Heartworm Testing, Prevention and Treatment
Heartworms are parasites which mature into adults inside the heart of a dog. They are carried from dog to dog by mosquitos. The infestation begins when a mosquito harboring heartworm larvae bites a dog. In the process, the larvae are released into the dog under the skin, or into tiny blood vessels, while the mosquito feeds on the dog’s blood. These larvae mature in stages, leading up to their migration towards the heart, where the adult heartworms take up residence. If there are enough heartworms in the heart, they will begin to obstruct the vessels. A dog’s heart which is obstructed in this way will need to pump harder and harder to overcome the new resistance against blood flow. In time, this will result in the failure of the heart.
Heartworms damage not only the heart and the major blood vessels which surround it, but also the lungs. They can cause inflammation of lung tissue, known as pneumonitis. While its lungs are inflamed, both the dog’s ability to breathe and to exchange oxygen normally is impaired. Pneumonia and heart failure can both cause the dog to cough, so annual testing for heartworms is critical in order to achieve early intervention.
A dog may live for months or even years infested with heartworms, but without treatment, they are always fatal. Additionally, if the dog does receive treatment, the damage already done at the time of the treatment will remain. The quality and quantity of life after treatment depends upon the number of worms present and the damage they have already caused at the time of treatment. If the number of heartworms is few, and the damage they have caused is minor, then a dog can live for a normal lifespan, and will be less impacted by treatment. On the other hand, dogs with more extensive pre-treatment damage may need medication for the rest of their lives.
Fortunately, heartworms are very easy to prevent. Heartworm prevention generally requires nothing more than monthly medication. Preventative Medications kill any larval heartworms present before they have a chance to develop into adult heartworms. In most cases, these medications are safe and effective, and some of them offer protection from other parasites as well. To counter our region’s year-round population of mosquitoes, we strongly recommended year-round preventative medication.
Heartworm in Cats
Although cats do not typically host heartworms, they can become infected in the same way as dogs, that is, through the bites of infected mosquitoes. Since cats do not host heartworms naturally, heartworms will often fail to mature in cats. However, it is possible for them to do so. When heartworms do mature in cats, they tend not only to reach maturity in the heart, but also the cat’s lungs. Cats will typically show different symptoms of heartworm infestation from dogs. The signs of heartworms in cats are not always definitive, which leads to increased difficulty in diagnosis. Some possible signs of heartworms in cats include chronic vomiting, coughing, or asthma-like signs.
Unfortunately, sudden death is among the more common signs for cats. Even if heartworm infection is diagnosed in cats before they die, no known treatments can kill the worms without also posing a great risk of killing the cat that hosts them. The best treatment which does not pose this risk can only provide relief for whatever symptoms occur. However, safe heartworm prevention is available for cats at risk.