Ask a vet online – ‘ Is too many wormer tablets bad for my dog?’

Question from Gillian Richards

I have a American bull dog and every couple of weeks as worms I have giving 1 dose wormer tablets but is to many wormer tablets bad for her or is their another wormer I could use to treat it many Thanx

Answer from Shanika Winters MRCVS, Online Vet

Hi Gillian and thank you for your question about worming your dog. I will start by discussing the common worms that affect dogs and then treatment options.

When we say a dog has worms we are usually talking about intestinal (gut) worms but we are now much more aware that worms can also affect the lungs and heart of dogs. Worms have a life cycle and this can include other species sometimes such as cats, foxes, sheep, slugs, snails and mosquitoes. The worms are a parasite, the animal it is living in is called the host, and if the worm as part of its life cycle has to pass through another animal then this animal is called an intermediate host.

Common worms affecting dogs include the round worm Toxocara canis, tapeworm Dipylidium caninum, whip worm Trichuris vulpis, hookworm Ancylostoma caninum, heart worm Dirofilaria immitis and the lung worm Angiostrongylus vasorum.

The life cycle of the round worm is as follows:

Worm eggs are eaten or licked up by the dog, these hatch in your dog’s stomach and develop into larvae.
Larvae pass into your dog’s blood, are carried to the lungs where they climb up the trachea (windpipe) and are coughed up and swallowed. These larvae then mature into adult worms. Larvae can also remain inside your pet in an encapsulated (protected stage) in different body tissues.

Adult female worms produce eggs which are then passed out in your dog’s faeces (poo). These eggs can then be eaten by your dog or other animals. Worm eggs can survive in the environment for a long time.
Round worms can be passed directly from pregnant bitches to the puppies both before and after birth.

How can you tell if your dog has worms?

Most healthy adult animals show little or no signs of having intestinal worms. Passing worms in the faeces, segments in the case of tape worms around your dog’s bottom which look like grains of rice, intermittent diarrhoea, vomit plus or minus worms, weakness and anaemia may be seen. Very young animals, those which are severely infected or with a weak immune system may show the more severe signs listed when infected with intestinal worms.
If there are no obvious signs of worms or we are trying to work out which exact type of worms your dog has then test can be carried out of faeces and blood samples from your dog.

How do we treat intestinal worms?

Most pregnant bitches are given several doses of an appropriate worm treatment throughout pregnancy and lactation (milk production). We advise regular worming of puppies from birth to 6 months of age. Puppies 6 months of age and adult dogs are advised to be routinely wormed three to four times a year.
It is safest to discuss which wormer to use with your vet to ensure it is safe for your dog, its life stage and that the correct dose is given. Worm treatments tend to kill the adult worms and larvae inside your dog, the encapsulated larvae are only killed by certain worm treatments. It is very easy for your dog to pick up worms soon after treatment from eggs in the environment, faeces and other animals.

Worm treatments:

The worm treatment drugs come in the form of tablets, pastes, granules and spot on preparations. The exact type you use should be decided after discussion with your vet especially in the case of recurrent infestations. It is always important to use the correct dose of a drug and one that is safe for your pet’s age and health status. Reasons a worm treatment may not appear to be working include: pet reacts badly to certain drugs, the worms they have are not being killed by the drug given, their immune system is weakened by other conditions or they are being exposed to a high level of worms.

Many combination drugs are available that treat different types of worms and some other parasites also. A list of drugs commonly found in worm treatments include, fenbendazole, praziquantel, milbemycin, pyrantel, moxidectin, selamectin and flubendazole.

In conclusion regular worming of your dog with a suitable drug is important for dogs of all ages, the exact drug used can be chosen after discussion with your vet based on your dogs needs. If worm infestation is recurrent then your vet may suggest performing tests to work out exactly which worms are present, helping to choose the best drug to use and an individual worming regime can be set. Worm treatment is a constant battle as re infestation occurs to easily. I hope this has helped you and that your dog’s worms are soon under control.

Shanika Winters MRCVS (online vet)

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101 thoughts on “Ask a vet online – ‘ Is too many wormer tablets bad for my dog?’

  1. Hello, I was just wondering if it would be dangerous to my cat if I have him one too many deworming pills I put them in his wet food but he just hasn’t been acting himself very drowsy and I’m not sure if it’s from the de wormers

    1. Hi, our advice would be to give your own vets a call – tell them the tablet type and the symptoms. They might want to see your cat as a check-up just to be sure! Thank you, David RVN

  2. Hello, I was just wondering if it would be dangerous to my cat if I have him one too many deworming pills I put them in his wet food but he just hasn’t been acting himself very drowsy and I’m not sure if it’s from the de wormers

    1. Hi, our advice would be to give your own vets a call – tell them the tablet type and the symptoms. They might want to see your cat as a check-up just to be sure! Thank you, David RVN

  3. Hi I just want to no what affect it has on a dog if they hav to many tablets at once wormed my dogs this morning and dropped on and one of my other dogs (that I already done ) ate it I tryed to get it out but was to late is it harmful should I take her to the vet. Thanks in advance

  4. Hi I just want to no what affect it has on a dog if they hav to many tablets at once wormed my dogs this morning and dropped on and one of my other dogs (that I already done ) ate it I tryed to get it out but was to late is it harmful should I take her to the vet. Thanks in advance

  5. hi i worm my dogs on drontal was just wondering if dogs get immune to worming tablets like we do on antibiotics ??
    thanks

    1. Hi Magenta,

      Your dog should not get immune to Drontal, however if you have concerns that they might still have worms, then trying a different wormer is always an option.

  6. hi i worm my dogs on drontal was just wondering if dogs get immune to worming tablets like we do on antibiotics ??
    thanks

    1. Hi Magenta,

      Your dog should not get immune to Drontal, however if you have concerns that they might still have worms, then trying a different wormer is always an option.

  7. Hi took my puppy to the vets a bought and was given a worming tablet and to take half of it .when I give it to him he was sick 5 mins later aint sure if it’s working and to give him the other half cause he has worms in his poo one was alive in one lot .The other it was dead .don’t know wot to do .

  8. Hi took my puppy to the vets a bought and was given a worming tablet and to take half of it .when I give it to him he was sick 5 mins later aint sure if it’s working and to give him the other half cause he has worms in his poo one was alive in one lot .The other it was dead .don’t know wot to do .

  9. I found a stray puppy (about 8 weeks old) about three weeks ago. I took her to the vet who gave her a deworming pill and got her to a foster. The foster gave her another deworming pill yesterday (so at roughly 11 weeks), and she passed away several hours later. Could she have overdosed, or is this likely something else? I live in a very difficult areas for strays, and parvo and distemper are pretty common. I’m heartbroken and wondering of this could have been prevented. Thank you.

  10. I found a stray puppy (about 8 weeks old) about three weeks ago. I took her to the vet who gave her a deworming pill and got her to a foster. The foster gave her another deworming pill yesterday (so at roughly 11 weeks), and she passed away several hours later. Could she have overdosed, or is this likely something else? I live in a very difficult areas for strays, and parvo and distemper are pretty common. I’m heartbroken and wondering of this could have been prevented. Thank you.

  11. Hello, my puppy was born November 10 and on December 26 he was given a home injection of parvo but my dad said my puppy was to small and wanted a vet to do the job. We took my 1.25 lb dog to the vet on January 31st he was given a dewormer and a day later he got very ill. Took him back they told me he had parvo. I did my research and he had diarrhea for about two days, no bloody stool or vomit. He was vomiting and he was very active! I was giving him fluids “pedi light” some food given to us and antibiotics. It seemed to be working but then it didn’t. We wasn’t eating on his own still it was forced at times he would but rarely. by like Wednesday he had no more diarrhea but vomiting water because of all the fluids. On Thursday my dad gave my puppy a vomiting pill that was given to my other dog a while back but he cut it up, he said when he did he foamed at his mouth. He didn’t mean to and he doesnt know if that’s what messed him up. This past Friday morning February 6, 2015 he was on the floor with no control over his body couldn’t lift his head or move he’d take his fluids but wouldn’t open his mouth he had very short and long breaths he passed later that day around 3pm. Where did it go wrong…. The dewormer? The doctor saying he had parvo? Or the pill? I can’t seem to let it go, I need closer. My little puppy touched my heart the few time I had him and I just need to know.

    1. Hello we are sorry to hear about your puppy. From what you say, it strongly suggests that your pup died from Parvo. It is very highly unlikely that a dewormer caused it or the anti sickness pill. The possible reason your pup foamed at the mouth is the pill is covered with a coating to stop a bitter taste, therefore the coating was broken causing foaming. The symptoms you have described all point towards parvovirus. David RVN

  12. Hello, my puppy was born November 10 and on December 26 he was given a home injection of parvo but my dad said my puppy was to small and wanted a vet to do the job. We took my 1.25 lb dog to the vet on January 31st he was given a dewormer and a day later he got very ill. Took him back they told me he had parvo. I did my research and he had diarrhea for about two days, no bloody stool or vomit. He was vomiting and he was very active! I was giving him fluids “pedi light” some food given to us and antibiotics. It seemed to be working but then it didn’t. We wasn’t eating on his own still it was forced at times he would but rarely. by like Wednesday he had no more diarrhea but vomiting water because of all the fluids. On Thursday my dad gave my puppy a vomiting pill that was given to my other dog a while back but he cut it up, he said when he did he foamed at his mouth. He didn’t mean to and he doesnt know if that’s what messed him up. This past Friday morning February 6, 2015 he was on the floor with no control over his body couldn’t lift his head or move he’d take his fluids but wouldn’t open his mouth he had very short and long breaths he passed later that day around 3pm. Where did it go wrong…. The dewormer? The doctor saying he had parvo? Or the pill? I can’t seem to let it go, I need closer. My little puppy touched my heart the few time I had him and I just need to know.

    1. Hello we are sorry to hear about your puppy. From what you say, it strongly suggests that your pup died from Parvo. It is very highly unlikely that a dewormer caused it or the anti sickness pill. The possible reason your pup foamed at the mouth is the pill is covered with a coating to stop a bitter taste, therefore the coating was broken causing foaming. The symptoms you have described all point towards parvovirus. David RVN

  13. hey dr.I have white boxer male..he isn’t well since one week..I gave him deforming tablets ..today morning…and I thinking to give him antibiotic tablets also

    tell me will he face anyproblems..with those medicines

    1. Hi Nancy, I’m afraid we cannot give information for medicines here, due to legal and safety reasons. Please speak to your own prescribing vet for any concerns.

  14. hey dr.I have white boxer male..he isn’t well since one week..I gave him deforming tablets ..today morning…and I thinking to give him antibiotic tablets also

    tell me will he face anyproblems..with those medicines

    1. Hi Nancy, I’m afraid we cannot give information for medicines here, due to legal and safety reasons. Please speak to your own prescribing vet for any concerns.

  15. hi i gave my dog worming tabs this morning and it says do not feed for 8 hours but hubby came in and forgot and fed him after 4 hours will this affect the tabs

  16. hi i gave my dog worming tabs this morning and it says do not feed for 8 hours but hubby came in and forgot and fed him after 4 hours will this affect the tabs

  17. Hi my bitch has not long had pups she is perfectly healthy and had a litter 8 healthy pups, but she sees lost alot of weight I’ve upped her food intake and dewormed her again today, but how long would it take till she starts putting it back on ( Pups are 5weeks old and weaned very chuncky pups)

  18. Hi my bitch has not long had pups she is perfectly healthy and had a litter 8 healthy pups, but she sees lost alot of weight I’ve upped her food intake and dewormed her again today, but how long would it take till she starts putting it back on ( Pups are 5weeks old and weaned very chuncky pups)

  19. I wormed my 10month old staff 1week ago can I re worm here aweek on just to double check they’ve all gone don’t wana over dose here etc so is 7days on ok to do so ???

  20. I wormed my 10month old staff 1week ago can I re worm here aweek on just to double check they’ve all gone don’t wana over dose here etc so is 7days on ok to do so ???

  21. Hi..i gave my dog 2 tablets of dewormer today..my friend told me that it only needs 1 tablet per deworm..is it possible that he will be overdosed?.what shall i do?

  22. Hi..i gave my dog 2 tablets of dewormer today..my friend told me that it only needs 1 tablet per deworm..is it possible that he will be overdosed?.what shall i do?

  23. I have an approx 1 yr old dog I got from HS. Shes very malnourished & has lots of watery stools. I’ve tied all sorts of diets . Chic/rice, hypoallergenic, grain free. Well she did end up having tapeworms & was treated but shes still sick. I talked to HS who said they had also treated 3 times. I’ve heard too many doses can cause liver disease. Should I check labs, eg liver, pancreatic enzymes etc. Wouldn’t they all be off anyway with so much diarrhea. (she occasionaly has formed stools) or should I do xray to look for blockage (no vomiting, only once) . Sometimes stools are tarry sometimes not. Shes very lethargic. Had low grade fever 102. I’v espent so much money not sure what to do next? Thanks, Kris

    1. Hi Kris, your poor dog, it seems like you are really trying to help sort her out. We would suggest you have a blood sample and faecal analysis completed, especially for bacteriology (Campylobacter, Salmonella) – bacteria along those lines. It doesn’t sound like a typical blockage, so we would suggest lap work first. Hope that helps a bit, good luck.

  24. I have an approx 1 yr old dog I got from HS. Shes very malnourished & has lots of watery stools. I’ve tied all sorts of diets . Chic/rice, hypoallergenic, grain free. Well she did end up having tapeworms & was treated but shes still sick. I talked to HS who said they had also treated 3 times. I’ve heard too many doses can cause liver disease. Should I check labs, eg liver, pancreatic enzymes etc. Wouldn’t they all be off anyway with so much diarrhea. (she occasionaly has formed stools) or should I do xray to look for blockage (no vomiting, only once) . Sometimes stools are tarry sometimes not. Shes very lethargic. Had low grade fever 102. I’v espent so much money not sure what to do next? Thanks, Kris

    1. Hi Kris, your poor dog, it seems like you are really trying to help sort her out. We would suggest you have a blood sample and faecal analysis completed, especially for bacteriology (Campylobacter, Salmonella) – bacteria along those lines. It doesn’t sound like a typical blockage, so we would suggest lap work first. Hope that helps a bit, good luck.

  25. My 3 month old puppy eat a dewormer tablet for my 3 year old yorkie will he be fine . He was wormed around 3 weeks ago.

  26. My 3 month old puppy eat a dewormer tablet for my 3 year old yorkie will he be fine . He was wormed around 3 weeks ago.

  27. I gave my dog a reformer for tape worms she’s 15lbs but the tabs sd 114mg I gave her half well she die recommended dose was 30mg

  28. I gave my dog a reformer for tape worms she’s 15lbs but the tabs sd 114mg I gave her half well she die recommended dose was 30mg

  29. Hiya.. I just notices loads of slugs in my garden at nite.. My pup ( 16 wks) smells them the runs away frm them.. Am i better to give her lung worm tsbs just to be safe. She.s on her usal worming tab for het age.. Thanks linda

    1. Hi Linda, speak to your vet for advice and check whether the wormer the pup is on covers lungworm. It’s good for peace of mind!

  30. Hiya.. I just notices loads of slugs in my garden at nite.. My pup ( 16 wks) smells them the runs away frm them.. Am i better to give her lung worm tsbs just to be safe. She.s on her usal worming tab for het age.. Thanks linda

    1. Hi Linda, speak to your vet for advice and check whether the wormer the pup is on covers lungworm. It’s good for peace of mind!

    1. Hello Adele, she sounds fabulous! Unfortunately we cannot give advice on drug dosages and will always refer you to your vet. Safety is a priority!

    1. Hello Adele, she sounds fabulous! Unfortunately we cannot give advice on drug dosages and will always refer you to your vet. Safety is a priority!

  31. My miniature jack Russell had 4 puppies nearly 6 weeks ago she is still feeding them even tho they are weaned can I give her a wormer whilst she is still feeding or wait another 2 weeks wen they have gone to their new homes x

  32. My miniature jack Russell had 4 puppies nearly 6 weeks ago she is still feeding them even tho they are weaned can I give her a wormer whilst she is still feeding or wait another 2 weeks wen they have gone to their new homes x

  33. Hi I have a 35 kg shar pei x and I wormed her a month ago and is still showing symptoms of having worms, can I deworm her again so soon or should I wait? Cheers

  34. Hi I have a 35 kg shar pei x and I wormed her a month ago and is still showing symptoms of having worms, can I deworm her again so soon or should I wait? Cheers

  35. Hi I have an adult dog and a 5 month old puppy.I had different worming tablets for both of them to suit their ages but they ended up eating each other’s.The puppy ate one with 144mg pyrantel embonate,50mg praziquantel and 150mg febantel will he be ok

  36. Hi I have an adult dog and a 5 month old puppy.I had different worming tablets for both of them to suit their ages but they ended up eating each other’s.The puppy ate one with 144mg pyrantel embonate,50mg praziquantel and 150mg febantel will he be ok

  37. I gave my puppy too much dewormer medicine and she is walking around like she is very drowsy but still eat and drink water . Will it eventually get out of her system ?

  38. I gave my puppy too much dewormer medicine and she is walking around like she is very drowsy but still eat and drink water . Will it eventually get out of her system ?

  39. I gave my dog Praziquant according to the dosage. It does not seem to be working. Do I give her more praziquantel or wait longer.

    1. Hi Shawna, I recommend that you take her to your vet and discuss the best plan of action with them. There may be a requirement for different or additional treatment. Best wishes

  40. I gave my dog Praziquant according to the dosage. It does not seem to be working. Do I give her more praziquantel or wait longer.

    1. Hi Shawna, I recommend that you take her to your vet and discuss the best plan of action with them. There may be a requirement for different or additional treatment. Best wishes

  41. Hello. I have an 8 week ols bichon frise and I took him tobthe vet forvhis 2nd round of shots and wormer. Tonite he was throwing up and it was a white and foamy. He has been wiening and crying. Should I call my vet? Should I be worried? Could it be the wormer making him sick? He had his first wormer 3 weeks ago and oopped out some spagetti looking worms. So far he hasn’t popped out any more just throwing up.

    1. Hi Delsie, I think you should take him to be checked over by your vet again. Something’s obviously going on and with such young puppies it’s important to address illness sooner rather than later. Best wishes

  42. Hello. I have an 8 week ols bichon frise and I took him tobthe vet forvhis 2nd round of shots and wormer. Tonite he was throwing up and it was a white and foamy. He has been wiening and crying. Should I call my vet? Should I be worried? Could it be the wormer making him sick? He had his first wormer 3 weeks ago and oopped out some spagetti looking worms. So far he hasn’t popped out any more just throwing up.

    1. Hi Delsie, I think you should take him to be checked over by your vet again. Something’s obviously going on and with such young puppies it’s important to address illness sooner rather than later. Best wishes

  43. My puppy is 3 months old and manage to get into cat wormer and drunk the whole bottle is there anything I can do

    1. Please take him to the vet ASAP, without knowing the details, he could become rather poorly. Thanks and best wishes

  44. My puppy is 3 months old and manage to get into cat wormer and drunk the whole bottle is there anything I can do

    1. Please take him to the vet ASAP, without knowing the details, he could become rather poorly. Thanks and best wishes

  45. we picked up a dewormer for our puppy. my husband misread and gave her one pill for an adult dog instead of a pill for puppy. Will the adult pill hurt her?

    1. Hi Stephanie, without knowing the details, we’d recommend you contact your vet. Puppies by nature are delicate and any illness/poisoning is better acted on early. Best wishes.

  46. we picked up a dewormer for our puppy. my husband misread and gave her one pill for an adult dog instead of a pill for puppy. Will the adult pill hurt her?

    1. Hi Stephanie, without knowing the details, we’d recommend you contact your vet. Puppies by nature are delicate and any illness/poisoning is better acted on early. Best wishes.

  47. Hi was just wondering if I can give my dogs worming tablets today as they had there flea tablets yesterday just needed abit of advice thanks

    1. Hi Carol, it depends which flea tablets/worm tablets you use. Give your vet a ring and they will happily advise we’re sure. Many thanks.

  48. Hi was just wondering if I can give my dogs worming tablets today as they had there flea tablets yesterday just needed abit of advice thanks

    1. Hi Carol, it depends which flea tablets/worm tablets you use. Give your vet a ring and they will happily advise we’re sure. Many thanks.

  49. Hi I’ve got a 9 week old shih tzu only had him for 1 week he’s had very loose poos was due injections yesterday but vet said because of loose poos it could be worms so would rather treat that first before injections, it was just 1 tablet, my worry is day after he had 2 loose poos that nite and early hours but following day his poo started to firm up but as I went to get cleaning wipes he ate the poo, does this mean he will be infected with worms again?

    1. Hi Dawn, if your puppy is shedding live worms/worm eggs then there is the potential to re-infest himself. Give your vet a ring for advice as they’ll know what you’ve treated him with and will be able to advise you more specifically. Best wishes, enjoy your new pup!

  50. Hi I’ve got a 9 week old shih tzu only had him for 1 week he’s had very loose poos was due injections yesterday but vet said because of loose poos it could be worms so would rather treat that first before injections, it was just 1 tablet, my worry is day after he had 2 loose poos that nite and early hours but following day his poo started to firm up but as I went to get cleaning wipes he ate the poo, does this mean he will be infected with worms again?

    1. Hi Dawn, if your puppy is shedding live worms/worm eggs then there is the potential to re-infest himself. Give your vet a ring for advice as they’ll know what you’ve treated him with and will be able to advise you more specifically. Best wishes, enjoy your new pup!

  51. Hi I’m Lisa and I have a question my puppy was pooping out worms I gave them more medicine about 3 days ago should I give them more today

    1. Hi Lisa,

      You don’t say if the worms were still alive? Most wormers kill the worms in the intestine and sometimes they are shed in the poop which owners can see, but are in fact dead worms…

  52. Hi I’m Lisa and I have a question my puppy was pooping out worms I gave them more medicine about 3 days ago should I give them more today

    1. Hi Lisa,

      You don’t say if the worms were still alive? Most wormers kill the worms in the intestine and sometimes they are shed in the poop which owners can see, but are in fact dead worms…

  53. Hi, I bought some safeguard 8 in 1 dewormer for my 9 month old micro teacup schnauzer. I followed the directions and fed her the treatment only to realize that this specific medication did not treat Diplidium Caninum tapeworm. One week later she still has tapeworm segments coming out obviously because the dewormer did not treat the specific tapeworm she had. Is it okay if I buy a different dewormer that will treat Diplidium Caninum and treat her right away? It has only been a week since I gave her the full treatment of the other dewomer. But she definitely needs to be wormed because segments are coming out daily. But I don’t want to overdose her on wormer. Is one week later too soon to treat her again? If it is how long should I wait before I treat her? Thank you so much 🙂

    1. Hi Jesse,

      Worms are so horrible! As there are so many types of dewormers I’m afraid we cannot give specific advice about dosages, and strongly suggest you contact your own vet for advice as they will have the latest details on your schnauzer.

  54. Hi, I bought some safeguard 8 in 1 dewormer for my 9 month old micro teacup schnauzer. I followed the directions and fed her the treatment only to realize that this specific medication did not treat Diplidium Caninum tapeworm. One week later she still has tapeworm segments coming out obviously because the dewormer did not treat the specific tapeworm she had. Is it okay if I buy a different dewormer that will treat Diplidium Caninum and treat her right away? It has only been a week since I gave her the full treatment of the other dewomer. But she definitely needs to be wormed because segments are coming out daily. But I don’t want to overdose her on wormer. Is one week later too soon to treat her again? If it is how long should I wait before I treat her? Thank you so much 🙂

    1. Hi Jesse,

      Worms are so horrible! As there are so many types of dewormers I’m afraid we cannot give specific advice about dosages, and strongly suggest you contact your own vet for advice as they will have the latest details on your schnauzer.

  55. Hi my 1 year dog is not eating food so I took him to vet he gage a slayworm tablet, still he is not eating food so I gave him another slayworm tablet after a month is good for him and please suggest what to do to feed him

    1. Hi Harika, he needs to be seen by the vet again by the sound of it. There are many potential reasons that he’s not eating. Please take him soon and explain your concerns. Best wishes

  56. Hi, I gave my 2 year old shit zhu wormer this morning, dosage was 1 tablet for 5-10 kilos, i gave her 1 tablet and she has since been sick few times, does anything happen if its been to much for her??

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