Page 1485 - Small Animal Internal Medicine, 6th Edition

CHAPTER 94
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Polysystemic Bacterial

Diseases

CANINE BARTONELLOSIS human beings with evidence of infective endocarditis (Fig.
94.1) particularly if culture negative using routine media
Etiology and Epidemiology (Okaro et al., 2017; Fenimore et al., 2011; Sykes et al., 2006).
Bartonella vinsonii subspecies berkhoffii was initially isolated Recently, ineffective erythropoiesis was detected in a dog
from a dog with endocarditis in North Carolina (Breitschw- positive for B. henselae that subsequently responded to anti-
erdt et al., 1995). Bartonella vinsonii (berkhoffii) is thought to biotics (Randell et al., 2018). In one study of valvular endo-
be tick-borne but has also been amplified from fleas collected carditis, all dogs with Bartonella spp.–associated disease were
from dogs (Yore et al., 2014). In a recent seroprevalence also seropositive for Anaplasma phagocytophilum (MacDon-
study of 15,451 dogs, 3.26% of dogs were Bartonella spp. ald et al., 2004). Whether the co-infection potentiated the
seroreactive with B. henselae (2.13%), B. koehlerae (2.39%), Bartonella-associated disease is unknown.
or B. vinsonii subsp. berkhoffii (1.42%, P < 0.0001) organisms
(Lashnits et al., 2018). Bartonella henselae and B. koehlerae Diagnosis
are transmitted by fleas. In the seroprevalence study, Barton- Serum antibodies can be detected in both healthy and clini-
ella spp. antibodies were detected more often in intact males cally ill dogs, so the presence of antibodies does not always
(5.04%) than neutered males (2.87%, P < 0.0001) or intact correlate to illness. However, because approximately 50% of
or spayed females (3.22%, P = 0.0003). This result and the dogs with bartonellosis are seronegative, serum antibodies
documentation of Bartonella spp. infections in dogs in areas should never be used as the sole diagnostic method in
where vector-borne diseases are uncommon like Colorado suspect cases (www.galaxydx.com). Bartonella spp. can be
and Wyoming suggest direct transmission may also occur difficult to amplify from dogs because the organism is fre-
(Fenimore et al., 2011). Many other Bartonella species have quently present in low numbers. Thus amplification of DNA
been isolated from dogs from which DNA has been ampli- by polymerase chain reaction (PCR) assay with or without
fied from blood or tissues, and include B. clarridgeiae, B. culture is often necessary to confirm infection; blood or
washoensis, B. quintana, B. rochalimae, and B. elizabethae. affected tissues may also be used for PCR (Duncan et al.,
Each of these organisms can potentially induce illness in 2007; www.galaxydx.com). If positive test results are detected
dogs. Dogs infected with a Bartonella species are commonly in a clinically ill dog and no other explanation for the illness
co-infected with other agents such as Anaplasma spp. or is obvious, treatment is indicated.
Ehrlichia spp., which may play a role in the pathogenesis of
disease. Treatment
Dogs with suspected bartonellosis have failed treatment
Clinical Features with doxycycline alone; thus failure to respond to this drug
Bartonella henselae and B. vinsonii (berkhoffii) seem to be should not exclude the diagnosis. Azithromycin therapy has
the most likely species to be associated with clinical disease been successful in some dogs, but it is now recognized that
in dogs. Clinical findings or syndromes most frequently B. henselae can become resistant to this drug more quickly
attributed to Bartonella spp. infections of dogs include than fluoroquinolones (Biswas et al., 2010). Dual therapy
endocarditis, fever, arrhythmias, hepatitis, granulomatous is believed to be more effective than monotherapy by some
lymphadenitis, cutaneous vasculitis, rhinitis, polyarthri- veterinarians, but more information is necessary. Doxycy-
tis, meningoencephalitis, thrombocytopenia, eosinophilia, cline at 5 to 10 mg/kg, orally (PO), q12h combined with a
monocytosis, immune-mediated hemolytic anemia, epi- veterinary fluoroquinolone like enrofloxacin at 5 mg/kg, PO,
staxis, idiopathic cavitary effusions, and uveitis. Bartonella q24h is used by most veterinarians working with Bartonella
spp. infection should be considered in all dogs, cats, and spp. infected dogs (Breitschwerdt, 2017). Rifampin used with

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