When are antibiotics necessary for animals, and how do you cope with the side effects

Q&A with Dr. Erika Sullivan, Because Animal’s Chief Veterinary Officer.

The prescription of antibiotics are a mainstay in the treatment of dogs and cats in Western medicine. But that doesn’t mean they are without risk. Here, we ask Dr. Erika more about antibiotics for our pets.


When are antibiotics prescribed?

Just like in human medicine, veterinary practitioners are warned about prudent antibiotic use – meaning prescribing them only when necessary. The unnecessary prescription of antibiotics for viral diseases – which antibiotics don't treat – or without a proper diagnosis can ultimately lead to more antibiotic resistance in patients in the future.

Are there side effects of antibiotics?

Many antibiotics come with side effects. Some cause gastrointestinal upset, like vomiting or diarrhea.

There are normal, healthy, and even essential bacteria that live in the gastrointestinal tracts of all of us. And, depending on the species, different bacteria are necessary for health and wellbeing. For example, giving oral penicillins to a dog or cat may be fine for that species, whereas oral penicillins can kill the natural microbes in a rabbit's intestinal tract and lead to dysbiosis and death. For that reason, it is critical that the correct antibiotic is prescribed for the correct pet.

As well, just like in humans, pets are individuals and there is a chance they could have an allergic reaction to a particular antibiotic. This unfortunately cannot often be predicted, so it is important that pet parents and veterinarians are aware of any abnormal reactions that occur in a pet after administration of a given antibiotic.

Are there things I can do to avoid side effects of antibiotics for my pet?

It is not uncommon to prescribe probiotics, which are essentially a healthy dose of "good" bacteria. Probiotics function by repopulating the gastrointestinal tract with healthy bacteria after treatment with antibiotics (where antibiotics kill both "good" and "bad" bacteria). Adding probiotics to your pet's food can hasten any unwanted side effects from antibiotics, especially when a patient needs to be on them for extended periods of time.

Probiotics are also advantageous for juvenile animals, like puppies and kittens, whose bacterial flora in their intestinal tract is not yet fully developed.

If you know your pet is sensitive to antibiotics, it is also important to tell this to your veterinarian as there are many different types of antibiotics and some are more "gut-friendly" than others.

Likewise, sometimes dietary changes alone can curb unwanted responses to antibiotics, by providing naturally digestible ingredients that are easy for the gastrointestinal tract to process and assimilate.

Just as humans, many cats and dogs are intolerant to dairy as they also don't have natural enzymes to digest milk. Because of this, I always advise a non-dairy probiotic.

A proper prescription (for the species and illness being treated), any known intolerances, easy-to-digest foods, and probiotics are all key to avoiding unnecessary and unwanted side effects of antibiotics.


Dr. Erika, also known as The Globetrotting Veterinarian, graduated from the Ontario Veterinary College, where she led a successful campaign to end the euthanasia of animals used in surgical training. Erika makes routine visits to Thailand where she treats disabled elephants; leads a yearly spay-neuter clinic in India; and is a PADI Open Water Scuba Diving Instructor, which allows her to better promote the protection of marine life. She currently lives in Adelaide, Australia, where she works at a vet clinic that sees tropical birds as some of her patients, a few of which she brings home!