Heartworm season is here

Spring is here and so are those pesky bugs!

The Life Cycle of Heartworm

Heartworm is a parasitic round worm (Dirofilaria immitis) which lives in the heart and lungs of dogs and occasionally in cats, ferrets and other mammals. Mosquitos transmit the parasite from dog to dog. The parasite is a major problem in many regions of the North America and in other countries, especially in areas where mosquitoes are present year-round and areas with warm temperatures.

It takes 6 to 7 months after an infected mosquito bites a dog before the larvae develop into adult worms and are present in the heart and lungs where they cause severe disturbance to function. The adult worms lodge in the heart, lungs, and surrounding blood vessels and begin reproducing. Adult worms can grow up to 12 inches in length, can live 5 to 7 years. A dog can have as many as 250 worms in its system! Dogs may go into heart failure, and marked coughing and loss of health are common. Dogs with very light infestations may be free of symptoms. The adult worms produce tiny “microfilariae” which enter the general blood circulation from where they can be acquired by another mosquito when it sucks blood. The life cycle requires an incubation period in the mosquito and is completed when the infected mosquito goes on to bite another dog (the next host).

Treatment

Treatment of an established case of heartworm is involved, expensive and not always effective, but preventative medication is effective, safe, easy to administer and can be used in puppies from 6 weeks of age. Not treating heartworm in timely fashion will lead to heart and lung damage and eventually death.

Prevention is by far the best course of action and is recommended by veterinarians and by the American Heartworm Society. Heartworm preventative is not costly (about $35 to $80 per year, depending on the dog's size). Although all states in the US and many provinces in Canada have had cases of heartworm, some areas are more severely affected than others. Central Oregon is an area where we have limited exposure but if you plan to travel with your dog to an area with heartworm, then having your dog on a preventative would be a good idea.