Canine anaplasmosis most commonly presents as a subclinical or mild febrile illness, with the most frequent clinical signs being fever, lethargy, inappetence, lymphadenomegaly, splenomegaly, and bleeding tendencies including petechiae and ecchymoses.MSD Vet Manuals+1 Dogs infected with Anaplasma phagocytophilum can additionally develop lameness and inflammatory polyarthropathy.MSD Vet Manuals+1 Vomiting, diarrhea, uveitis, hepatomegaly, and polyarthritis have also been reported.Canadian Veteri…+1
Common laboratory abnormalities include thrombocytopenia, anemia, neutropenia, and lymphopenia.Canadian Veteri…+1 Morulae within neutrophils on peripheral blood smear are specific for active infection when identified, though cytology is an insensitive diagnostic method.Journal of Vete… Increased liver enzyme activity is a frequent concurrent finding.Journal of Vete…
Atypical but documented presentations include cavitary effusions. Pericardial effusion causing cardiac tamponade has been confirmed as a manifestation of A. phagocytophilum infection in dogs, with morulae found within neutrophils in the pericardial fluid and PCR confirmation from both pericardial fluid and blood.Journal of Vete… Myocardial damage is also reported.BMC Veterinary…
Doxycycline is the treatment of choice, dosed at either 5 mg/kg PO q12h or 10 mg/kg PO q24h for four weeks.BMC Veterinary… Dogs treated during the acute phase typically improve within 24–48 hours of initiating therapy.BMC Veterinary… Most patients recover within 1–2 weeks, though doxycycline's therapeutic effects develop over several days to weeks.BMC Veterinary… The optimal treatment duration has not been definitively established; while a four-week course is standard, the minimum effective duration remains undefined.BMC Veterinary…
In the confirmed pericardial effusion case, doxycycline at 5 mg/kg PO q12h for 14 days combined with pericardiocentesis resulted in complete resolution with no recurrence of effusion on echocardiogram at one-month recheck.Journal of Vete…
Alternative antibiotics with documented efficacy against A. phagocytophilum in dogs include orbifloxacin (5 mg/kg SC on day 1, then PO q24h for two weeks) and enrofloxacin (5 mg/kg SC, then PO q24h from days 2–8).BMC Veterinary… Rifampicin and levofloxacin have demonstrated in vitro activity.BMC Veterinary… Corticosteroids carry a risk of exacerbating infection or worsening clinical signs and are not routinely recommended.BMC Veterinary…
| Drug | Dose & Route | Duration | Key Caveat |
|---|---|---|---|
| Doxycycline | 5 mg/kg PO q12h OR 10 mg/kg PO q24h | 4 weeks | Improvement expected 24–48 h; optimal duration not definitively established |
| Orbifloxacin | 5 mg/kg SC day 1, then PO q24h | 2 weeks | Alternative when doxycycline not tolerated |
| Enrofloxacin | 5 mg/kg SC day 1, then PO q24h | Days 2–8 | Shorter documented course than orbifloxacin |
Serologic antibodies can persist for years after infection, so a positive ELISA does not confirm active disease and must be interpreted alongside clinical signs and other diagnostics.BMC Veterinary…+1 ELISA sensitivity is reduced within the first four days of clinical infection, and antibodies may not appear until 8 days post-infection — meaning early acute presentations can yield false-negative point-of-care tests.Journal of Vete…
Would you like guidance on how to interpret and sequence the available diagnostic tests (ELISA, PCR, blood smear, and IFA titers) when clinical suspicion is high but initial ELISA is negative?