of germane blood. His contention is that a wolf will cross with a dog of any breed, even one the tap root of whose origin is remote from that from which the lupine line sprung, and that the produce of such out-crosses will not be sterile. My own views are confessedly but theoretical, whereas my correspondent has had practical proof that such out-crosses are far from uncommon for instance, he knows of a case where a cross between a mastiff or boar- hound (presumably Great Dane) and a she wolf produced a most impressive creature, which was able and willing to procreate. By the way, Mr. Brooke discards the term hybrid and adopts that of cross-bred," holding that the wolf, being a genuine member of the canine genus any stock begotten by itself when mating with any member of the dog family-- no matter of what variety is not a hybrid in the true meaning of the term, but simply a cross-bred dog. He goes on to point out how certain it is that the so-called Alsatian is directly descended from the wolf, and how from time to time the pure blood of the latter has been reintroduced either by accident or design, in the latter case with the avowed intention of preserving or reinvigorating the desirable lupine characteristics. This in spite of a tabulation of alleged pedigrees reaching back for several centuries. I am in a position to endorse this. I have lived to learn that pedigrees either of humans, dogs, thoroughbreds, and any and every kind of domestic stock, are not always what they profess to be! (Illustrated Sporting and Dramatic News, 23rd October 1926)

DOGS OF THE DAY. By Major Harding Cox. CROSS-BREDS AND HYBRIDS. IN one of my earlier articles I had something to say about cross-bred dogs and hybrids between the canine and the lupine and vulpine species. I am now returning to the subject, stimulated by the controversy which has waged between the Alsatianists and their scientific supporters of the one part and those that hold that the wolf and the domestic dog are descended from a common ancestor or tap-root of the other. The contention of the former group is that the wolf has nothing whatever to do with the Alsatian type as recognised to-day by experts who have devoted years of intensive study to the history and ancestry of the breed. They bank upon the authority of von Stepanitz, whose opinions and theses undoubtedly carry great weight, but there are other authorities and cynologists in general who hold diametrically opposite views. For instance. Mr. HC Brooke, of Taunton, who has had unrivalled experience in the crossing of the lupine with the canine species, scoffs at the idea that the progeny of such matings are hybrids, a term which would imply that the blood of their parents is not germane, and that such must be mules," i.e., infertile. He prefers to allude to such as cross-breds," which in no case are sterile owing to their parentage. Mr. Brooke holds that a wolf will interbreed with a dog of any breed, and that a wolf is, in fact, a dog, and nothing but a dog No doubt breeders of Alsatians have most carefully and jealously guarded the pedigrees of their stock. They may be able to prove that the lupine taint (if it can be so regarded) has been most sedulously excluded from the veins of their favourites for countless decades, but atavism is a force which will not be denied, and which displays itself sporadically and almost indefinitely, in recrudescent form, throughout a long succession of generations. [. . .] the dingo and wolf cross, which has been, without a shadow of doubt, established by Mr. Brooke and others, who testify to the fact that the off spring of such coitions almost invariably prove fertile when mated with one of their own kind, or with a dog or a wolf. The said Alsatianists seem to be much perturbed because in a short article I recently called attention to the fact that an animal directly descended from a wolf had been exhibited at a championship show as an Alsatian. As a matter of fact, the villain of the piece turned out to be but a quarter-bred wolf. Otherwise my facts were correct. (Illustrated Sporting and Dramatic News, 27th November 1926)

By A. CROXTON-SMITH. The late H. C. Brooke, who made all sorts of experiments with out of the way dogs and wolves, once declared that he would rather handle a genuine wild wolf than a wolf-dog hybrid. The photographs that I have seen of such hybrids certainly suggest that they must have been sly and un- dependable. Their expressions were not such as to inspire confidence. (Illustrated Sporting and Dramatic News, 13th January 1934)

According to "Dogs In Britain, A Description of All native Breeds and Most Foreign Breeds in Britain" by Clifford LB Hubbard, 1948: The true Husky is not a large dog; the dogs of 27 inches height and even more are cross-bred with wolves or white breeds (husky/hound cross-bred dogs) [ ]The Timber-Wolf Dog is not confined to one district but is spread throughout the areas from Alaska to north of Hudson Bay; the Yukon basin appears to be its adopted home to the largest extent. It is, as its name applies, a first-cross between the true Husky and the timber-wolf of the North American backwoods; gaunt, ferocious, the largest of its type and the most wolfish of all sled dogs. Owing to its size and strength it is capable of being a good leader or king dog for a team, but otherwise it is not the best type for general use, as is the Husky itself which can be used in summer for pack carrying. Its heavy build handicaps it on very long journeys though for short heavy loads the breed is frequently in demand.

In general shape it is nearer the timber-wolf than the Husky; longer in back and coat (the coat does not stand stiffly out); longer couplings and greater angulation of the hindlegs; a more loping gait which is not the best for long journeys; the head usually having non-erect ears, scarcely any stop and a slightly longer muzzle. Colour is grey, or grey or sable with white throat, chest, belly, feet and tail-tip; rarely pure white. In height it stands about 27-28 inches, and in weight ranges from 85 to 100 pounds (outstanding specimens equal the height of an Irish Wolfhound and weigh as much as eight stone). The tail usually hangs low and is heavy in brush.

For many years, the German Shepherd Dog (called Alsatian in the UK due to two wars with the Germans) was believed to be a wolf-dog hybrid. Hubbard wrote in 1948: It must be understood that in the 1920s the breed was not only the best-loved but also the most-hates; its nom-de-mal of [Alsatian] Wolfdog, its lupine features, and the existence about that time of too many highly strung and nervous specimens (which whenever they bit anyone were referred in the Press as dangerous wolf-hybrids) together contributed to its decline. [ ] people have been told by those who should have known better, or who never will know better, that the German Shepherd Dog is half wolf [ ] should be authoritatively told that whatever wolf blood was in the breed about seventy-five years ago is bred entirely out now." (This is an interesting parallel with the types of dogs - based on appearance - demonised in the late 20th and early 21st century)

Dog genes also flow into wild wolf populations. Wolves acquired the genetic mutation for dark coat colour through mating with domestic dogs (Marco Musiani, University of Calgary, Canada and Greg Barsh, Stanford University, California in Science Magazine, 2009). Light colour coats predominate in wolves living on open tundra, but the dark colour is common in wolves in wooded or forested areas. The results came from a genetic analysis of wolf populations in Europe and North America. The studies suggest black wolves appeared after grey wolves bred with prehistoric domestic dogs that accompanied settlers into the continent 10,000-15,000 years ago. Those domestic dogs became extinct, however the genes from the extinct domestic dogs live on in the wolf population. Modern domestic dogs in North America are descended from European dogs over the last 500 years (some of which have again been crossed with wolves). A trait developed by humans in domestic dogs, which were developed from wolves, has found its way into the wolf population. Because wolves don't rely on camouflage for hunting success, there must be other reasons the mutation is beneficial to the woodland wolves. The protein involved in the coat colour mutation may be linked to the immune system. The change to the immune system may be the real advantage while the pigmentaiton is a side-effect.

In parts of Europe where wolves have been killed by shepherds, the remaining wolves have interbred with stray dogs. The strays have tended to be the blonde-furred sheepdogs (used to guard the flocks and merge in with the sheep) resulting in strains of cream-furred wolves. Unfortunately in this situation, low wolf numbers mean they risk being mongrelised out of existence and supplanted by feral dog populations.

The Grey Wolf bred with the Indian Wolf in Regent s Park Zoo (London Zoo), but the Indian Wolf is now considered a subspecies rather than a full species. The Grey Wolf breeds with the Red Wolf, but the Red Wolf was derived from Wolf x Coyote hybrids (and has since become a species in its own right) so this is unsurprising. The Grey Wolf may possibly hybridise with the Ethiopian Wolf.

The Spitz. The Humboldt Union, 14th April, 1877. Dr. Hammond of New York, the distinguished authority on nervous disorders, thinks the Spitz dog is really more dangerous than other breeds. It is a hybrid, being a cross between a Pomeranian hound and the Arctic fox, and such animals are always bad. He is inclined to think the saliva of the Spitz is always poisonous, especially when the animal gets excited, as he is very liable to do. The Doctor favors the extermin ation of the pretty but perilous pets.

Harmsworth Natural History (1910, main authors R Lydekker, Sir H Johnston & Prof JR Ainsworth-Davis) notes the inability of the dog to form hybrids with the fox: Additional testimony that foxes have nothing to do with the origin of domesticated dogs is afforded by the fact that hybrids between the fox and the dog, notwithstanding numerous specimens of supposed hybrids of this sort which are from time to time brought to notice, are of extreme rarity, if not altogether unknown.

Buffon, and later naturalists, claimed that hunters in the Guianas cross their domestic dogs with the Crab-eating Fox (Cerdocyon thous, formerly Canis cancrivorus). Others have cited hybrids between the dog and Pampas Fox (Lycalopex gymnocercus). A Pampas Fox allegedly produced two hybrid litters when mated to a male Fox Terrier with whom she had been raised, the offspring resembly the Pampas Fox (reported in the 1920s). Only one of the purported hybrids survived to maturity.

A mongrel dog (Alsatian (German Shepherd Dog)/Bull Terrier mix) allegedly sired offspring on an Indian/Bengal Fox (Vulpes bengalensis) in the 1950s. Hybrids of both sexes were born and were doglike in appearance, but had straight bushy tails and were nocturnal like the fox. The Indian Fox usually forms a lifelong pair bond, but will also mate outside of the pair bond, so the offspring cannot be confirmed as hybrids.

There was a report of a dox in Saskatchewan, Canada. This was believed to be the result of a miniature sheltie bitch with a wild fox (fox species not identified). One out of the three offspring survived, this being a sterile female that resembled a fox. However, the variability of dogs in appearance make it impossible to determine whether an animal is hybrid based on looks alone. I have not found genetic evidence to support the hybrid identity.

A hybrid, bred from a fox and a dog, is always a sidling, shambling beggar, and won't come to you straight when called; he makes a lot of S's with his body as he sneaks to you. For all that, these hybrids make rare varmint killers, and are capable - as are foxes - of great affection for those to whom they are known, and by whom they are well treated. (Illustrated Sporting and Dramatic News, 5th June 1886)

"Mr A. D. Bartlett, the Superintendent of the Zoological Society a Gardena, says wolvea, jackals, doga, and foxes are found spread nearly all over the world. All wolves, if taken young and reared by man, are tame, playful, and exhibit a fondness for those who feed and attend them. The same may be said of all the species jackals. This being so, it is highly probable that both wolves and jackals were for many ages found in the company of man, and that owing this association the different species these animals may have bred together and become mixed. I have found no difficulty crossing wolves and jackals with domestic dogs, when suitably matched. is a well-known fact that the Esquimaux frequently allows his dogs to breed with wolves, order keep up the strength, the power endurance, and the courage of the race. But as regards foxes, so far as my experience goes I have never met with a well-authenticated instance of a hybrid between a fox and a dog, notwithstanding numerous specimens of supposed hybrids of this sort which from time to time have been brought to notice. " (St. Andrews Citizen, 9th April 1892)

"I have had not a little experience regarding the destruction of Australian foxes, or what is known as the dingo or Australian wild dog. [. . .] the foxes used to frequent the dams for water during the night. Beside the dams are the shepherds' huts, and among the many foxes I have destroyed I have found that five out of six were not pure, but crosses between our collie and the Australian fox. And I have observed that this mongrel was even more cunning than the pure-bred fox. (Aberdeen Press and Journal, 22nd February 1901). The dingo is, of course, a dog and not a fox and this added confusion to the debate.

"The following article appeared from the pen of the present writer in the County Gentleman, and Land and Water," last week: "It is singular that there should be be so much doubt as regards the interbreeding between dogs and foxes. It is singular in a way, though naturalists are by means unanimous on other less interesting points. Generally speaking, it seems to me the arguments on this question may be placed under two headings, (1) those who procure evidence from observations made regarding tame foxes, half domesticated, and can say positively they cannot bring data to prove the hybrid; (2) those who can quote several instances of crosses which have taken place between naturally-reared foxes and domesticated dogs, and yet lack the actual proof that such cross did take place. , , , Personally. I firmly believe in the dog and fox hybrid, and, except for actual observation, can quote two cases which would seem to conclusively prove the statement that the hybrid is by no means uncommon. . . . A bitch of the canine species was born and bred in the isolation of a big woodland where foxes were numerous and stray dogs never seen. A dog fox was seen more than once near her kennel, and in due course, she gave birth to a litter of pups. . . . One of these has been kept, and I saw it the other day. The teeth, formation of the head, and brush, are all most suggestive of a vulpine cross, though the bitch herself does not resemble the contemporary species. The story, of course, lacks the fact which the naturalist will demand: 'Who saw the twain actually mate?' . . . I believe a Bournemouth innkeeper had a tame dog fox which mated with an Irish terrier bitch, with the result that a hybrid litter was born, but I have no personal knowledge regarding this instance." (Whitby Gazette, 3rd April 1908)

"Is there such a sheepdog on either [Australia or New Zealand] which has been found to be superior to our own collie in tending flocks? This dog, I am informed, is half-collie and half-fox Is that an actual fact? Then is it a reality that such a cross dog and fox will breed again and prove fertile? These are the items I would like answered. "J S Whyte" brings in the dingo. Will this wild dog breed with the collie and will its progeny also breed and prove fruitful? If so, perhaps your correspondent may be right in substituting the dingo for the fox. But until I hear other views, my faith clings to what my Australian friend told me viz. that the sheep-dog is a breed between a collie and a fox. " (The Scotsman, 18th April 1911) This again highlights the confusion caused by calling the dingo a fox.

"One hears of hybrids produced from dogs and foxes, notably the Spanish rabbit dog, but the authenticity is doubtful, and has never been proved in this country. (Illustrated Sporting and Dramatic News, 1st May 1915)

"The statement published a day or two ago that a gentleman at Bishopston had succeeded in mating a fox to a dog and that the progeny was exhibited at the recent Bristol dog show, has evoked considerable interest. Among the many who discussed the subject yesterday with the writer of this note was Mr F Peter, the respected agent of Lord Berkeley. Mr Peter [. . .] knows a deal more about foxes and dogs than most people, yet he had never known of a case in which the fox and the dog had been successfully mated. [. . .] it may be said that Mr Cox of Berkeley Road, Bishopston, who owned the fox and the fox terrier, has acted in perfect good faith in the matter. He has had a lot of experience with dogs, and from his own personal knowledge he affirms that the alliance was genuine. He urges that the colour of the pups coats is that of their father the fox and he states that the youngsters can see as well in the dark as in the light. But Mr Cox did not keep the amorous couple under lock and key; they had the run of the garden, and the ingenuity and persistency of the canine Romeo is known to all who have kept dogs. The late Mr Bartlett, superintendent of the London Zoo, conducted experiments over a long series of years, but failed to produce fox and dog hybrids, and like Mr Pocock, the secretary of the London Zoological Society, has stated definitely that he never heard of a successful case of hybridism. It is to be regretted that Mr Cox cannot produce another litter under conditions that would leave no doubt, for the fox is dead. " (Western Daily Press, 3rd January 1920)

"MY penultimate article, in which I dealt with fox-dog hybrids, brought me some very in teresting correspondence. In two of the letters further cases of the cross were cited. Miss F. M. Duke, whose so-called Pomeranian wolf -dogs were depicted in this paper on April 25, tells me that she saw one of these alleged fox-dog hybrids the type of which closely resembled that of the aforesaid Pomeranian wolf-dogs. She was informed that it was a genuine specimen of the cross, but she does not appear to have been provided with any definite evidence of the fact. . . . A more definite instance of the fox-dog hybrid is furnished by a scientific friend of mine, who gives chapter and verse in support of the allegation that this cross was known to have been achieved many years ago by Tom Egglestone (gamekeeper to Sir William Chaytor, of Witton Castle, Witton-le-Wear, Co. Durham), who owned a sort of nondescript collie bitch, which he used with the gun as a finder and retriever." When she was in season he tied her up in a covert where he knew that a fine old dog-fox lurked. In due course a litter arrived, but his story does not say of how many whelps it consisted. Anyhow, they were distributed among friends, but as they grew up one and all proved so treacherous and intractable and such persistent robbers of hen-roosts that they were put down" seriatim." (Illustrated Sporting and Dramatic News, 9th May 1925)

"I must premise an error small in itself, but very detrimental to face-value, which crept into my second thesis on the "dog-vixen" and "fox-bitch alleged hybrids. When recalling the evidence provided by John Eggleston, the game-keeper, I laid particular stress upon the fact that, after tying up his rank bitch in the covert which he knew to be the favourite quarters of an old dog fox, he hid himself in order to observe developments, and in the end witnessed the act of coition. Of course, this was the very pith of the evidence. Without an acceptance of the fact, it is worth less. Since the article in question appeared there have been several other cases of such hybridism adumbrated. One writer in a contemporary quotes from early script of the past century, setting forth several well-authenticated cases. I think we can leave it at that. "(Illustrated Sporting and Dramatic News, 23rd May 1925)

"JUST at this moment, when much discussion has going about breeding hybrids, a letter which recently appeared in a contemporary about alleged dog-fox hybrid may be of interest to the casual reader. The hybrid in question was the regimental mascot and pet the Inniskillen Dragoons when quartered some years ago in Dublin. According the writer from whom I quote, it was extremely fox-like in appearance, but three times the size of ordinary fox, was sable in colour, with prick ears and absolutely fox head amber eyes, puffy cheeks and all - and had a magnificent white-tipped brush and white chest. It walked with the characteristic slinking crouch the fox and invariably burrowed under the straw in its loose box instead lying on it as a dog would do. The dam was a sable collie bitch, who broke loose one night and escaped into a wood infested by foxes, being eventually found with her broken lead entangled in some tree roots. The hybrid in question appeared in due time and there seemed no possible reason to doubt that, if ever there was genuine dog fox hybrid, this was one. " (Yorkshire Post and Leeds Intelligencer, 31st July 1925)

"I have received among an avalanche of letters (quite 95 per cent, of which uphold my views) one from a correspondent who claims to have secured a litter of hybrids as between a black Pomeranian bitch and a dog fox. The two were kennelled together, and it was quite impossible for any dog or animal other than her pal, Charles James," to have access to her. The act of coition was not, however actually witnessed but circumstantial evidence and signs were not wanting. At the right time the said Pom gave birth to five whelps (three males and two females), which unfortunately only survived a few days. This is how my correspondent describes them. Just before their death they weighed three-quarters of a pound, having fairly large heads with very fine muzzles, ears rather large, extra long tails of short, bristly fur and a coat of medium length. Their colour was red and silver with black on legs and underneath with no white visible on any parts." Now this colouration is, to my mind, one of the most convincing proofs of the vulpine infusion, it being just what I should expect from such a cross as described. Perhaps some of my readers will remember that a time back I described how a brace of fox-dog hybrids had been born at La Turbie in the Alpes Maritimes, and how all the proofs were sworn to before the mayor of that village. Also, there appeared in the Illustrated Sporting and Dramatic News a photo of one of the hybrids and the dam, in which the characteristics of the former were unmistakably vulpine. It has been proved to my entire satisfaction that the wolf will mate readily with any female dog, and that the progeny of such a union is not sterile but I very much doubt if a fox-dog hybrid would beget stock, since the vulpine genus is far more remote from the canine than is the lupine. " " Major Harding. (Illustrated Sporting and Dramatic News, 6th November 1926)

A captive dog-fox, again, is willing to mate with a female terrier, but I should like hear of case in which a vixen, similarly placed, has paired with a domestic dog. That wild beasts of distinct species will inter-breed in the captive state, is,of course, well known, but it would be difficult to establish an instance under truly wild conditions. There has always been a tendency to discredit the notion of fox and dog hybrids. That such exist, however, there can be no doubt. I well remember such an animal who lived for many years in a quiet Devonshire village though he was never exploited for the benefit of the scientist or the sceptic. The appearance of this dog was sufficient to banish any doubts as to his pedigree, and to watch him at work in the fields amounted to nothing short of an education. He was soon keen, alert, and yet so silent, but in no way did his ancestry evince itself more significantly than in his uncanny aptitude at catching moles the favourite far of his wild brothers. Most remarkable of all, perhaps, was his trick of going to ground. This he was apt to do when exhausted at the end of a long day s shooting. It is nothing unusual for spaniels or even hounds to curl up at such times in the most comfortable spot they can find and go to sleep if allowed to do so. This strange animal, however, went one better. Instead of curling up in a bush where he might be disturbed, he would seize an opportunity to slip into some deep, dry burrow, from which, once safely ensconced, nothing would induce him to move. It might be interesting to add that upon one occasion a bitch of the same family went to ground to whelp, and weeks passed before access to the puppies was obtained. (Western Morning News, 30th January 1930) [The behaviour noted above is also seen in feral dogs and is not proof of hybrid ancestry, just of strong instincts.]

"The little war over this question of hybridisation between the fox and the dog carries on uabated and the two factions seem to be equally confident of victory. So far Mr Henshall (and the late major Robson-Scott) have carried the attack with great vigour into the enemy s country and have backed their arguments with a great deal of formidable fact, Mr Henshall contending that a cross is impossible because the fox and the dog are two distinct species." (The Tatler, 25th April 1934)

"I was of the opinion that the dog and fox hybrid had for ever been scotched by the scientists who tell us that such a mating is a physical impossibility. When my old friend the late TF Dale wrote his book The Fox, forty years ago, he went so far as to say: The dog and the wolf and the jackal will interbreed, and in some cases the hybrids are fertile. But the fact of a cross between the dog and the fox still remains to be proved. In June of the year this book was published (1905) I went to Duncombe Deer Park (Helmsley), to see a litter of supposed hybrid puppies a small sheep-dog, owned by Maynard, had laid up in a fox earth. She had been chained to an outdoor kennel in the middle of the extensive park (in which foxes abounded), and one of the litter certainly bore considerable resemblance to a fox, but this was not proof. I have since seen a good many dogs possessing vulpine characteristics, which it was claimed were hybrids, but have never been satisfied. If the cross was possible, why have so many who have taken bitches of all manner of breeds to fox infested woodlands and left them all night secured by plenty of length of rope, not been able to secure a litter of hybrids? The question has once more arisen because a dog owner at Peel, near Bathurst, Australia, claims to have disposed successfully of the scientific statement that a fox and dog cannot mate. He states that he has succeeded in mating one of his kelpie bitches with a fox, and adds The bitch had four pups three dogs and a bitch an all were identical with their sire, even to the white tip on their tails. A bitch of this fox-kelpie cross was mated with a pure-bred kelpie dog and each of the litter of four has the appearance of a kelpie, but the manners and bearing of a pure fox. (Harrogate Herald, 27th February 1946) This again confuses the matter because the Australian 'fox' in the account is actually the 'dingo' a dog.

According to "Dogs In Britain, A Description of All native Breeds and Most Foreign Breeds in Britain" by Clifford LB Hubbard, 1948 "A few alleged fox-dog hybrids have been mentioned from time to time, but the details concerning the matings have not been authentic. Though perhaps strange, considering their external appearance, it perfectly true that the dog and the fox do not breed together and that because of the very structural and osteological differences which prohibit their free cohabitation they are scientifically classified apart, the dog being as we know of the genus Canis and the fox being in the genus Vulpes. At one time, until comparatively recently [recently to 1948] in fact, the fox was called Canis vulpes (and therefore accepted as a species of the true dog family), but with the advancement of cynological study and research it was finally given a genus of its own, being now generally believed to be quite apart from the true dog".

The Illustrated London News, 19th December 1953, eventually printed a longer and learned essay on the matter, but still sits on the fence as the possibility of fox-dogs. The matter would not be settled until the 'DNA Age' decades later, and even today there are those who cling to the myth of fox-dogs.

UNUSUAL HYBRIDS. By MAURICE BURTON, D.Sc. HAVING referred on this page (September 26, 1953) to a dog-fox hybrid, purely as a subsidiary in a story of direction-finding. I have been asked by several readers, by letter or verbally, what was the proof that the animal in question was really hybrid. Hybrids from the most oddly-assorted parents are known, and their authenticity readily accepted. But with dogs and foxes it is different. Douglas St. Leger- Gordon, in his recent book, The Way of a Fox," puts the position succinctly: The question of hybridisation between dogs and foxes is hardy annual which even scientific pronouncements have failed entirely to kill. It is one of those subjects upon which a strong case can be made for either side, and the attitude towards most controversial questions fluctuates with the tendency of the times." Thus, a quarter of a century ago there was a marked tendency to believe in it, especially by experienced sportsmen who, although not biologists, knew something of dogs and foxes. The tendency to-day is to dismiss the idea out-of-hand. The circumstantial evidence in favour of this particular form of hybridisation is strong. There are, for instance, many accounts of dogs showing interest in the trails left by vixen in the wild, or pairing up with a tame vixen in captivity; even of vixens showing similar interest in dogs. On the other hand, there are fewer examples of a dog-fox and a bitch taking notice of each other. Side by side with this there are, it is true, other accounts of domestic dogs and tame foxes, male or female, living together in captivity as inseparable companions yet showing no signs of mating. There are, in addition, several apparently well-authenticated accounts of hybrid offspring. Captain L. Lloyd states in his Field Sports of the North of Europe" that dog-fox hybrids are not uncommon in Sweden and gives the specific example of a young male fox, chained up until fully grown, which paired with a pointer-bitch, who produced a litter of which one was markedly fox-like. Heck, in Cosmos (1932). gives a picture of an apparently authentic hybrid from a male fox and a small, spitzlike female dog, although it is not definitely stated that the mating was controlled. An instance is given in Horse and Hound in recent years, and St. Leger-Gordon himself gives one that came within my own experience . . . a remarkable terrier said to have been sired by a tame fox, since his existence could not be accounted for otherwise. If untrue, one can only say that the manner in which he lived up to his supposed pedigree was a more remarkable coincidence."

We have noted already that in all alleged instances of dog-fox crosses, the supposed vulpine ancestry is seen more in behaviour than appearance. May this not be, theoretically, an argument in favour, for it seems that the less closely related the parents, the more readily is the offspring marked off from either of them. A mule is less markedly unlike either a horse or an ass than is a hybrid from an ass and a zebra. Perhaps dog and fox are more closely akin than we normally suppose. At all events, after reviewing the evidence, to say, as is sometimes dogmatically asserted, that dog-fox hybrid is impossible is quite unscientific. The best we can say is that the case for it has not been incontrovertibly proven.

An unconfirmed female fox-dog hybrid (terrier/fox) has been reported in the UK, unfortunately it was euthanized when the owner died because no suitable home could be found for it. Although gamekeeper folklore claims that Terrier bitches can produce offspring with dog Foxes, there are no authenticated hybrids between domestic dogs and Red Foxes. According to anecdote, "dox" (fox/bitch) hybrids are stronger and more vigourous than either parent and can be bred to other doxes. Thus far, all reported dox hybrids have turned out to be natural variation in the domestic dog. The great genetic mismatch between red foxes and domestic dogs makes the dox hybrid no more real than a cabbit (cat-rabbit) hybrid.

In 2021 a young female “dog-fox” hybrid, called a 'dogxim' was reported in Brazil. It had been hit by a car and taken to a vet where staff couldn't work out if it was a dog, or a fox. Extensive genetic tests found it to be a cross between a female Pampas Fox and a male domestic dog. The Pampas Fox (Pampas Zorro) is not a true fox, but is a fox-like canid more closely related to dogs, wolves and coyotes. The dogxim had a mix of dog and fox characteristics: large pointed ears, thick wiry fur and a long narrow snout. She was initially very wary of humans, but eventually allowed herself to be petted. Although not as docile as a dog, she was shy and cautious, but not aggressive like a wild canid when handled.

She refused dog food, but ate live rodents, barked like a dog and sometimes played with toys, but moved like a Pampas Fox. She died in 2023 of unknown causes, but scientists believe she may have been fertile. It is thought to be the first recorded instance of a fox and dog breeding, however the Pampas Fox is not a true fox. The typical Pampas Fox is yellowish-grey with lighter colour legs. The hybrid was dark with a small white patch on the chest. (Interestingly, the black colour in North American wolves came from domestic dogs.)

Genetic tests found the dogxim to have 76 chromosomes; a domestic dog has 78 (38 pairs) and Pampas Fox has 74 (37 pairs). A true fox e.g. Red Fox has 34 chromosomes (17 pairs) + some supernumerary “B chromosomes” and is genetically incompatible with dogs.

Hybridization between the Pampas Fox and domestic dog may have harmful effects on Pampas Fox populations due to the potential for introgression (dog genes entering the Pampas Fox gene pool) and disease transmission from dogs to the Pampas Fox population.

Szynwelski, B.E.; Kretschmer, R.; Matzenbacher, C.A.; Ferrari, F.; Alievi, M.M.; de Freitas, T.R.O. Hybridization in Canids - A Case Study of Pampas Fox (Lycalopex gymnocercus) and Domestic Dog (Canis lupus familiaris) Hybrid. Animals 2023, 13, 2505.

Coy-dogs (male coyote/female dog) have occurred e.g. a Coyote/Irish Setter mix (resembling a liver-coloured, spaniel-like dog) has been reported. Coydogs were once believed to be present in large numbers in Pennsylvania due to Coyotes being in decline and domestic dogs being available as mates. Most were probably naturally occurring red or blond Coyotes or feral dogs. The breeding cycles of dogs and coyotes are not synchronized and studies indicate that Coyote-Dog interbreeding is uncommon. If it such interbreeding was common, the Coyote population would acquire more and more dog-like traits.

The converse mating results in a Dogote and there is currently one known Dogote which arose from a male German Shepherd/female coyote mating in the wild. Hybrid pups were found after a female coyote was shot. The adult Dogote resembled a German Shepherd in colour.

Coyotes have also been crossed with Australian dingoes. This cross was made at a time the dingo was considered to be different species to the domestic dog.

The dingo has also been crossed with the wolf. According to Vol 1 of "Animal Life and the World of Nature" (1902-1903), Mr HC Brooke owned a female wolf which had become quite tame and was an excellent mother. This wolf was the mother of the wolf-dingo hybrid owned by Lord Walter Rothschild. The book also depicted a tame dingo owned and exhibited by Mrs HC Brooke, so it's likely that one of those dingoes was the sire of Lord Rothschild's hybrid. Dingo x Indian Wolf (C. pallipes, now considered a subspecies of Grey Wolf) have hybridised in captivity in Australia the 1930s

Dingo (C. familiaris dingo/C. lupus dingo, formerly C. dingo) breeds freely with the domestic dog. Dingo x New Guinea Singing Dog/New Guinea Highland Dog (C. familiaris dingo/C. lupus dingo, formerly C. hallstromi) breeds freely with the domestic dog. Dingo and New Guinea Singing Dog will also interbreed in captivity. Dingos and Singing Dogs exist in the wild and as semi-domesticated animals.

Coy-wolves (Coyote/Wolf) have occurred in captivity or, rarely, in the wild where the choice of same-species mates has been limited. Coyote/Red Wolf hybrids have been found. Some consider the American Red Wolf is not to a true species because it can hybridize with both the Grey Wolf and the Coyote; however it is now known that hybridization between species (in general) happens more often than previously thought. Some consider it a Grey Wolf/Coyote hybrid and use this argument to prevent conservation of the Red Wolf. Some hybridization occurred when pure Red Wolves were in decline and interbred with more numerous Coyotes. More recent studies in many mammals shows that true species can and do hybridize and that the species boundary is preserved by geographic or behavioural separation (wolves will kill coyotes), not by genetic separation.

Coywolf appearance depends on the proportions of Coyote and Wolf genes. The Texas Red Wolf species (C. rufus rufus) originated as hybrids between the Grey Wolf and Gregory's (or Mississippi Valley) Wolf (Canis rufus gregoryi); over a long period of time these gave rise to a consistent appearance.

Coyote Red Fox (Vulpes vulpes) in 1975, two male hybrid pups were born at Cohanzick Zoo (Connecticut), but died of maternal neglect after 3 days (though the mother may have neglected them due to abnormalities). The parents were familiar with each other from a young age.

The Wolf and Jackal (an African wild dog) can interbreed and produce fertile hybrid offspring. In Russia, Dog/Jackal hybrids were bred as sniffer dogs because Jackals have a superior sense of smell and Huskies are good cold climate dogs. Male Jackal pups had to be fostered on a Husky bitch in order to imprint the Jackals on dogs. Female Jackals accepted male Huskies more easily. The half-bred Jackal-Dogs were hard to train and were bred back to Huskies to produce quarter-bred hybrids (quadroons). These hybrids were small, agile, trainable and had excellent noses. They are called Sulimov Dogs after their creator and may one day be registered as a working breed of dog.

So-called Coywolves are living and evolving in forested areas of eastern North America, from Florida to Labrador. Scientists prefer the term Eastern Coyote. Because genetic tests in 2015 found them to be a mix of three species: predominantly coyote, but with a percentage of wolf and/or dog genes. The percentages vary depending on geographical location and on the sensitivity of the test used. Coyotes in the Northeast were 60%-84% coyote, 8%-25% wolf and 8%-11% dog. This mixture changes as you move south or east. In Virginia, these Coyotes are, on average, 85% coyote, 2% wolf and 13% dog. Those from the Deep South average 91% coyote, 4% wolf and 5% dog. None of the tested animals were purely coywolf, but a few were coydog with almost no distinguishable wolf genes. This means there is no coywolf species, but there are populations of coyotes with variable amounts of wolf and/or dog genes.

All Eastern Coyotes have evidence of past hybridization, but no evidence that they are still mating with dogs or wolves. Although genetically compatible, the three species only interbreed if they don t have a same-species mate available. When isolated from their own species, the reproductive drive is so strong that they will overcome natural enmity to mate with a related species. Outside of this situation, wolves and large dogs will kill coyotes, while wolves may also kill domestic dogs.

There s evidence of multiple hybridisation events in the three species. The gene for black coat colour in North American wolves and coyotes (and absent from European wolves) originated in dogs taken to the continent by prehistoric Native Americans. There was further hybridization in the 1800s when high demand for sled dogs meant that trappers and gold-miners used any suitably large dog for that purpose. Husky bitches on heat were sometimes tethered so that wolves would mate with them and produce offspring that were hardier than domestic dogs.

Around 100 years ago, wolf populations in the Great Lakes area were so low that wolves resorted to mating with coyotes. The hierarchical structure of wolf packs, where only the dominant pair breeds, means subordinate animals leave the pack in order to breed, and some evidently mated with coyotes. The estimated date of the most recent hybridization that created Eastern Ccoyotes was about 50 years ago with dogs. There are dark-coloured Eastern Coyotes in North Carolina resembling German Shepherd Dogs in colour and pattern. The colouration is believed to have entered the coyote gene pool around 50 years previously, although there have been deliberate German Shepherd/coyote hybrids in the last two decades, some of which were allegedly let loose into the wild due to their un-dog-like temperaments.

In the east, more recent coyote/dog hybridization has occurred at the leading edge of the coyote colonisation wave. Female coyotes reached upstate New York, where there were plenty of feral dogs, but no other coyotes. Modern Eastern Coyotes, and modern Great Lakes wolves, both have plenty of mates available these days and no longer interbreed. Coyotes also expanded north into Alaska, but there is currently no sign of hybridization in that range extension. In Central America, they have expanded from Mexico and into Central America. There are photographs of very dog-like coyotes at the southern edge of this coyote colonisation wave.

Hybridization across compatible species is a natural evolutionary phenomenon. It creates new genetic combinations, some of which have a survival advantage over the parent species. Wolf genes make the Eastern Coyotes a bit larger and more able to tackle the abundant deer in forested areas. It may make them more sociable and more likely to hunt in groups rather than pairs. Dog genes might make the coyote more bold and better able to survive in proximity to humans. It s possible that several distinct geographical varieties of Eastern Coyotes will arise, and if they don t interbreed they may evolve into separate species.

This extract from the "Book of The Dog" by William Youatt (1846) demonstrates nineteenth century beliefs about hybridisation between different species. It was known that a dog and wolf could be crossed and that the union would produce vicious mongrels, but there were claims of hybrids now known to be impossible: "There are some naturalists that even go so far as to state that the different varieties of dogs are sprung from, or compounded of, various animals, as the hyaena, jackal, wolf, and fox. The philosophic John Hunter commenced a series of experiments upon this interesting subject, and was forced to acknowledge that "the dog may be the wolf tamed, and the jackal may probably be the dog returned to his wild state. The ancient Cynegetical [dog] writers were not only acquainted with the cross between the wolf and dog, but also boasted the possession of breeds of animals, supposed to have been derived from a connection with the lion and tiger. The Hyrcanian dog, although savage and powerful beast, was rendered much more formidable in battle, or in conflict with other animals, by his fabled cross with the tiger. In corroboration of this singular, but not less fabulous belief, Pliny states that the inhabitants of India take pleasure in having dog bitches lined by the wild tigers, and to facilitate this union, they are in the habit of tieing them when in heat out in the woods, so that the male tigers may visit them."

In "Origin of Species" (1859) Charles Darwin wrote The German Spitz dog unites more easily than other dogs with foxes [...] certain South American indigenous domestic dogs do not readily cross with European dogs ..." and in "Darwinism An Exposition Of The Theory Of Natural Selection With Some Of Its Applications" (1889), Alfred Russel Wallace commented: "Dogs have been frequently crossed with wolves and with jackals, and their hybrid offspring have been found to be fertile _inter se_ to the third or fourth generation, and then usually to show some signs of sterility or of deterioration." (The deterioration was due to inbreeding among the hybrid offspring)

In "The Variation Of Animals And Plants Under Domestication" Charles Darwin wrote: "Buffon got four successive generations from the wolf and dog, and the mongrels were perfectly fertile together. [...] M. Flourens states positively as the result of his numerous experiments that hybrids from the wolf and dog, crossed inter se, become sterile at the third generation, and those from the jackal and dog at the fourth generation [attributed to inbreeding]. ('De la Longevite Humaine' par M. Flourens 1855 page 143. Mr. Blyth says ('Indian Sporting Review' volume 2 page 137) that he has seen in India several hybrids from the pariah-dog and jackal; and between one of these hybrids and a terrier. The experiments of Hunter on the jackal are well-known. See also Isid. Geoffroy St.-Hilaire, 'Hist. Nat. Gen.' tome 3 page 217, who speaks of the hybrid offspring of the jackal as perfectly fertile for three generations.) [...] Mr. Philip P. King, after ample opportunities of observation, informs me that the Dingo and European dogs often cross in Australia. [...] Several years ago I saw confined in the Zoological Gardens of London a female hybrid from an English dog and jackal, which even in this the first generation was so sterile that, as I was assured by her keeper, she did not fully exhibit her proper periods; but this case was certainly exceptional, as numerous instances have occurred of fertile hybrids from these two animals. [...] We have already seen how often savages cross their dogs with wild native species; and Pennant gives a curious account ('History of Quadrupeds' 1793 volume 1 page 238.) of the manner in which Fochabers, in Scotland, was stocked "with a multitude of curs of a most wolfish aspect" from a single hybrid-wolf brought into that district. [...] the jackal is prepotent over the dog, as is stated by Flourens, who made many crosses between these animals; and this was likewise the case with a hybrid which I once saw between a jackal and a terrier. "

Gray Fox (Urocyon cinereoargenteus) x Red Fox (Vulpes vulpes) a supposed wild-born hybrid was described in 1944, having black ears, feet, and stockings, the body of a Grey Fox, but the face and white-tipped tail of a Red Fox.

Indian/Bengal Fox (Vulpes bengalensis) x Red Fox (reported as Desert Fox V. leucopus) a supposed hybrid was shot in 1871 near Hyderabad.

Arctic Fox (V. lagopus) x Red Fox - sterile hybrids have been bred for the fur trade for decades using male Red Foxes and female Arctic Foxes, usually through artificial insemination. Female Arctic Foxes have larger litters, which is desirable to fur farmers. Although they are very pretty, hybrid foxes are uncommon in the exotic pet trade, being sterile and often aggressive. They are bred in a very wide range of colours, but it is sad that this is done on purely in order to kill them after a life in close confinement. There have been reports of hybrids in the wild, but the two species are natural enemies and the Red Fox often kills and eats the Arctic Fox. The Red Fox is moving into the Arctic Fox s range due to climate change and the species now come into regular contact. An Arctic-like fox displaying an unusual reddish winter coat was observed in 2013 in Nunavut, Canada, a colouration previously unknown by Inuit people, but genetic analysis found it to be a pure Arctic Fox.

Kit Fox (Vulpes macrotis) x Swift Fox (Vulpes velox) come into contact naturally and there is a hybrid zone in southeastern New Mexico and western Texas. Kit Fox x Red Fox. Three probable hybrids were found in western Texas in the 1970s.

Silver Fox (formerly V. fulva) x Red Fox. The Silver Fox, also known as the North American Red Fox and is no longer considered separate from the European Red Fox. However, female hybrids between the two races have been inseminated with Silver Fox semen have miscarried, but this may also have resulted from stress. The Silver Fox is a melanistic form of Red Fox, but tends to by ashy-grey rather than jet black. Red Fox x Silver fox matings produce offspring with a black dorsal stripe.

Cross Fox (formerly Canis/Vulpes decassatus) x Red Fox these were once considered separate species (and hunters sometimes still treat them as such), but the Cross Fox is a partially melanistic for of Red Fox, being black with a red dorsal stripe. It is more common than the Silver Fox and less common than the Red Fox. Intermediates occur between the 3 types and were formerly considered hybrids.

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