Puppy care shorts: Heartworm and worming


Flea/Tick Preventative

If desired, use Frontline or Advantage every four to eight weeks. Four for ticks, eight for fleas. If you are in an area where there are ticks OR where Lyme disease (or anaplasmosis or ehrlichia) is prevalent, make sure to have Frontline (not Advantage) applied BEFORE tick season starts (April) and be faithful until the first hard frost. If there are not ticks or tick-borne diseases in your area, you may not have to ever use flea preventative unless you actually see a flea on your puppy. Do not use anything but Frontline or Advantage without checking with me first. Do not use an over-the-counter product like BioSpot or Zodiac or similar, and do not use ProMeris. We recommend none of the tablets (Sentinel, Program), as the flea or tick must bite the dog before it dies. These products do not prevent tapeworm or flea bite dermatitis (hot spots) the way a direct flea-killer like Frontline does. Revolution works by putting a potent pesticide into the skin and blood, so unless the dog has mites we recommend against its use.

Heartworm Preventative

We do not recommend a year-round heartworm treatment if you are in an area with good hard winters. That is because the medicine in monthly heartworm medications, ivermectin, is chemically harder on the dog’s system than one of the “gentle” wormers like strongid (pyrantel). For that reason, in New England we recommend a heartworm test (which will also screen for Lyme and the other tick-borne diseases, so you should do the test even if you’re not worried about heartworm) in April or May and preventative from May to October or November (the last dose should be given after the first hard killing frost). Before that point and after that point the temperature is too cold for the heartworm larvae to mature inside the mosquito’s system and your dog is not in danger. DO NOT (and I cannot emphasize this enough) use the six-month heartworm medications or ANYTHING besides Heartgard, Heartgard Plus, or Interceptor without checking with me first. 

The effective time of each preventative is 45 days (six weeks). Therefore, don’t panic if you miss the 30-day dosing. 

In warm climates where there is not a killing freeze, it is safer to give heartworm preventative year-round. 

If your dog tests positive at any time, contact me immediately.


Your puppy was wormed periodically from two weeks of age. You should plan on checking a stool sample sometime around ten to twelve weeks, or anytime if your puppy develops a “wormy” appearance, with ribs showing but a full belly (a “potbelly”). Worms do not indicate that you have not cared for your puppy or that your puppy is not otherwise healthy—they go into the puppies via the mother’s blood supply and through the milk even when she is herself free of active worms. They are simply an annoying problem in the first months of life and hopefully never thereafter. A stool sample is important because there are several types of worms and not all medicines kill them all. DO NOT buy “supermarket” piperazine. Strongid (pyrantel pamoate) is what should be used for roundworms, which are the only ones your puppy is likely to have. Panacur (fenbendazole) can be used for a resistant infestation. Do not fall into the trap of “more is better”—some vets will push for Drontal, which also contains a medication for tapeworms, when the puppy doesn’t have tapes. Ask for a stool analysis and then worm with the gentlest and simplest wormer you can.

There are simple ways you can prevent the reinfection of your puppy with worms. Make sure her crate and surrounding area are kept clean and that messes are promptly cleaned up and disinfected. Don’t feed her in the same area that she eliminates in. Don’t allow her to eat feces (many puppies go through this stage). And pay attention to the signs she is giving you—if she starts to suddenly grow more slowly, loses her appetite, vomits more than once or twice, or develops a potbelly, take a stool sample to the vet.

If your puppy is on certain heartworm medication, she does not also need to be wormed. Heartgard Plus contains the same medication as is in Strongid and will worm the puppy automatically.

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