Heartworm disease (HWD) is caused by a nematode parasite named Dirofilaria immitis, and is transmitted by mosquitoes. The lifecycle is complicated, and involves migration through tissues, deposition into the vasculature, the pulmonary arterial tree and heart.
HWD is a preventable entity in dogs, and has the propensity to cause serious and longstanding tissue and organ damage or death. Due to the prevalence of prophylaxis in Australia, there is a low incidence of HWD, but risk of infection is increased in Northern Australia and tropical countries. Cats can also become infected with heartworm, but the incidence of infection is about 10% of that for dogs in the particular region. Cats tend to react excessively to presence of worms, and diagnosing and treating HWD in cats can be challenging.
Preventative therapy generally being commenced early and maintained for life, affording protection to the dog and negating requirement for intensive diagnostic workup or therapy later in life. However, if compliance with preventative treatments is not optimal, the dog may be at risk of infection, which can complicate the clinical picture. This is because of the fact that there is risk associated with treatment, causing sudden death of the parasite, leading to serious and possibly fatal conditions in the dog. For this reason, it is important to know if the dog is infected or not, prior to commencing any form of prophylactic treatment. Significant HWD can require intensive treatment +/- hospitalisation.
Thankfully, prevention of HWD is much easier than curing it! There are a wide range of products that can be administered monthly via a tasty chew or a topical spot on. Otherwise, there is an injectable product known as Proheart SR12; this is given once a year at the time of the health check & vaccination and eliminates the worry over forgetting to administer a monthly product.
See you and your furry friend soon!