Its not uncommon for pups to require a few rounds of dewormer before they are worm free.

However, Interceptor is supposed to remove round worms and hookworms. I'd probably check the dose and of course ask your vet...

Its only heart worm that needs the pretest, because if the dog has severe heart worms, and the meds then kills the worms, the dead worms have to pass through the heart/circulatory system... the dead worms can clog up the system and kill the dog. Dead Round worms and hookworms are passed through the intestines with no danger to the dog.

A lab grows rapidly in 6 months. The doses of Interceptor are 2-10, 11-25, 26-50, and 51-100 pounds. It is highly unlikely that a lab puppy is in the same weight class at 6 months that she was at 2 months, so she may be underdosed as joepyeweed mentioned.

Some reasons that a dog that is on appropriate doses of Interceptor and had been properly dewormed could still have roundworms are:

1. Roundworms can live in an inactive state within the dog (encysted). They can then emerge at any point, but especially during times of stress (pregnancy is the classic example, but being in heat and other stresses apply). While encysted, they are impossible to kill by ANY dewormer.

2. The dog could be eating an intermediate host (rodents, birds, others) that are infected with roundworms, causing an infection.

3. Interceptor only kills GI parasites that one time per month that you give it. It is NOT a month-long prevention for GI parasites, just a once-monthly dewormer. So your dog could get roundworms (or other GI parasites) at any point, but once monthly the Interceptor kills it.

4. The roundworms may be resistant to milbemycin and another dewormer (pyrantel, fenbendazole) may be needed.

5. The prepatent period (period from infection to seeing eggs in the stool) for roundworms is only 3 weeks, so if the puppy dewormings/interceptor were done on a 4 week basis, then you're missing a week's worth of egg production which can result in encysted or active worms.

The most important thing about roundworms is that it is a zoonotic disease. You can get roundworms, causing serious internal injuries, blindness, or in rare cases even death. Young, old, and immunocompromised people are the most likely to be affected. The most important control factor is to pick up your pet's stool immediately because it takes time before the eggs in the stool become infective. Eating infective eggs in poop is also how dogs become reinfected, so just doing that can help control the infection in your dog as well.

Thanks Joepye and Meghane.

She's actually a Samoyed, so she doesn't grow quite as fast as a lab, but we have upped her doses as she's grown. She's currently 35 lbs and the past two months we've given her the 26-50 dose.

You've mentioned seeing eggs in her stool. It wasn't eggs that we saw. It was an actual worm several inches long. DH is great about checking stools, so I'm suprised we didn't see any signs before this. I don't know the growth rate of these, but imagine she had to have had this guy in her for a while to get as long as it did.

I'm definately aware of the zoonotic part (though I didn't know that was the term for it). It actually has me pretty freaked out. We also have our 5 year old GSD, and as an extra precaution have started taking her to a different area in the yard to do her business. DH is taking a sample of hers to the vet this morning to have it checked.

She definately hasn't eaten any intermediate hosts - she's never left outside alone. My guess is she walked where another dog went who had worms and then licked her paws. Or it was passed to her from her mommy.

And I can't help but feel bad thinking another dog may have been infected because of her. I'm fanatical about picking up poo when we're on walks, etc., but there's always the chance something remained. :-(

Thanks again.

Correct me if I'm wrong, but I believe the eggs are microscopic when they are shed in the stool, so they may be there but you cannot see them.

Meghane - what's the size dosages for Drontal Plus? My vet bill has written on it a dosage for 1.5 tablets at 11-30 lbs. But everything I've found online is for 2-25lbs, and then 25-60. But the tablets have a 30 on them.

I'm afraid they've given us too small of a dosage for her size.