What is heartworm?
Dog heartworm is a serious and unfortunately, dangerous disease common in canines.. It is caused by a nematode (roundworm) that belongs to the family Filarii,dae. The worm, discovered in 1856 by the American parasitologist Joseph Leidy, has been given the scientific name Dirofilaria immitis. The adult worms live in the heart and large vessels of the lungs. Adult female Dirofilaria measure from 9 to 16 inches in length. The males are a little more than half as long and are characterized by the cork screw turns of the posterior end often referred to as the “pigtail.”
Both male and female live within the chambers of’ the heart, usually extending through the valves. The worms prohibit proper valve closure as blood is pumped from one chamber to the next, seriously impairing the operation of the heart. In serious infestations the worms travel up the pulmonary artery and clog the blood vessels of the lungs. The results are loss of weight, dropsy, chronic cough, shortness of breath, muscular weakness, disturbances of vision, chronic heart failure, and eventual death.
How does the mosquito carry heartworms?
Adult worms living within the heart produce minute organisms known as microfilariae that circulate in the blood stream. Microfilariae, named because they are microscopic, are actually the larvae of heartworms that are incapable of reaching the adult stage without first passing through a developmental stage in the mosquito.
Mosquitoes feeding upon an infected dog take up a number of these microfilariae with the blood meal. The freshly acquired microfilariae migrate through the digestive tract of the mosquito to the abdominal region where they undergo a transformation. Within 14 to 21 days they reach the infective stage. Then the larvae are actually miniature adults that are small enough to live within a mosquito.
Next, they break into the body cavity of the mosquito and migrate to the mouth parts.The mosquito is now ready for its second blood meal. As the mosquito feeds upon its host, the infective larvae are passed on the skin. These small worms travel into the dog and lodge in the tissue where they remain for months. Worms that enter hosts other than canines generally die within several days.
After they increase in size, the worms leave the tissue and enter the blood stream through the wall of a small vessel. Then they move through the blood stream and lodge into the chambers of the right side of the heart where they develop into adult heartworms. This cycle takes approximately 9 months. Remember that the microfilariae cannot complete their life cycle without first living in a mosquito. Of the millions of microfilariae that are produced by the adult worms, only a few get a chance to pass through a mosquito. The remainder circulate through the blood of a dog where they eventually die; however, they are continually being replaced with fresh microfilariae supplied by the breeding adults living in the dog’s heart.
How do infected canines react to the disease?
Since symptoms of dog heartworm vary considerably in different animals, a veterinarian is the only person qualified to give a diagnosis. Most dogs show the first visible indications of infection only after the illness has gotten to the point where treatment is no longer possible. Active dogs generally show a tendency to tire easily. Shortness of breath or repeated coughing are the positive signs of heartworms Hunting dogs are often no longer able to maintain the rapid pace of the chase and frequently drop from exhaustion. Jaundice, convulsions, and disturbances of vision may occur in extreme cases. Emaciation often comes before death. All dogs with adult heartworms should show some microfilarial activity in the blood system. A blood test made by a veterinarian is the only way to know for sure whether or not your dog has heartworm disease. Since microfilariae generally appear in the blood within 9 months after an infection occurs, mild cases of the disease can and should be detected and treated long before any symptoms appear.
What can you do?
Protecting dogs from mosquito bites may be necessary in those areas where mosquito populations are numerous. Screening the dog’s sleeping areas is essential to prevent repeated bites. Additionally, you should consider receiving monthly yard treatments from a professional mosquito treatment service. Preventative medication should also be used, especially in areas of known infection.
A periodic blood test is the most secure precaution measure because it will reveal an early infection animal. Because a pet appears healthy is not a reason to believe that it does not have the disease. Your dog could be the carrier responsible for an entire local outbreak.
Purebred, or mix breed, isn’t your dog’s well-being worth protecting it from dangerous, biting, life threatening mosquitoes?
#mosquitoescarryheartworms #mosquitosquadpetsafety #americanheartwormsociety