Adult Dirofilaria repens in a subcutaneous granuloma on the chest of a dog

A 10-year-old, 9 kg, intact male crossbred dog was treated for nasal mites with milbemycin oxime using a dose of 1 mg/kg bodyweight orally, three time s at 10-day intervals. One month after the initiation of this treatment a s ubcutaneous nodule developed on the sternum of the dog. The nodule was remo ved and found to contain a single, 82 mm long, thread-like nematode. Severa l exotic parasites were suspected as possibilities because the dog had been imported to Norway from South Africa. Microfilariae were not detected in t he blood and heartworm antigen tests were negative. The worm was identified morphologically as an adult, female Dirofilaria repens, This is the first report of D repens from Norway. The case is of interest because of the diff erential diagnostic problem it posed and because infestation was recognised following treatment of another parasitic condition with a broad-spectrum, antiparasitic drug. In addition, the case provides a reminder of the necess ity to be aware of geographical differences in disease occurrence which can produce unexpected disease in non-endemic areas as a consequence of increa sed international travel with pets.