Several bacteria of the salmonella species are capable of producing acute infectious diarrhea in dogs. Salmonella remain alive for many months or years in soil and manure. In dogs, the disease is acquired by consuming raw or commercially contaminated foods, by eating animal manure, or by making oral contact with surfaces that have been contaminated by the diarrhea of an infected dog. This bacterial infection is a risk in dogs fed a raw diet, unless excellent food-handling hygiene is practiced at all times.
Puppies and young adults are most susceptible, as are dogs whose natural resistance has been compromised by a viral infection, malnutrition, parasites, or being housed in crowded, unsanitary quarters.
Signs of illness include fever, vomiting, and diarrhea. The stool may be bloody and foul smelling. Dehydration develops when vomiting and diarrhea are prolonged. Bacteria in the bloodstream can cause abscesses in the liver, kidneys, uterus, and lungs. The acute illness, which lasts four to ten days, may be followed by a chronic diarrhea that persists for more than a month. Dogs with chronic diarrhea shed salmonella in their feces and are a potential source of infection to other animals and humans.
The diagnosis is made by identifying salmonella bacteria in stool cultures when the dog is in the carrier state, or in the feces, blood, and infected tissues of dogs suffering from acute infection.
Treatment: Mild cases respond well to fluid replacement. Many salmonella species are resistant to common antibiotics. In fact, antibiotics can favor the growth of resistant bacteria and prolong fecal shedding of bacteria. Accordingly, antibiotics are used only for seriously ill dogs. Sulfa drugs and the quinolones are the antibiotics of choice.
Public health considerations: Salmonellosis is a zoonotic disease, so care must be taken to practice excellent hygiene when dealing with a dog with salmonellosis. It is important to wear gloves when cleaning up feces and to disinfect areas where an affected dog has eliminated.