The Yorkshire Vet Julian Norton finds the cause of Charlie the Spaniel's illness - a potato

Tests were required to find out what was going on. He’d had plenty of medication to help his pain but the distended stomach, clearly visible on the radiograph, demanded immediate exploratory surgery.

An exploratory laparotomy – an operation to look inside the abdomen– is often necessary to achieve a definitive diagnosis and is always exciting.

There is no substitute for actually seeing the contents of the abdomen, feeling along the intestines and examining the liver and spleen in real life, rather than the

two-dimensional, grey and white shades of a scan or X-ray.

And this proved to be exactly the case for Charlie.

There, in front of us, was the answer. In his duodenum, directly opposite the pancreas, there was a large ovoid object causing a complete blockage.

It was solid and smooth like a pebble but had been invisible on the X-rays.

Was it rubbery? Maybe. Anne, who was holding the scalpel, and I could only guess what it might be.

Anne’s sharp incision allowed the foreign body to bulge out through the intestinal wall, emerging like a new-born baby with a plop into my waiting fingers.

Neither of us had seen anything like it before. Well, we had. But not inside a dog.

“It’s a potato,” we exclaimed in unison as the smooth, boiled spud appeared. In other circumstances it would have looked delicious, but not now.

By some potato miracle it had been swallowed whole. The vegetable had avoided any form of digestion and become stuck in the intestine.

It reminded me of a similar incident a couple of years ago.

I had been treating a heifer that had been grazing along the banks of the Swale all summer. The pneumonic signs she had been suffering had not improved with my injections and frothy fluid continued to emerge from her nose and mouth.

She died the day after and the farmer and I decided a postmortem was required.

When the report came back I called the farmer with the unusual and unexpected diagnosis: a potato had lodged in the lower part

of the chest. The farmer was totally amazed at this, exclaiming, just like Anne: “A potato?” I confirmed the laboratory diagnosis and the vegetable.

“But we don’t feed our cows potatoes,” the farmer protested, emphasising potatoes just as forcefully.

“Well apparently there was one stuck inside your heifer,” I said again.

“Wait a minute,” came a more considered response after a short pause. “These cattle have been grazing along the river. There’s a chance these potatoes [he didn’t shout it so loudly this time] could have washed up in the floodwater.”

It was definitely a possibility. Grazing beside a river prone to flooding is fraught with problems like this.

He went on in a much more pragmatic tone: “I bet that’s what’s happened. Well, it’s a relief because that’s just one of those things, isn’t it? Nothing else could have been done.”

But with Charlie there was little chance he had swallowed a washed-up potato from the river, because this one was scrubbed and boiled.

After the op, Anne and I drew straws to decide who would phone the owner. I won and made the call. As I explained the findings, two words came booming back down the line: “A potato?”