Heartbreaking News about Heartworm Disease

Categories: Dog Health
By Laura Yurchak

I always thought “it will never happen to my dogs” until now. I have always given my dog’s heartworm preventative so I didn’t really worry about them getting this very serious and possibly fatal condition. Years ago I actually saw the heart of a dog that was full of worms. It was a shocking and eye opening experience. The late Dr. Wolf actually had a heartworm diseased heart that he would display at his open house and educational events. Once you see something like that you don’t think twice about giving your pets a preventative.

Well, my foster dog, Brandy, wasn’t as lucky as my Tasha and Terra were. Brandy, only about 2-1/2 years of age, was just diagnosed with heartworm. I honestly thought that the day she would leave our home she would be going to her perfect forever home and now we are frantically looking for a new foster home. I have researched this condition to find out that although early stages of heartworm are treatable the dog must not have any exercise during treatment or it could be fatal. Brandy is in the early stage so she has a real good chance of beating this thing.

Heartworm is a type of roundworm that lives in the arteries in the lunges and/or the right side of the heart. Brandy was infected when a mosquito carrying the “larvae” bit her. It takes about 2 months for the “larvae” to transport to the arteries of the lung and a total of 6 months for the “larvae” to mature into adult worms. The adult worms then produce more worms. The number of worms can range from 1 – 250!!!! Adult heartworms can live in a dog for 5 – 7 years according to the American Heartworm Association.

To determine what stage of heartworm Brandy is at the veterinarian will do some or all of the following: blood tests, x-rays, urine test, angiography and an ultrasound. Amy Wence, Loving Paws trainer and author of articles in the newsletters, guided me to a website that really listed the classifications of Heartworm nicely.

  • Class I: Lowest Risk. Young healthy dogs with minimal disease evident on radiographs, normal blood work, and no symptoms of illness. They may cough only occasionally if ever, they only fatigue with exercise, and their chest radiographs are normal.
  • Class II: Moderately Affected. Healthy dogs with minimal signs as above, occasional coughing, fatigue only with exercise but with radiographs that show definite evidence of heart disease. Lab testing shows mild anemia, urine dipsticks show some protein, but not severe urinary protein loss.
  • Class III: Severely Affected. Dog is suffering from weight loss, cough, difficulty breathing, blatant damage to the vasculature is apparent
    on radiographs, laboratory work reveals a more severe anemia and marked urinary protein loss.
  • Class IV: Caval Syndrome. Dog is collapsing in shock and dark brown urine is evident. Heartworms visible by ultrasound in the AV valve of the right side of the heart, and blood work is very abnormal. These dogs are dying and can only be saved by the physical removal of adult heartworms via an incision through the jugular vein. If such a dog can be saved from this crisis, further heartworm infection treatment cannot be contemplated until the dog is stable enough to fit into one of the other categories above.
Dogs have three groups of heartworms in their body:
  • The microfilariae, which are the newborn children of the adult worms living in the heart and pulmonary arteries. The microfilariae are swimming freely in the bloodstream, possibly in large numbers, and it is the microfilariae that can spread to other dogs through a mosquito.
  • The new arrival heartworm larvae, delivered from mosquito bites in the last 6 to 7 months. These are L3 and L4 larvae living in the skin (having arrived within the last 3 months). These will continue their maturation and repopulate the heart and pulmonary arteries if they are not killed before the adult worms.
    A dog heart congested with heartworms
  • The L5 larvae and adult worms living inside the heart and pulmonary arteries. This group requires the arsenic compounds for destruction while the other two groups can be killed with less toxic products.

There are some differences in the way some veterinarians treat heartworm. I have asked Dr. Lewis from Care Animal Hospital to help me with Brandy’s treatment. Although some veterinarians helping out the shelters will go directly to injections to save the shelters money I hope that the Humane Society can afford the cost of Brandy’s treatment so she can have the same treatment that my dogs would have had.

So, the first step is to clear out the immature worms. If we don’t get rid of the immature worms and go directly to attacking the adult worms then we will give the immature worms a chance to grow up into adult worms. Also the fewer worms dying at once are less risky. We will do this by giving Brandy Heartgard. Yes, Heartgard is what many of you give your dogs to prevent heartworms. The only difference is that Brandy will not be active when given this medication. We don’t want the dying worms to block an artery and cause problems or death.

After 1-3 months of giving the Heartgard the adult worms will be addressed. She will receive 1 – 3 injections of melarsomine dihydrochloride (Immiticide® by Merial). This is a painful injection and she will be very sore afterward. The veterinarian may have to give her pain medication and possibly an anti inflammatory to help her get through this. The injection site can be so painful that if touched the dog may bite. Some dogs have a reaction at the sight and may have a permanent lump.

Brandy will have to be confined from activity for one month after the final treatment also. So from start to finish she will have to be kept as quiet for 1-4 month. So after reading this I hope you take Heartworm infection/disease as seriously as I do.

Please let me know if you know of anyone that can help us by fostering Brandy during her treatment. I can’t keep her here with me because we adopted an 8 month old Border Collie puppy just days before we found this out about Brandy.

American Heartworm Association www.heartwormsociety.org.
Dr. Wendy C Brooks, DVM, DipABVP www.veterinarypartner.com.
Dr. Brooke Lewis, Care Animal Hospital, Kenosha WI