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Readers Respond: Has your pet ever had a bad reaction to a medication or topical treatment?

Responses: 34


Has your pet experienced an adverse reaction to a drug or topical product? There were several reports about Promeris in 2008 and flea and tick products in 2009.

The first thing to do is call your vet as soon as possible. It is a good idea to write down any details you can remember - the time and method of administration, what signs were noted, and what time(s) those signs appeared.

Please report your pet's adverse reaction, either via your veterinarian or yourself. It is important to report these events to provide data and alert other veterinarians, regulating agencies and ultimately, to protect other pets.

Share your story here

Frontline Plus

My 3.5 year old healthy Great Pyrenees has used Frontline Plus without incident since I adopted her 1.5 years ago. I have also used Frontline products on my two 10-year-old cats since they were kittens, as well as misc. foster animals. The last time I applied Frontline Plus to my Pyrenees was two days ago and she has a huge second degree chemical burn everywhere that the chemical made contact with her skin. There is a lot of fluid in that vial for 45-88 lb. dogs. I will no longer use topical pesticides because the chance, however small, of a horrible reaction is not worth taking and there are non-toxic alternatives. I suggest that if people use these products they apply them at a time when they can monitor for a sudden reaction and get emergency treatment it is needed. My dog should be running around in the yard and instead she has to lie down and take medicine and wait for this big painful burn to heal. I will say however that Merial, the Frontline manufacturer, has been very courteou
—Guest Liz

Nexgard - Negative Reaction

We tried a new flea and tick medication called Nexgard and our dog is having an extremely negative reaction to it. A couple of hours after giving it to her she became agitated and extremely itchy. After giving her 3 Benadryl she settled down, but continues to itch, is pulling clumps of hair out, and her skin is red and extremely irritated. Her skin “quivers” when we touch her. The vet said she hadn't heard of another dog having this kind of reaction, but said it definitely sounds like an allergic reaction. The manufacturer or the medication is @merial_pet. ‪#‎nexgard‬ Please share this information!
—Guest Dawn

Frontline bad reaction

We used frontline for 6 yrs no did effects, we used frontline plus this year, our mini. Schnauzer became lethargic,won't jump, need to carry her up and downstairs. Drastic change in hours from application. Called vet, couldn't get in over weekend. Kept an alert eye on her, still eating, drinking,no vomiting, but lethargic, won't play, sleeps. By Sunday, began to get energy back, will still not jump up, can do stairs, but only in the morning, needs recover in between. We see vet Monday. No pain in limbs, back, spine, we checked her over. Didn't eat anything odd, only change frontline plus.
—Guest Healing

Lost my cat from Frontline

I put Frontline on six cats, all of whom were healthy and happy eating and running around playing. Patches, about 12 years old started to walk funny after one hour. Washed her off and gave fluids-to flush any Frontline out ... she stumbled and rolled over for 4 days and had to be feed orally with syringe, but bounced back. Tucker, 4 years old, and healthy, was unlucky. He stumbled as well, washed him off, gave him fluids and he tried so hard to walk and eat, his head was bobbing hours later and the vets said it appeared he had some neurological damage. Lab reports were fine except a little high Glucose level. That may have been due to me given him Pediasure by syringe because he wasn't eating. He died 9 days later. The other 4 cats are fine, but Now I will seek alternatives to Frontline.
—Guest Patty

Severe reaction to Frontline for cats

I applied Costco-supplied frontline for cats treatments to my healthy 22 pound Neutered male mix breed cat and within a day he became very lethargic, threw up all his food and developed an inch and a half large bald spot where the medicine was applied. Now I fear using any of these flea treatments for they may cause a very severe allergic reaction.
—Guest Dave


I gave my 2yr. old male 11# cat Frontline in Dec 2013. Almost immediately he was frothing at the mouth, gagging and drooling. In a few minutes he appeared to be fine and there were no further symptoms. It was purchased from my vet. In Jan. I gave him the Frontline purchased from Costco at a much lower price, w/the same immediate short-lived reactions. Called the vet and was told that it was oke and to go ahead and continue giving it. NO WAY!!!!
—Guest Beth Miller

Kirkland Signature Flea and Tick for Cat

This product put my healthy cat in the vet emergency facility this morning, barely able to breathe. Horrible product with many many many reports of adverse effects including fatalities. Do not use!!!!!!!
—Guest Jeff


In May 2013 I put frontline on our 12 year old Golden retriever and our 11 year old Great Pyrenees within 3 hours our golden girl threw up 7 times,was totally lethargic looked death warm over,our Great Pyr was fine.I called the vets office immediately told them of the frontline and the heart guard,they told me to get her to the office immediately so I carried her to the car and was at the vets office in less than 20 minutes and they had her in the back washed her off and gave her a shot to protect her organs.Doc did tell me if I did not get her in so quickly she would have died,and stated that she had a severe reaction to the frontline.She still has nerve damage in the spine,if she runs to fast her back legs give out on her,summer was physical therapy swimming in the pool,at first she needed a life jacket but she did better as she went along,but this winter we might have to give her injections to help support her muscle.front line denied all responsibility.
—Guest Deborah pond

20 year old cat

I have used frontline plus many times, but this time my dear cat is pain when you touch his back and he seems confused.
—Guest Paula

Frontline severe adverse reaction - cats

I've applied Frontline Spot on to my two cats, 13 and 2 years old, both healthy. I applied the ampule as described on instruction sheet, as far as I was able to see, neither of the cats was able to lick it. Both behaved lethargic and showed a lack of appetite next day. While younger cat recovered without any visible consequences within 24 hours, the older took a downfall. He stopped eating, wasn’t able to walk straight, and suffered from pain attacks. Veterinarian diagnosed massive liver damage, cat developed ascites as well. Now, 6 weeks pass, he seems to be recovering his appetite and behaves clinically well, but his prognosis is bad, due to liver damage. Fronline LOT# I used: G21252AS; Exp Mar2014. Date of application ~20-June-2013.
—Guest Tamara K

Miscarriage x 2

I am a hobby breeder for 40 years and have been a veterinary nurse for 30 years . I believe I am a responsible breeder and a asset to my community of dog lovers. Last month I bred 2 of my spaniels and wanted to have them flea free during that time so I placed ProMeris on them for their size, ONLY after reading the label and calling the company to verify if this was alright for a pregnant dog, which they said it was. My girls where verified pregnant and at day 45 they BOTH started a horrible miscarriage !! I thought I would have to euthanize them and really worried that I had some hormonal abnormality within my breeding dogs...... Needless to say they are now very healthy as always, BUT no puppies ! I have since then bred my other girls and of course NO flea control !! They are pregnant and happy passing the 50th day ! So, in my opinion, which I value......the only thing I did differently with my 2 other Happy, Healthy breeding dogs was to place ProMeris on them. You tell me....
—Guest concerned

adverse reactions

I took another of my cats to the vet. She is 18. She was given antibiotics (£42). He recommended frontline flea treatment at the cost of £22 and told me it could only be bought through a vets. He also assured me it was safe as it is used on 2 day old kittens. I have 5 cats and treated them all using the minimal amount, as I really do not like pesticides/chemical use on animals. I told the vet this but he reassured me it was safe. My cat Wesley seemed unwell on Friday, walking with a wobbly gait. I put him in his box on his blanket, he curled up but was not interested in eating or drinking. As I don't drive I started making arrangements for a friend to take us to the vets when I went back to the box he was dead!! Initially I thought well he is old and we buried him. We were all upset but I was even more upset next day when a friend told me her cats fur had dropped out after using the Frontline treatment. I googled information on the product.


I have a chocolate lab, about 90lbs, he has had NO problem with Promeris. It is the ONLY thing that keeps his mange at bay!!!!
—Guest Paula

Promeris reaction

Shiba Inu 6 years old given May 4, 2012. Lethargic, drooling, stagering, high as a kite! This is her second dose. Gave her a dose w same reaction a year ago- Vet said then after I notified then of the bad reaction first time it was impossible to be from Promeris. Decided to try again - same reaction. I feel like I'm killing my dog-watching her suffer.
—Guest Cyndee

Promeris caused tremors

Day 1 I saw mild tremors when my 2 yr old ACD (Blue Heeler) went to bed with us. Didn't think much of it (thought she was dreaming or something), but the next day they were much worse. Vet said that Collie breeds and Heelers were sensitive to the active ingredient... Now we have to pay for injections of the antidote every 4-6 hours! Thanks for a wonderful product Promeris!
—Guest Jason F

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