Heartworm disease in dogs

Heartworms (Dirofilaria immitis) are large roundworms that live in the right side of the heart and the blood vessels that supply blood to the lungs. The mature form of the worm can grow to a length of 23-30 cm, and in severe cases a dog may be infested with hundreds of worms.

Heartworm infestation can potentially cause damage to the heart, lungs and liver as well as obstruction of blood flow and eventually, death due to respiratory and heart failure.

Although dogs are the natural hosts for Heartworm, cats will occasionally become infested as well.

Heartworms are spread by mosquitoes. Mosquitoes are active in warm temperature environment. The high-risk areas in Canada are the Okanagan valley in British Columbia, southern Ontario, southern Quebec and Manitoba. Heartworm is also found in most states in the US.

A mosquito bites an infected dog, sucks its blood and acquires the worm. The worm develops in the mosquito’s body, and passes to an uninfected dog with mosquito’s saliva in its next bite. The worm in immature form travels through the blood stream and lodges in the right side of the heart and the blood vessels that supply the lungs, where it matures and multiply.

There are no symptoms at all until the disease is very advanced. Then, the symptoms are those of congestive heart failure:  dull coat, lack of energy, coughing, difficulty breathing, perhaps fainting spells and an enlarged abdomen.

A blood test available and is the most common method of diagnosis. It takes approximately 6 – 7 months from the time of infection until the test becomes positive. The dead worm poses a lot of potential damage by breaking loose, obstructing blood vessels and causing respiratory failure and death.

Treatment for Heartworm disease is available. However, treatment is costly and not without risks. The treatment consists on series of injections. While on treatment the dog has to be kept on strict activity to allow the body to absorb the dead worm.

Prevention is the Key, Preventive drugs are highly effective and when regularly administered will protect more than 99 percent of dogs and cats from Heartworm. I

recommend to administer the preventative medications throughout the warm months of the year ,in the active period of the mosquitoes. Here in our beautiful warm Okanagan Valley the medications should be administered between April- October.

consult your veterinarian about diagnosis and prevention of canine Heartworm disease.