Brucellosis in Dogs: Symptoms, Causes and Treatment

What is Brucellosis in Dogs?

Brucellosis is a bacterial infection that can affect dogs and various other animals, as well as humans. It is caused by bacteria of the genus Brucella, with Brucella canis being the primary species involved in canine brucellosis.

Dogs typically contract brucellosis through contact with infected animals or their bodily fluids, such as urine, blood, or reproductive secretions. The bacteria can be transmitted through breeding, consumption of contaminated materials, or direct contact with infected tissues. The infection can also be passed from an infected mother to her puppies during birth or through nursing.

What are the Symptoms of Brucellosis in Dogs?

Brucellosis is a bacterial infection that can affect various animals, including dogs. It is caused by the bacteria Brucella canis and is typically transmitted through contact with infected reproductive fluids or tissues. The symptoms of brucellosis in dogs can vary but may include:

• One of the most common signs of brucellosis in breeding dogs is infertility, both in males and females. It can lead to difficulty conceiving, failure to conceive, or spontaneous abortions.
• Male dogs may develop inflammation of the testicles or scrotum, leading to pain, swelling, and discomfort.
• Infected female dogs may exhibit abnormal vaginal discharge, which can be intermittent or persistent. The discharge may be bloody, pus-like, or have a foul odor.
• Some dogs may experience back pain due to infection spreading to the spine, resulting in inflammation of the spinal discs.
• Dogs with brucellosis may have swollen lymph nodes, particularly in the groin area or around the reproductive organs, although fever is uncommon, may appear lethargic, depressed, or show a decreased interest in usual activities, accompanied by a decrease in appetite.
• In some cases, brucellosis can lead to joint inflammation (arthritis) and lameness, with dogs exhibiting difficulty in moving or stiffness.

Other Animals at Risk of Infection with Brucella Canis B. 

Canis B seems well adapted to causing disease in canines (i.e. dogs and other similar species such as foxes and wolves) and is not very effective at causing disease in other species. Apart from in people, disease in other animals is exceptionally rare. Cats have been reported to produce antibodies to B. canis but no disease in cats due to B. canis has been reported. Other UK-living species, for example, horses, pigs, cows, sheep, goats, and birds appear resistant to infection. Testing of non-canine animals is not recommended. The exception to this might be testing of other mammalian carnivores if there has been significant high exposure, for example, contact with birth or abortion products. 

How Common is Brucellosis?

Until very recently the UK has been free from Brucella canis but, unfortunately, it’s endemic (common) in certain parts of Eastern Europe, Asia, Africa and the Americas. Although case numbers are still low in the UK, since 2020 there has been a significant increase in reported cases due to the rise in dogs being imported into the UK, and pet dogs travelling out of the UK with their owners.

What Causes Brucellosis in Dogs?

Brucellosis in dogs is caused by a bacterial infection with the organism Brucella canis. It is primarily transmitted through direct contact with infected animals or through contact with their reproductive fluids (such as urine, vaginal discharge, semen, and aborted fetuses). 

• Contact with infected dogs
• Infected males can transmit the bacteria to females during mating, and infected females can transmit the
• Infection to males.
• Sniff or lick the genitals of infected dogs, especially females in season.
• Occur through the placenta, as well as during birth or through nursing.

How to Test for Brucellosis in Dogs？

Testing for brucellosis in dogs typically involves a combination of blood tests and specialized laboratory procedures. 
After a dog is exposed to brucellosis it can take up to 16 weeks for it to show up in a blood sample, so if it’s been less than that since your dog was at risk, they will need to be retested after 16 weeks.

The first step is usually an initial screening test, such as a rapid slide agglutination test or a serological test. 

If the initial screening test shows a positive result or if there is a high suspicion of brucellosis, further confirmatory testing is the complement fixation test (CFT).

In some cases, a bacterial culture may be performed to isolate and identify the Brucella organism. This involves collecting samples from tissues or body fluids, such as blood, semen, or vaginal discharge. The samples are sent to a specialized laboratory for analysis. Bacterial culture is more complex and time-consuming than serological tests but can provide definitive confirmation of the infection.

Depending on the specific circumstances and the veterinarian's recommendation, additional tests may be performed. These can include radiographs (X-rays) to evaluate the reproductive organs, ultrasound examinations, or other diagnostic procedures to assess the extent of infection or complications.

What is the Treatment for Canine Brucellosis?

Although antibiotics (most commonly minocycline or doxycycline and possibly enrofloxacin) can be used to help control the infection, no treatment can be completely effective in eliminating the bacteria because it can persist in the tissues. Therefore, any dog infected with Bifidobacterium canis should be considered to be infected for life. Even if the acute infection can be controlled with antibiotics, the dog may excrete the bacteria intermittently for the rest of its life.

Surgical sterilization of an infected dog will reduce the release of microorganisms into the environment, thereby reducing the risk to other dogs. Supportive treatment of any other organ systems affected by the bacteria is also indicated for specific cases.

Is Brucellosis in Dogs Contagious to Humans?

Yes, Brucellosis in dogs is considered zoonotic, which means it can be transmitted from animals to humans. Brucellosis is caused by bacteria belonging to the genus Brucella, and several species within this genus can infect dogs. The most common species associated with canine brucellosis is Brucella canis.

Transmission of Brucella bacteria from infected dogs to humans usually occurs through direct contact with infected tissues, fluids, or secretions. This can happen during the birthing process, through contact with aborted fetuses or placentas, or through contact with reproductive fluids (such as semen) from infected male dogs. Other potential routes of transmission include ingestion of contaminated food or water, inhalation of infectious aerosols, or through breaks in the skin.

What Are the Symptoms of Brucellosis in Humans?

Brucellosis is a bacterial infection caused by the Brucella species. The symptoms of brucellosis in humans can vary widely in terms of severity and duration. Some individuals may have mild symptoms or even be asymptomatic, while others may experience more severe manifestations. 

• A recurring or continuous low-grade fever
• Excessive sweating
• Fatigue
• Joint and muscle pain
• Headache
• Swollen lymph nodes
• Back pain
• Abdominal pain
• Weight loss

Signs of illness can occur within one week but up to six months after exposure. On average, signs and symptoms will begin within three to four weeks following infection. If brucellosis is diagnosed the treatment is dual antibiotic therapy for a period of several weeks.

Preventing Transmission of Disease to People When Dogs are Infected

Currently there is no vaccine available for canine brucellosis to protect either dogs or people. For infected
dogs, there are measures that owners can take to reduce the risk of humans or other dogs acquiring the
infection. However, it should be noted that only euthanising the infected animal can be considered absolutely effective in terms of stopping potential future transmission of infection by that animal.

If infected dogs are not euthanased then they should be neutered (if not already castrated/ spayed) whilst being treated with antibiotics. 

Infected dogs should ideally be tested for B. canis regularly for the rest of their life as stress or other disease may affect their likelihood of transmitting B. canis or developing clinical disease caused by B. canis. 

Daily control measures include:

• Avoid contact with other dogs and environments shared by other dogs.
• Practice good hygiene. Wear gloves when cleaning up areas contaminated by dog faeces or urine and
• Wash hands thoroughly when done. Properly dispose of dog waste, and launder potentially
• Contaminated clothing or dog blankets regularly at high temperatures. Contaminated wet areas can be dried and disinfected with a 1% bleach solution
• Limit the dog's contacts to as few people as possible. Do not allow the dog to lick people or other
  dogs.