Animal Hospital Heartworm Disease Update

In the Niagara Region April is the time of the year when Welland veterinarian start to check dogs  for exposure to heartworm disease that they may have been infected with during the previous mosquito season. If your dog was infected last mosquito season, they won’t show any clinical evidence of a problem at this early stage of the disease.  Diagnosis is based on a laboratory blood test that detects antibodies to the parasite.  As with any disease, the earlier a diagnosis is made and treatment is begun, the better the chances your dog will have for a full recovery. Give your Welland veterinarian a call early this spring so that your dog can be tested for heartworm disease.

Heartworm disease begins when a mosquito feeds on the blood of an infected dog/coyote/fox.  When the mosquito stops by for a meal it  inadvertently sucks up a number of immature Heartworms circulating in the blood. These are known as Microfilaria.  Once inside the mosquito’s body, the microfilaria go through a number of growth stages and eventually migrate into the salivary glands of the mosquito.

When this mosquito bites another dog, the microfilaria move from the salivary glands in the mosquito’s mouth to the bloodstream of the dog.  The microfilaria have now infected the new host with Heartworm disease.  These Microfilaria develop further into adult Heart Worms which  arrive in the heart.  It is in this location  where they stay and grow rapidly in length and size.  Some pets are infected with numerous worms. They can form a  mass of twisted and intertwined heartworms which can severely obstruct normal blood flow.  Some adult female worms have been known to grow up to 14 inches long.  According to a Welland veterinarian the adult heartworms will continue to live in the heart until they die ( 5-7 years ).

As heartworms grow larger in the heart and in the main arteries supplying the lung they cause great mechanical obstruction to blood flow, damage the surrounding tissue of the heart and vessels and cause substantial inflammation. The smaller your dog is the smaller their heart is, therefore it takes fewer worms  to cause a problem.  As the Adult Heartworms mature they produce young heartworms that travel in the blood stream, these can end up invading tissues such as the eyes, kidneys, liver and brain.

Over a period of time (depending on how many worms a dog has been infected with) the tissue of the heart can become weak and can fail.  In most cases of untreated heartworm disease dogs will die of failure of their heart, lungs and circulatory system caused by heartworm infection.  A Welland Veterinarian has the greatest concern becuase dogs with heartworm infection only begin to show noticable symptoms of the disease when it is in more advanced stages.  This is why yearly testing for the disease is so critical.

It is much simpler to prevent heartworm disease than to treat it. At the Main West Animal Hospital we can provide excellent medications to help prevent development of Heartworm disease. The most common preventatives on the market kill the immature heartworm larvae before they can cause a problem. The choice of which preventative to use will be determined by a discussion with your Welland veterinarian. Ideally puppies should be started on monthly heartworm prevention by 8 weeks of age.  Dogs older than 6 months old should be tested yearly for Heartworm Disease (even if they are given preventative medication) and they should be using preventative medication throughout the Mosquito season (In Niagara- May through December).