From: American Heartworm Society | FAQs How long does it take before heartworm infection can be detected by blood tests? ANSWER In the dog it takes 5 to 7 months from the time a dog is bitten by infected mosquitoes until a blood test can accurately detect the presence of adult worms (positive antigen test).
In the cat it takes a little longer, about 5.5 to 8 months to test
antigen positive; however, the
antibody test can detect the presence of young, immature heartworms (larvae) in as little as 2 to 3 months following infection.
Both the Antigen test and the antibody test only test for adult female heartworms in dogs.
Is a puppy born with immunity to heartworm disease? ANSWER No, even nursing puppies are at risk for heartworm infection. Puppies of any age exposed to mosquitoes carrying infective larvae can become infected. Thus,
it is important to begin prevention by 6 weeks of age whenever possible.
Six Weeks??? I thought they just said 6 months! Which is it? I can see where this is over medicating (like with antibiotics). Is this all really necessary?
My dog has heartworms. My vet started her on monthly prevention before he started treatment. Is this OK? ANSWER Yes, it is recommended in the American Heartworm Society's Guidelines to do so. This should be done under the direct supervision of a veterinarian because dogs with
microfilaria (baby worms in the blood that the mosquito picks up when feeding) could possibly have a reaction to the preventive. Veterinarians check the blood for microfilaria and pre-medicate dogs with preventives before treatment. Although not labeled to be used in this manner, beginning a heartworm preventive prior to performing a heartworm treatment is recommended. However, it is important that your veterinarian assesses the severity of the disease and chooses the proper preventive accordingly. By starting the prevention program you are ensuring that your dog will not get a new heartworm infection while being treated for the existing heartworm disease.
Furthermore, you are helping to keep your dog from being a source of heartworm larvae (microfilaria) for mosquitoes to pick up and eventually infect other dogs. This approach makes the treatment of the existing infection more effective.
In the red above: Is this another 'Test' or looking under the microscope? I guess it would be billed as a test. If this is the test Bchgirl was referencing... then her method would work.
In the blue above: I don't believe this is true. By my understanding, a monthly dose of preventatives wipes out the microfilaria in the dog at the time the dose is given, and does not remain in the dog for the entire month. So after that dose is gone from the dog's system, a mosquito could bite and re-infect the dog, which will make your dog a source of HW larvae anyway, until the next dose is given.
I also have a question: Is there a difference between the babies produced from the adult worms in a dog, and the larvae that is deposited on a dog through a mosquito bite?
I ask this bc I just read that in order for babies to infect another dog and grow to adulthood, they have to pass through a mosquito. Does that mean that the babies produced by worms in the dog do not grow into adults? I don't think they do... if they did it would kill all the dogs with reproducing adults. Just food for thought...