Salmonella bacteria are responsible for a spectrum of maladies ranging from uncomplicated intestinal disease and diarrhea, to life-threatening systemic illness. Clinical salmonellosis in cats is relatively uncommon and few references to it exist in the scientific literature. Stray cats, shelter cats, and hunter cats are more likely to be carriers and to be excreting salmonellae in feces than are housebound pet cats. Cats appear to be highly resistant to salmonella infection unless they are stressed by overcrowding, dietary changes, transport, hospitalization, antimicrobial therapy, or concurrent illness at the time of salmonella exposure. Contamination can arise from rodent or bird feces, raw or undercooked or contaminated meat and table scraps, or commercially prepared foods that are contaminated during processing.
Cats usually acquire salmonellosis by ingestion.
Once ingested, the bacteria can cause a spectrum of clinical signs. Salmonellae that survive the acidity of the stomach go on to invade the small intestine and local lymph nodes. From this point, the bacteria either are contained by the body's defenses or proceed to invade the bloodstream, from which they reach other tissues such as the liver and spleen. Because of their fastidious grooming habits, infected cats quickly contaminate their fur and environment with salmonellae. Clinically ill animals often shed large numbers of bacteria in feces and sometimes in saliva.