1Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
2Department of Parasitology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
3Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
4Department of Clinical Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
Between July and August 2009, a total of two hundred crossbreed dogs in three contiguous littoral provinces of Guilan, Mazandaran and Golestan were sampled. Circulating antigens and/or microfilariae of Dirofilaria immitis were found in 25.5% of dogs in the whole studied area. The highest infection rate was found in Guilan (51.42%), followed by Golestan and Mazandaran provinces (15.38% and 7.69%, respectively). Prevalence values were not influenced by age and sex in the whole area; the values detected in low altitude regions were 4.6 times the values found in high altitude areas. This is the first detailed survey on canine dirofilariasis in these coastal provinces of Iran. Guilan province, with its certain hyper endemic counties, was shown to be the most endemic for canine heartworm infection in the country. hemoprophylaxis should be considered for the dog population in these areas.