I realise that some people pay good money to be peed on, but it's never appealed me and I certainly didn't enjoy being peed on, while sleeping, by a medicated hyperthyroid moggy protesting against weeks of house-arrest. In fact typing this, almost a year later, brings back memories of fresh cat pee.

One night, my dream of sugar plum fairies suddenly became a dream of paddling in warm tropical seas vivid enough to wake me. As I surfaced from sleep, the warm wet sensation remained. Thenie, unable to go outdoors and duff up the tabby intruder in the garden, had dumped a bladder-load of warm pee where my feet were.

"Grrrr whaddaya do thatfer?" I mumbled.

Thenie sat on the windowsill looking inscrutable. The bedclothes got flung in the washing machine, and the affected part of the duvet was washed in situ and dried with a hairdryer. The offending black, fluffy feline was shut out of the bedroom while I snatched a few hours sleep on the dry side of the bed. Next morning, I wandered barefoot downstairs to feed her and found the living room rug distressingly wet in one corner. The phantom rug-tiddler had struck once more. By a process of elimination – Thenie and I were the only ones in the house and domestic waterworks and my waterworks were not to blame – I narrowed the list of suspects down to one.

"She's normally clean indoors?" asked the vet after Thenie's blood sample was taken.

"Fastidiously. I keep the litter tray so clean I could eat from it," I replied, "Could it be a side effect of the thyroid tablets?"

"I've not heard of it being a side-effect; it sounds more like stress," he says, "I take it you're not letting her out at the moment?"

"She tends to go off on 2 day hunting trips in the local woodland and she'd miss her medication so I've got her under house arrest."

"Sure. Hopefully her T4 count will be down low enough for us to do surgery."

For the next few nights, Thenie behaved impeccably and was allowed back on the bed. Unfortunately her T4 count hadn't gone down which meant 2 more weeks of Al-cat-traz and tablets. One night, I dreamt I was in Thailand in monsoon season without a brolly. Thenie had surpassed herself and peed on my head. Luckily, a effect of her condition or medication was very dilute, nearly odourless pee. Unluckily, there was a lot of it, most of which was absorbed by the pillows (thankfully washable) while the rest was absorbed by my hair. Though also washable, the latter had been freshly cut and styled that morning. Perhaps Thenie hadn't like the new style?

Over the next two weeks the sheepskin rug was washed twice and finally hidden in the cupboard. Sure, Thenie used the litter trays, but she couldn't stage a good protest by using a litter tray. A good protest required carefully placed puddles right where I'd tread in them..

"Her count still isn't down," the vet said glumly at the next consultation, sensing he had a very stressed owner in the room. "Can you cope with another 2 weeks of medication?"

"I can, but my furnishings can't"

"Aah, she's still stressed out?"

"To be honest, I'm not sure which of us is more stressed right now. I'm not willing to live in a house that's starting to stink of cat pee. It's getting harder to tablet her as she's no longer ravenously hungry."

"The tablets are very obviously doing their job, but her T4 just isn't going down. Can you cope with giving tablets more frequently and we'll do the surgery regardless in 2 week's time regardless?"

Thenie adopted a rapt expression and emptied her bladder on the consulting table. How could a medium-sized moggy hold so much pee? I'd seen horses produce less.

"I think we'll take that as a yes," said the vet, calling for a mop.

Around 2 a.m that night I was woken by a furry lump sitting on my head. Aaah, I thought, Thenie is snuggling up on the pillow like she used to do when all three mogs slept with me on cold nights. Sadly I was wrong. My head was abruptly drenched with pee in a re-run of previous events and Thenie was banned from the bedroom.

The vet was as good as his word and, though her T4 count wasn't ideal, Thenie went in for surgery. It was a difficult time as I'd recently lost hyperthyroid Cindy during emergency surgery to remove a damaged eye and Motley had succumbed to a brain tumour. Around 4 o'clock the vet surgery phoned me. My heart sank – for them to call me meant there was a problem.

"Mrs Hartwell? Is there any chance you can come and collect Thenie?"

"Aaah, couldn't she have surgery?" Was I facing more weeks of soggy rugs and drenched duvets?

"The surgery went fine. She was up on her feet within 10 minutes and is obviously desperate to go home."

Though Thenie seemed oblivious to her serious operation, there was an important difference in her demeanour. She was far more relaxed and only peed in her litter tray. She was allowed back in the bedroom. After several weeks to allow the fur to re-grow, she returned to hunting pigeons and getting on top of a mouse population that had exploded during her several months' incarceration.