Giardia, Clostridium perfringens enterotoxin, and Cryptosporidium are important causes of diarrhea in dogs and cats. Tritrichomonas foetus is an important problem in cats. These disorders should be investigated early in the course of diarrhea, whether it is persistent or intermittent, along with evaluation for dietary causes of GI signs, nematode parasites, bacterial and viral causes, and acute idiopathic colitis.
Vomiting is among the most common reasons that dogs and cats are presented for evaluation. Because there are a multitude of causes of vomiting, ranging from simple to complex, this can be a challenging problem for clinicians to accurately diagnose and manage.
Dysphagia is defined as difficult or painful swallowing. It may be due to obstruction, motility disturbance, or pain. Although dysphagia most commonly indicates a disorder involving the oral cavity or pharynx, esophageal disorders can cause this clinical sign as well.
Disease caused by parvovirus in dogs (destruction of intestinal crypt epithelium, lymphocyte depletion, neutropenia) is generally more severe than that caused by coronavirus (destruction of intestinal villi).
It is important that the clinician formulate a treatment protocol based on a correlation of clinical course, laboratory and gross findings, and histologic findings rather than relying on histologic changes alone.