Description
In dogs,Borrelia?spp. infection (Lyme borreliosis, mainlyB. burgdorferi) most often causes intermittent, shifting lameness, fever, lethargy, anorexia, and peripheral lymphadenopathy; some dogs develop painful, swollen joints consistent with immunemediated polyarthritis, and a subset develop Lyme nephritis with proteinlosing nephropathy, oedema, and weight loss. Cats are frequently exposed but rarely develop overt clinical disease; when signs are reported they resemble canine cases (fever, lethargy, lameness) but are poorly documented.
Diagnostic samples include serum for serology (ELISA, IFA) to document exposure, plus blood or, preferably, synovial fluid or skin at the tick bite site for PCR when clinical signs suggest active infection; synovial fluid is more sensitive than blood because spirochaetaemia is often low and intermittent. qPCR on these samples can detect and quantifyBorreliaDNA, but a negative result does not exclude disease, so results must be interpreted with tickexposure history, clinical signs, and serology.
Ehrlichia canis?in dogs (classic canine monocytic ehrlichiosis) typically presents with fever, lethargy, weight loss, lymphadenopathy, splenomegaly, and bleeding tendencies (epistaxis, petechiae, ecchymoses) due to thrombocytopenia; chronic cases show pancytopenia, cachexia, and ocular or neurologic signs. Peripheral blood (EDTA) is used for cytology, CBC/biochemistry (cytopenias, hyperglobulinemia), and PCR, while serum is used for serology (IFA/ELISA) to support exposure. qPCR on whole blood is particularly valuable early in infection, allowing sensitive detection and quantification of? E. canisDNA, monitoring response to therapy, and confirming infection when morulae are not visible and serology is equivocal.
Anaplasma platys?infection in dogs primarily causes cyclic thrombocytopenia with mild or absent systemic signs; some dogs develop fever, lethargy, mucosal pallor, petechiae, or epistaxis during thrombocytopenic episodes. Blood (EDTA) is the key sample for CBC (documenting fluctuating thrombocytopenia) and for PCR to detect organisms within platelets; morulae can occasionally be seen cytologically but are often rare. qPCR on whole blood is the most reliable way to confirmA. platys?infection, differentiate it from immunemediated thrombocytopenia, and quantify bacterial load over time.?
Anaplasma phagocytophilum?in dogs causes an acute febrile illness with lethargy, inappetence, shiftingleg lameness or stiffness, and peripheral lymphadenopathy; thrombocytopenia is common and mild nonregenerative anaemia may occur. Blood is again the main sample: CBC, blood smear, plus PCR and serology. qPCR on EDTA blood is the preferred test during acute illness because it confirms active infection, distinguishes? A. phagocytophilum?from other tickborne agents, and can be used to track treatment response; serology alone cannot distinguish past from current infection.
Babesia canis?(subspecies?canis?and?vogeli) in dogs typically causes an acute haemolytic syndrome with fever, lethargy, pale or icteric mucous membranes, dark urine (haemoglobinuria), tachycardia, splenomegaly, and variable thrombocytopenia;B. canis vogeli?is often milder thanB. canis canis?but can be severe in puppies or splenectomised dogs.Babesia gibsoni?often produces more chronic, waxingwaning anaemia, lethargy, weight loss, and splenomegaly, and can be associated with immunemediated haemolytic anaemia and thrombocytopenia; it is classically linked to fighting breeds (e.g., American Pit Bull Terriers). Thin blood smears (capillary or peripheral blood) are used to look for intraerythrocytic piroplasms, but parasitaemia may be low, especially in chronicB. gibsoni?infection, so PCR on EDTA blood is preferred to detect and speciateBabesia. qPCR on blood allows sensitive detection and quantification, helps differentiate between large and small Babesia species and subspecies, and is valuable for monitoring treatment success, asBabesiaDNA may persist at low levels even after clinical recovery.
