Canine granulocytic anaplasmosis: a review.
Authors: Carrade D D, Foley J E, Borjesson D L, Sykes J E
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Canine Granulocytic Anaplasmosis Anaplasma phagocytophilum, an Ixodid tick-transmitted pathogen affecting horses alongside dogs and humans, has emerged as a globally significant concern; Carrade and colleagues reviewed current understanding of this organism's pathogenesis, clinical presentation, and management in canine populations. The bacterium evades immune clearance by parasitising neutrophils and systematically disabling their antimicrobial functions—impairing motility, phagocytosis, oxidative burst capacity, and apoptotic pathways—whilst multiple circulating strains may exhibit variable virulence and host specificity. Clinical signs in infected dogs range from non-specific acute illness (fever, lethargy, inappetence) to lameness, respiratory or gastrointestinal involvement, and haemorrhages, with diagnosis confirmed through blood film examination for morulae, paired serology (immunofluorescent antibody), or PCR-based detection of bacterial DNA. Current evidence suggests anaplasmosis responds reliably to two weeks of doxycycline therapy and likely represents a self-limiting infection in dogs, though questions remain regarding persistent infection versus reinfection susceptibility following natural exposure. For equine practitioners, this review underscores the importance of tick control protocols and maintaining diagnostic awareness of anaplasmosis in horses presenting with acute febrile illness, particularly in endemic regions where coinfection with other tick-borne pathogens (notably Borrelia burgdorferi) may complicate clinical presentation.
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Practical Takeaways
- •Not applicable to equine practice—this review focuses exclusively on canine anaplasmosis and does not address equine disease management or pathophysiology.
- •While the paper mentions A. phagocytophilum affects horses as an emerging pathogen, no equine-specific clinical guidance, diagnostic protocols, or treatment recommendations are provided.
- •Equine practitioners should consult species-specific literature on equine granulocytic anaplasmosis rather than relying on this canine-focused review.
Key Findings
- •A. phagocytophilum disables critical neutrophil functions including motility, phagocytosis, oxidative burst, and apoptosis regulation.
- •Multiple strains of A. phagocytophilum with differential host tropisms and pathogenicity are circulating in wild and domestic animal populations.
- •Canine anaplasmosis presents as acute febrile illness with lethargy and inappetence, responsive to 2-week doxycycline therapy.
- •Coinfections with Borrelia burgdorferi and other tick-borne pathogens commonly occur, complicating clinical presentation.