Vomiting is the forceful ejection of stomach and proximal duodenal contents through the mouth. Vomiting can be induced by vestibular, vagal, chemoreceptor trigger zone, or direct input to the emetic center. Diarrhea is a characterized by increased frequency of defecation, increased fluid content of the stool, or increased volume of stool.
The 2 major differentials for elevated body temperature (> 102.5 F) are fever (pyrexia) and hyperthermia. Hyperthermia results from increased muscle activity, increased environmental temperature, or increased metabolic rate (i.e. hyperthyroidism). Fever develops when the thermoregulatory set point in the hypothalamus is increased, resulting in increased body temperature from physiologic mechanisms inducing endogenous heat production or heat conservation.
Herpesvirus 1 (rhinotracheitis; FHV-1) and calicivirus (FCV) are the most common viral causes of sneezing and nasal discharge in the cat. If oral ulcers are present, calicivirus is most likely. If corneal ulcers are present, herpesvirus 1 is most likely. FHV-1 has now also been associated with chronic stomatitis, facial dermatitis, and endogenous uveitis. Viral rhinitis with or without secondary bacterial infection can be recurrent.