Bartonella Infection in Horses
If you haven’t heard of bartonella, you’re definitely not alone. I recently learned about this type of bacteria which can infect not only horses, but also cats, dogs, cattle, humans, and several other mammals. But the resulting infection, known as bartonellosis, seems to be a widespread, yet mis/undiagnosed problem in many horses. Mainstream veterinary medicine appears to know very little about it, but according to this 2017 study, it may be much more common than we think.
In humans, the most commonly known form of Bartonella infection is “cat scratch fever”, from Bartonella henselae. This is transmitted by a scratch from a cat carrying B. henselae and causes a rash followed by symptoms such as low grade fever, headache, sore throat, and conjunctivitis 3-10 days after the scratch. However, symptoms are usually not life-threatening and often resolve without treatment.
We now know that there are many more species of Bartonella though, and different symptoms can arise depending on the type of infecting Bartonella species and likely, the state of the animal or person’s immune system.
Some horses may show no signs at all, some, mild symptoms, and still others, severe symptoms. Many sources also mention that bartonellosis is a co-infection of Lyme Disease.
In another study, it’s mentioned that B. henselae was identified in two adult horses, one with vasculitis, and the other with chronic, intermittent, shifting leg lameness. This same Bartonella species was also reported in an aborted equine fetus, as well as in a horse that died from hemolytic anemia.
As far as we know, Bartonella bacteria are transmitted to horses by biting insects such as ticks, mosquitoes, fleas, etc. (or passed from mother to foal) where they take up residence in the lining of the blood vessels. Horses may not show symptoms until the infection has spread to multiple parts of the body, and since a large bundle of blood vessels lies beneath the shoulder as well as in the groin area of the horse, unexplained shortened stride length may be one of the first symptoms noticed. Many other symptoms have been associated with bartonellosis, including:
- enlarged lymph nodes
- muscle cramps
- urinary discomfort (standing in a “camped out” position)
- respiratory problems
- hypersensitivity (such as when brushing or with flies)
- sore soles
- patchy sweating
- explosive outbursts
To see a full list of possible symptoms, I suggest reading this article.
Many horses being treated for chronic conditions may, in fact, have bartonella infection, but the problem is that it can be difficult to recognize and diagnose.
Diagnosing and Treating Bartonella Infection
Since the bacteria can “hide out” within the circulatory system, collecting and testing blood samples on at least three alternate days is usually necessary in order to get an accurate diagnosis. A company called Galaxy Diagnostics carries Bartonella testing kits which doctors or veterinarians can order.
Several antibiotics have been used to successfully treat Bartonella infection, but antibiotic resistance is said to be a problem and multiple rounds of antibiotics maybe needed.
Herbs and homeopathy appear to be an alternative treatment option, but I could find little information on this. I did find a Bartonella nosode carried by this company, however. Supporting the immune system with a healthy, whole foods diet as well as adaptogenic herbs may play a big part in recovery as well.
According to a comprehensive article by Dr. Brenda Bishop, VMD, most Bartonella horses have depleted magnesium stores and can benefit from supplementation. Dr. Bishop offers consultations on Bartonella and other chronic equine infections so she may be your best bet if you suspect the condition in your horse and your own vet isn’t able to help.
Please note that I share this information not to cause alarm, but to make others aware of Bartonella and the harm it can possibly cause. While some horses who tested positive for Bartonella showed no symptoms (according to study results), others have become quite ill. If your horse has been suffering from any kind of chronic condition, I’d definitely consider Bartonella infection as a possible culprit and do some further investigation.
Sources and Further Reading