There are a number of different types of parasitic worms that can infect a dog, but heartworms are far and away the most dangerous of them. An unchecked heartworm infection in a dog will nearly always be fatal as the animal will have heart failure because of the worms. A mosquito bite is how heartworm disease in dogs gets started, and with bites the microfilariae are introduced into the dog’s bloodstream. The infective larvae usually grow into adult Dirofilaria immitis worms and begin doing damage to the chamber of the dog’s heart as well as blood vessels.

Heartworm Disease in Cats

The disease and infection that starts it will have the same process for cats, although they tend to get mosquito bites less often than dogs. A cat heartworm infection can happen, but one of the major differences between dogs and cats is that the infective larvae usually do not survive long enough in cats to grow into adult Dirofilaria immitis worms. If they do, however, the risk of dying from heart failure because of heartworm disease in cats is just as high for a cat as it is for a dog. Heartworms can affect the lungs too and lead to fibrosis of lung tissue.

Heartworm Disease Symptoms

Pet owners will typically have any number of heartworm disease symptoms to look for as signs that their pet has the worms, and they include:

   
• Coughing
   
• Vomiting
   
• Lethargy
   
• Breath shortness
   
• Convulsions
   
• Accelerated heart rate
   
• Fainting
 

More chronic clinical signs may be seen too, including chylothorax, which is an accumulation of fluid around the lungs that may cause the dog or cat to have a ‘wet’ cough.

Stages of Heartworm Disease

In the early stage of a heartworm infection, there will be little if anything to tip owners off to the fact that their dog has heartworms. It is for this reason and the risk of death from heartworms that most owners will have their dog on a heartworm prevention medication like Nuheart heartworm tablets. This is the best approach to preventing heartworms in dogs or cats, and one tablet each month will keep them safe from getting heartworms all year long.

After this initial stage of heartworm disease, the next stage is the development stage where the microfilariae grow into worms. In stage 2, symptoms will start to appear, most notably cough and tiredness. Stage 3 is when the fully adult worms have multiplied to the point that they have an extensive presence in the heart. More severe symptoms with a sickly appearance and breathing difficulties may be seen here. Stage 4 is when the damage to the heart has been going on unchecked for a long time, and heart failure is likely imminent.