By Dr. Russell Petro
Historically Heartworm disease started in the deep south due to the high number of mosquitoes. In the 1950’s people started traveling from the northeast to southern locations like Florida during the winter months and many of them brought their dogs with them. Unfortunately most dogs were not on any preventative so they got infected via mosquito bites and then brought the disease up north when they returned in the spring and thus started to infect our mosquitoes up north. Since that time we have recognized the disease and most dogs have gone onto preventative medication. Several years ago Hurricane Katrina hit the south severely and caused many animals to become orphans. Many rescue groups started to mobilize these animals up here and unfortunately many of the dogs were infected with heartworm. Due to that fact we are starting to see many cases again.
The life cycle of heartworm is fairly simple. The mosquito bites an infected dog and ingests tiny heartworm larvae. At this point the larvae develops into an infective stage. This all occurs in the mouthparts of the mosquito. The mosquito then can infect a healthy dog and give that animal heartworm if it is not on preventative medication.
Once the heartworm is in the dog with time it will develop into the adult stage as a worm inside the right side of the heart. These worms can grow up to a foot long. Clinical signs of heartworm disease present as coughing, difficulty breathing, and sluggishness. If not treated many of these pets will die from congested heart failure.
The treatment involves a medication that is hard to obtain, expensive and can be painful upon administration. Heartworm is a very easy disease to prevent that involves a once a month chewable or non-chewable pill or if you wish you can give a transdermal medication once a month. These medications will cost anywhere from $6 to $15 a month depending on the weight of the dog.
Other animals that heartworm has been documented in are foxes, ferrets, and coyotes. The majority of these animals are not on preventative so they act as a source of heartworm for our mosquitoes. Unfortunately cats can also be bit by mosquitoes and get heartworm but they get an occult form of it because they are the wrong host. The heartworm ends up in the lungs and can cause Feline Bronchial asthma.