Two types of heartworm infections occur in dogs; Dirofilaria immitis and Angiostrongylus vasorum. Dirofilaria immitis is a disease spread by mosquitoes in warmer climates, and does not occur naturally in the UK ( but must be considered in animals travelling back to the UK from abroad under Pet Passports, but Angiostrongylus vasorum has been seen in the UK with increasing frequency.
Angiostrongylus vasorum, sometimes referred to as French Heartworm lives in the heart and pulmonary arteries of affected dogs and is contracted by eating snails and slugs which are contaminated with the parasite.
In fact the large numbers of foxes that we currently see in our gardens and streets, eat slugs and snails, and then pass the parasite in their faeces back to re infect more slugs and snails.
The expanding numbers of foxes may well have contributed to the increasing frequency that we now see the disease in the pet dog population in the UK.
Dogs cannot contract this disease from foxes ( unlike Sarcoptic mange), but from ingestion of slugs and snails contaminated with the immature stages of the worm.
Once infected the worm may cause a variety of signals, varying from bleeding disorders, through to coughing, breathing disturbances and heart failure. Provided antiparasitic agents are given early enough, or preferably routinely the condition is very treatable.
Recently we were presented with a patient affected at the clinic. Here is Ginnys’ story.
Ginny a 10 year old Springer Spaniel presented with swelling of her right eye, and pain, of sudden onset. Although the owner could see the eye sweling in fact on examination it was obvious that the eye was being displaced forwards by swelling behind the eye.
Ultrasound examination of this area identified no abscessation, and no neoplastic or cancerous tissue, and treatment for inflammation was prescribed, and surgical drainage of the area carried out. Initial response was good, and the eye swelling reduced, but within 3 days she began to bleed from the drainage site.
Bleeding was controlled, and Ginny appeared to make an uneventful recovery.
Four weeks later, Ginny was represented, as she was now bleeding from a small wound to her nostril- this slow bleeding continued for several days prompting investigation for a bleeding disorder. Blood results identified a coagulation disorder characteristic of infection with Angiostrongylus, and although we never managed to identify the parasite in faecal samples as it is intermittently shed, the response to treatment was immediate and curative.
Left untreated even this small wound would have resulted in death due to bleeding and anaemia.
Routine topical antiparasitic treatments can eliminate infection as well as prevent disease and are easy to apply and also protect from fleas