Epidemiological, Molecular, and Hematological Characteristics of Infection by Anaplasma Spp., Babesia Spp., Ehrlichia Spp., and Hepatozoon Spp., in Shelter Dogs from Northeastern Colombia

Tick-borne pathogens represent a significant health problem for dogs, particularly in shelters, where overcrowding and limited veterinary care can facilitate transmission. Although these agents are widely distributed throughout Colombia, epidemiological studies in shelter populations remain scarce. This study evaluated 112 dogs from nine shelters in the Metropolitan Area of Bucaramanga (MAB), Santander, to determine the frequency of infections caused by tick-borne pathogens of the genera Anaplasma, Babesia, Ehrlichia, and Hepatozoon. Overall, 5.35% (6/112; 95% CI: 0.20–11.3%) of dogs were positive by blood smear, whereas 42.85% (48/112; 95% CI: 33.5–52.6%) tested positive by conventional PCR (cPCR). The κ index between blood smear and cPCR indicated slight agreement (κ = 0.077; 95% CI: −0.159 to 0.005). Ehrlichia canis was the most frequent infection (27.67%; 95% CI: 19.6–36.9%), followed by Hepatozoon canis (8.92%; 95% CI: 4.4–15.8%), Babesia vogeli (7.14%; 95% CI: 3.1–13.6%), and Anaplasma platys (6.25%; 95% CI: 2.5–12.5%), respectively. Four coinfection patterns (E. canis + B. vogeli, E. canis + H. canis, B. vogeli + H. canis, E. canis + A. platys) were identified in 7.14% (8/112; 95% CI: 3.1–13.6%) of the dogs. Hematological analysis revealed thrombocytopenia, reduced mean corpuscular hemoglobin, and increased monocyte and basophil counts in dogs infected with E. canis, while A. platys infection was associated with basophilia (P<0.05). Interestingly, coinfected dogs exhibited more pronounced alterations, including decreased red blood cell count, hematocrit, hemoglobin concentration, and platelet count (P<0.05). In the epidemiological analyses, shelter of origin, sex, municipality, and the presence of tick infestation were associated with infection by E. canis and B. vogeli (P<0.05). This study provides the first molecular surveillance of multiple tick-borne pathogens in shelter dogs from northeastern Colombia, revealing a high frequency of infections and coinfections, as well as the main hematological alterations associated with each pathogen. These findings contribute to a better understanding of the clinical and epidemiological characteristics of tick-borne diseases in this population.