Wednesday, February 22, 2012


I have not treated my dogs for heartworm since moving from New Jersey to California. During a recent trip to the vet, I was informed that heartworm has been found in two surrounding counties. I have decided to start preventative treatment.
What is heartworm? Heartworm (Dirofilaria immitis) is a parasitic roundworm that is spread from host to host through the bites of mosquitoes. The heartworm is a type of filaria, a small thread-like worm. The definitive host is the dog but it can also infect cats, wolves, coyotes, foxes and other animals, such as ferrets, sea lions and even, under very rare circumstances, humans. Heartworm infection may result in serious disease for the host.
Dogs show no indication of heartworm infection during the 6-month-long prepatent period prior to the worms' maturation, and current diagnostic tests for the presence of microfilariae or antigens cannot detect prepatent infections. Rarely, migrating heartworm larvae get "lost" and end up in unusual sites such as the eye, brain, or an artery in the leg, which results in unusual symptoms such as blindness, seizures and lameness. But normally, until the larvae mature and congregate inside the heart, they produce no symptoms or signs of illness.
Many dogs will show little or no sign of infection even after the worms become adults. These animals usually have only a light infection and live a fairly sedentary lifestyle. However, active dogs and those with heavier infections may show the classic signs of heartworm disease. Early signs include a cough, especially on exercise and early exhaustion upon exercise. In the most advanced cases where many adult worms have built up in the heart without treatment, signs progress to severe weight loss, fainting, coughing up blood and, finally, congestive heart failure.
If an animal is diagnosed with heartworms, treatment may be indicated. Before the worms can be treated, however, the dog must be evaluated for heart, liver, and kidney function to evaluate the risks of treatment. Usually the adult worms are killed with an arsenic-based compound. The currently approved drug in the US, melarsomine dihydrochloride.
Prevention of heartworm infection can be obtained through a number of veterinary drugs. The drugs approved for use in the US are ivermectin (sold under the brand names Heartgard, Iverhart, and several other generic versions), milbemycin (Interceptor Flavor Tabs and Sentinel Flavor Tabs) and moxidectin (ProHeart) administered as pills or chewable tablets. Moxidectin is also available in both a 6-month and 12-month sustained release injection, ProHeart 6, ProHeart 12, administered by veterinarians.
All information was provided by Wikipedia, which was redirected from Heartworm.
I am waiting for the results of the boys blood tests and then we will start on the preventative treatment.


Giupetto and Gianna Tails said...

Good post Annie.
We treat ours year round. Becuase we do we only get tested once a year, but I remain anxious for the results each time.

Art and Sew Forth said...

It would be interesting to find stats on what percentage of dogs have heartworm today vs 30 years ago. We never did anything for our dogs when I was young except rabies!