Diagnosis of canine heartworm disease:: A comparative study between ELISA and Woo tests

In order to compare the accuracy of ELISA and Woo tests for the diagnosis of canine heartworm disease, blood samples from 69 dogs with and without clinical signs were evaluated. Statistically, dogs were separated into two groups of different ages and breeds. The first group with 49 suspected cases of filariosis, was selected from the Policlinica Veterinaria Universitaria and one private veterinary hospital in Maracaibo. The second group was randomly selected in the Santa Rosa de Agua community in the same city. Whole blood sample in EDTA tubes were collected from the cephalic vein. Hematological variables studied were: packed cell volume (PCV), white blood cell count (WBC count) and differential leukocyte count (Diff). Microfilariae in wholeblood were demostrated by woo test. Blood plasma was examinated for dirofilaria immitis antigens using ELISA test (Assure/ch, synbiotics, co). Thoracic lateral and dorsoventral radiography were performed in positive cases to identify animals with cardiovascular anomalies. Data was analyzed with the SAS statistical program. From a total of 69 dogs studied, two cases (2,89%) were ELISA negative and Woo positive. Fourteen dogs were ELISA positive and Woo negative, meaning that 20,28% were occult infections. Fifteen positive dogs (21,73%) were detected with both tests and 38 (55%) dogs were negative. Dirofilariosis was detected in 44,9% of the total dog population studied, 38.7% corresponded to group I and 55% to group II with 20% occult infection. Eosinophylia was present in 67,86% (P<0,05) of the 28 ELISA positive dogs. Eosinophylia also was observed in 64,71 % (P<0,05) of the 17 Woo positive dogs and in 63,6% of the group II positive dogs. The most frequent radiographic sign showed by total ELISA and total Woo positive dogs and by group II, was Right Heart Enlargement (P<0,05).