Heartworm Disease

February brings Valentine’s Day, where we share our hearts with those we love. For most of us, that includes our four-legged family members. They give us their whole hearts and unconditional love, so we owe it to them to care and protect those hearts full of love. To do that, we have to protect those hearts from heartworms and heartworm disease. Heartworms do not actually live in the heart, but actually live in the large vessel around the heart. Because of where they live, heartworms can cause strain on the heart and interfere with the ability of the heart to pump blood effectively and can also cause stress the lungs thereby reducing lung function. If heartworms go undetected and untreated, the adult heartworm load can become so great that the right side of the heart becomes enlarged and weak. When this occurs, the heart cannot pump blood to the rest of the body. Additionally, blood gets backed up and eventually animals develop fluid in the abdomen due to congestion. These two events will ultimately lead to premature death. Adult heartworms can also break off and cause pulmonary emboli, or clots in the lungs.

Pets get heartworms from mosquitoes. The mosquito will first bite an animal infected with heartworms and while taking a blood meal, ingest a baby heartworm known as a microfilaria. In approximately two weeks the microfilaria will develop into the infective stage and wait to be transported to another animal when the mosquito bites again. Once in the dog or cat, the baby heartworm, will continue to grow and develop as it travels through the tissues and into the bloodstream until it becomes an adult and reside in the pulmonary artery. The time it takes for a microfilaria to develop into an adult is approximately 6 months. Once an adult, the heartworm is now able to reproduce and make more baby heartworms that continue the cycle.

We obviously cannot prevent our pets from getting bit by mosquitoes, even our indoor pets can get bit, but we can give preventative to help kill the microfilaria and prevent them from becoming adults. Before dispensing heartworm prevention, your vet must perform a test to make sure your pet does not currently have heartworms. This test is performed out of safety for your pet, because certain preventions are known to cause severe adverse reactions in animals that are heartworm positive. Heartworm disease is increasing rapidly throughout the country and here in Texas, for animals not on heartworm prevention, it is not a matter of if your pet will get heartworms, but rather, when will your pet get heartworms. Texas has one of the highest heartworm disease rates in the country. Therefore, it is recommended that all dogs and cats receive monthly prevention, even if they are indoors only. Mosquitoes will find their way into your homes and will bite your indoor only pet, so please, make sure your pets are on prevention.

The only product currently available for the treatment of adult heartworms is melarsomine dihydrochloride, known as immiticide. The heartworm positive patient receives an intramuscular injection deep in the lower back muscles. This can be a painful injection and it is common for the patient to be quite sore afterwards that is why I take extra steps to minimize this pain. After treatment, the patient must be strictly confined for one month with controlled walks and no running around. The dog must live a quiet indoor life. The reason for this is that an embolism is possible and it is important to minimize embolism-related problems. Exercise increases heart rate and oxygen demand and we need the heart to rest during this recovery period. I strongly recommend owners purchase heartworm prevention each month so they can ultimately save money down the road. This is because treating heartworm disease can be very expensive and stressful on your pet.

As you can see, there is more to heartworms than you may have previously believed, therefore, please visit your family veterinarian to further discuss heartworms and heartworm prevention for your pets. Remember, your family veterinarian can help guide you through your pet’s health care!

I’d like to thank everyone who brought in donations for our Christmas for Little Woman Home for Animals. It was a huge success and all donations were greatly appreciated. Thank You!!!!