Heartworms are one of the most dangerous types of parasites seen in dogs. They are worms that live inside of the heart and blood vessels of your dog. Heartworms can cause damage to your dog’s heart and lungs. It can be a fatal disease.
How Are Heartworms Transmitted to a Dog?
Heartworms can be passed to your dog if your dog is bitten by an infected mosquito. It takes only one bite to pass the parasite to your dog if your dog is unprotected.
Mosquitoes become infected with heartworm larvae when they feed from an infected animal such as another dog that has heartworms. Once infected, the maturation process for the heartworm continues inside of the mosquito and the mosquito will eventually be able to infect your dog when it bites.
When bitten by an infected mosquito, your dog will be infected with a larval stage of the heartworm. Once this larval stage enters your dog, it will continue to mature and will eventually find its way to your dog’s heart, where it will live as an adult heartworm. These adult heartworms will reproduce, sending heartworm larval (also called microfilaria) into your dog’s bloodstream.
Once your dog has microfilaria circulating in his blood, he can pass heartworms on to any mosquitos who bite him. At this point, your dog becomes a threat to other animals in the area because of his potential to spread the disease. However, heartworms require a mosquito to be passed from one dog to another. They are not passed directly from dog to dog under normal circumstances.
What Are the Symptoms of Heartworm Disease in Dogs?
Some dogs infected with heartworms show no signs of disease. They appear to be perfectly healthy and happy. However, heartworms have the potential to cause serious damage to the heart, blood vessels and lungs of an infected dog.
Symptoms that are most commonly seen in dogs suffering from heartworm disease include:
- exercise intolerance, tiring easily
- difficulty breathing
- cyanosis (purple coloration of gums resulting from a lack of oxygen)
- bloated, fluid-filled abdomen (a condition known as “ascites”)
How Is Canine Heartworm Disease Diagnosed?
In dogs, heartworm infection can be diagnosed relatively easily with a simple blood test. The blood test is known as a heartworm antigen test and detects a protein caused by the heartworm that is found in the dog’s blood stream.
If your dog tests positive for heartworms, additional testing may be required to evaluate how much damage has been done by the heartworms. This testing may include additional blood screening (including a complete blood cell count and blood chemistry profile) and chest radiographs (x-rays).
Is Heartworm Disease Treatable?
If your dog is infected with heartworms or is suffering from heartworm disease, a decision regarding treatment will need to be made. This decision will need to based on your dog’s physical condition and the availability of medications needed for treatment. In recent months, the medication that is most effective in treating heartworm disease, a drug called Immiticide, has been difficult and sometimes impossible to obtain.
For more information on treatment options, please read Canine Heartworm Disease Treatment.
Can Heartworms Be Prevented?
Fortunately, heartworms are easily prevented and there are numerous medications that are effective in protecting your dog from infection when given monthly. There is also an injectable heartworm preventive medication that is administered every six months.
It is far healthier and safer to prevent heartworm infections for your dog. Both heartworm disease and heartworm treatment (i.e. treating an existing infection) can be fatal for your dog.
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