Dog Heartworm Disease is a clinical condition in dogs caused by a roundworm, Dirofilaria immitis, which resides within the dog’s heart and lungs. This disease, a serious and possibly fatal veterinary problem, is associated with dogs, coyotes and foxes. Canine Heartworm is transmitted by the bite of an infected Western Treehole Mosquito.

The adult worm lives in the right side of the heart and the adjacent large blood vessels and lungs, where it may attain a length of 6-12 inches.

Many other mosquito species feed on dogs, but the Western Treehole Mosquito is the most common carrier of heartworm.

The outward symptoms of the disease are not noticeable in most cases until reduced blood flow caused by adult worms damages the heart, lungs, liver and kidneys. Advanced symptoms of heartworm may include: rapid tiring, shortness of breath, chronic soft dry cough, listlessness and weight loss.

If you live in or travel to areas where treehole mosquitoes occur, check with your veterinarian regarding treatment and prevention. Drugs are available to prevent the disease, and it is curable if diagnosed in the early stages.

In the San Francisco Bay area, the time of highest risk for dogs to contract heartworm is April through August; however, unseasonable rainfall may extend this period.

• Cause: Disease caused by a mosquito transmitted filarial worm that primarily affects dogs.
• Incubation: period – none. 70 to 90 days for the worms to become mature in dogs.
• Symptoms: Long term symptoms: chronic cough that is aggravated by exercise, unusual tiring after exercise, and shortness of breath.
• Diagnosis: By veterinarian.
• Treatment: With anti-filarial drugs.