Once considered a parasite of southern climates, the heartworm parasite is now recognized as a major global pest affecting dogs, cats, wolves, coyotes, foxes, and other animals. The areas with large mosquito populations have a high rate of infestation.
To make owners aware of this serious disease, a majority of veterinary clinics will have many pictures posted in the clinic, however many owners still gamble that their dogs will never be bitten by an affected mosquito (“My dog never goes outside”), and not contract heartworm.
Heartworm prevention is simple and involves a small blood draw to ensure that the parasite is not present, then regular dosing with preventive medication.
Heartworm infestation is very dangerous. Untreated dogs die, and treated dogs go through a long treatment and discomfort while the worms are killed and eliminated from the body.
About the parasite:
Parasites need to go through a few life stages before becoming adults. The mosquito is an intermediate host of the larval stage called microfilaria. The mosquito ingests the larva from an infected dog and then when it takes the next meal from an uninfected dog, it can transmit the parasite. Microfilaria (the larvae) will go through a few stages before becoming an adult, when it travels to the right side of the heart to reproduce. An adult worm can be 12 inches long and reside in the dog’s heart for years.
The time lag between the initial infestation with the larvae and reproduction by adult is 6-7 months. Females will release thousands of larvae that can stay in circulation for months waiting for the mosquito to ingest them. In the mosquito, they will undergo a series of changes that can take 10 days in warm climates and 6 weeks in colder climates.
Symptoms of Heartworm Disease:
The first sign of heartworm infestation may not occur for a year or more from the initial infection, and starts with a soft cough that gets worse with exercise, and is often dismissed by the owner. More active dogs may show symptoms of infection earlier than less active dogs. The cough will get worse, and can lead to fainting from exertion. Dogs become tired very easily, are weak and listless, start losing weight, and may cough up blood in advanced cases. These pets often do not want to go for walks or run in the park. The progression is dramatic, leading to congestive heart failure. At that point the dog is in very grave danger.
Where is Heartworm found?
The disease is present in every continent (with the exception ofAntarctica) where these four factors are present:
- Susceptible host population (dogs)
- Reservoir of the disease
- A population of vectors which spread the parasite (mosquitoes)
- Climate that supports the parasite’s life cycle
The dog is considered the definitive host and reservoir of the disease.
There is a Heartworm test, which is a simple and quick blood test recommended to be done in the spring before the mosquitoes return. It is important to test for the presence of Heartworm before starting any preventive medications. Radiographs (X-rays) can also show a large population of worms in the heart or lungs.
Treatment for existing heartworm can be risky depending on the severity and stage of the disease. Medications can be used for treatment, but can put the dog’s health at risk. Animals can die as a side effect of treatment., making prevention extremely important.
How can I prevent Heartworm Disease?
This is the best option to deal with this devastating disease.
There is topical or oral medication that is very effective in the prevention of the disease. Many of these medications also treat intestinal parasites.
Contact us at Heartland Veterinary Clinic to discuss heartworm testing and the appropriate preventive program for your pet.