This week I had one of those emergency callouts that reminded me of my first year in veterinary practice. The caller told me that her puppy had stolen a foil of human prescription drugs and had managed to tear through the tiny blisters to swallow half the contents.

I advised her to meet me at the clinic immediately and half an hour later I was introduced to a bouncy seven-month old white and tan female King Charles Cavalier spaniel named Ellie. Although Ellie’s clinical signs seemed normal, it was still well under an hour since she had swallowed the tablets and the only safe option was to give her apomorphine.

Apomorphine is a derivative of the more famous cousin morphine and it is specifically used in dogs as an elective emetic drug. Emetic drugs are typically used in emergency situations to treat poisoning by food, plants, drugs or toxins that have been taken orally – through the mouth.

They are effective when administered during the early stages of the poisoning, usually within the first four hours, and they typically remove around 40 to 60 per cent of the stomach contents. The most effective emetic drugs are those that stimulate the vomiting centre in the brain, and apomorphine is just such a drug.

The body of many animals has been designed to survive by vomiting. Cats, for example, vomit on a regular basis to rid their stomachs of hairballs. Dogs, on the other hand, being inherently voracious eaters of anything that can be eaten as well as much that shouldn’t, vomit as a reaction against harmful substances.

The most effective emetic drugs are those that stimulate the vomiting centre in the brain

Unfortunately, not all harmful substances consumed will induce natural vomiting and when they happen to be toxic, the only way to save the animal is to artificially induce vomiting. And this is what apomorphine does.

The use of the drug apomorphine is usually restricted to dogs. Cats do not react well to the drug since it can stress them out. Rabbits and rodents also cannot take apomorphine since these species lack the ability to vomit effectively. In dogs, however, the drug is extremely efficient and can be administered in several ways.

The most common form of administration of apomorphine, and the technique that produces the fastest reaction, is by intravenous injection. This produces a reaction within a couple of minutes, sometimes less. The drug can also be administered by injection into the muscle or under the skin and produces a reaction within five or more minutes. The least effective method is when apomorphine is administered orally in the form of tablets since it is poorly absorbed by the body. This method is unlikely to be used to treat an emergency.

Curiously, the drug can also be administered topically through the eye mucosa with a soluble tablet that is placed directly onto the eye. The medication is absorbed into the body through the fine film that coats the eye and vomiting usually happens after about 10 minutes, whereupon the eye is flushed clean to remove any residual drug.

This method is less reliable than the intravenous or intramuscular approach, but can still be useful depending upon the circumstances of the case.  Indeed, it was just such a case that reminded me of my first year in practice when a dog was brought into the 24 hour emergency clinic. Just like this week’s case, the dog had ingested prescription drugs and had to be given apomorphine.

The only form of apomorphine that I had available was the tablet form. I ground the tablet and with the addition of a couple of drops of sterile water I administered the drug onto the dog’s eyeball. After about 10 minutes watching the dog with nil output, the owner asked whether the drug was ever going to work when the dog suddenly and copiously vomited all over him.

Whichever method is used, apomorphine behaves by stimulating the specific receptors within the brain that induce vomiting. This form of stimulation may sound alarming, but the fact is that although the act of vomiting is an inherently physical reaction, the impulse to vomit originates in the brain.

Apomorphine is a very strong drug which should only be used in dogs by and on the recommendation of the veterinarian. If you find or suspect that your pet has eaten anything potentially harmful, contact your veterinarian immediately. Depending on the history, when and what was ingested, and taking into account the clinical condition of your dog, apomorphine may be the right choice.

Ellie was given apomorphine intravenously. Within a couple of minutes she quietened down and her face looked decidedly worried. Her breathing quickened and she started to gulp. Ellie was feeling nauseous. Sure enough, she suddenly started to heave and vomited three times. The apomorphine had worked.

Dr Martin Debattista is a veterinary surgeon.

thisweekwiththevet@gmail.com

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