Demonstrating the presence of Ehrlichia canis DNA from different tissues of dogs with suspected subclinical ehrlichiosis

Abstract

Background: Nowadays, Ehrlichia canis receives more attention because of its great morbidity and mortality in animals. Dogs in the subclinical and chronic phases can be asymptomatic, and serologic tests show cross-reactivity and fail to differentiate between current and past infections. Moreover, there could be low parasitaemia, and E. canis might be found only in target organs, hence negative by PCR in blood. Methods: We evaluated by PCR the prevalence of E. canis in blood, liver, spleen, lymphatic nodules, and bone marrow in 59 recently euthanized dogs that had ticks but were clinically healthy. Results: In total, 52.55% of the blood PCRs for E. canis were negative, yet 61.30% yield positive results in tissue biopsies as follows: 63.15% from bone marrow, 52.63% from liver, 47.36% from spleen and 15.78% from lymphatic nodules. In addition, 33% had infection in three tissues (spleen, liver and bone marrow). Conclusions: Our results show prevalence of E. canis in tissue from dogs that were negative by PCR in blood. E. canis DNA in tissue was 30% lower in dogs that tested negative in blood samples by PCR, compared to those that were positive. However, it must be taken into account that some dogs with negative results were positive for E. canis in others tissues.

Hematological and histopathological changes in medular aplasia resulting from Ehrlichia canis infection in a Border collie dog

“…According to SOUSA et al ( 2010), the clinical manifestations of the subclinical and acute phases may present themselves in a mild or severe form in the chronic phase. Additionally, RODRÍGUEZ-ALARCÓN et al (2020) reported that cases that evolved to the chronic phase may present pancytopenia associated with medullary aplasia, hemorrhagic diathesis, and general debilitation, which corroborates the findings of this report, that found leukopenia, hematuria, hematomas, pale oral and ocular mucosa, and prostration. Phlegmons and abscesses may also be found, as in the present case, due to leukopenia, associated with the breakdown of the protective skin barrier (CONCEIÇÃO; SANTOS, 2011).…”

“…Canine Monocytic Ehrlichiosis (CME) has a high morbidity and mortality rate in dogs, therefore being an infectious disease of great importance in Veterinary Medicine (RODRÍGUEZ-ALARCÓN et al, 2020). Among the forms of presentation of CME mentioned by Procajlo et al (2011), the chronic form is the most consistent with the present report.…”

New sensitive real-time PCR targeting p28 gene for detection of Ehrlichia canis in blood samples from dogs

“…In addition to these factors, E. canis might be only found in determined organs. For these reasons, it is possible to obtain false-negative results in PCR on blood samples (RODRÍGUEZ-ALARCÓN et al 2020). Despite this detection bias, many studies have shown that molecular techniques present fewer false-negative results for ehrlichiosis diagnosis than other methods (RAMOS et al, 2009;NAKAGHI et al, 2010).…”