Peer-reviewed veterinary case report
Tracking Ehrlichia canis bacteria in infected dogs over 60 days
By Sumpavong, Peeravit et al.·Published in Veterinary microbiology·2026·Department of Veterinary Technology·View original on PubMed →
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Original publication title: Longitudinal assessment of Ehrlichia canis bacterial load in naturally infected dogs using droplet digital PCR.
- Species:
- dog
Plain-English summary
A group of 41 dogs with signs of Ehrlichia canis infection, a tick-borne disease, were treated with doxycycline but still showed detectable levels of the bacteria in their blood even after treatment. Using a highly sensitive test called droplet digital PCR, researchers found that many of these dogs still had traces of the bacteria 30 and 60 days after treatment, especially those with low red blood cell counts. This suggests that some dogs may continue to harbor the bacteria at low levels, which could mean they need further monitoring or treatment. The study highlights the importance of using advanced testing methods to track this infection in dogs.
People also search for: dog Ehrlichia canis symptoms · doxycycline treatment for dog Ehrlichia · why is my dog still sick after treatment
Abstract
Persistence of detectable Ehrlichia canis DNA after a full course of doxycycline treatment remains poorly described. Highly sensitive molecular tools are essential for monitoring this phenomenon. This study aimed to monitor E. canis DNAemia in naturally infected dogs over a 60-day follow-up period using droplet digital PCR (ddPCR) and to compare its performance with TaqMan real-time PCR (qPCR). Forty-one seropositive dogs (identified by the IDEXX SNAP 4Dx Plus test) exhibiting clinical signs consistent with canine monocytic ehrlichiosis (CME) were enrolled as the Day 0 group. Follow-up samples were collected during recovery from partially overlapping cohorts at Days 30 (n = 21) and 60 (n = 14). At Day 0, ddPCR detected E. canis in 33 of 41 dogs (82.92 %), outperforming qPCR (25/41; 60.97 %). At Days 30 and 60, ddPCR detected E. canis DNA in 12 of 21 (57.14 %) and 5 of 14 (35.71 %) dogs, respectively, while qPCR detected only 2 of 21 (9.52 %) at Day 30 and none at Day 60. Quantification of bacterial loads showed a significant decline from a median of 2.28 DNA copies/µL at Day 0-0.067 copies/µL at Day 30 (P < 0.05), and 0.0614 copies/µL by Day 60 (P < 0.05). Dogs with hematocrit (Hct) levels below 25 % on Day 0 were significantly more likely to have ddPCR-positive results at Day 30 (P = 0.035), suggesting a potential association between severe anemia at diagnosis and persistent DNAemia. The high sensitivity of ddPCR revealed persistence of detectable E. canis DNA with very low bacterial loads. These prolonged bacterial DNAemia require further studies incorporating viability assays to clarify whether residual DNAemia reflects persistent viable infection or non-viable bacterial DNA.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/41558229/