Trifexis Toxicity in Dogs – Charlie had a scare!

Charlie… our beast!

We had a scare this past week. It was time for Charlie’s Trifexis dose, a combination heart worm and flea preventative. I gave him food, then the pill and as usual he didn’t feel too good during the day. Normal, it can cause stomach upset, vomiting, etc. I always time the dose so I make sure he makes it past the one hour point without vomiting. He did. Whew, I thought, coast is clear. Not. About six hours later he started to stumble. He was disoriented. He was stretching his neck back and his eyes were partly closed. He had tremors. I felt his heart. Not knowing what “normal” was I did know that his chest felt quite like an explosion over and over. We took him to an emergency vet clinic in Mount Pleasant, SC called Veterinary Specialty Care. These people were nothing short of amazing. They acted promptly. They took him in the back to be seen by the doctor. Then we were called into a room where the doctor told us that his heart rate was dangerously high, 220. After trying to rule out everything in the world, his diagnosis, as she suspected was Trifexis toxicity. Trifexis works on fleas by messing with their neurological system. Sometimes it can do the same in dogs which would explain the odd behavior, the tremors… he stayed overnight so that he could be monitored, he was sedated so he could sleep through this reaction. They’ve seen it many times. UGH! Ever since Sentinel disappeared off the market we’ve all been steered toward Trifexis, in part because the darn fleas have gotten clever and are starting to not respond to the older meds. I can tell you it was a scary time. It took a few days before he was fully himself again, now he’s left with nothing but a shaved leg 🙂 – so he’s fine, and all is well! We did take him to our regular vet for a follow up, and this was the second Trifexis Toxicity case in three days… I don’t want to alarm you, I just want to make you aware.

If you have any questions about giving Trifexis I would research it thoroughly, I thought I did, but…

Sentinel is back on the market (YAY!), so I have updated this post…

IF YOUR DOG IS HAVING ANY OF THESE SYMPTOMS, (not acting normally, arching head up oddly, difficulty walking, stumbling, if their heart rate feels strangely fast, drooling (other than normal), tremors, vomiting and more…) GET THEM TO THE VET OR EMERGENCY VET IF YOU CAN. 

UPDATE: Charlie’s latest regimen is Sentinel for fleas and heart worm prevention. He’s been on that over a year, and so far, so good!

NOTE: TRIFEXIS contains SPINOSAD (combat fleas) + milbemycin oxime (heartworm prevention) – 

****COMFORTIS also contains SPINOSAD as the key ingredient! So, if you’re dog is having symptoms from Trifexis they can experience the same from Comfortis since it’s essentially the same drug. Trifexis just has heart worm prevention in addition to flea protection. I am not a vet. Check with your vet after your dog has a reaction. LET THEM KNOW WHAT YOU GAVE THEM so they don’t get it (or anything like it) again…

Like people, some medications react differently to some animals. So if there was a reaction once, I (me, being the non-vetirinarian expert, sigh) would steer clear…

This is from the Trifexis website:

For technical assistance or to report a suspected adverse drug reaction, contact Elanco Animal Health at 1-888-545-5973. Additional information can be found at Alternatively, suspected adverse drug reactions may be reported to FDA at 1-888-FDA-VETS or    

Thank you to my many Facebook friends who sent well wishes and prayers, it made all the difference! Catch you back here tomorrow!

54 thoughts on “Trifexis Toxicity in Dogs – Charlie had a scare!

  1. Miya

    Everybody wants to cut corners by using combo products like Trifexis, but from doing my own research, there’s no better combo than heartgard and frontline. just saying.


    1. Hmmmm, cut corners? Trifexis is quite expensive. It was never our intention to “cut corners”. His previous regimen was Sentinel and Comfortis (the part of Trifexis that caused the reaction). Sentinel has been taken off the market due to manufacturing problems. Every vet in our area is recommending TRIFEXIS, in part because the fleas have gotten pretty smart and aren’t responding as well to Frontline, Advantage, etc. Our new regimen is Advantage Multi, which is heart worm and flea together… Your regimen is a good one, and one that he was on a while back. I’m not sure if you’re located in or near Charleston, SC where the flea population is sky high or if you are located elsewhere. Be glad that your combo is working for you and your pet, I hope it continues to! Thanks for commenting.


    1. marion

      Hello Barbara. I have a toy poodle (Inga) and I am giving her trifexis, she has not had any issues yet but I am hearing more and more negative stories about this med. I will take her off that stuff before it does more damage. I feel bad for having given her these nasty chemicals. I live in Florida so fleas are a big problem all year long…Thank you for sharing, I will try your regimen 🙂


      1. Marion, don’t feel bad! Trifexis does work for many dogs… the reaction Charlie had was frightening, and was after he was on it for a while (not his first dose)… darn fleas are bad here in SC as well… good luck with your new regimen… Charlie also gets hosed down (he gets so hot) after walking our greenway (public pathway)… not sure if that could possibly help any! You sound like a good “dog mom” too Inga 😉


    2. Judith

      There’s a natural product ”Flea Free” formulated in Florida, available at Amazon, which prevents fleas and mosquitos (sources of worms and disease) from biting. It’s a liquid added to food and/or water and the ingredients coat the element in the blood the biting insects need to reproduce. After using the Flea Free since April, I have not seen any fleas on the dog or in my house, (even tho the squirrels in my Florida back yard are scratching like crazy!) and testing last month for heartworms was negative. Also, when resting on the back porch at dusk with plenty of mosquitoes hovering around, schnauzer never reacted to any bites (so they went for me)! (My Schnauzer has had weak, trembling back legs for 2 years since using Trifexis and now is experiencing seizures.) You don’t have to poison your animal friend!


    1. Charlie weighed about 24 pounds and was given the 20.1-40 pound dosage… as your post suggests, it’s the dosage for the size dog that may be a problem… however, since he was taking Trifexis, and part of that is for heartworm, we couldn’t lower the dosage (especially since we live where mosquitoes are abundant)… I enjoyed your post, full of great information! And GREAT observation to the reaction/dosage of the dog – for now the Program and Heartgard is working great… fingers crossed! Also… I just received something in the mail about SENTINEL… that’s what he was on originally, and the manufacturer had problems and stopped producing it for years… apparently its back on the market. I’m sticking with what we’ve got for now… thanks for commenting!


      1. So glad to hear that your regimen is working, and that there are no more negative reactions from Charlie. Scary what your emergency vets said about seeing so many incidences of Trifexis toxicity though! Makes me wonder if the manufacturers are listening??

        We also separate flea and heartworm medication, and stagger dates of administration whenever possible. The whole mess with heartworm medication manufacturers is so frustrating.


  2. Pingback: Comfortis: monthly flea protection in an oral dose | The House of Two Bows 雙寶之屋

  3. Elise

    Barbara do you have an email address? I just want to ask you some questions about trifexis and charley. I have a puppy and she has the same symptoms and it started last night, went to that same vet and everything! Very very worried about her! :.-(


      1. I have a similar situation with weak hind legs. My Akita/Border Collie is almost 4 years old. She is very active a high strung. She normally will stand up on her back legs for a treat “stand up” she fell over and I am still concerned. There are a few possibilities that come to mind. #1 Chicken Jerky treats made in China (there have been recent articles of these causing paralysis and death. #2 I recently changed her food to a healthier blend and reduced the amount of food, she’s a little hefty and have been trying to cut back on her weight (another thing that can cause joint and hip issues) and maybe something in the new food is toxic. #3 I recently have changed her heart worm/Tick medicine to Trifexis and have heard some dogs have bad reactions to it. #4 she jarred herself pretty good while on a steel cable tie out. She was chasing a possum and actually popped the clasp and cable loos, thought maybe pinched a nerve. #5 I exercise her a lot… or used to me on a skateboard and her running a mile or 2 every other day and releasing her into the woods to run around on family land. #6 she picks up who knows what sometimes from the ground, I promptly remove anything from her mouth when I catch her. I have been giving her deep tissue massages and doesn’t have any pain issues with me putting substantial pressure throughout her body muscles and joints. After a day she is much better, I haven’t taken her to a vet, but most assuredly will if she has another episode like the initial weakness. Please email me if anyone finds out anything else, thank you all for sharing possible causes.


      2. Jeffrey, please give your vet a call, just in case it is one of the more serious options you listed. I am not a vet professional in any way, I’m just sharing my experience so that those who run across the same symptoms will know it is very serious. I hope your dog feels better soon! Any concerns I would call my vet!!


      3. Eamonn Kneeshaw

        Yes definitely see a vet. but start by no more Trifexis The problem is your vet will say it has nothing to do with the problem. But it is one symptom that has shown up very often in the dogs that have a problem with this drug. It is better to be safe then sorry. My dog Started to loose his balance in his back legs. Just going out the door step and his back legs would give out, or when he first got up from his bed he would be very unsteady on his back legs. My little guy died after his first dose it took a month buy that was one off several symptoms.


  4. Chris

    Thanks for this information. My Australian Shepard puppy is staying overnight at the vet’s and she was in really bad shape when I left here this afternoon. Signs are pointing to Trifexis toxicity, in my opinion. Feeling scared and hopeful. Glad for Charlie. 🙂


      1. Thank you for commenting… The stories are so sad… I wrote this post to share my experience… Trifexis I’m sure is safe for some dogs, but clearly not all… Read the stories and become well informed. I personally would never use Trifexis again, it’s scary what your animal goes through and I’ve heard too many stories of dogs not making it through the night. HEARTBREAKING to say the least… Thank you Lisa…


  5. How long before Charlie started acting normal again?

    We have a dachshund who had her leg amputated last week (she couldn’t walk before surgery so it wasnt a change for her) and was on a whole slew of meds when she got her trifexis yesterday around 9 AM… By the afternoon she was all stumbly and shaky….not like her behavior for the previous week post-op.

    I’m wondering if the meds cause the trifexis to be absorbed differently. She spent the day at the vet and he wants her off all meds for the next day or two to see if that helps.

    She’s back home with us tonight because she doesn’t do so well in cages… We will take her back in in the morning.


    1. Eamonn kneeshaw

      Hi Jessica
      I would take him of trifexis. It killed my dog, but took a full month before he eventually died. One of the symptoms was stumbling especially in his hind kegs


  6. Gary Eaker

    My, once athletic AmStaff, experienced severe weakness in both rear legs after his 5th dose of Trifexis. He was 70 lbs of pure muscle prior to the drug and could leap and clear a 4 foot barrier standing. Now he can barely climb stairs or jump/crawl onto a low couch. He also has tremors. I am hoping he will recover as time goes by without this drug that I believe has poisoned him.

    Read more:


    1. Gary, I am so sorry to hear about your dog. Did this happen recently? If so, please take him to a vet, Charlie would not have made it if we didn’t… I read that article that you linked. When dogs get a dose of Trifexis, and case after case, they exhibit the same symptoms… to the point where many are fatal, I do not know how they can say that the drug is not linked to any deaths. It cannot be proven? Dog is alive. Takes Trifexis. Dog is sick. I realize some dogs are OK taking this… but many dogs are not. I wish they would be more responsible. But that’s where we, as pet owners, have to stand our ground. If you don’t feel comfortable doing something, TRUST YOUR GUT… find another option. So frustrating… thoughts and prayers are with you and your dog… I hope he returns to normal very, very soon!


    2. Eamonn Kneeshaw

      Hi I am so sorry to hear about you dog.
      Trifexis is dangerous. Elanco gives a false figure. The reported deaths to the FDA from trifexis is more then the reported deaths from jerky treats from China. This is on the FDA reports
      By Jim Strickland

      ATLANTA —

      Channel 2 Action News has discovered the number of dog deaths pet owners blame on the popular pet medication Trifexis outnumbers the cases involving the Chinese jerky treats.

      Elanco, the company that makes Trifexis, refused repeated requests from Channel 2 consumer investigator Jim Strickland to turn over its data.

      Strickland filed a Freedom of Information request with the Food and Drug Administration and got the agency’s data instead. It showed that since Trifexis hit the market, every 36 hours, a pet owner reported that Trifexis killed their dog.


  7. Amber

    I am sorry to read that you dog went throughout that! We just had a scare with my labradoodle who had his second dose of Trifexis on Tuesday evening. Shortly after the dose, he began staring at the ceiling, almost as if he was following a moth with his eyes. The next day, Christmas, he was stumbling/tripped when he woke up and vomited his breakfast later that afternoon. Trembling started in the evening. Yesterday he regained his coordination and has been eating and eliminating without an issue. Today, he stools have been loose. At first we thought perhaps he had eaten something he wasn’t supposed to, but upon searching the web for possible causes, Trifexis toxicity was the only thing that makes sense. We are watching him like a hawk and he will never be getting Trifexis again–we had just switched from Interceptor. I am surprised more information on these horrible reactions isn’t readily available; I understand no drug comes without its possible reactions, but I had absolutely no idea that this was even a possibility. The vomiting, yes…the neurological effects, no. I feel awful having given it to our dog! Glad to hear Charlie is ok.


    1. Amber, I’m so sorry to hear your dog is going through this. Charlie almost didn’t make it, I felt the same way you did… awful… for giving it to him. If your dog doesn’t get back to normal it’s worth a call to the vet just to be sure there isn’t anything else to do. I know with Charlie, they gave him lots of fluids and all kinds of stuff and also sedated him so he could get through it. Ugh. We were one of the lucky ones… too sad. Thinking of you and your dog and hope all is well soon!


    2. Amber

      Thank you. We have been monitoring him 24/7 and we are hopeful that he is over the worst now. Today, outside of the loose a.m. stool, he is back to his normal self, still eating and drinking good and not passing up one treat. I just couldn’t believe with all the horrible stories out there that this med is still a recommended drug. I will be talking to my vet asap about this; and we’ll be continuing to monitor him. Eamonn, I am so sorry to hear about your loss. 😦


  8. Eamonn Kneeshaw

    Please keep a real close watch on him, These are the definite symptoms from Trifexis. if you need to take him to the vet, the problem will be your vet will claim it is something else but stick to your guns tell him it is from trifexis and you need it washed from his system. Hopefully everything will be OK but just in case. Please keep a watch on your dog for change in eating habits at this time. Like not wanting his favorite treats.
    I lost my baby after one month this is the worst drug to hit the market.


  9. Ky G

    I am not using triflexis but am using comfortis. The reactions are the same as tri.f using comfortis. I purchased the 40-60 pound range for my BC/Aussie. I gave him only 1/2 the pill and the reactions were: confusion, hiding, weak and collapsing back legs and panting_he was scared. Since I went online and calculated by weight _1/2 pill was under the recommended dosage. But it worked. I will NOT be giving him the full dosage calculated by weight as 405mg seemed to kill all fleas STAT. If we can work with 405mg as opposed to the dosage for his weight then I will stick with that for a while. From what I have been reading, dogs do not get used to the medication but rather toxicity BUILDS OVER TIME and can cause severe reactions even months down the line. Just a few months creates the above as well as enlarged heart, blindness, paralyzed legs, failing liver. As far as HW meds, they are actually only required every 45 days as opposed to every 30 days so I will stick with that regimen. I have tried all the natural regimens didn’t do the trick and frontline plus ceased working, I will cautiously opt for comfortis for the time being. Note, I reside along trails, squirrels, raccoons, wild hogs, possum are abundant_ever increasing the flea population. I will also try alternating between topical and internals. I’m keeping his dose as lower than his weight recommends_the issue I will watch out for is the build up in his system over time. This is only the first month and keeping a constant watch on him. As he is my SD_we are together 24/7 so now my eyes have to be as alert to seizures with him as he is with me. Love goes around ❤


    1. We are now using SENTINEL (heartworm and flea prevention) and so far so good! Is that an option for you? It sounds like your dog has a reaction to Comfortis (which is in Trifexis as well). Wow, builds over time… that makes sense, month 4 is when Charlie’s body could no longer handle it… There is also a new flea prevention pill out on the market NEXGARD, you may want to ask your vet about it? I believe you would still give your dog Sentinel but supplement the Sentinel during the warmer months when you see more fleas. So far the Sentinel is working great and we have not had to use the Nexgard! Hope this help! Good luck to you 😉


  10. Christine Nichols

    Wow after reading all these stories and comments I’m scared… My little Jasmine a 9 lb 11month Chihuahua was given her third dose of Trifexes this evening at 8:30 PM I came home around 10:45 PM and she was in the yard with my 4 other dogs and was pooping at the time which was good because she normally does it in the house. After about 45 minutes I noticed her acting very strange compared to her normal self. That’s when I realized something was wrong!! Found that she had vomited twice no pill to be seen in vomit and she was exhibiting strange behavior . Neck posturing while closing eyes, severe trembling, screaming when I touched her. I looked online and saw that this is reactions to Trifexis I called the 800 # and spoke to a Elanco Rep. and was told that this could happen… Am waiting for the Vet to come in at 8AM so far Jasmine is resting in a dark quiet area which has seemed to help. So far no seizures or paralysis .. God Bless my little Jasmine will keep you posted 🙂 Christine Nichols


    1. Am thinking about you and your little friend… I hope she is OK… it’s so scary!We had to take Charlie to an emergency vet hospital, scary stuff… hope all is well, please do keep me posted!


  11. John

    We have an English shepherd named Mr. Fluffy Bear. He is about 14 months old and very healthy. At least up until now. I gave him his dose of trifexis yesterday evening around 5:00 and within about an hour he had puked up everything in his gut. Immediately I noticed the same effects that most everyone on here has encountered; shaking, spaced out acting, very lathargic, neurological symptoms, trouble standing up, and just an overall sick puppy dog. Up until I gave him his dose he was acting like a normal Mr. Fluffy Bear… Full of energy and very playful. Today he still didn’t feel too good, but he did act much better than he did last night. Today I layed down on the couch and dozed off. It wasn’t long before he woke me up whimpering and whining. I got up to see what was wrong and realized that he couldn’t stand up. He was somewhat paralyzed in his back quarters. As the day went on he has developed severe pain in his back legs and/or hips. This seems like a very odd side effect to have from a medication, but he had no similar symptoms prior to his trifexis dose. I’m wondering if anyone else has experienced their dog developing symptoms of pain after administering a dose of trifexis? I might add that this was his sixth dose with no prior bad reactions. He took the 60-120 pound pill.


    1. Julie

      Dear John, I experienced the exact story you described with my 5 year old Greyhound, a few days ago. Thank you for specifically sharing the paralysis piece, as my vets are not agreeing that it was part of the adverse reaction. I had also been administering Trifexis for several years and only this dose caused the adverse event, which leads me to wonder what the quality control is like for production consistency. Fortunately, Maple is on the road to recovery. I thought we were going to lose her…


  12. Katrina

    Hello Barbara and Readers! First of all thank you for sharing your story. I have been giving trifexis to my dog Max, 8 years old 12 lb silki terrier, for years and he never had any issues. I gave him his monthly trifexis yesterday and he was fine. But today….. He is not himself, looks very tired and sad, spent in bed all day. He did not eat anything all day and threw up in a couple of spots on the carpet. I called my veterinarian and all they told me is to take him to the emergency room if he gets worse throughout the evening. I have been watching him for a couple of hours now and it seems like he is getting better. He ate a little, went for a short walk and went to the bathroom. As of now he is laying down and watching TV (Yes, he likes to watch TV). I am praying reaction to trifexis is gone for good and he is going to be allright. Just wanted to share……I will not be giving him any more trifexis.


    1. Hey Katrina! How is Max today? Charlie’s reaction was frightening. You would think if they had been taking Trifexis with no symptoms then they would be ok. Scary. Hope he is doing much better now! As of right now, we have Charlie back on Sentinel, it seems to be working for him. From what I’ve read a lot of these Trifexis reactions are in smaller dogs. I guess it’s like medication for humans. Some people are fine and others have reactions. Hope Max is feeling much better today!


      1. katrina

        Hello Barbara and readers! I also have another dog , boston terrier. Today I gave him Comfortis for his monthly flea prevention. He never had a problem with Comfortis but today he thew up about an hour after i gave him a pill. He threw up everything : pill and all of the food that he ate. I m done with Elanco products. It is making my dogs sick. Please share what you use for your doggy as a monthly preventatives and how it is administered. Thank you! Katrina


      2. Katrina – based on your comment, I just updated my post. Comfortis contains SPINOSAD (the ingredient in Trifexis that you think caused the reaction in Max). Comfortis is spinosad (for fleas). Trifexis is a combination product that has spinosad (for fleas) and milbemycin oxide (for heart worm prevention). Don’t use Comfortis if your dog had a reaction to Trifexis (and vice versa)… Frightening how it happened to both dogs. I don’t think that it’s the company, it’s the ingredient that your dog can’t have. After you gave your Boston Terrier the Comfortis and he vomited the pill back up, did you give him another? Charlie is now on Sentinel for heart worm and flea protection and it seems to be working great, you may want to ask your vet about that, see what their opinion is? Ugh!!!


  13. Katrina

    Hello Barbara! After my boston terrier Bo Bo vomited the pill and all of his food, I did not give him another one. I do not want to make him sick again.
    I was reading about Sentinel and will try it for Max as heartworm/flea preventative. Bo Bo is taking Iverhart Max for heartworm and has no problem. I am looking for another flea preventative for him. Any recommendation? If Sentinel works for Max, I might switch Bo Bo to Sentinel as well (after he is done with three Iverhart Max pills that I have left for him). Katrina


  14. Lisa

    Anyone experiencing these symptoms may want to try Liv A New cleansing formula. Empty 2 capsules in food 2x a day. My 4 month old baby is almost fully recovered. He went from being unable to even stand up to running around within 2 weeks. He was 45 lbs and had lost down to 37now on his way back up. It hit him hard for being on the big side for a puppy. There is no confirmation on what caused his sudden illness, but it was a second and worse reaction following monthly dose of Trifexis. I believe the liver cleanse saved his life, but once again there is no proof,


  15. Cindy

    We just gave our frenchies this Trifexis Sunday evening. A friend was over for dinner and she is a vet tech so I thought it would be a good idea to give them the meds while she was there. These are rescues, we’ve had them for 3 weeks so this is the first time we used the drug on them.

    One frenchie had zero reaction, she was her bouncy self the next morning. The other frenchie didn’t get out of her bed all day after her morning walk, slight trembles and completely lethargic. She is getting a little better today but still very, very slow. Yesterday she was very uneasy on her legs, as if she had a pulled muscle. We thought maybe that was what had happened as the neighbors were over that same evening we Trifex’d the dogs and their friends dog got into a tiff with our frenchie who isn’t feeling well. So we thought maybe she pulled something and wasn’t feeling well.

    After reading on line all the horror stories of this drug, now I see that it is clearly the drug doing this to her. Labored breathing all night, not her usual long heavy snores.

    She is eating and drinking water normally with normal BMs.


    1. Cindy, it’s so scary to see your dog not feel “right” for lack of a better word. Charlie’s symptoms were more pronounced, but still, it all sounds similar doesn’t it. That is one of the symptoms we saw with Charlie, very weak, barely able to walk. So glad yours are both OK now. Charlie has been doing great in different regimens, I hope you find one that works for you MINUS the side effects!


  16. vikki

    Wow! Are these dogs okay now? My almost 10 year old Chesapeake Bay has always acted a little strangely after her trifexis dose. This time, she has deteriorated over a 2 week period to where she cannot stand up. Her hind legs fold up under her. We carried her to the vet, and with several small tumor type growths, we were told possibly cancerous tumor on spine or in brain??? Trembled with her head in my lap all the way to the vet’s office. Neck was stiff and vet was unable to move it. Multiple meds and she was a bit better last night. Lots of research and decided to try milk thistle for liver toxicity. Today, she has not moved much at all, and is still having issues arising from laying down and falling while in forward motion. She whines quietly, as if she’s in pain. Her appetite is fine, and no issues with meds wrapped in liverwurst – her favorite. Not drinking much, but I believe that is so that she doesn’t need to relieve herself as often, as it’s a lot of work. My concern is will she get better? And what should I do or give her? Does it just need time? Feedback please, as I am extremely worried and feeling quite guilty for continuing to give her this poison.


  17. Kari

    I have just had the same issue with my miniature dachshund. We gave her Trifexis and within a couple days she was unable to walk. Of course since she is a dachshund, it was immediately a back issue and she was given steroids and neuropathy meds. I told them that we had always been very proactive with our dog since we knew that she was susceptible to back issues. She isn’t allowed to climb stairs or jump on and off of furniture…plus she is only 5! She was better in a few weeks and we were told that we would need to make a “decision” and decide if we would do a $5000-7500 surgery on her back. A few more weeks passed. Thinking nothing of the trifexis, we gave her the next dose. Within days she couldn’t walk at all. We took her to an ER near St, Louis. They did a back xray and said she had a few mineralized discs. Again, I listened and gave her the meds. She was completely immobile for over two weeks. We couldn’t afford the surgery and after having her immobile with no quality of life, we made the decision to have her put to sleep. LITERALLY MINUTES before we took her into the vet, her back legs began to move. The vet said to give it some time and more meds. When her next trifexis came due, we started thinking how strange it was that she had issues right after the last two doses. We have chosen to stop the trifexis. She is a house dog so we aren’t concerned about fleas or heartworm for her. We will figure out an alternative for the fleas if a need arises. Lets just say, that my sweet dachshund (who was almost taken from us) is doing much better. She is walking more every day and can get around with little issue. I am glad I found this article. I will be printing it out for the vet to read at the next visit. We were told trifexis “couldn’t have caused this.”


    1. Whew, I have tears in my eyes reading your comment. I am so happy to hear that your dog moved her legs! From what I’ve been told some dogs cannot handle this medication. It seems more prevalent with small dogs or dogs who are on a dosage but weight-wise at the low end. I am thankful that the emergency vet did acknowledge Trifexis (the Comfortis part of it) to be what caused our dogs problems. It was frightening to watch, but he made a full recovery. I hope yours will too! I am so glad you didn’t pay for a surgery that is tough not only on the wallet but on the dog as well if it’s truly not needed. There are other things Charlie can take safely (Sentinel and Capstar if there is a flea). Every dog is different, so be sure to check with your vet as I am in no way a professional, just a person who has been through it. Best wishes to you!


    2. Julie

      Hi Kari,
      It is frustrating to hear your story. I thought perhaps my batch of Trifexis was somehow defective, but years later the issue persists with other dogs! If it is any consolation, we have not had any long term issues since we discontinued Trifexis and Maple is a very healthy dog! You may want to contact Trifexis to report the adverse event so it can be reported. They also reimbursed my vet bills. Good luck!

      Liked by 1 person

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