Although heartworm is often thought of as only affecting dogs and cats, a ferret may also be infected by this dangerous parasite. Heartworms (Dirofilaria immitis) mature in the chambers of the heart and block major arteries to the lungs, causing heart failure and death. Because a ferret's heart is so small, it takes only one or a few worms to cause death.
Mosquitoes become infected with tiny immature forms of the heartworm, called microfilariae, when they bite an infected animal. Inside the mosquito, the microfilariae develop into larvae. When an infected mosquito bites a new animal, these larvae enter into the new animal's body. The larvae continue to grow and after about 3 months, they finish their migration to the heart of the animal. Here they grow into adult worms, sometimes reaching a length of 14 inches. Within 6-8 months after first entering an animal, heartworms mate and produce new microfilariae, which are released into the bloodstream.
How your veterinarian will diagnose heartworm in your pet
Your veterinarian may use a combination of factors to determine whether your ferret has heartworm disease, including history, signs, x-rays, and a combination of blood tests commonly used for cats and dogs. Blood tests, by themselves, are not enough to make a diagnosis of heartworm disease. The same blood test often used in dogs is not as accurate in ferrets, and the test most often used in cats, because of its sensitivity, may show positive results when the ferret does not have the disease.
Treatment for ridding your pet of adult heartworms is available, but it is an extremely risky procedure in ferrets because of their tiny blood vessels. Due to the high risk of treatment, prevention is especially important for ferrets.
Ferrets who spend any time outside are more at risk for heartworm disease, but even indoor ferrets may encounter mosquitoes that transmit the disease. Talk to your veterinarian about the best heartworm preventive regimen for your ferret. Generally, preventive medications kill the larvae transmitted to ferrets by mosquito bites, but do not kill adult heartworms.
| Some signs that a ferret with heartworm may exhibit include:
Other heart diseases, specifically cardiomyopathy, may also cause some of these symptoms.
- Chronic cough
- Shortness of breath
- Exercise intolerance
Your veterinarian will also let you know when to give the medication, usually the entire year. Mosquito season depends on where you live in the country - warmer and humid climates will have a longer season than other, cooler parts of the United States. Areas such as Florida have mosquitoes all year long, and thus ferrets that live there must be on year-round preventives.
To decrease the risk of heartworm disease and decrease your ferret's exposure to mosquitoes is keeping him indoors or in a screened area. If you take your ferret outdoors at all during mosquito season, make sure you avoid times when mosquitoes are most active, such as at dawn and at dusk.