Spirometra Mansonoides In Dogs And Cats

This is the egg of Spirometra we see on the microscope. Spirometra spp. got into your pet because he ate something that was the first intermediate host, such as a bird, snake or frog. Preventing him from eating those will prevent future infestations with Spirometra.

Spirometra mansonoides is a tapeworm parasite that commonly infects bobcats, domestic cats and dogs.

Unlike the more common tapeworm of dogs and cats, Dipylidium caninum, which uses the flea as its intermediate host, Spirometra have two intermediate hosts.

The life cycle begins with an infected animal (bobcat, dog, cat, racoon, and other mammals) passing eggs in worm segments called proglottids. Eggs mature into a larval stage that infects a copepod, which is a tiny aquatic animal. In the ocean, copepods are a major component of the food source known as plankton. Copepods are equally numerous in fresh water, and may be swallowed by a rodent, frog, snake or bird drinking contaminated water. Thus, the copepod is the first intermediate host and the rodent, frog, snake or bird, is the second intermediate host.

The definitive host becomes infected by eating the second intermediate host. The bobcat is Spirometra’s preferred host, but it can reproduce satisfactorily in your house pet, hunting dog or outdoor cat.

Most people are unaware of their pet’s infestation with Spirometra until we perform a routine fecal flotation. We see the characteristic eggs of the parasite, which appear on the microscope, to me, like a folded omelet. Attentive pet owners may notice proglottids of Spirometra in their pet’s stool or attached to the hair of the perineum.

Spirometra infestation rarely causes overt disease in pets, although vomiting, diarrhea and weight loss are possible when the parasite is present in large numbers.

The risk to humans is discussed in this article.

Dr. Randolph.


  1. My daughter’s 3year old cat was diagnosed with Spirometra. She has stable obstructive hypertrophic cardiomyopathy, treated with Atenolol 25mg.
    The vet treated with her with Praziquantel 45mg SQ on 6/28/22
    Follow up fecal flotation test on 7/11/22 showed Spirometra persists.
    The vet then treated her with Cestex 50mg on 7/14/22 and 7/15/22. A repeat fecal test on 8/1/22 showed that the Spirometra remains.
    The vet called and told us that she had done everything she could for the cat and to seek treatment elsewhere. She recommended my daughter take her to the University of Georgia veterinary clinic ( my daughter attends UGA)
    I have researched Spirometra in cats and it’s treatment, and believe that the cat was not given the recommended dose of Praziquantel.
    I would sincerely appreciate your recommendation and advice.

    Thank you.

    • It takes a LOT of praziquantel to kill Spirometra. You have two choices: Ask your local doctor to consult with a UGA parasitologist for the maximum dose or, as directed, take your kitty to UGA for treatment. ALSO, keep in mind that reinfestation is VERY common with Spirometra. If your kitty is outdoors, drinking from puddles or eating snail(s) or other intermediate hosts, the problem may not be failure to clear but simply getting more Spirometra before she gets retested. It shouldn’t be impossible to clear, however, we have a number of “repeat offenders” in our practice, resulting from their lifestyle. Thanks for reading, Dr. Randolph.

      • Thank you for your response. After contacting you, I informed our veterinarian, and after much research done by herself, she determined the oral dose. She has contacted several pharmacies to see if they could compound it, still waiting for response. In the meantime, I asked her if we could use human tablets. She was agreeable, so I am calling our local pharmacies. Please, let me know how you have administered the high dose Praziquantel to your feline patients, and would you use the scored human version.
        Thank your time and expert opinion.
        Wissal Byrnes

        • I made a commitment when we first started this blog not to publish or comment on doses. I have never treated Spirometra orally, but I’ve used some really big doses of praziquantel injectable with 100% safety. Thank you for your correspondence. Please stay in touch, Dr. Randolph.

  2. My 10 month old dog just got diagnosed with Spirometra. She said the only treatment that she knows of is 2 doses of Praziquantel at $190. Per dose. I also read that surgery is another option. Is this drug the only safe treatment and will it prevent him from it coming back

    • It’s expensive to treat large pets because it takes so very much medication to kill this parasite. By the way, there is NO way surgery is an option for treatment. Yes, the medicine is very, very safe. Prevention involves keeping him from drinking water or eating the intermediate hosts. Typically, we don’t see this parasite in pets kept in clean, controlled conditions, therefore, if you provide him with clean drinking water and don’t let him drink from puddles when out walking, you should be able to prevent reinfection. The medicine is treatment only, not prevention. Thanks for reading, Dr. Randolph.

      • Hi! Quick question. We found and took in a stray kitty approximately 6 weeks ago. He tested positive for FeLV and has been quarantined from my other cats. Aside from the abysmal prognosis there, I noticed 2 days ago that he had a *massive* tapeworm. I guess he passed it outside of his box, or maybe he threw it up, but the pile was probably a good US dollar coin size. He’s a small cat, only about 7lbs now (6 when we found him). Vet seems to think it’s diplyidium, but I’m not sure he’s correct based on what the worm looks like. Either way, kitty was given NexGard combo, which has 74.7mg of preziquantal (per the box; also contains esafoxolaner and eprinomectin). This is a little low for his body weight if the recommended dose is 30-35mg/kg, but do you think it’s enough? If so, when should we expect him to stop passing giant masses of worm? He’s quarantined in a different (more easily cleanable) room currently because he kept dropping huge piles of worms and poop everywhere, but it’s very small and obviously not a lot of fun for him. Also his poor stomach sounds so upset and the smell is absolutely rancid; I’m sure he doesn’t feel well at all!

        • It’s easy enough for your veterinarian to send this tapeworm to his favorite parasitologist for identification. Expect to pay a fee for this service and to have a definitive answer in about a week. That may not be the CAUSE for “stomach sounds so upset and the smell is absolutely rancid.” He may require a referral to a board-certified veterinary internist to work that problem up. Let us know what is determined. Thanks for reading, Dr. Randolph.

  3. My cat was diagnosed with Spirometra tapeworm. He is 13 pounds and the AAV website says: “praziquantel at the elevated dosage of 30 to 35 mg/kg body weight would cause the elimination of these parasites”.

    Does that mean he should be given 35mg per kg of body weight? He weighs 5.9 kg. Would the dosage be 206.5 mg?

    He is currently on 2 Drontal pills (18.2mg of praziquantel in each pill). And repeat again in two weeks.

    His first fecal exam was in June because I saw the tapeworm in his stool. They found tapeworm and lung fluke eggs. He was given a topical praziquantel on the back of his neck. He was still coughing in September and another fecal exam showed the lung flukes but no tapeworm. He was given 2 Drontal pills 3 weeks ago. His most recent fecal exam showed no lung flukes and Spirometra tapeworm. He was a stray but has been an indoor cat since November 2018.

    I’m wondering if he is getting the correct dosage for both the tapeworm and the lung flukes? What is your opinion? I want to share the info I found on the AAV website but don’t want to have misinformation.

    Thank you!

  4. I just took in a stray cat (about 6 weeks of age) who was diagnosed with Spirometra tapeworm. They are wanting her to get a tad bit older before giving the medication, which is fine. However, I have another kitten I had just adopted a week before this one showed up on my door step, plus I have 3 large dogs. I am worried about steps needed to keep from transmitting or “spreading” the tapeworm. We are keeping stray kitten on our sunroom with fresh water, food, own litter box, etc. but I do have to escort my dogs through that room to outside multiple times a day. (the other cat is secluded in house in her own room for time being). Besides making sure the dogs do not get in the stray kitten litter box and access to her stool, are there other things I should worry about? She is on flea prevention, but if by chance she has a flea get on one of the dogs, can they then contract the tapeworm? I am concened about the kitten, but also wanting to make sure take all precautionaries that it does not spread. Once she is under control and treated, she will be come part of our inside family. 🙂

    • Go back and re-read the life cycle of the parasite. Your other pets can’t get Spirometra from your kitten; the life cycle must be completed from beginning to end in the intermediate hosts. And, fleas are not part of the Spirometra life cycle, as they are with Dipylidium. Thank you for rescuing this baby!

  5. My daughters 7 month old lab puppy just had his second injection (20 mg) does today for spirometra,,

    I am so concerned and upset! None of the vets have ever seen this before and are getting most of their info from online sources as well.

    Please tell me the most effective treatment protocol and if there is a specialist on Florida or anywhere really.

    My daughter lost her other lab in February and cannot go thru another loss

    • Spirometra is common enough that I doubt “None of the vets have ever seen this before.” And, there is no need for them to go online, except, possibly, to email their parasitology professors for advice. Many sources of parasitology textbooks will contain both diagnostic and treatment information. Deaths from Spirometra are virtually unheard-of because of the low level of disease the parasite causes and the safety factor of appropriate treatment. Even though the dose of medicine for Spirometra is higher than the dose for, say, double-pore tapeworm, the therapeutic index for the medicine is quite broad. This should be comforting information for you and your daughter. Let us know if you have more questions, Dr. Randolph.

      • Yes, this is promising news.. I got worried when I read the below message stating extreme infestation of Spirometra that has been resistant to treatment. We are now trying natural remedies in hopes of saving him.”

        Our vets have told us they have never treated a case before this..
        How long should it take to know worms are gone forever…
        His centrifuge stool test was negative after last dose and now they are back.

        Thank you for responding,

        • Two considerations: 1, be sure your pup doesn’t have access to stagnant water and crustaceans, so he’s not reinfecting himself. 2, If they don’t clear, I’d be happy to talk to your veterinarian, although the best source for help would probably be his/her parasitology professor or the parasitologist at the nearest veterinary school. Many of the commercial diagnostic laboratories also have board-certified parasitologists with whom he/she could consult at no charge. The way you know he’s clear is through periodic retesting. Please keep us posted, Dr. Randolph.

  6. Our dog has been diagnosed with an infestation. He sometimes eats out of our cat box. Should we be concerned about our cats or his disgusting habit?

    • At our house, we use a kiddy (child) gate to block the dogs from eating from the litterbox. It’s a pain in the neck for people to step over, but it solves the problem. Now, as for Spirometra infestation, the prevention is keeping the pets from drinking infected, stagnant water and eating the intermediate host, which is often a crawfish or other arthropod. Thanks for reading, Dr. Randolph.

      • Hi Doctor,

        I adopted a cat from the shelter a week ago and yesterday he was diagnosed with spirometra. The vet seemed alarmed and said I needed to keep him isolated from the other cats and the kids. They said my kids could get it from the cat. I’m now panicked. He’s isolated now and I’m concerned. The kids pediatrician said it can’t be passed to the kids via the cat or cat litter. I don’t know what to believe. Can the kids get this parasite from the cat or litter or cat touching toys the toddler puts in her mouth?

  7. Hi,

    I visited the vet with my 32.6lb dog who tested positive for spirometra tapeworms. The vet offered a medication that is $100 called Dronset. I asked her is praziquantel effective as well and she said yes but if I get the over the counter Bayer formula in store instead of the 3 pills listed as her dosage i would need to give her 11 tablets a day for 2 days… so 22 34 mg praziquantel tablets in 2 days is a correct comparison of dronset or no?

    I received advice to give her 3 tablets and then 3 tablets 10 days later from someone else.. I am very afraid to follow the instructions with such a smaller dog as she is and there was no direction on how to administer my dog 11 PILLS! Is it morning? Night? Noon? With food or no?

    It seems dangerous and incorrect to me.

    • I’m sorry, but I don’t have enough information on the pills to give you an answer, but I do have some concerns: 1, as far as I know praziquantel is an FDA-controlled medication. If I am correct in that, no one should be selling it OTC, which would then make me question the safety, purity and source. 2, it takes a LOT of praziquantel to kill Spirometra, WAY more than Dipylidium or other species of tapeworms. Therefore, it’s not surprising that your doctor’s fee would be the amount you stated. I would feel most comfortable recommending you let your pet’s veterinarian treat him safely and effectively. Thank you for reading http://www.MyPetsDoctor.com.

  8. Hi Dr. Randolph,

    Is Spirometra transmissible to humans FROM the dog, the dog’s stool, or the dog’s saliva? Please advise.

    Thank you!

  9. Our 7 month old puppy has an extreme infestation of Spirometra that has been resistant to treatment. We are now trying natural remedies in hopes of saving him. Can this be passed on to humans or our other dog? We’ve been battling this since October 2014.

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