Heartworm preventatives work retroactively. This means they work backwards to protect your pet from disease they may have been exposed to in the previous months. Because of this, the American Heartworm Society recommends giving heartworm preventative 3 months after the first frost. By that time in Minnesota we start warming up again. Therefore, we recommend giving heartworm preventative year-round. Pledge to protect your pet's heart every 30 days!
What is heartworm disease?
Heartworm is a parasitic roundworm transmitted through the bite of a mosquito. Heartworms live in the heart and vessels surrounding the heart and lungs. This infection can lead to heart failure, lung disease, and other organ damage. Both cats and dogs can be infected.
How is it transmitted?
When a mosquito takes a blood meal from an infected animal, it picks up baby heartworms called microfilaria. The next stage develops inside the mosquito to become infective larvae. When this infected mosquito bites another animal, the infective larvae are deposited on the skin and enter the animal through the bite wound. It then takes over 6 months for the larvae to mature into adults. Only mosquitoes can transmit heartworm disease.
How is it prevented?
Heartworm preventatives should be given year-round to protect against heartworm disease. All heartworm preventatives work "backwards" by killing one month old larvae. For example, a dose given in June is clearing an infection your pet developed in May. If larvae are older than one month, the heartworm preventative will not kill them and they will continue to grow into adults and infect the animal. And since mosquitoes can adapt to cold climates, even in Minnesota it is important to treat year-round.
How do you test for it?
In dogs, a blood test should be performed every 12 months. A positive test indicates there are adult heartworms in the body. If larvae have not yet developed into adults, which takes over 6 months, a false negative result may occur. In cats, diagnosing heartworm disease can be more difficult as cats tend to have fewer worms or be infected with only immature larvae. A series of tests may be required in cats.What are the symptoms?
- Dogs - symptoms are related to heart failure or lung disease and can include a persistent cough, reluctance to exercise, fatigue after exercise, labored breathing, anemia, or fainting spells. With early infections, there are no symptoms at all.
- Cats - symptoms appear like asthma and can include wheezing, coughing, shortness of breath, or gagging.
How is it treated?
In dogs, an arsenic compound called Immiticide is injected to target and kill the adult worms. The dead worms then decompose and are reabsorbed by the body as there is no other route for their elimination. This period is very dangerous as these worm fragments can cause clots and inflammation in the lungs. Strict rest for 4 weeks following treatment is crucial. There is no safe or effective treatment in cats, so prevention is key.
Has your pet been checked for heartworm disease? Call us with any questions or to set up an appointment.