Ivermectin is one of the most effective and widely used antiparasitic agents ever discovered because of its broad spectrum activity against nematodes and arthropods. Therefore, the study was conducted to determine the comparative anthelmintic efficacy of ivermectin by giving through oral and subcutaneous routes in clinically infected dogs and also to check the prevalence of gastrointestinal nematode in dogs in Bhubaneswar, Odisha. Total 154 dogs with clinical signs of gastroenteritis were examined for the presence of nematodal ova in their faecal sample and 64 were found positive (41.56 %). The screened dogs were divided in to two groups (n = 10 each), first group of animals were treated with ivermectin @ 0.5 mg/kg body weight by subcutaneous route and the second group with same dose of ivermectin through oral route. Efficacy of ivermectin was evaluated based on egg per gram (EPG), haematological and biochemical parameters. It is concluded that, Prevalence of gastrointestinal nematodes are high in dogs in the climatic condition of Bhubaneswar, Odisha. Ivermectin was found effective when administered through either of the routes. Haemato-biochemical parameters were restored after administration of ivermectin and also significant reduction in EPG was found in dogs treated with ivermectin by both the routes, but no significant difference was observed in EPG between oral and subcutaneous treated dogs in various intervals of study.