PREVALENCE, DRUG PRESCRIPTION PATTERNS, CLINICAL FINDINGS IN CANINE GASTROENTERITIS AND GENETIC ANALYSIS OF CANINE PARVOVIRUS ISOLATES IN NIGERIA

Abstract

Gastroenteritis is a frequent presentation in canine practice with challenges in its diagnosis and management. Canine Parvovirus (CPV) is a common cause of gastroenteritis, mortality, and economic losses with recurrent vaccination failure. Due to limited documented information on the condition in Nigeria, this study was designed to investigate the prevalence, aetiologies, clinical presentation, and management of canine gastroenteritis, and characterise CPV isolates in Nigeria. Retrospective data of 3,882 dogs presented to ten veterinary clinics from seven locations (Abeokuta, Abuja, Ibadan, Jos, Makurdi, Onitsha and Warri) in Nigeria from January to December 2016 were analysed for prevalence and drug prescription patterns for gastroenteritis. Also, 157 cases of gastroenteritis were prospectively evaluated for their aetiologies and usefulness of clinical pathology in prognostication using standard procedures. Electrocardiograms of 40 dogs with confirmed Canine Parvovirus Enteritis (CPE) using rapid in-clinic assay kit and polymerase chain reaction were evaluated for cardiac involvements. Protocols of CPV vaccination failure (94/157) were examined for appropriateness. Polymerase chain reaction was done on the vaccine and positive clinical samples using primers specific for parvoviral DNA and subjected to sequencing and phylogenetic analysis. Data were analysed using descriptive statistics, Chi-square, and logistic regression at α0.05. Prevalence of gastroenteritis was 41.2% and was influenced by dog breed (α=0.014), vaccination status (α=0.047) and period of the year (α=0.03). Polypharmacy was high with an average of 5.4 drugs prescribed in each treatment regimen. Antibacterials (48.3%) and antiparasitics (23.8%) were extensively prescribed. Canine parvovirus (92.9%), gastrointestinal parasites (12.1%), coronavirus (2.6%), liver disease (0.6%) and undetermined causes (1.9%) were identified as the aetiologies of the clinical cases. Colic (Odds Ratios [OR]=0.01; α=0.001), leukopaenia (OR=3.5, α=0.01), hypoalbuminaemia (OR=7.1; α=0.006) and pancytopaenia (OR=0.2; α=0.002) at initial time of presentation were prognostic for prolonged duration of management and poor outcomes. Electrocardiographic changes comprising ST-depression (7.5%), tall T-wave (27.5%), S-wave deepening (20.0%), prolonged QT-duration (25.0%), prolonged P-wave duration (17.5%), and tachycardia (15.0%) were seen in 70.0% of confirmed CPE cases. Vaccination failure was associated with the protocol adopted, with one-, two-, three- and four-dose protocols having failure rates of 51.1%, 28.7%, 19.1% and 1.1%, respectively. Sequence and phylogenetic analysis of 11 clinical samples showed that CPV-2c (63.6%) and CPV-2a (36.4%) were the predominant strains and were genetically closely related to Asian and European strains. Amino acid changes (T301S, D305Y, Y323I, Q370R, T440A, Y444S and I447M) were observed in the VP2 protein of the clinical isolates. The vaccines that were sequenced contained CPV-2a only. Canine parvovirus and gastrointestinal parasites were the leading causes of canine gastroenteritis in Nigeria. Prescription patterns used in managing several cases were injudicious. Presentation with colic, hypoalbuminaemia and leukopaenia are useful indicators for poor prognosis and prolonged management. Assessment of cardiac functions in canine parvovirus enteritis is recommended. Inappropriate vaccination protocols, viral mutations, and incorporation of only CPV-2a strain in vaccines licensed for vaccinating dogs against canine parvovirus portends risk of vaccination failure.