Parkway Animal Hospital's

PET OWNER'S GUIDE TO

Canine Heartworm Disease

---

• Adult Heartworms live in the right side of the heart.
• They are 6-14 inches long. Several hundred may be present in the dog!
• Heartworms impair blood circulation, resulting in damage to the heart, lungs, liver, and kidneys. Serious damage may occur, even before outward clinical signs are detected by the owner.
• Advanced signs include difficult breathing, coughing, tiring easily, listlessness, and loss of weight, and fainting.
• Heartworms are found throughout the United States. Year round in this region of the country.

After ingesting blood from and infected dog, the MICROFILARIA (“baby” heartworms) is transmitted to another dog or cat when the mosquito bites it. Once the heartworms mature, they begin reproducing additional microfilaria. This MICROFILARIA IS NOT DANGEROUS TO THE INFECTED DOG. A mosquito must ingest the microfilaria before they can become infectious. The mosquito must then inject the heartworm larvae into the susceptible pet. It takes 3 to 6 months for adult heartworms to develop in a dog after an infected mosquito bites it. Heartworms occur in all breeds of large and small, shorthaired and longhaired, inside dogs and outside dogs. Heartworms also now are known to infect 10-14% of the cat population. Diagnosis of Heartworms is by blood test to detect the “baby” heartworms in the blood. A special test to detect “occult heartworm disease” is sometimes required when heartworms are suspected, even if the initial screening test is negative, because a small number of dogs may have adult heartworms but yet have no microfilaria in the bloodstream. Treatment is very SUCCESSFUL when the disease is detected early. The adult worms are killed with an injectable drug given in a series of 2 injections. A few days later, the worms begin to die, and are carried by way of the bloodstream to the lungs where they lodge in small blood vessels. They slowly decompose and are absorbed by the body over a period of several months. Other injections are required to kill the microfilaria (baby heartworms) at a later time.

We strongly recommend oral once a month heartworm preventives, which also aid in the prevention of other internal parasites. It should be given all year long. Routine testing for heartworms once each year is needed by all dogs in endemic areas such as North Carolina.

1. Interceptor: This is a chewable tablet given once monthly. Interceptor protects against heartworm infection as well as 3 intestinal parasites – hookworms, roundworms, and whipworms. Because of its broad spectrum of parasite control and rare incidence of side effects, Interceptor is our #1 choice of heartworm preventative.

2. Heartgard: This is a chewable treat also given once a month. Heartgard protects against heartworm infection as well as hookworms and roundworms. This is a good choice of heartworm preventative for those dogs that don’t tolerate or don’t like the taste of Interceptor. It is our preventative of choice for dogs whose owners may have forgotten or delayed the heartworm preventative, as it has a slightly longer duration of protection than Interceptor. It is also safe to use in dogs that already have heartworm disease so they don’t continue to develop more heartworms.

Note: You can sign up with Pet Portal, found at the bottom of the page, to get a monthly reminder to give the heartworm preventative.