Four Stages of Heartworms in Dogs

Stages

• The four stages of heartworm disease in a dog are determined by the severity of the heartworm infestation, the age of the dog, and the animal’s overall health. During stage 1, a healthy young dog demonstrates no symptoms and only small changes can be perceived on an X-ray. The severity of the disease is considered mild. Stage 2 is when the disease appears on X-rays, but the dog shows only mild symptoms, predominately a cough. The infection is moderate at this stage. By stage 3 the dog will have a hard time breathing, weight loss, more coughing, and liver and/or kidney damage. The damage from the infection is severe and can be clearly seen on an X-ray. During stages 1, 2, and 3 the dog can still be treated with medication, but by stage 4, the dog is in critical condition, often in shock. The only hope for treating heartworm disease at this stage is surgery.

Treatment

• Immiticide works quickly and is generally administered during stage 1. Two injections are given deep in the muscle of the lumbar region, near the spine. The shots are given 24 hours apart, and the dog must then be strictly confined for the following four to six weeks to ensure that its physical exertion is minimal. Antiparasitic medication, such as ivermectin, is a preventative for heartworm as well as an early stage treatment. When given orally once a month, it slowly kills off the worms over a period of one or two years. It is not necessary to confine dogs taking this medication. In severe cases of heartworm disease, the heartworms are surgically removed, followed by one of the more standard treatments.

Prevention

• Prevention of heartworm infestation is achieved by giving your dog a monthly antiparasitic medication. Heartworm larvae are transmitted by mosquitoes, but even if your dog doesn’t live in an area with a heavy mosquito population, it is best to administer these preventative pills year-round for the rest of the dog’s life.