Common Bacterial Diseases in Dogs
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.
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.
Bordetella bronchiseptica bacteria are frequently found in dogs with the kennel cough complex and other respiratory diseases. Signs of upper respiratory illness caused by bordetella include a dry, hacking cough accompanied by a clear nasal or eye discharge. In puppies and immune-compromised adult animals, secondary bacterial invasion of the lower respiratory tract following viral illness may cause life-threatening pneumonia. Dogs who are carrying the organism and may not even be ill themselves, may still cough or exhale the organism into the air. Healthy dogs can then be infected by breathing in that contaminated air.
The bacteria can be cultured from nasal swabs or transtracheal washings.
Treatment: Treat all upper respiratory infections by placing the animal in a warm, draft-free environment, humidifying the atmosphere, and avoiding stressful activities that can interfere with a smooth recovery. Antibiotics are indicated if the dog develops fever and a mucopurulent nasal discharge. Antibiotics are also indicated for all cases of upper respiratory infection in which bordetella is isolated. Antibiotics given by nebulizer may be more effective than those given orally or by injection. This is because the bacteria attach to the mucosal surface of the respiratory tract and are difficult to reach with systemic antibiotics.
Prevention: Bordetella vaccinations are not routine, but may be advisable for show dogs, boarded dogs, dogs who go to grooming salons or obedience classes, and dogs who live in kennels.
Campylobacteriosis is a disease that produces acute infectious diarrhea in puppies. It also occurs in kennel dogs and strays-most of whom are in poor condition and are suffering from other intestinal infections.
The bacteria is acquired by contact with contaminated food, water, uncooked poultry or beef, and animal feces. Campylobacteria can survive for up to five weeks in water or unpasteurized milk.
The incubation period is one to seven days. Signs of acute infection include vomiting and a watery diarrhea that contains mucus and sometimes blood. The disease usually runs its course in five to fifteen days, but may be followed by chronic diarrhea in which bacteria is shed in the feces.
Treatment: Treat mild diarrhea. Keep the dog warm, dry, and in a stress-free environment. More severely affected dogs will require veterinary management with intravenous fluids to correct dehydration. Antibiotics may be advisable. Erythromycin and ciprofloxin are the drugs of choice.
Public health considerations:Campylobacteriosis is a common cause of diarrhea in humans. Most human cases arise from contact with newly acquired kittens and puppies who are suffering from diarrhea. Parents should be aware that puppies with diarrhea may harbor a human pathogen. Good hygiene is essential, especially for young children and people who are immunocompromised.
Coliobacillosis (E. Coli)
Coliobacillosis is an infectious diarrhea caused by the bacteria E. coli. There are some strains of E. coli that are not part of the normal intestinal flora. When ingested, these strains are capable of producing acute diarrhea. E. coli can be acquired from infected drinking water, food, or fecal matter. This bacterial infection is a risk in dogs fed a raw diet, unless excellent food-handling hygiene is practiced at all times.
This article is excerpted from “Dog Owner’s Home Veterinary Handbook” with permission from Wiley Publishing, Inc.
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