As a veterinarian practicing in Tulsa, I have too often seen the devastating and deadly effects of heartworms. This spring alone, we diagnosed 3 dogs with heartworms in the Tulsa area. One is a house dog. One of the reasons it is one of my biggest “pet” peeves is because it is completely preventable.
In Oklahoma, heartworms pose an especially dangerous threat to dogs and cats. The temperate springs and humid summers create a prime breeding ground for mosquitoes which spread heartworm larva (called microfilariae) from infected dogs to unprotected dogs & cats. During late February & early March, female heartworms in infected dogs will release massive amounts of larva. Clinical signs include one or more of the following: lethargy, coughing, decreased to no appetite, fever, and nosebleeds. Signs may persist for 2 weeks. This happens again in September & October. If your dog is not on heartworm prevention & becomes ill during these months make sure he/she is checked for heartworms. For cats the signs are a bit more vague but usually involve a chronic respiratory problem that can resemble feline asthma.
While cats can be infected and become sick from the parasite, heartworms cannot reproduce in cats and therefore do not pose as great a risk as it does for dogs but it is still best to prevent them from becoming sick. Although house dogs have less exposure to mosquitoes, I like to remind people that mosquitoes can get inside and even house dogs go outside 2 to 3 times a day.
Heartworms are diagnosed with blood tests. Antibodies in the blood to the female adult heartworm are checked for using an in clinic test “card” that looks similar to the human pregnancy test. 1 line/dot no = heartworms; 2 lines/dot = heartworms. In dogs that have active larva the larva can actually be seen under the microscope in the blood sample & sometimes even a urine sample.
As a pet owner, keeping your pets on heartworm preventative is the only way to keep them safe. Heartworm prevention kills a certain stage of the developing parasite (remember biology 101 & life cycles of insects?). This means if your pet was exposed from a mosquito bite to the heartworm larva the prevention, given once a month, will keep the larva from developing into a mature worm. Since mosquitoes can hatch in 60 degree F & above AND heartworms are endemic in this state, I recommend keeping your pets on heartworm prevention year around in Oklahoma.
Heartworms can be treated fairly safely but the drug to kill the adult worms is expensive & it is hard on your pet’s body. The treatment causes the adult worms to die and they then enter the lung where the body’s defense system has to break it down. The pet’s activity is restricted which is also hard on them. As you can see, prevention is really the better course.
To make sure my four-legged clients are safe from this terrible parasite, I counsel pet owners on the importance of heartworm prevention. In addition, my practice is to test your pet every two years to make sure no larva have slipped through the prevention process and developed into mature worms. A low number of adult heartworms will not produce clinical signs so it is better to be safe than sorry. Also, if your pet is infected with a low number of heartworms, it is easier for your pet to breakdown 2 worms than 10.
There are several different preventions available and they all work. I am always available to help you choose a preventative if you are uncertain about which is best for your pet. If your pet is not currently on heartworm preventative, a heartworm test is needed to determine if your pet might be currently infected. Puppies can be safely started on prevention by 3 months without a test.
I cannot say this enough: Please, please, please put your pets on monthly heartworm prevention. As your pet’s care giver, it is up to you to keep him or her safe from these deadly parasites. I’m here to help!
For more detailed information about heartworms, visit americanheartwormsociety.org.