What are the most common reasons for diarrhea in dogs and cats?

Again, I refer to something Vets and Vet Techs refer to as “Signalment”, the age, breed, and sex of the patient.

For example:

If an owner brings an intact 14-week-old female Mixed Breed Terrier who was recently found at a park and subsequently rescued, but has explosive diarrhea and is beginning to vomit. I am going to consider Gastrointestinal Parasites a strong possibility for the diarrhea. Also, with likely no vaccines on board, I am also going to be concerned about Parvovirus. The sketchy history, possible exposure, and young age all contribute to why it is important to rule out Parvovirus and Gastrointestinal parasites.

If an 8-year-old female, spayed Domestic Shorthair cat comes in with a history of diarrhea, chronic vomiting, and weight loss I would rule out GI parasites as a cause, but I would be inclined to look for other causes such as Hyperthyroidism, Inflammatory Gastrointestinal Disease, or possibly Cancer along with some other GI issues.

However, with any diarrhea in a cat or dog, it is important to rule out the common, easy things such as sensitivity to a diet regimen or Gastrointestinal Parasites. With any animal ailment, it is always important to remember that common things happen commonly.

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