At six years old Marcus is still a young cat. If you saw him chasing the leaves in the sunshine today you would hardly think he had grown out of being a kitten, yet earlier this year it was a very different story.

Back in February he started to cough one day. He had not been away from home and there were no other cats in the household. He could have met a strange cat in the garden but this was hardly a regular occurrence where he lived and he was fully vaccinated, which would protect him from cat flu.

He did not look ill and continued to eat well, but he coughed several times a day. Over the next few days he coughed for longer and seemed less happy. Sometimes he would cough for a minute and a half as if he really had something stuck, so his owner brought him along to the surgery.

He did not actually cough when I examined him, though his chest was definitely wheezy. His temperature was normal and his eyes were bright and his nose clear. Although it seemed possible he had a chest infection, I was quite unsure what exactly was causing the cough.

In consultation with his owners I decided it was time to do some further investigations, so I admitted Marcus to my hospital for some tests next day.

By the next morning he seemed less wheezy, though only later did I realise why. Under an anaesthetic I took x-rays of Marcus' chest and looked down his throat and windpipe with an endoscope. I also took a sample of his blood and washed a sample of cells from deep in his lung with a few drops of saline.

I could not see any sign of a growth or a foreign body and there was no pus to suggest an infection.

The next day I got the report on his blood test and the fluid from his lung. At last I had an answer. The fluid in his lung was filled with tiny allergy cells. Marcus had asthma - an allergy to something he breathed in.

There were even signs of allergy in his blood. With a clear diagnosis Marcus began taking tablets to control his allergy. It was only some months later that his owner realised that all his problems had started after she bought a duck-down cushion that he took to sleeping on.

Now that Marcus is kept away from anything with feathers in he needs fewer tablets and is well again.

Converted for the new archive on 30 June 2000. Some images and formatting may have been lost in the conversion.