Time Frame

• Heartworms are spread through mosquitoes when a mosquito feeds on an infected animal and becomes infected with young heartworms called microfilae. The mosquito then injects the larvae into another animal it feeds on.
  
  

Treatment

• The current approved method for treating heartworm is an adulticide called Immiticide (melarsomine dihydrochloride); a veterinarian will give a series of three injections. Immiticide is an injectable form of arsenic and can be very painful when injected.
  
  

Toxicity

• When the veterinarian injects Immicide, she injects it into deep muscle tissue within the lumbar region so that the Immicide will slowly enter your dog's blood vessels. Immicide is painful because the arsenic burns and has some toxicity, but not enough to kill your dog. It kills the heartworm in your dog's heart, lungs and blood vessels.
  
  

Warning

• The dead and dying heartworms from the treatment must go somewhere and while some are cleaned up by white blood cells, pieces often go into arteries and may block them; dogs can die from this. Limit your dog's activity for two months and bring your dog to the hospital if your dog has a high temperature (102.5 degrees Fahrenheit or higher), vomits, acts depressed on consistently refuses to eat.
  
  

Considerations

• The veterinarian may add anti-inflammatories, heartworm preventatives (to kill off the microfilae), antibiotics (to kill off secondary bacterial infections) and pain medications.