The Heart of the Matter...

April 11, 2017
hello world!

Have you heard of Heartworm disease in dogs?  Ever wonder what it is?

Heartworm disease is a condition in which microscopic, parasitic worms enter the bloodstream of dogs, and as they mature over time (approximately 6 months), they can clog the major blood vessels within the heart when they become adults.  Often times, many dogs will not show any signs after initial infection, but when the signs appear, they often have a cough or have trouble with prolonged exercise or activity.   More severe cases can suffer from sudden collapse, weight loss, difficulty breathing, shock or even death.  

How does my pet get it?

The parasitic worms are spread by the bites of mosquitoes.  All that a mosquito needs to do to spread heartworm disease in an area is bite an infected dog, carry the microscopic worms off with them and bite another dog to transfer the infective worms in their saliva.  Dogs are the natural host, both domesticated and wild, so the disease is very difficult to eradicate.

How do you treat it?

Once a dog is infected with heartworms, treatment is based on the symptoms they are showing at the time they are diagnosed.  If it is found when they receive a routine heartworm test and are starting to show signs, treatment includes: 3 injections of an anti-parasitic drug, exercise restrictions for weeks between injections and sometimes additional anti-inflammatory and antibiotics may be sent home.  Treatment itself can be risky, because the adult worms are being killed within the blood vessels and this can lead to severe allergic reactions.  

In severe cases, surgery is required to physically remove the adult worms from the heart.  This is a major surgery, and can be a risky procedure to undergo.    

Should I prevent it?

There is a proverb which states: An ounce of prevention is worth a pound of cure, and it could not be more true!  It is much easier to prevent a disease than to treat it after it has progressed.  There are a number of heartworm preventatives on the market today, ranging from once monthly chewable tablets (such as Heartgard and Trifexis), topicals such as Revolution, and injections that offer 6 months protection (ProHeart).  Ask your veterinarian about which product best suits your pets needs and your family’s lifestyle.  There are also topicals with an insect repellant (such as Vectra 3D) that helps work in conjunction with your monthly heartworm preventative to keep mosquitoes from biting your pet and spreading heartworm disease.

How common is heartworm disease?

According to data from the Companion Animal Parasite Council, of the dogs tested in California, approximately 1 out of 134 dogs (4,356 positive cases out of 584,678 dogs tested) were positive for heartworm disease. Of these cases, 1 out of 298 positive cases of heartworm disease are from Alameda County (77 positive cases out of 22,966 dogs tested).  These numbers are significantly higher in other parts of the country!

What does that mean for my dog?

Essentially, all it takes is one heartworm positive dog to spread the disease to other dogs in the area.  Although pest control can decrease the number of mosquitoes, we cannot completely wipe out the presence of mosquitoes from California.  Therefore, it is generally safer to keep your pets on heartworm preventative all year round to avoid infection.

Can my cat get it?

Although it is less common, cats can be infected with heartworm disease.  Cats are considered dead end hosts for heartworms, and it is rare for the worms to reach the adult stage, so their reproduction in cats is very limited.  However, the microscopic worms can cause serious damage to their lungs, causing heartworm associated respiratory disease.

Can I get it?

Yes, although it is rare. According to the CDC as of 2005, there have been 81 cases of human infection with heartworm, a condition called “Dirofilariasis,” since 1941. People displaying symptoms may have a cough, chest pain, fever and even a buildup of fluids in their chest cavity!

The most important thing to remember is that this disease is transmitted by the bites of mosquitoes.  And by protecting your dog against infection, you are not only sparing him from a potentially life-threatening disease, you are also helping to prevent further spread of this disease to the population - human and animal alike!

Talk to your veterinarian about getting your dog tested for heartworm disease and starting him or her on prevention today. It's a decision you won't ever have to second guess.

 Yvonne D'Monte - RVT at Hills Veterinary Hospital