Epidemiological and clinicopathological factors associated with infection by multiple pathogens transmitted by Rhipicephalus sanguineus sensu lato in naturally infected dogs in the Semiarid area of Northeastern Brazil.

Domestic dogs are frequently exposed to tick-borne pathogens such as Babesia vogeli, Hepatozoon canis, Anaplasma platys and Ehrlichia canis, which can cause a wide range of clinical manifestations, although little is known about the epidemiological and clinicopathological profiles of mono- and co-infections. This study aimed to characterize infection patterns and identify clinical and epidemiological factors associated with mono-infections, and co-infections with two or more pathogens in naturally infected dogs. We analyzed 181 dogs from a hospital population with suspected hemoparasitic infections, assessed hematocrit and platelet counts, and used statistical models (Chi-square, Fisher's exact test, odds ratios, and multinomial logistic regression) to evaluate associations between infection types and clinical or epidemiological variables. This is the first comprehensive Brazilian study correlating infection type with clinical and epidemiological factors. Dogs with a history of tick infestation were 3.41 times more likely to be co-infected with two pathogens, and infections involving two (84.6%) or three or more pathogens (90.9%) were more frequent in dogs without the use of tick control medications. Male dogs and those presenting epistaxis, hyporexia or anorexia, dehydration, onychogryphosis, and ectoparasites were more likely to be co-infected with three or more pathogens. Thrombocytopenia was common in all groups, with dogs co-infected with three or more pathogens showing 16.3 times higher odds and dogs co-infected with two pathogens had increased odds of anemia (OR = 2.11). These results underscore the importance of tick control and comprehensive pathogen screening in endemic regions, especially in Brazil's semi-arid northeast, to enhance diagnosis, management, and prevention strategies.