Heartworm Prevention

What is Heartworm?

Heartworm, also known as Dirofilaria immitis, is an endo-parasitic organism spread by mosquitoes.


How is it spread?

Once a mosquito bites an infected pet (a cat or dog), developing microfilariae are transferred from the pets bloodstream to the mosquito where they are incubated. The infected mosquito is now a host vessel for the spread of heartworm disease and is capable of infecting healthy pets with subsequent bites.

What happens once a pet is infected?

Microfilariae larvae introduced via the mosquito bite travel through the tissues and into the circulatory system where they continue to develop.

The circulatory system transports the maturing larvae around the body to finally settle in the tissues of the heart and lungs, where maturation of the larvae continues into adult heartworms.


What are the signs of heartworm?

An accumulation of heartworm in the heart and lungs may cause lethargy and inappetance, an enlarged abdomen, persistent coughing and a reduction in cardio-vascular fitness.

The above signs of a cardio-vascularly impaired animal left untreated will result in the death of the infected pet.


Heartworm infection is treatable but preventative care is the best and safest option for your pet.


At BVS we recommend a yearly heartworm injection for dogs, and a monthly oral tablet for all our feline patients.

It is important to note that if your pet has not been on a regular preventative treatment for heartworm, or their method of prevention has lapsed, a heartworm test should always be carried out prior to any further treatment to ensure that your pet is healthy and fit for the medications administered.