Heartworm disease (dirofilariasis) is a serious and potentially fatal disease in dogs. It is caused by a blood- borne parasite called Dirofilaria Immitis.
Heartworms live in the heart and pulmonary arteries of infected dogs. They can live up to 5 years, producing millions of offspring (microfilaria). These microfilariae livemainly in the small vessels of the blood stream. The immature heartworms cannot grow into adults without the involvement of mosquitoes.
The female mosquito bites the infected dog and ingests the microfilariae during a blood meal. The microfilariae develop further for 10 – 30 days in the mosquito. When the mosquito bites a dog the infective larvae enter the blood steam and move to the heart and adjacent vessels where they grow into maturity over 2 -3 months completing the cycle.
The disease is seldom diagnosed in a dog less that one year of age because it takes 5 – 7 months for young worms to mature. Adult heartworms cause disease by clogging the heart and major vessel leading to he heart. They interfere with the valve actions in the heart. By clogging the main blood vessels, the blood supply is reduced to other organs and can cause malfunction.
Most dogs do not show clinical signs for as long as two years. Unfortunately by the time clinical signs are seen the disease is well advanced. The signs of heartworm disease depends on the number of adult worms, location of worms, length of time present, and the degree of damage to the heart and other organs. The most obvious signs are soft dry cough, shortness of breath, weakness, nervousness, listlessness and loss of stamina. With severe infections dogs may die suddenly during exercise or excitement.
Diagnosis of heartworm disease can be made by a blood test run in the veterinary clinic or laboratory. If a dog is positive on the blood test then additional blood chemistry, EKG and x-rays may need to be preformed to determine the severity of the disease.
Treatment of heartworm disease in dogs is done by giving an injectable drug for 2 days that kills the adult heartworms. The adult worms die in a few days and start to decompose. They are carried to the lungs and small vessels where they are eventually reabsorbed by the body. It is essential to keep the dog quiet and not allow exercise for one month following treatment. The first week is very critical because the worms are dying. Other supportive care may be necessary depending on how the dog reacts to the treatment.
All of this can be prevented by giving your dog a monthly preventative for heartworms. It is critical that the medication be given each and every month at the same time all year long. Only start the preventative after your dog has had a negative heartworm test and consulting your veterinarian. If you miss a dose contact your veterinarian for advice.
Call us today to schedule your dogs heartworm test.