What are Heartworms?
Heartworms are a deadly infestation that can infect your dog's heart. Mosquitoes transmit these nasty worms from dog to dog. The adult female worm produces many microscopic immature heartworms, called microfilaria, which circulate in a dog's blood and are picked up by the biting mosquito when they feed on the infected dog. These microfilaria live in the mosquito for ten days to two weeks and are then deposited in a dog when the mosquito bites and the process continues.
Heartworm disease is no longer limited to the south and southeastern parts of the country. Now, virtually everywhere there are mosquitoes, there is the potential for heartworm disease.
Once the microfilaria are deposited in a dog's blood stream, they will remain in the dog's tissue for three to four months, during which time they grow to about an inch in length. They then travel to the heart where they remain, growing to as much as 14 inches in length. At that time, the process begins again with the adult females producing more of those microscopic heartworms.
Symptoms of heartworm include, difficulty breathing, coughing, listlessness, weight loss and lack of energy.
The only way to determine if your dog has heartworms is through a simple blood test. The test looks for the presence of antigen (heartworms) in the bloodstream. This is a very sensitive and specific test which usually only takes about 5 minutes to run. This test needs to be performed annually even though year round heartworm prevention is given. Since the most common prevention these days is the once-a-month tablet, if a month is inadvertently missed or if a tablet is given and your pet vomits the pill or has other gastrointestinal problems, this can reduce the absorption of the medications in the blood and shorten the duration of protection. Therefore, yearly testing is necessary to accurately detect the presence or absence of these potentially deadly worms before continuing prevention. Early detection of the disease leads to safer, more effective treatment of the disease.
Prevention is the best defense against heartworms. After the blood test has been given and your pet has been found to be free of heartworms, your veterinarian will prescribe a preventive medication for you to give to your dog. This medication takes several forms, from daily pills to monthly pills, chewable and non-chewable, a once every 6 month injection and a topical monthly form.

Many of these medications now have added advantages of prevention and control of fleas, ticks and intestinal parasites. With help from your veterinarian, you will be able to decide which medication will work best for you and your dog; it is very important that you do not start your dog on the preventive medication before he or she is tested for heartworms. If they are not tested prior to beginning the preventive medication and they have heartworms, depending on which preventive medication is used can cause serious problems, even death.
Heartworms can be cured if your dog should have a positive blood test result. The cure process is long and can be dangerous to your dog. If your dog has contracted heartworms, you will have to play a very active role in his or her treatment. Dr. Wood will give you very precise instructions for your pet's care during the treatment period.

If my dog has heartworms, can it be treated?
Yes, heartworm disease can be treated in dogs. An arsenic compound is used in a 2 shot protocol given 24 hours apart. Arsenic is used because if it's ability to accumulate in the heartworms and causing them to die over a 3-4 week period. As the heartworms live in the side of the heart that pumps blood to the lungs, caution is used to not cause a rapid die off of these worms and cause a pneumonia and death. Since the treatment involves a controlled poisoning of worms that die and flood the lungs and are reabsorbed by the body, inherent risk in heartworm treatment is obvious. The dog is sent home after a one night stay and kept quiet for the next 30 days. After a month, we see them back and keep them for a day. At this time an oral medication is given to kill off any immature worms (microfilaria) and heartworm prevention is started at this time. We then recheck the heartworm test in 3-4 months to document success of treatment. Due to the risks involved as well as the increased cost of treatment, heartworm prevention is the obvious choice.