Bacterial Diseases of Dogs
Commonly seen bacterial diseases of dogs are salmonellosis, campylobacteriosis, brucellosis, leptospirosis, tetanus, etc.

Salmonellosis in Dogs
Salmonellosis is a bacterial disease that most commonly causes enteritis (inflammation of the intestines), septicemia (systemic disease due to the presence of bacteria or their toxin in the bloodstream) and abortions.
Salmonellosis in dogs is not uncommon for the infected individual to be a subclinical carrier, which is a carrier with no symptoms.
Salmonellosis is caused by any one of more than 2000 serotypes (subtypes) of the Salmonellae bacteria. It is seen in both dogs and cats.
In dogs, clinical disease is most commonly seen in immature puppies and pregnant bitches.
Diagnosis
- Complete blood count (CBC)
- Biochemical profile
- Urinalysis
- Fecal flotation
- Platelet count
- Screening thoracic (chest) and abdominal radiographs (X-rays)
- Fecal Culture
- Blood Culture
Treatment
Depending on the severity of clinical signs, treatment options may include out patient care or may necessitate hospitalization.
Affected individuals are contagious, and should be kept in isolation and handled carefully. Food restriction may be recommended for those patients with severe gastrointestinal signs.
Supportive care, to include fluid and electrolyte therapy, and/or intestinal adsorbents and protectants, may be indicated.
Antibiotic therapy may be indicated in certain cases, but contraindicated in others.
Campylobacteriosis in Dogs
Campylobacteriosis is a common cause of enteritis (intestinal inflammation) in man and several animal species, including dogs and cats.
The disorder is caused by a bacterium, Campylobacter jejuni.
The conditions associated with an increased risk of developing campylobacteriosis are:
- Animals with diarrhea
- Young animals
- Crowded housing conditions
- Poor sanitation
- Stressful conditions, such as pregnancy, surgery or other illness
- Concurrent infection with other intestinal pathogens such as parvovirus, Salmonella, Giardia or parasites.
Campylobacteriosis is a leading cause of intestinal disease in people. Puppies and kittens can serve as a source of infection for humans.
In many cases, dogs and cats are carriers of the organism, but show no clinical signs.
When clinical signs are present in dogs and cats, it is usually in animals younger than six months of age.
Diagnosis
- Microscopic examination of feces
- Culture
- Serology
Treatment
- Antibiotics
- Supportive care
Brucellosis in Dogs
Brucellosis in dogs is a contagious disease of dogs caused by Brucella canis, a small bacterial organism. It affects primarily the reproductive system.
The disease causes late abortions and infertility in bitches, and infertility, testicular and scrotal inflammation in males.
Brucellosis may also cause puppies to be stillborn or very weak at birth. Certain non reproductive signs may also develop. It occurs mainly in dogs and has not been reported in cats.
There is no evidence that some dog breeds are more susceptible that others, but there is a high prevalence in beagles.
Brucellosis is more common in sexually mature dogs, but can affect dogs of any age. Both males and females are affected, but it is more common in females.
Dogs from breeding kennels, pack hounds and stray dogs are most commonly affected, because of their increased risk of exposure.
Brucellosis is transmitted by contact with infected fluids (vaginal, preputial), especially during breeding or birth. Brucellosis may be transmitted from dogs to people.
Diagnosis
Brucellosis can be difficult to diagnosis in dogs. Confirmation of the disease may require several tests be performed, including the following:
- A complete blood count (CBC), biochemical profile and urinalysis are recommended in all animals suspected of having brucellosis, but they may be normal or show only vague changes.
- Serological blood tests that measure antibodies to the bacteria are the most frequent tests used to diagnose brucellosis.
- There are screening tests for Brucellosis that may be performed in your veterinarian’s office or local laboratory.
- If the screening tests are positive, then further specialized testing is required to confirm the diagnosis.
- Radio graphs (x-rays) of the spine may show changes in the vertebrae (spine) consistent with brucellosis.
- The organism may occasionally be cultured and isolated from blood cultures, vaginal fluid cultures, semen cultures or urine cultures.
- Negative cultures do not rule out the disease, however.
- Examination for semen quality may be helpful. Male dogs with brucellosis often have abnormal semen.
- Lymph node biopsy may confirm diagnosis, but it often requires special staining techniques to identify the organism.
Treatment
Because brucellosis can be transmitted from dogs to people, there is concern about whether all infected dogs should be treated. In some cases it may be preferable to euthanize the animal.
Treatment is not recommended for breeding animals, as it is unlikely that they will ever be fully cured and will continue to pass on the disease or will remain sterile.
When treatment is attempted, the goal of treatment is to eradicate B. canis from the patient, but this can be difficult to accomplish.
Any intact dogs are spayed or castrated. Medical treatment is often begun as an outpatient, although some of the antibiotics used for the disease must be given as injections.
A combination of two antibiotics are often administered. Choices include tetracycline, minocycline and doxycycline given with one of the aminoglycoside antibiotics, such as gentamicin.
The antibiotics are usually administered for about four weeks and may need to be repeated at various time intervals for several months.
Leptospirosis in Dogs
Leptospirosis is a zoonotic disease that can pass from animals to humans. It is a bacterial disease that damages the liver and kidneys of dogs, sometimes resulting in renal failure and death.
It is caused by a spirochete (spiral shaped bacterium) called a leptospire. Leptospires live in fluids from infected animals, including urine, saliva, blood and milk.
The disease is transmitted by direct contact with the fluids or with an infected animal.
It is also transmitted by indirect contact such as vegetation, food and water, soil and bedding materials.
Leptospires enter the body through mucous membranes or through breaks in the skin.
The disease may be carried for years in animals without any apparent symptoms of the disease.
Any age, breed or sex of dog is susceptible to leptospirosis, although in general, young animals are more severely affected than adults.
Large breed outdoor adult dogs are most commonly affected.
Leptospirosis can cause irreversible kidney damage, liver damage, uveitis (inflammation of the inner part of the eye), and damage to other organs.
Diagnosis
- Veterinarian need to do a complete review of history and physical exam findings to develop a list of possible causes for your dog’s illness.
- In order to make a definitive diagnosis of Leptospirosis, however, various diagnostic tests may be recommended.
- Leptospirosis test: A microscopic agglutination test (MAT) is the most frequently used serological test for Leptospirosis.
- It evaluates the presence of serum antibodies to Leptospirosis antigens.
- General blood and urine tests.
- Kidney biopsy.
Treatment
If the disease is caught in time, it can usually be treated successfully with penicillin and tetracycline drugs.
However, those with renal failure may or may not recover, or may recover only partial renal function. Animals with acute renal failure should be treated with appropriate fluid therapy.
Tetanus in Dogs
Tetanus is a highly fatal disease that affects the nervous system of all animals. It is caused by the neurotoxin Clostridium tetani, a bacteria found in the soil and in the intestinal tracts of animals and people.
Wound contamination is the most common way that people and animals become afflicted with tetanus.
Tetanus is very rare in dogs, and dogs have been shown to be quite resistant to the toxin. Rare cases usually affect dogs with injuries around the mouth or pups that are teething.
Horses and people are much more sensitive to the tetanus toxin, so for these species, vaccinations are recommended.
However, the potential risks inherent in the vaccine, such as allergic reaction, along with their normal resistance to the toxin, make this vaccine rarely given in dogs and cats.
Clinical Signs
Clinical signs include limb stiffness and difficulty walking. Spasms of the facial muscles cause abnormally erect ears and retraction of the lips that resembles “risus sardonicus” seen in humans with tetanus.
Dogs can’t eat or swallow, and as a result, often develop pneumonia.
Thorough cleaning of wounds and appropriate use of antibiotics is generally effective in allowing a dog’s wound to heal.
Treatment
There is not treatment available for tetanus in dogs or other species. But prevention can be done by active anti toxin.