In the Beginning
Myra’s life began in the gutter. No, not that kind of gutter: an actual gutter on the side of a house. Filled with stagnant water, Myra floated in a raft of eggs with two to three hundred of her siblings for about 48 hours until she hatched and became a larva. Her life in the gutter lasted another week or so when she became a pupa and then began her metamorphosis into an adult mosquito.
Myra’s search for food, a blood meal from you or your dog, could take her to just a few feet away or as far as a mile or two. With her travels she also carries the opportunity to infect with Eastern Equine Encephalitis (rare), Encephalitis, West Nile Virus, or Heartworm disease.
Myra’s particular search for food leads her to a dog who is infected with heartworm disease. She fills her belly-well it’s a abdomen if you want to be technical-with blood containing microfilariae that mature inside of her into a larval stage. In Myra’s short life she then travels to an uninfected dog, bites him or her and deposits the larvae into the skin where they then migrate into the new host—your dog.
An entire new life cycle begins when the larva Myra deposits mature to adult worms that live in the heart, lungs and associated blood vessels. They mate and produce offspring that can be detected 6 to 7 months from infection. Heartworms can live 5 to 7 years. The fact that Myra can carry larva inside her tiny abdomen that eventually can become worms four to 12 inches long is utterly gross and disgusting, and yet amazing.
Your veterinarian can administer an in-house Antigen test that is accurate for detecting infection if there are female heartworms present that are at least seven to eight months old. The good news is that heartworm disease can be successfully treated; the bad news is it can be expensive.
It is much cheaper and easier to prevent infection with a heartworm preventative. Monthly heartworm prevention also treats other internal parasites.
Ivermection (Heartgard, Heartgard Plus), Iverhart and Tri-Heart are generics. If your dog is infected with larvae as long as two months prior to starting ivermectin treatment, it will stop them from developing.
Milbemycin (Interceptor, Sentinel)
Selamectin (brand name Revolution) is applied topically.
Moxidectin (Advantage Multi) is applied topically, or available as a 6 month injectable (ProHeart 6).
The heartworm society geographic maps of reported incidences of hearworm disease illustrate that from 2001 to 2007 there has been a significant increase in the geographic area reported and also in the number of cases reported. The Heartworm Society recommends year round use of heartworm prevention. I’ll discuss that, treatment and other subjects, in part 2.
Certain breeds, such as Collies and Australian Shepherds, are more sensitive to certain drugs. Go to Washington State University Veterinary College for more information.
If you want to read more about heartworm go to the Heartworm Society.