Most pet owners are aware of the importance of flea and tick preventative, but unfortunately, many owners in our area still don't know much about heartworms and heartworm prevention - and the consequences can be fatal to pets.
April is national heartworm awareness month, so let's start with the basics: taken directly from the American Heartworm Society (AHS), a nonprofit organization that is dedicated to scientific progress in the study of heartworm disease, as well as advancing effective procedures for heartworm diagnosis, treatment and prevention.
1. What are heartworms?
healthy heart (left) vs heartworm infected heart (right)
Heartworm disease is a serious and potentially fatal disease in pets in the United States and many other parts of the world. It is caused by foot-long worms (heartworms) that live in the heart, lungs and associated blood vessels of affected pets, causing severe lung disease, heart failure and damage to other organs in the body.
2. How are heartworms transmitted?
The heartworm lifecycle
The mosquito plays an essential role in the heartworm life cycle. Adult female heartworms living in an infected dog, fox, coyote, or wolf produce microscopic baby worms called microfilaria that circulate in the bloodstream. When a mosquito bites and takes a blood meal
from an infected animal, it picks up these baby worms, which develop and mature into “infective stage” larvae over a period of 10 to 14 days. Then, when the infected mosquito bites another dog, cat, or susceptible wild animal, the infective larvae are deposited onto the surface of the animal's skin and enter the new host through the mosquito’s bite wound. Once inside a new host, it takes approximately 6 months for the larvae to mature into adult heartworms. Once mature, heartworms can live for 5 to 7 years in dogs and up to 2 or 3 years in cats. Because of the longevity of these worms, each mosquito season can lead to an increasing number of worms in an infected pet.
3. What are the signs of heartworm disease in dogs?
In the early stages of the disease, many dogs show few symptoms or no symptoms at all. The longer the infection persists, the more likely symptoms will develop. Active dogs, dogs heavily infected with heartworms, or those with other health problems often show pronounced clinical signs.
Signs of heartworm disease may include a mild persistent cough, reluctance to exercise, fatigue after moderate activity, decreased appetite, and weight loss. As heartworm disease progresses, pets may develop heart failure and the appearance of a swollen belly due to excess fluid in the abdomen. Dogs with large numbers of heartworms can develop a sudden blockages of blood flow within the heart leading to a life-threatening form of cardiovascular collapse. This is called caval syndrome, and is marked by a sudden onset of labored breathing, pale gums, and dark bloody or coffee-colored urine. Without prompt surgical removal of the heartworm blockage, few dogs survive.
4. What are the signs of heartworm disease in cats?
Signs of heartworm disease in cats can be very subtle or very dramatic. Symptoms may include coughing, asthma-like attacks, periodic vomiting, lack of appetite, or weight loss. Occasionally an affected cat may have difficulty walking, experience fainting or seizures, or suffer from fluid accumulation in the abdomen. Unfortunately, the first sign in some cases is sudden collapse of the cat, or sudden death. There is no current treatment for cats diagnosed with heartworm disease.
For a long time, heartworm disease has been mainly a concern in the South-eastern part of the US. However a mixture of climate change, and adopted dogs coming into the area from hurricane affected southern regions - the cases of heartworm positive dogs has increased greatly in the northeastern US (for example, following Hurricane Katrina, 250,000 pets - many of them infected with heartworms - were “adopted” and shipped throughout the country). Once mosquitos are infected they can pass the disease from pets to stray animals and then from those hosts to more mosquitoes... and so on.
The fact is that heartworm disease has been diagnosed in all 50 states, and risk factors are impossible to predict. The treatment for heartworm disease is costly and takes a large toll on your pet. Even with treatment, certain side effects of having the disease cause irreparable damage to the internal organs and some pets experience symptoms for the rest of their lives.
** Prevention is KEY **
Keep in mind: a lifetime of heartworm prevention for dogs is cheaper (and of course much safer) than the treatment itself,
and there is NO treatment for cats!
Check back in for more articles about heartworms, prevention, diagnosis, treatment and more. If your pet needs their annual heartworm test or more heartworm prevention please call our veterinary staff at 215-232-0831