Heartworms Are in Oregon Too!

Heartworms are caused by a parasite called Dirofilaria immitis, which is carried by mosquitoes that have bitten infected animals. The worms reside in the blood of the heart and nearby vessels of infected dogs. Heartworms can damage the heart and cause liver, kidney, and lung disease. They thicken the blood vessels in the lungs, lowering blood pressure and increasing the heart’s workload. Fluid builds up in the lungs and disrupts the circulation of blood to organs, causing damage. Heartworm disease progresses slowly, often with no visible symptoms until the advanced stages. If your dog’s heartworm test is positive treatment is usually recommended. It kills the adult heartworms in the heart and adjacent vessels. Approximately 1 month following treatment to kill the adults, the dog is returned to the hospital for administration of a drug to kill the immature heartworms (microfilariae). Seven to ten days later a test is performed to determine if microfilariae are still present. If they have been all killed, the treatment is complete. If there are still some present in the blood, treatment for microfilariae is repeated. After treatment your dog would need to be on strict exercise restriction for 1 month.

When a dog has been successfully treated for heartworms, you cannot sit back and relax because dogs can be reinfected. Therefore, it is essential to begin a heartworm prevention program. We recommend two products for the prevention of heartworm disease: Interceptor™ and Sentinel™. One of these should be started immediately after the treatment of an infected dog is complete. All dogs (beginning in puppy hood) should be on heartworm prevention year ‘round and tested for heartworms every 2 years. A heartworm test is required before an adult dog can begin a prevention program and if there is any break in the prevention program. Canine heartworm disease occurs all over the world. In Oregon, heartworm disease is found regularly in Southern Oregon. In the Hillsboro area, we have seen cases of positive dogs that have moved here from higher risk areas. Even though this is not a prevalent problem here it should not be ignored but prevented.