I was curious to know how dogs actually get this dangerous and often fatal illness, and even though there is heartworm treatment for dogs available (much like flea prevention), less than half of dog owners actually use any type of preventative measures against heartwood, on their dogs at all. How do dogs get heart worm in the first place? Is my own dog at risk of heart worm? What can I do to protect my dog?
What is heartworm in the first place? Heartworm is a parasite spread by mosquitos when the dog gets bitten, and can be fatal in dogs. Dogs who get heart worm often carry the parasite for months before they show very serious symptoms (6 months or so), and even then, they may not be serious enough for owners to pay heed, or for owners to know what they are looking for.
Heartworm takes a while to fully mature, around 90-120 days. Heartworm parasites (spread by mosquitoes) start out as larvae in the lungs. Depending on the size of the dog they are attacking, as the larvae reach full maturity (and turn therefore into worms) they can rest in certain arteries in the dog. Smaller dogs will typically have fewer mature heartworms that large dogs do. For example, a beagle may have 10 worms in their system, whereas a larger dog, like a lab, can have as many as 50 or more. Regardless, the worms at maturity do migrate toward the heart, resting in ventricles until they take over the dog and eventually kill the animal, or the dog gets treatment to kill and destroy the heartworm infection entirely.
Dogs will usually contract heart worm during the wet spring season where mosquitos are maturing.
The heartworm can take about 10-14 days to incubate, and mature within 90-120 days after contracting the illness. Dogs usually won’t show major symptoms of heartworm (like wheezing or coughing) until the larvae begin growing in their lungs before maturity.
If you live in a known mosquito area (heartworm is prevalent in all 50 states – where there are mosquitos there may be heartworm), then you would be wise to protect your dog against heartworm by keeping your dog medicated against the parasite and allowing your dog to wear mosquito repellent when they are outdoors.