Dogs, even your extremely fast and powerful Weimaraner, are considered the most definitive host of heartworms. Heartworm is a parasitic, small thread-like worm that commonly affects dogs but can also infect cats and other canids such as wolves, coyotes and foxes. It can also infect other animals such as ferrets, sea lions and even humans.

Heartworm disease is transmitted from animal to animal, although not directly from one dog to another. Mosquitoes of different species are the vectors of this disease. When a mosquito bites an infected animal, microfilariae enter into that mosquito's system. The microfilariae develop into larvae for about two weeks. The larvae are then injected into another animal through the mosquito's bite. As the larvae mature into adults, they move through the animal's body, reaching the blood vessels of the lungs and later the heart. A heartworm may reside in the pulmonary artery of its host for many years.

Clinical signs of heartworm disease may not be recognized in the early stages of the disease. After repeated mosquito bites and as the disease progresses, infected dogs may show signs such as cough, reluctance to move or exercise, difficulty breathing and reduced appetite which eventually leads to weight loss. Infected dogs may also seem to tire quickly after exercise.

Apart from the patient history and varied clinical signs, the presence of heartworms can be detected through blood tests: filtration test and occult test. Filtration test finds microfilariae in the blood while occult test finds adult worms in the heart. Ultrasound and x-rays of the heart and lungs are occasionally used.

Most dogs infected with heartworm disease can be successfully treated except the most advanced cases. Treatment includes killing all adult worms with an adulticide and all microfilariae with a microfilaricide as well as treating the problem related to heart, liver or kidney. Infected dogs with more severe cases can be successfully treated but there is an increased possibility of complications and mortality. Surgical removal of adult heartworms can also be done in advanced cases.

Heartworm disease is extremely fatal and serious disease but fortunately, a preventable disease. Heartworm disease can be prevented through various veterinary drugs. The prevention should be administered from the month of the onset of mosquito season until a month after the end of the season. Ask your veterinarian for suggestions as to the best method of prevention based upon your pet's risk factor. These veterinary drugs are highly effective in preventing the disease especially when administered regularly.