How does your dog, cat or ferret get heartworm disease? Mosquitoes! Unfortunately, it is fairly easy for your pet to get infected by heartworms, especially in San Antonio. It is fairly warm for the most part and mosquitoes are present almost all year. The mosquito is the carrier- it bites the pet and injects the larvae into the bloodstream. The larvae migrate into the blood and die if the pet is on a preventative medication. If not, the larvae will grow, mature and live. The adult worms can grow up to 14 inches long, and make their home in the right side of the heart. That is quite disgusting, really. If your pet isn’t tested regularly for heartworm disease, you can miss the time he or she becomes infected. If your pet is infected and is not on continuous heartworm prevention, the worms grow and mature and start to reproduce. Once this occurs there is circulating microfilaria (baby heartworms) in the blood stream.
There are two ways your pet can become sick- reaction to adult worms causing right sided heart enlargement, thromboembolus or anaphylaxis caused by the baby heartworms. The adult heartworm is not transmittable to other pets but the microfilaria can be carried to other pets by mosquitoes. So if your pet (a dog, in this case) is heartworm free and on prevention, but your neighbor’s dog is infected, your dog is at risk to contract the disease if you ever forget his/her monthly prevention. This is also true for cats and ferrets.
Many people don’t even know their dog has heartworm disease until it is often too late. Dogs that are carrying the worms can live symptom free while the worms mature and become large and start to put pressure on the right side of the heart (the right atrium) causing heart enlargement, a backup in blood flow and ultimately causing heart disease and heart failure. The end result is something called pulmonary edema.
Heart failue on a radiograph: the heart has a D appearance, the right side is enlarged, there are a lot of infiltrates in the lung compatable with pulmonary edema (a microchip is seen)
At this stage, heartworm disease can often be deadly since the pet is in end stage heart disease and fulminent pulmonary edema is present. At this point it is usually necessary to physically remove the worms from the heart. This is when heartworm disease becomes an emergency! Pets often turn blue, they cannot breath, they have crackles in their lungs and need oxygen!!! Diuretics and aggressive care are also needed at this point in order for the pet to maybe survive.
If heartworm disease is found when the pet only has a mild cough or at a routine appointment (an annual veterinary exam) where heartworm testing is routinely performed, it is usually not an emergency. Treatment is often rewarding, allowing almost a full recovery in many cases.
Apparently healthy dog that tested positive for heartworm disease and was treated.
However, treatment occurs over a period of months, includes painful deep muscle injections and additional medication. During treatment the pet has to be on strict exercise restriction for up to 16 weeks depending on the protocol. How hard is that? It is much better to prevent the disease than to treat it! So call your vet and have your pet heartworm tested and started on prevention today!
Until next time, please spay and neuter your pet and keep them healthy and indoors!
Ariana Finkelstein, DVM
I-10 Pet Emergency
10822 Fredericksburg Road
San Antonio, TX 78240