The goal of heartworm treatment in dogs is to eliminate adult heartworms and microfilaria. Treatment is expensive and takes several months to complete.
Once the diagnosis of heartworms has been made it is important to perform additional testing before your veterinarian begins heartworm treatment in dogs. Heartworm disease can cause a combination of problems in the heart, lungs, liver and kidneys. Infected dogs are staged by veterinarians into classes based on their clinical signs, blood work, and radiograph results.
- Stage 1: Mild heartworm disease with early infection. These dogs are not showing any symptoms and have no abnormal findings on lab results or chest x-rays.
- Stage 2: Moderate heartworm disease. These dogs are coughing, exercise intolerance and have abnormal lung sounds. They may have a few abnormal lab results and mild changes visible on chest x-rays.
- Stage 3: Severe heartworm disease. In addition to all the signs listed in Stage 2, these dogs can also have enlarged liver, fluid in the abdomen, abnormal heart sounds and can even die suddenly. These dogs are often anemic and have elevated kidney and liver values along with severe changes visible on chest x-rays.
The American Heartworm Society just revised their recommendations for the diagnosis, prevention, and treatment of heartworms in dogs and cats in January of 2014. I have been practicing for 20 years and we are still learning new things about heartworms. As we have learned more about heartworms, treatment protocols have changed to help us develop a more successful outcome.
The first part of heartworm treatment in dogs is to get them on a safe monthly heartworm preventative. There are a few brands of heartworm prevention that are not safe to give if your dog is positive for heartworms. The purpose of starting them on prevention is to prevent them from getting infected with additional larvae from infected mosquitoes. An antibiotic is also given for the first month to help sterilize and shrink the adult heartworm.
The second part of heartworm treatment in dogs involves giving Immiticide, which is an arsenic derivative that kills the adult worms that are in the heart. The American Heartworm Society recommends waiting until 60 days after starting month heartworm prevention before Immiticide is given. Steroids are also given for 4 weeks during each Immiticide treatment to help decrease inflammation from the dying worms. A single injection is given in the back muscle and the dog has to be confined/restricted activity for 30 days. One month after the 1st injection, the dog returns for two more injections given 24 hours apart. This is followed by another 30 days of confinement/restricted activity.
The third part of heartworm treatment in dogs is to check for microfilaria (circulating baby heartworms that are picked up by the mosquito) 30 days after the last Immiticide injection. If present an oral medication is given at a veterinary clinic and the dog is monitored for an allergic reaction.
All dogs should be tested 6 months after the completion of this treatment to make sure the treatment was successful. Dogs that have been positive in the past should be tested every year for heartworms. All dogs should be on heartworm prevention all year around.
Slow kill method: This method involves only giving your dog heartworm prevention and waiting for the adult worms to die on their own instead of giving the immiticide injection that will kill the adult worms. This is NOT recommended treatment by a veterinarian or the American Heartworm Society. It can take up to 3 years for the worms to die on their own, allowing them to continue to do damage in the heart and lungs. Recent studies have also shown that this method is causing heartworms to become resistant to heartworm prevention medication.[Tweet “Heartworm treatment in dogs is expensive and takes several months to complete”]