Heartworm disease is caused by mosquitoes biting your dog and injecting small parasites into your dog’s blood stream. It takes about 6 months for the parasites to be detectable in a blood test. The parasites grow to adult worms that live in the heart and lung blood vessels. They will kill your dog if not treated.
The easiest way to avoid this problem is by giving your dog monthly heartworm preventative. It can be purchased from your regular vet as long as you can provide proof of a very recent negative test.
Remember, heartworm preventative will save your dog’s life.