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My dog took heartworm pill by accident, no test. Will he be okay?

Updated on September 23rd, 2025

Pet's info: Dog | Pit Bull Terrier | Male | neutered | 85 lbs

I accidentally gave my dog a heartworm pill, thinking I was giving g a flea pill. The problem is I haven't given him one since October, and haven't had a heartworm test since beginning of last year! I'm worried sick I have harmed my boy!!

2 Answers

Most Helpful Answer

Answered By Angel Alvarado, LVT

Licensed Veterinary Technician

Published on January 9th, 2017

Murphy should be fine, especially if you are not in a heartworm endemic area. The meds will kill any circulating juveniles (microfilariae). Be sure to have him properly tested before the next dose. It takes 5-8 months for a female heartworm to mature into a reproducing adult. Ideally, every dog should be tested every 6 months but since most dogs are on meds year round (for the added intestinal parasite protection), once yearly testing is typical.

1Pet Parents found this answer helpful

Related Answers from Veterinarians

Answered By Lauren Jones VMD
Veterinarian
Published on June 28th, 2022
Anytime heartworm prevention is late or missed, there is a chance of acquiring heartworm disease. Given your southern zip code, you're in an area of a much higher incidence of heartworm disease relative to those of us further north. With that said, I don't think you need to panic! Since your puppy is still so young, they're too young to run a terribly accurate test for the presence of heartworms. The tests that we use as a screening tool check for the antigen from adult female heartworms, which take at least 5-6 months post infection to show up on a test. My point being, I think it's worth asking your vet to run a heartworm test on your pup in another 6 months. In the meantime, certainly continue giving the heartworm preventive medication consistently every month. Remember that as your puppy grows, their dose will change, so keep in touch with your vet regarding your puppy's current weight and dosage. I hope this helps to clear up any confusion and that everything goes well for your pup!
2Pet Parents found this answer helpful

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Related Questions

Health & Wellness

My dog missed a monthly heartworm/flea dose. Do I need a vet visit?

No, there is no need to go to the vet for missing the dose. Your dog should be fine. SHould there be microfilariae present, the next dose you gave should kill them. Just keep giving the heartworm medication as prescribed. Your dog will need a heartworm test anyway every year. No worry!

Updated on September 23rd, 2025

Health & Wellness

I accidentally missed my dog's Heartgard. What now for heartworms?

If you only missed 1 month, you should be fine. Just resume Heartgard right away . If you just want peace of mind, then you can have Lilly retested in 6 month from now; however, the chances of infection are pretty low. Thanks for visiting Petco Pet Education Center, formerly Petcoach and best wishes with your pet Lilly. Take care!

Updated on September 23rd, 2025

Health & Wellness

Is it safe to give heartworm meds after missing doses without a test?

If he has always been on it and hasn't missed any doses, then he should be fine to continue with the prevention. Now, that being said, no prevention is 100% effective so the reason we test every year is to check and make sure there was no break-though issues with the product. If a dog has heartworm disease there is a chance the prevention could cause a medical problem. In this case, I think the benefit of him taking the heartworm prevention outweighs the very tiny risk that he could be positive and have a reaction to the medication. Hope this helps. If you have more questions you can always opt for a private consultation where we can chat back and forth. That way you can ask as many questions as you'd like. Best wishes!

Updated on September 23rd, 2025

Health & Wellness

My dog missed Heartgard. Is he safe from heartworm? What to watch for?

Rocky should be ok. Heartworm disease is in fact transmitted by mosquitos. Thankfully in your location during the time missed there are not that many mosquitos around. It can take 6 months to show up positive on the test so I would recommend testing in October of this year the latest. I wouldn't stress too much. You can look out for coughing and exercise intolerance. Just continue giving the medication monthly at this point. Here is a website for the Heartworm Association if you have questions. https://www.heartwormsociety.org/pet-owner-resources Thank you for using PetCoach.

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Can I give my 5-month-old puppy heartworm medicine without a test?

Yes, I usually start dogs under six months on a heartworm medication without a blood test. The test checks for antibodies to adult worms and they need six months to grow into adults so that’s why the test isn’t needed. I’m glad you are using heart guard since it’s safe to use even if by some chance he has an early heartworm infection. Certainly have his blood tested at your annual exam and vaccinations. Thanks for using Petco Pet Education Center, formerly Petcoach to help you care for Jac.

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Just adopted a dog, when should I get her tested for heartworm?

Heartworm medication should be given to a dog every month, but if a dog does have heartworm, it will take at least six months for a dog to test positive after being infected. I would have Holly checked for heartworm now so she can be put on a preventative if she is negative for it. I hope this helps!

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My puppy ate his Milprazon worming tablet. Is he going to be okay?

Worming tablets are designed to be eaten and are recommended monthly up to 6months because pups catch worms from their mothers. I recommend you check the strength of the tablet in relation to his weight but side effects other than mild gastrointestinal issues are very rare even if they eat too much. Monthly treatment for life is recommended if you are in a heartworm or lungworm affected area and every 3montgs otherwise

Updated on September 23rd, 2025

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