Heartworm Disease Transmission in Dogs
If you’ve never heard of Dirofilaria immitis, don’t be embarrassed. That’s the scientific name for what are currently known as “heartworms.” Now that the warm weather has arrived in full force, so have the mosquitoes – and those little demons are what can cause serious (and sometimes fatal) problems for your dog.
According to the U.S. Food and Drug Administration, heartworms are transmitted when an infected dog has been bitten by a mosquito. When a dog has mature heartworms, there are actually immature heartworms released into the blood. These immature heartworms, known as microfilariae, can be picked up by a mosquito when it bites the infected dog.
Once inside the mosquito, over a period of ten to fourteen days, the microfilariae literally transform themselves into infective larvae. The amazing thing is the only way the microfilariae can become infective is by first passing through a mosquito.
Once a mosquito carries the infective larvae, when it bites another dog, those larvae are then passed into the bloodstream of the dog. Over a period of six to eight months, the infective larvae mature into adult heartworms. At that point, the adult heartworms continue to mate, and the female heartworms eject their immature offspring into the bloodstream of the dog. This brings the lifecycle full circle.
The only way to determine whether or not a dog has heartworms is by having the animal tested. Dogs should actually be tested whenever a dog has gone through a prolonged period without being given heartworm preventative and also when a dog is being switched from one type of preventative to another. In addition, if the dog has spent time in an area where heartworm disease is prevalent, it’s always a good idea to have pet tested.
Before putting a dog on heartworm preventative medication, it’s important to have a heartworm test performed. The medication does not kill adult heartworms. It only destroys the immature larvae. Therefore, a dog might have adult heartworms still alive inside of it, even though it is on a monthly preventative medication.
Heartworm positive dogs can be treated with melarsomine dihydrochloride, a drug containing arsenic. It is FDA-approved to eliminate adult heartworms in dogs. The treatment can be both expensive and can also be hard on the dog. For this reason, rather than risk having to undergo treatment, many pet owners feel it’s best to simply do whatever they can to prevent the disease.