A Severe Clinical Case of <i>Ehrlichia canis</i> and <i>Toxoplasma gondii</i> in a Dog (With the First Morphological Detection of Tachyzoites in Peripheral Blood)

Vector-borne pathogens (VBPs) are frequently identified in domestic dogs, particularly in endemic areas or in individuals lacking protection from anti-feeding products. Diagnostic procedures in veterinary clinics for symptomatic animals primarily include rapid serological assays; however, more definitive, albeit time-intensive tests typically require well-equipped laboratory facilities. A 5-year-old female mixed-breed dog was presented to a veterinary clinic exhibiting neurological abnormalities, dyspnoea, lethargy and anorexia. Multiple ticks, predominantly of the genera Rhipicephalus and Dermacentor, were observed attached to the animal's integument. A blood smear examination revealed tachyzoites morphologically consistent with Toxoplasma spp. and intracellular morulae indicative of Ehrlichia canis infections. These findings were subsequently confirmed via polymerase chain reaction (PCR). This report documents a rare and fatal canine co-infection of ehrlichiosis and toxoplasmosis, initially diagnosed through microscopic examination and serology, with definitive confirmation achieved through PCR analysis.