Once a Puppy Receives Worm Treatment, Are the Worms Gone?

Heartworms and other parasitic worms can infect your puppy, making the little guy really sick. If your vet has diagnosed little Fido with worms and given him medication to get rid of them, most of the worms will soon die and pass from his body. Unfortunately, sometimes the dead worms can cause further problems. Repeated treatments may be necessary to get rid of immature worms remaining in his system.

Little pups can pick up worms while still in their mother's womb or when they nurse from her. This is why most vets recommend giving them their first worming treatment as early as 2 weeks old, according to the Doctors Foster and Smith website. Broad-spectrum anthelmintic medications contain ingredients that kill off most types of worms in a pup's system. Some of these wormers kill the worms off over a period of time, after which your pup will expel them in his feces. Other wormers not only kill the worms but dissolve them, too.

While some wormers work with only one treatment, you need to repeat others for them to kill all of the worms in Fido's body. Many wormers kill only adult intestinal worms or heartworms, leaving their immature larvae behind to reinfect your pup, warns petMD. You need to repeat these medications after a period of time, usually within days or weeks, as directed by your vet. Without repeat treatment, your pup will still have worms. Sometimes a combination of medications is prescribed, one to kill off the adult worms and another, administered later, to rid Fido of the immature worms. Such a combination is used for treating canine heartworms, according to the American Heartworm Society website.

While a worming medication may kill the worms in your pup's system, they are not gone until his body expels or absorbs them. Unfortunately, sometimes these dead worms become lodged in his intestinal tract, capillaries or arteries, leading to a possibly life-threatening blockage. When large amounts of heartworms die off and get stuck in the blood vessels of his lungs, they can obstruct the blood flow, resulting in coughing, fever or death. Sometimes anti-inflammatory drugs can help. Large amounts of intestinal worms may cause a gastrointestinal obstruction. If those worms don't pass through his intestines after treatment, that blockage might remain unless it's removed by your vet.

Your vet needs to determine which kind of worm your pup is suffering from before prescribing him a medication, because broad-spectrum anthelmintics don't treat all types of worms. Using the wrong medication won't kill the worms in your pup's system. If the correct medication does kill the worms in Fido's body, you still need to clean up his environment, removing feces from your yard and washing his bedding to prevent him from becoming reinfected with any remaining worms or their eggs. You'll also need to test and treat any other pets in your home to prevent them from passing the worms back to your pup if they are infected, too.