Urban Jungle | South China Morning Post

This week: Foreign bodies and I don't mean UFOs!

It has always surprised me the stuff that dogs, and less often cats, swallow. It is not only food, but often stuff that they just don't digest. We call these things in the veterinary world 'foreign bodies' and when it is stuck in the gastrointestinal tract we call it an intestinal foreign body. Foreign bodies occur much more often in animals than they do in humans due to your pets' often non-discriminatory tastes and insatiable curiosity.

The things that result in intestinal foreign bodies are quite surprising and is almost limited only by your imagination. In my experience, the most common cause of foreign bodies in Hong Kong are corn cobs. Dogs love to chew the sweetcorn on the cob and once it gets to a certain size the dog then attempts to swallow the remaining cob. The cob's rough outer surface makes it very easy to get stuck in the small intestine of the dog.

The most common sign of a foreign body, such as a corn cob, is vomiting. Sometimes it is severe and the dog even vomits up water, but sometimes vomiting is very intermittent and other food eaten is able to bypass the foreign body and get defecated. I remember a case where I removed surgically a durian seed from the small intestines of a dog. The seed had been there for six months before it caused any detectable trouble.

The most common diagnostic tool for foreign bodies is the humble x-ray. We use it not only to diagnose the problem but also see where the foreign body is stuck so we know where to perform surgery if needed or at least monitor its progress through the intestinal tract. But little do most people know, not all things turn up on x-rays. There are things that are what we call radiolucent - which means x-rays go straight through radiolucent things, like plastics and durian seeds, as if they don't exist. These radiolucent things are harder to diagnose as a result. We often employ a radiopaque dye which we get the dog to swallow and then see where the dye gets stuck to pinpoint the foreign body's location.

One of the most memorable and sad stories is that of a miniature schnauzer brought to me because it was vomiting. The owner told me she had witnessed the dog eat not one, but two, of her boots, laces and all! I was shocked and asked why she didn't bring the dog in immediately. She said: 'She seemed fine and was quiet, unlike her usual hyperactive self. She was rather cute.'

I was left stupefied with her blatant naivete. I had a moment of anger at her stupidity, but I got on with treating the problem. I could feel the boot when examining the abdomen and on the x-rays I could clearly see the heel of a boot in the dog's rectum. An emergency exploratory laparotomy was necessary, which means I had to surgically open the dog's abdomen to get a better understanding of the problem. I found the heel of both boots in the rectum and the pointy metal tip of both boots in the stomach and in between threaded throughout the whole length of the intestine was the leather lace portion of the boot and the body of the boot.

It was hopeless. Despite a marathon five hour surgery, we had to open the intestine in more than places to get the shoe piece by piece out of the gut. The dog died during the suturing process.

Not all stories are as sad and require surgery. I remember a very happy and active Golden Retriever swallowed about a metre of Christmas tree lights on Christmas day a few years ago. We took x-rays and because the Christmas lights and the wire in between the lights were made of metal, and metal turns out very opaque like bone on x-rays, the x-rays were very festive and it looked as if we lit the Christmas lights inside the dog. As the dog wasn't sick, we were able to observe the dog to see if he could past the Christmas lights out on its own. After 24 hours of waiting the owner called me up to say that he was able to excrete the lights on Boxing Day.

Another funny story was a Doberman that ate a pepper shaker. The owner during dinner dropped the pepper shaker on the floor, the greedy dog then promptly swallows the whole thing. I got a call during the night and I told the client to observe the dog for a day or two to see if it passed through the animal naturally. I got a call from a happy owner the next morning, thanking me for telling him to observe and, hence, saving him an emergency fee. But while he was on the phone, the dog ate the pepper shaker again! I told him to keep an eye on the dog again and it turned out fine again. I told the owner to throw away the pepper shaker and to hide the salt shaker.

Other intestinal foreign bodies I have found include screwdrivers, live ammunition, glass bottles, office stationary, plastic toys, stones, large amounts of sand, an iPod, watches, billiard balls and an unopened can of soft drink. So the next time you can't find your keys, they could be inside your dog.

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