Defining the Epidemiology, Clinical Presentation, and Diagnostics for Acute Canine Anaplasmosis, an Increasingly Prevalent Tick-borne Disease in Pennsylvania
Open Access
- Author:
- Rodriguez, LuzKarla
- Area of Honors:
- Veterinary and Biomedical Sciences
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Justin D Brown, Thesis Supervisor
Lester C Griel, Jr., Thesis Honors Advisor
Robert John Vansaun, Faculty Reader - Keywords:
- tick-borne disease
anaplasmosis
dogs
Pennsylvania - Abstract:
- Canine anaplasmosis (referred to herein as anaplasmosis) is an increasingly common tick-borne disease in the Northeast caused by the bacterium Anaplasma phagocytophilum. Thus, it is important that veterinarians be familiar with the clinical presentations, laboratory findings, and diagnostic tests for this disease. False negative results can occur when using a common in-clinic serologic test (SNAP 4Dx Plus, IDEXX, Westbrook, Maine, USA) during the acute stages of anaplasmosis, prior to the development of a detectable antibody response. Consequently, alternative in-clinic diagnostics are necessary so that treatment can be implemented as soon as possible. Between November 2015 and July 2020, 61 cases of suspect anaplasmosis were diagnosed at Metzger Animal Hospital (MAH) in State College, Pennsylvania, based on examination of blood smears or fluid analysis. These 61 cases represented 10 counties in Central Pennsylvania. Two of these cases were determined to be reinfections with Anaplasma spp., based on history. Of the remaining 59 cases, 42.37% (25/59) were referred to MAH, for acute onset of fever of unknown origin, inappetence, lethargy, or a combination of these clinical signs. Antibodies to Anaplasma spp. were detected in 27.27% (15/55) of the cases using the SNAP 4Dx Plus. Blood smears from all cases had morulae in neutrophils, consistent with A. phagocytophilum. Polymerase chain reaction (PCR) and genetic sequencing confirmed all these cases to be infections with A. phagocytophilum, specifically the Ap-human active strain. Based on history, tick prophylaxis was not used in 79.31% (46/58) of the anaplasmosis cases. Common clinical signs upon presentation at MAH included fever, lameness, anorexia, lethargy, vomiting, coughing, and diarrhea. A number of laboratory abnormalities were detected on Complete Blood Count (CBC) and blood chemistry. The most common CBC abnormalities included thrombocytopenia, eosinopenia, lymphopenia, and decreased plateletcrit. A plethora of blood chemistry abnormalities were detected, but elevated alkaline phosphatase (ALP) was the most common. Overall, the results of this research will help to improve the understanding of anaplasmosis in Pennsylvania and in-clinic diagnostic approaches that can be used to confirm a diagnosis.