Investigating Brucellosis In Dogs

The highly contagious canine reproductive disease brucellosis is alarming to dog breeders. Rightfully so, considering that the bacterial disease can wipe out an entire kennel, causing devastating emotional impact and economic losses. Considered a lifelong infection, brucellosis does not respond to treatment. 

Dog breeding kennels provide a perfect environment for an outbreak, as dogs can contract the Brucella canis bacterium through ingestion, inhalation or contact with infected semen, vaginal secretions, saliva, nasal secretions, and urine. Contaminated objects, including food or water bowls and bedding, also are a source for infection.

Although few prevalence studies have evaluated disease occurrence in the U.S., experts say brucellosis is of increasing concern due to the increasing numbers of infected dogs seen by veterinarians as well as the potential threat posed by importation of infected breeding dogs and semen for artificial insemination. Besides affecting dogs, brucellosis is a zoonotic disease that can make people sick, particularly those having contact with infected dogs and their body fluids.

Brucellosis is a challenging disease to diagnose partly because the clinical signs resemble other diseases, thus it is sometimes called “The Great Imposter.” Misdiagnosis and underdiagnosis are presumed to be common. Meanwhile, the disease can quickly spread throughout a kennel.

Veterinarians diagnose brucellosis based on clinical suspicions followed by blood tests, such as the commonly used RSAT (rapid slide agglutination test). Accurate blood testing is diminished in chronically infected dogs, because the bacterium can be intermittent and because dogs treated with antibiotics may test negative despite having B. canis infection, making it a diagnostic challenge in some cases.

Treatment consisting of neutering, appropriate antibiotics and pain relief is not a panacea for brucellosis. Recovery is very poor, and it is extremely difficult to eradicate from an affected kennel.

Signs of Brucellosis

Sadly, many dogs infected with B. canis do not develop typical clinical signs of brucellosis, and thus it can be months before it is diagnosed. During this time, they may intermittently shed low concentrations of the bacteria in their semen, vaginal secretions, saliva, nasal secretions, and urine, potentially infecting other dogs and humans. Reproductive failure is the red-flag sign of brucellosis. Other signs of this devastating disease are:

• Mid- to late-term abortion during days 45 to 59 of pregnancy, followed by an odorless brown-to-yellow vaginal discharge for one to six weeks
• Embryonic death with resorption, appearing as conception failure after an apparently successful mating
• Epididymitis (inflammation of the epididymis tube at the back of the testicle), prostatitis (swelling and inflammation of the prostate gland), and orchitis (inflammation of one or both testes)
• Neurological or spinal disease, such as discospondylitis, causing severe back or neck pain
• Puppies infected in utero or through nursing may appear healthy yet harbor the B. canis bacterium, or may be weak and die shortly after birth

ADVANCING BRUCELLOSIS UNDERSTANDING

The AKC (American Kennel Club) Canine Health Foundation recognizes brucellosis as a top infectious disease health concern. Here is a review of two funded research studies focused on learning more about the disease.

Does Kennel Cough Vaccination Hinder Brucellosis Diagnosis?

A six-year study at the University of Minnesota investigated whether dogs vaccinated against kennel cough falsely test positive for brucellosis using the most common screening test, the rapid slide agglutination test (RSAT). “We vaccinated dogs against Bordetella bronchiseptica, and then drew blood samples at six- and eight-week intervals after vaccination. We discovered that dogs did not exhibit false positive reactions due to having the kennel cough vaccine,” says lead investigator Christina Larson, DVM.

Go to study online: https://bit.ly/2Ucnljw

Brucellosis Vaccine for Dogs

A research team at Texas A&M University led by assistant professor Angela Arenas-Gamboa, DVM, PhD, DACVP, is working on a vaccine to protect dogs from brucellosis. “We have developed the vaccine candidate, and we are determining if the vaccine is capable of inducing an adequate immune response and is safe for dogs including pregnant animals,” she says. A protective vaccine against brucellosis has the potential to significantly impact canine and human health by limiting the spread of B. canis. 

Go to study online: https://bit.ly/2Qwsl37

TIPS FOR BREEDING KENNELS ON DISEASE PREVENTION

1. Annual screening tests are advised, and dogs bred outside your kennel should be tested two to four times a year.
2. Always wear personal protective equipment, such as gloves, scrubs and rain boots, when breeding dogs naturally or via AI and when assisting with whelping and handling newborn puppies. Wear protective gloves and be extremely cautious when handling aborted material or fetal placentas or when collecting blood and tissue samples for analysis.
3. Kennel whelping areas should be cleaned daily using appropriate disinfectants.
4. Artificial insemination (AI) is the safest way to breed your stud dogs to outside bitches, with the semen shipped to the outside kennel. When breeding your bitches to outside stud dogs, use semen from stud dogs tested and proven negative for B. canis.
5. Quarantine all new dogs until they receive two negative brucellosis screening tests performed 30 to 60 days apart. The best practice is not to allow dogs into your kennel until they have been tested for brucellosis.
6. Consult a veterinarian for disease risk assessment and outbreak management if dogs in your kennel have been infected with B. canis.

Sources: AKC Canine Health Foundation. Canine Brucellosis: Information for Dog Owners. https://bit.ly/2KQLTKv; and Hensel ME, Negron M, Arenas-Gamboa AM. Brucellosis in Dogs and Public Health Risk. Emerging Infectious Disease Journal. Centers for Disease Control and Prevention. 2018;24(8). https://bit.ly/2FS7PWG