Bayer’s Advantage® II flea treatment for cats contains unlisted inert ingredients that may cause permanent neurological damage to your cat or dog (vetinfo).
Advantage® II for cats contains an active ingredient which acts on the nervous system of the flea. It is called: midacloprid, an insecticide. It is interesting to me that it attacks the flea’s nervous system.
This chimes with at least two comments that I have noticed on this product. One is on this website and the other on Amazon. Here are the comments:
The first couple of days after applying this product to my cats it seemed to be working great. Especially for my cat who seems to be very sensitive to fleas. However today I watched one of them fall off a fairly tall piece of furniture twice (something he is on every day and has never fallen off of before) and strangely like he went limp or something. Then a little while later I watched as my other cat who was just standing on the floor fell with her back legs slamming together and her front paws trying to get a grip. Then I read on a few different websites that it has been found that in RARE occasions this product can have neurological effects….(Amazon).
My 4 year old cat cocoa is an indoor cat but she gets out sometimes i recently changed her liter to all natural liter and gave her a dose of small cat advantage 2 which was dose number two of three but instead of every month i give her every couple months never noticed her being allergic to it but after letting her inside one day the day after i noticed she was hiding out on top of a bin i lifted her up and she waslimp for the next couple of days she wouldnt eat or get up when she did it took a lot of energy i noticed a line of fur missing no wound and nowher belly near her nipples is reddish brown i have an appt in a couple days but it is killing me not knowning please help…(this website).
Each cat caretaker needs to check this out themselves but it appears that the insecticide can also attack the nervous system of the cat. The vetinfo.com website states in reference to its use on dogs:
It can enter his circulatory system and cause brain damage and nerve damage.
That statement supports the comments of the two users quoted on this page. Although, the website states it is one of the safest treatments for fleas on dogs.
Now, as far as I am concerned if a potential, albeit rare, side effect is this serious, it is unusable. It is about risk but it is also about the upside and downside of using drugs like these and insecticides are dangerous chemicals.
The vetinfo website adds an important extra bit of information about this drug. They say some of the inert ingredients in the product are not tested for safety because they don’t have to be under the law. Also, even if these inert ingredients are toxic they don’t have to list them. I’ll quote the site verbatim for the punch line:
Such undisclosed ingredients might be unsafe for use on your pet and the neurological damage caused by them may be permanent.
Has anyone more knowledge about this flea treatment? When I see “neurological damage” and “permanent” in one sentence as a possible side effect it puts me off buying it. Does it do the same thing to you?
Otherwise healthy cat now has front paw muscle tremors when laying down and stretching out his arms, I know due to Advantage II application. Now I’m fearing that it’ll get worse. I’m never putting it on him again. Has anyone experienced the same, did it get better, did it get worse does it stay the same? Hes 4 yrs old. If a cat licks this he ingests it then it gets into his bloodstream and into a central nervous system. The cat’s central nervous system and an insect central nervous system is different but still it’s a pesticide anyway you cut it!!
Wow, it must have been terrifying and as you say thank God the seizures past. Thanks for sharing Mary.
My cat had a seizure within 24 hours of applying Advantage II. He did not lick any part of it and it did not run down any part of his body after applying. He had a grand mal seizure every 4 days even after starting phenobarbital. Cost me a few thousand dollars in the specialty hospital. He never had any neurological symptoms of any kind before using this. Once the thirty days of the med was out of his system he never had another seizure. There is no doubt at all in my mind that this flea medication is what caused his seizures. I just thank God it didn’t seem to cause any permanent problems.
I presume you have stopped the Advantage treatment. I can’t really help – only hope that the cause is not Advantage. I think a good vet should be able to test for nerve damage without an MRI or spinal tap. The very best of luck.
My cat loves to jump off everything, so she has hurt her paw in the past. I just took her to the vet because all of a sudden her gate was different. I know she jumped pretty hard down off a stool onto the vinyl floor, so I took her to the vet yesterday. The vet said she is acting like a neurological or nervous system issue. I couldn’t think of anything, other than perhaps she hurt her back jumping. But now, I am wondering if the ADVANTAGE II I just administered a week ago has poisoned her. I did catch her scratch at the area I placed it with her paw and then was licking her paw. They are running several blood tests to try and determine if a viral or bacteria attacking her system. I will mention this to the vet. Does anyone know if a blood test would reveal if affected by the ADVANTAGE? My heart is just breaking to see my feisty active baby girl now walk a few steps and then lay down. I can’t afford an MRI and spinal tap.
Thank you, Chris, for passing on your experiences. Your comment is very interesting for the fact that your cat reacted so dramatically so early on even before the treatment. She must have reacted to the vapour, in minute quantities, that emanated from the vial. This tells us how potent this poisonous insecticide is. Personally, I hate flea treatments and avoid them as best I can. They are ultimately poisons. Every day I flea comb my cat to make sure that he is free of fleas. If he has a flea I kill it with my own hands. Fortunately at the moment I don’t have a flea problem and intend for it to remain that way.