Heartworm disease is caused by a potentially dangerous parasite that infects many dogs each year when proper precautions have not been taken by their owners to protect them. Newborn puppies are also in danger of getting heartworm if they are living in, or are exposed to, areas where any heartworm-carrying mosquito lives.
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Misconceptions
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Puppies cannot get heartworms from their mother, before or after birth. A puppy, as with any dog, can only get heartworms from being bitten by a mosquito that is carrying the parasites. Mother dogs can pass intestinal parasites to their puppies, but heartworms live in the atrium and the major vessels that bring the blood to and from the lungs, not in the intestines.
Life Cycle
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Adult heartworms of both sexes will mate and produce thousands of microfilariae (babies) within the heart and major vessels of the dog. These microfilariae cannot grow to adulthood inside the dog. A mosquito has to bite an infected dog, suck up the microfilariae and carry them inside for the next two to three weeks in order for them to develop into infected larvae. At this time, when the mosquito bites another dog, the infected larvae are transferred to that dog. It can take three months for migration to the heart to be completed and another three months for the heartworms to mature.
Preventing Heartworm Disease
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If you have your puppy tested for heartworms before 6 months of age, the test results might be negative because the parasites cannot be detected until six or seven months after infection. In areas that have a year-round potential for infection, your puppy should be started on heartworm prevention at 8 weeks. In areas where there is minimal risk in cold weather, your veterinarian might wait until spring to begin starting preventative medication.Having your dog tested for heartworm when she is older than 6 months is necessary before beginning preventatives as they can cause reactions that can be dangerous, or even fatal, to infected dogs.
Geography
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Heartworms have been detected in dogs in all 50 states. The heaviest infection areas are near the Gulf Coast, the Atlantic Coast and along the Mississippi River and its tributaries. Heartworm is considered a worldwide problem, however, and your veterinarian will have information regarding potential heartworm in your country. Your veterinarian might recommend year-round treatment for your puppy or dog, even if you live in an area considered only seasonally affected.
Effects Of Heartworm Disease
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Heartworm is difficult to detect until it begins to affect your dog's health. The first symptoms will usually be coughing and rapid tiring during exercise. If left untreated, heartworm can cause infection of the right side of the heart and major vessels, leading to blood clots and heart failure. Liver and kidney failure can also occur. Any of these conditions can lead to death.
Treatment
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An infected dog can be treated successfully, but recovery usually includes a hospital stay with medical treatment that includes substantial risk to the dog, and a long rest at home. For more information on treating heartworm infection, see References.
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