by Cats receive most of the attention when it comes to Bartonella prevalence and transmission because they are natural carriers of the bacteria. There is even an illness named after how they transmit Bartonella henselae to humans (cat scratch disease or cat scratch fever). However, competent vectors for Bartonella species (insects and arachnids that are able to spread the bacteria) can be found on both cats and dogs. How likely is it that our canine companions have bartonellosis?
Bartonellosis Symptoms in Dogs
We know that Bartonella species can make dogs sick. Bartonella vinsonii berkhoffii (Bvb), Bartonella henselae, and B. koehlerae have all been documented as causative agents of bartonellosis in dogs. In one study of military working dogs, Dr. Breitschwerdt and his team found that Bvb may lead to fatal endocarditis or myocarditis. Furthermore, a retrospective study of 30 dogs with culture-negative endocarditis in Spain detected Bvb in heart valve and blood samples using PCR.
B. henselae is associated with a myriad of health concerns, including vasculitis (inflammation of blood vessels). In 2015, a case report described a Golden Retriever that exhibited non-specific symptoms. After performing PCR on a splenic tissue sample, B. henselae was identified and antibiotic therapy was started. In 2018, a beagle with ear tip vasculitis had PCR and histological results that were consistent with B. henselae infection. Antibiotic treatment for 6 weeks led to complete resolution of the necrosing skin lesions. Furthermore, vasoproliferative lesions that can affect the liver or spleen in dogs have been associated with B. henselae. Read more in a previous post.
Bartonellosis Prevalence in Dogs
As discussed in earlier posts, it is difficult to determine how likely a population, whether it be human or animal, is to be affected by Bartonella. Bartonellosis (Bartonella-related infection) is currently not a reportable illness for humans or animals, which makes it hard for public health groups to create a reliable registry at the state or national level. This dilemma is further complicated by the complex illnesses and testing challenges associated with both human and animal bartonellosis.
A reliable source of information regarding the prevalence of vector-borne pathogens in dogs across North America comes from the Companion Animal Parasite Council (CAPC). CAPC creates interactive parasite prevalence maps using diagnostic testing data supplied by two major animal health reference laboratories: IDEXX and Antech. Unfortunately, Bartonella species are not included because they are not a standard target for yearly pathogen testing. The information available is only for heartworms and tick-borne agents such as Borrelia burgdorferi (Lyme disease), Ehrlichia canis, and Anaplasma.
The best that researchers can do is make inferences based on studies that use serological or molecular testing to determine the prevalence of clinically relevant Bartonella species in specific geographic regions or clinical populations. A sampling of studies are listed in the table below, along with overall PCR and serology positivity rates:
| Number | Demographics | Bartonella species | PCR Positive | Serology Positive |
|---|---|---|---|---|
| 1 | 15,451 Dogs in North America | B. henselae, B. vinsonii berkhoffii, B. koehlerae | N/A | 3.26% |
| 2 | 20 Rescued Stray Dogs; 46 Dogs from Breeding Colony in Iran | B. henselae, B. clarridgeiae, B. vinsonii berkhoffii | 18% | 74.2% |
| 3 | 3,417 Sick Dogs in California | B. henselae, B. clarridgeiae, B. vinsonii berkhoffii | N/A | 2.99% |
| 4 | 100 Pet Dogs in the UK | B. henselae | N/A | 3% |
| 5 | 190 Dogs in Italy | B. henselae | 0% | 5.8% |
| 6 | 206 Sick Dogs; 266 Healthy Dogs in Spain | B. henselae, B. vinsonii berkhoffii | N/A | 17.87% |
| 7 | 301 Sick Dogs in Southeastern USA | B. henselae, B. vinsonii berkhoffii | N/A | 31.9% |
| 8 | 139 Rural Dogs in Chile | B. henselae, B. vinsonii berkhoffii | 4.3% | N/A |
| 9 | 80 Shelter Dogs in Florida | B. vinsonii berkhoffii, B. rochalimae | 17.5% | N/A |
The findings of these studies indicate that there is a range in the likelihood of Bartonella exposure and infection across the world for dog populations. Prevalence of infection is affected by a number of factors, including:
- Geographic region variances: for example, the Southeastern USA has higher rates compared to the rest of the US, matching the higher rate of human cat scratch disease cases in the Southeast (Study 1 vs. Study 7);
- Health status, though exactly how that plays out remains a question: it is unclear whether bartonellosis makes the dogs susceptible to other illnesses or whether sick dogs are more likely to suffer from opportunistic infections including bartonellosis;
- Exposure to other canine vector-borne diseases: there is a higher Bartonella exposure rate for dogs exposed to other diseases;
- Being fixed: breeding dogs (male and female) seem to have a higher likelihood of infection compared to spayed/neutered dogs (Studies 1 and 2);
- Whether they live with humans: stray dogs have higher exposure than pet dogs likely due to increased exposure to arthropod that transmit Bartonella species.
Conclusion
When asking the question, “How likely is it that this dog has bartonellosis?” a number of variables related to the dog factor into the answer. One factor that is consistent is that avoiding contact with arthropod vectors is important to keeping dogs healthy. Flea and tick control is a central component of the “healthy pets, healthy people” concept that protects all members of the family from Bartonella species.
References
Müller, A. et al. (2018). Bartonella vinsonii subsp. berkhoffii and B. henselae in dogs. Epidemiology and Infection, 146(9), 1202-1204. doi:10.1017/S0950268818001127 https://www.ncbi.nlm.nih.gov/pubmed/29729679 – Molecular prevalence in Chile
Roura, X. et al. (2018). Polymerase chain reaction detection of Bartonella spp. in dogs from Spain with blood culture-negative infectious endocarditis. Journal of Veterinary Cardiology, 20(4), 267-275. doi:10.1016/j.jvc.2018.04.006 https://www.ncbi.nlm.nih.gov/pubmed/29807750 – Detection of Bartonella in culture-negative endocarditis dogs spain
Shelnutt, L. M. (2017). Death of military working dogs due to Bartonella vinsonii subspecies berkhoffii genotype III endocarditis and mycarditis. Military Medicine, 182(3), e1864-e1869. doi:10.7205/MILMED-D-16-00125 https://www.ncbi.nlm.nih.gov/pubmed/28290975 – Detection of Bartonella vinsonii in military working dogs
Companion Animal Parasite Council. (2019). Parasite prevalence maps. Available at: https://capcvet.org/maps – CAPC maps
Friedenberg, S. G. et al. (2015). Splenic vasculitis, thrombosis, and infarction in a febrile dog infected with Bartonella henselae. Journal of Veterinary Emergency and Critical Care, 25(6), 789-794. doi:10.1111/vec.12367 https://onlinelibrary.wiley.com/doi/abs/10.1111/vec.12367 -Bh causing vasculitis
Southern, B. L. et al. (2018). Bartonella henselae in a dog with ear tip vasculitis. Veterinary Dermatology, 29(6), e180. doi:10.1111/vde.12695 https://www.onlinelibrary.wiley.com/doi/10.1111/vde.12695 ear tip vasculitis
Lashnits, E. et al. (2018). Bartonella seroepidemiology in dogs from North America, 2008-2014. Journal of Veterinary Internal Medicine, 32(1), 222-231. doi:10.1111/jvim.14890 https://www.ncbi.nlm.nih.gov/pubmed/29197186
Diniz, P. P. et al. (2007). Canine bartonellosis: Serological and molecular prevalence in Brazil and evidence of co-infection with Bartonella henselae and Bartonella vinsonii subsp. berhoffii. https://www.ncbi.nlm.nih.gov/pubmed/17583666
Yore, K. et al. (2014). Flea species infesting dogs in Florida and Bartonella spp. prevalence rates. Veterinary Parasitology, 199(3-4). doi:10.1016/j.vetpar.2013.10.017 https://www.ncbi.nlm.nih.gov/m/pubmed/24268654/?i=4&from=/28249707/related