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Overview of Canine Bartonellosis (Cat Scratch Disease)
Bartonellosis is a disease caused by the bacteria Bartonella. There are several subspecies of Bartonella and each are associated with causing different problems. The organism infects red blood cells and endothelial cells in some animals. Some dogs may be infected without any clinician signs of illness and other may show symptoms of infection.
In cats, the disease is commonly known as Cat-scratch Disease (CSD), which is an infection in cats and humans. In humans, it most often occurs after prolonged contact with a young cat.
All ages, breeds, and sexes of dog are susceptible, however dogs in rural areas, herding breeds are thought to be at increased risk. The risk of disease is increased with pets exposed to the disease vectors such as fleas, ticks, lice and sand flies. Therefore, feral dogs and strays are at increased risk.
What to Watch For
- Some dogs may show no clinical signs of illness
- Lack of appetite (anorexia)
- Nasal Discharge
- Bloody nose (Epistaxis)
- Lymphnode enlargement
Signs of human disease include raised skin lesions that are red to purple in color. Anywhere from a few to over 100 may be found on the face, trunk, arms and legs. If cat scratch disease spreads internally, it can cause fever, weight loss and vomiting. Upon examination, the liver and spleen may be enlarged. Humans with immunodeficiency problems are at higher risk for disease.
Diagnosis of Bartonellosis (Cat Scratch Disease) in Dogs
In people, definitive diagnosis generally requires a biopsy for microscopic examination and culture. Other tests to diagnose the organism in dogs might include:
- Blood culture
- Polymerase chain reaction (PCR)
- Complete blood count (CBC)
- Serum biochemical profile
Treatment of Bartonellosis (Cat Scratch Disease) in Dogs
- Dogs that show clinical signs of illness may be treated with antibiotics and supportive care.
In people, Bartonella responds to several different oral antibiotics, such as erythromycin, clarithromycin, azithromycin and doxycycline. Antibiotics are usually given for 2 to 3 months unless there is bloodstream or internal organ involvement. In advanced HIV disease, long-term management with lower doses is usually necessary to prevent relapse.
Home Care and Prevention
There is no home care for bartonellosis. Preventive care is based on maintaining good hygiene. Wash your hands after handling pets and wash scratches or bites thoroughly. Never let a dog lick an open wound, and maintain meticulous flea control. Preventative flea and tick control is recommended. For more information on flea and tick control programs, go to Flea Control and Prevention in Dogs or How to Remove and Prevent Ticks in Dogs.
Blood cultures and serology should be performed on pets belonging to immunocompromised people.
In-depth Information on Bartonellosis (Cat Scratch Disease) in Dogs
There are several Bartonella subspecies that can infect humans. Bartonella organisms cause a wide range of clinical diseases in people including the following:
Bartonella henselae is the causative agent of cat-scratch disease in humans.
Bartonella vinsonii, Bartonella elizabethae, Bartonella washoensis may cause endocarditis in humans.
Bartonella clarridgeiae may cause cat scratch disease in humans.
Bartonella bacilliformis may cause Carrion’s disease, Oroya fever and/or verruca peruana in humans.
Bartonella quintana may cause endocardistis, bacillary angiomatosis and or trench fever in humans.
Children and immunocompromised people may suffer severe disease when infected by these bacteria. Cats are considered the major reservoir for these bacteria, although fleas and some other mammals have also been shown to play a role in the disease.
For more information on cat scratch disease in cats – go to Bartonellosis (Cat-scratch Disease)
Diagnosis In-depth of Cat Scratch Disease in Dogs
Dogs may show or may not show signs of illness related to bartonellosis. Test run on dogs may be similar to tests run on humans. Tests may include:
- Blood culture. Culture of the blood for Bartonella organisms may be performed on humans as part of the evaluation of suspected cases of CSD. It may also be performed on dogs suspected of harboring the organism. Blood culture can be difficult and prolonged.
- Serology. Serologic tests detect antibodies to Bartonella and imply exposure or infection with the organism.
- Polymerase chain reaction. This test is currently limited to special institutes and research laboratories, although it promises to be the most specific test for bartonellosis, and can distinguish between all of the Bartonella species.
- Complete blood count (CBC) is often normal in dogs. A mild anemia, low platelet counts, high white blood cell counts and elevated eosinophils may be present in some dogs.
- Serum biochemical profile is demonstrate elevated liver enzymes and low albumin levels.
- Urinalysis is normal in most dogs.
Treatment in Dogs
Antibiotics. For dogs that are symptomatic, antibiotics are recommended. The most commonly used antibiotic is Azithromycin (Zithromax®) although Doxycycline (Vibramycin®), Enrofloxacin (Baytril®) and other antibiotics have also been effective. Treatment for 4 to 5 weeks is often recommended. Supportive care including intravenous fluids and drugs to control vomiting may be needed.
Treatment in Humans
Treatment of Bartonella-related disease in people depends on the severity of the disease and the immune status of the patient. If a secondary bacterial infection is present, or if the patient is immunocompromised, antibiotic therapy is prescribed. Treatment is for 4 to 8 weeks in people with competent immune systems, and is extended to 8 to 12 weeks in people who are immunosuppressed. HIV positive people may require treatment for many months, and sometimes for life.
Follow-up for Dogs with Cat Scratch Disease
Optimal treatment for your dog requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your pet does not rapidly improve. Administer all prescribed medications as directed. Alert your veterinarian if you are experiencing problems treating your pet. Preventative flea and tick control is recommended. For more information on flea and tick control programs, click here.
Because of the uncertain effectiveness of these antibiotics, it is recommended that affected pets have cultures performed at two to four week intervals to determine drug effectiveness. Cultures should also be taken three weeks after discontinuation of antibiotics.
Because domesticated cats are a major source of the bacteria, common sense and good hygiene should be practiced, such as washing hands after handling pets. Scratches or bites should be cleaned thoroughly, and cats should never be allowed to lick a person’s open wounds.
Cat-scratch Disease is uncommon. Most people will never develop illness due to Bartonella henselae, and people with competent immune systems do not need to follow special precautions with their pets.
Although routine blood cultures and serologic testing is not widely available, it should be considered for pet cats whose owners are immunocompromised. Currently, the veterinary schools at the University of Georgia, Louisiana State University, Purdue University, North Carolina State University and Texas A & M University offer some method of diagnostic testing for cats. If a cat tests negative for Bartonella antibodies, it is unlikely to have the organism in the bloodstream, and may be a good criterion for choosing a pet for an immunocompromised person. Flea control may be the most important factor in reducing cat-to-cat and cat-to-human transmission, and is highly recommended for all pet cats.