09/10/2025
❗ANSWER TO YESTERDAY'S POP QUIZ❗
Domestic dogs are responsible for 99% of Brucellosis infections seen in humans!
Why does my dog need brucellosis testing?
Brucellosis is a contagious bacterial disease found in dogs, most commonly spread by mating. It is the ONLY bloodborne pathogen recognized by OSHA in veterinary medicine. The concern is that this bacteria is zoonotic, meaning it can be spread from animals to humans. Since 60% of American households own one or more dogs, there is valid concern that an infected dog can cause human illness.
Brucellosis in humans is also known as “undulant fever” as once infected, this chronic disease that is difficult to diagnose and can last a lifetime. It can be spread from a dog to humans by contact with any body fluid from a dog.
Brucellosis (cause by Brucella canis or B. canis) can be spread dog to dog without mating but this is the most common route of transmission. Even dogs that are spayed or neutered can be infected. Symptoms in breeding dogs include infertility, sterility, pregnancy loss, and infected testes. In non-breeding dogs, the most common symptom is discospondylitis – an inflammatory change in the spaces between the vertebrae.
Brucellosis is not considered curable in dogs. For this reason, a persistently infected dog is likely to be euthanized, often by state mandate. One infected dog in a kennel or household can lead to ending an entire breeding program.
Because this is an incurable disease and because it can spread to humans, retesting dogs is recommended prior to every breeding and prior to semen freezing. Remarkably, this bacteria has been shown to survive the semen freezing process, which can lead to an infected female when this semen is used.
The Society for Theriogenology, the veterinarians who provide veterinary care for breeding dogs, recognize Brucella canis as a threat to both breeding and pet dogs and their owners, as well as immunocompromised members of the community.
The Society for Theriogenology recommends that all breeding dogs be tested based upon risk factors and frequency of breeding and found to be negative prior to breeding. This means both male and female dogs be tested prior to each breeding, and prior to semen freezing, all male dogs should be tested and found to be negative.
In addition, the Society for Theriogenology recommends that all dogs and dog semen imported into the United States are negative for B. canis.
There have been an increasing number of outbreaks throughout the United States, particularly in commercial breeding operations. As infected dogs move out of these facilities and co-mingle with other dogs as breeding stock and rescued dogs, brucellosis may easily spread into other breeding facilities and client’s homes. Dogs may be exposed by routes other than venereal transmission, such as through casual contact with urine and genital discharges at dog events and breeders who rescue dogs from breeding facilities. Veterinarians and breeders must be less complacent about testing for this important and devastating disease.
Canine Brucellosis as a zoonotic disease: Canine Brucellosis in humans can be serious and difficult to diagnose. It is frequently overlooked by physicians. Symptoms in humans include recurrent fever, lung and heart disease, and bone infections. It is more likely to occur and cause serious symptoms in the immune-compromised patient (children, the elderly, patients on chemotherapy, patients on corticosteroids or organ rejection drugs, patients with HIV-AIDS, and those with chronic diseases such as diabetes or leukemia). Although few human cases have been reported, we have a responsibility to educate and protect our clients and staff.
Human exposure to Brucella canis can be by ingestion, mucus membrane contact, skin wounds, or inhalation of the organism. Masks, goggles and gloves should be worn by personnel handling suspected animals, bedding or tissues.
If a client or staff member is exposed or may have symptoms of brucellosis, he or she should contact their physician. Early symptoms include intermittent (undulant) or prolonged fever; body, muscle and back aches; loss of appetite; headaches; sweats; fatigue; other flu-like symptoms and enlarged lymph nodes. Early treatment with appropriate antibiotics is usually effective.
Symptoms of Canine Brucellosis in the bitch and puppies: Symptoms in the bitch include apparent infertility due to early fetal death, resorption, abortion, and the delivery of weak or sick pups. Late term abortion after 45 to 60 days of pregnancy is common. Abortion is accompanied by a long-standing vaginal discharge. Aborted pups often show signs of decomposition. Pups born alive may die soon after birth, or show signs of illness. The sick pups may have enlarged lymph nodes, recurrent fevers, and uveitis. Affected bitches may also have fevers of undetermined origin, discospondylitis, and uveitis.
Testing dogs for Canine Brucellosis: All dogs and bitches that have direct sexual contact with each other, dogs that will have their semen frozen, and all dogs and bitches with symptoms of brucellosis should have screening blood tests.
Transmission of Canine Brucellosis: Transmission of brucellosis dog-to-dog may occur venereally. However, other routes of transmission are more common – these include ingestion or inhalation of aborted materials, transplacental transmission, and contact of any bodily secretions with the mucus membranes. One of the first documented human cases (1966) was an air conditioner repairman who was exposed under a porch where a bitch whelped a litter of infected pups.
Prevention of an outbreak of Canine Brucellosis in a kennel: Once a year, test all breeding stock in the kennel. Test all dogs prior to introduction into a breeding colony twice at 4 to 6 week intervals. Females that abort should be assumed positive and should be isolated until proven otherwise.
Managing an outbreak of Canine Brucellosis: In many states, canine brucellosis is a reportable disease. This means if you confirm a brucellosis case, you must contact your state veterinarian. You only need to report a positive test result on the RSAT that is confirmed on either blood culture, PCR, and/or the AGID test. These veterinary authorities may dictate the management of testing and culling infected dogs and those in contact with infected dogs.
Euthanasia of all CULTURE positive dogs is frequently recommended. This is recommended because antibiotic regimens are not curative and the disease has zoonotic potential.
During an outbreak, all dogs in the kennel should be tested monthly for 3 months until the all the dogs housed in the kennel are negative on 2 successive tests. All females should be separated at birthing to reduce transmission in the kennel.
If an individual dog is infected, he or she must be sexually altered (ovariohysterectomized or castrated) and placed on long-term antibiotic therapy or euthanized. Antibiotic regimens that have been described include minocycline (25 mg/kg po SID x 14 days) with dihydrostreptomycin (5 mg/kg IM BID x 7 days) and tetracycline (30 mg/kg po BID x 21 days) with streptomycin (20 mg/kg IM SID x 14 days). Dihydrostreptomycin is no longer available; as a substitute, gentamycin or rifampin have been proposed but the side effects are considerable, including renal failure due to prolonged use of gentamycin. There is great cost associated with long-term antibiotic therapy, ongoing testing for monitoring resolution of the disease, and side effects associated with treatment.
Spayed females pose little risk of disease to family members after they are ovariohysterectomized. However, brucellosis can be harbored in the prostate, so it may not be possible to clear the male dog from this disease even with castration and long-term antibiotic therapy. The zoonotic risk of the disease must be discussed with the client, particularly in households with young children or immune-compromised members.
If one or more individual dogs in a group housing situation are infected, the entire colony must be euthanized or tested and culled multiple times. The following protocol has been recommended:
Confirm brucellosis is present based on PCR, blood cultures or cultures from infected tissues;
Strictly limit movement of dogs in or out of the kennel, for any reason;
Identify ALL infected dogs. Try to determine the source of infection and all dogs in contact with infected dogs. Blood cultures are the recommended test;
Cease breeding;
Test all animals in the facility, and cull all infected animals. This often means euthanasia of large groups of dogs;
Separate groups of dogs to minimize transmission;
Retest all animals in the facility every month. Continue to cull infected animals;
The facility is not considered clear of brucellosis until all the animals have tested negative for 3 consecutive months. This may require 5 to 7 months of testing and culling;
Unless the kennel is closed to incoming and outgoing dogs and breeding is temporarily ceased, the kennel may never be cleared of brucellosis.
Preventing a Canine Brucellosis outbreak in a household or kennel of breeding dogs: Breeders have a great deal at stake every time they breed naturally or introduce a new dog into their household or kennel. Many have spent a lifetime developing their genetic lines; an outbreak of canine brucellosis could destroy a lifetime of work in a moment of oversight or poor judgment.
All dogs and puppies the breeder is exposing their dogs to should have a negative canine brucellosis test. This is particularly important if they are introducing a rescue dog from a breeding kennel into the household or kennel.
Require that any stud dog or bitch the breeder uses for breeding have a negative brucellosis test. To protect your bitch and kennel, it is reasonable to require a stud dog be tested before each breeding, not just on a bi-annual basis as many breeders choose to do. This includes stud dogs having semen shipped as fresh extended semen and stud dogs prior to collection semen for freezing. Freezing preserves Brucella canis.
