Creature Feature
The truth about heartworms and what to do about them

Dr. Dan Meakin
By Dr. Dan Meakin

Heartworm Disease is becoming increasingly more common in this area.

The heartworm lives in the right side of the heart, and in the nearby large blood vessels. The female worms produce large numbers of immature heartworms, which circulate in the blood. These young worms, called microfilaria, are ingested by a mosquito when it bites an infected dog.

After living in the mosquito for 10-14 days, the microfilaria can infect another dog when the mosquito feeds. It takes about 6 months for the worm to become an adult after they are injected by the mosquito.

Dogs are infected with Heartworms when bitten by a mosquito carrying the immature Heartworm larvae.

There obviously is no way to keep your dog from being bitten by mosquitoes, and outdoor dogs are especially at-risk for contracting heartworms.

Fortunately, a preventive medication can be given to dogs which destroys the “baby” heartworms that can be injected into the dog by the mosquito before they have time to migrate through the body and grow up in the heart of your dog.

The important thing for dog owners to remember is that a great deal of damage can occur before any obvious signs are noticed. Delayed treatment may result in heart failure and/or permanent damage to the liver, lungs, and kidneys – with eventual death.

The signs of heartworm disease, which you are most likely to notice, include coughing, sluggishness, rapid tiring, and labored breathing.

Diagnosis is made by finding the microfilaria in a blood sample. It will be six or seven months after exposure before microfilaria can be detected in the blood.

Treatment for heartworms consists of destruction of the adult worms with intravenous medication given at the hospital. The dog usually must stay at the hospital for 3-4 days.

After treatment, the adult worms die and are carried by the blood to the lungs where they lodge in small blood vessels. There they decompose and are absorbed by the body over a period of several months. Reactions to the drugs are not uncommon, and there is always some risk involved in treating a dog for heartworms. Following treatment, complete rest is needed to prevent lung damage from the dead, decomposing worms for 6-8 weeks.

We strongly recommend using a safe preventive medication. These medications are available as a chewable treats or as part of a topical application from any veterinarian. Heartworm prevention has become quite economical, and only needs to be given once per month, while treating a dog for heartworms can be risky and is always very expensive.

You can give your dog heartworm prevention on the first day of each month to make it easier for you to remember!

If you forget, please give the medication as soon as remembered, provided it has been less than two months since the last dose. If it has been longer than two months since the last dose, you must bring the dog to the clinic for a blood test before again resuming administration of this medication. In this area, we recommend that the medication be given all year long since our mosquito season is quite variable.

Dr. Dan Meakin is the owner of All Creatures Animal Hospital, 1894 Ohio Pike in Amelia. Call (513) 797-PETS.