New Elanco Assurity for Cats Flea Control Product with Spinetoram - Is It Safe?
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New Elanco Assurity for Cats Flea Control Product with Spinetoram - Is It Safe?

A safety review of the new product, Elanco\'s Assurity for Cats, which contains a spinosyn called spinetoram. It is a relative of spinosad, the ingredient in Comfortis for Dogs. Alternative safer ways to treat for fleas and ticks.


Recently there has been a lot of interest in the safety of flea and tick products. They have been scrutinized by the Environmental Protection Agency (EPA) and been the source of lawsuits due to human and pet health danger, death and injury. These products have been reviewed for the level of toxins that they leave inside the home, petitions have been created and sent to the EPA calling for ban of some pet products and big box retailers selling these products have also been targeted by lawsuits and advocates.

It's a difficult time to be a responsible pet owner. Labels are confusing and ingredients are purposely deceptive in some cases. Flea and tick products include spot-on, squeeze-on, drops, collars, powders, sprays, shampoos, dips, bombs, room sprays and foggers.

Because tens of thousands of cats and dogs are injured or killed each year by these products (over 44,000 in 2008 & over 39,000 in 2009 from spot-on products only), the EPA is rushing newer pesticides to take the place of the old guard. New does not mean safer, however. Often it can mean more dangerous because in an effort to speed these products to market, some steps are skipped in the process of registration. Often a new pesticide is given what is called "conditional registration". This means that the product is brought to market before all toxicity testing and scientific studies are completed, theoretically required at a later time. Such is the case for spinetoram, a new type of pesticide:

“The speed with which we received our first registration is creating a lot of excitement in the marketplace over this new generation of pest control,” says Don Kelley, global product manager, insecticides, for Dow AgroSciences


Elanco has released a special flea control spot-on product for cats called Assurity for Cats. Elanco is owned by Eli Lilly and Company. Assurity contains a newer pesticide called spinetoram, in the family spinosyn. To understand where spinetoram came from, we have take a little look at history. First, spinosad (the first spinosyn product) is an ingredient in the dog flea product that comes in pill form called Comfortis. One of the boons of Comfortis is that it comes in pill form so it does not allow the active ingredient to deposit residues in your home or for toddlers to come into contact with it. Assurity for cats is a topical, or spot-on, product for use on cats only.

Assurity for Cats by Elanco is the first pet product to contain spinetoram. It will only be sold through vet offices, which is a marketing choice that some companies use to keep the costs high on their products and give consumers a sense of quality. The one exception to this is those pet products for fleas and ticks that are registered with the FDA and require a prescription. (Most are regulated as pesticides by the EPA and do not require a prescription.)


This is a very complex and science heavy question. If you want to learn more about the science, please read this comprehensive article at I will boil it down to the Top Ten Points here.

1) Spinetoram is a newer pesticide and safety studies performed on cats have not yet been released to the public. There is virtually no information for a cat owner to make an educated decision with, even if you hunt for it and know where to look and who to ask. The Case Manager for spinetoram at the EPA has assured me that Assurity - with it's entire formulary - was tested on cats extensively. However, "officially" I can find almost every other animal except for cats and I cannot find one single study on the entire formulary. It is common for each individual ingredient to be tested and this sometimes causes issues because different ingredients interact with each other.

2) Even the full ingredients are not disclosed to the public nor to the EPA. By law, currently manufacturers (called "registrants" at the EPA) can claim ingredients that are not primary, or "active", as confidential trade secrets.  According to the Materials Safety Data Sheet (MSDS) for Assurity, the ingredients are greater than 39.6% of a newer pesticide called spinetoram and lesser than 60.2% of "Trade Secret Aromatic Alcohol". Yet if you look at the patent information for Assurity, the patent states the carrier to be benzyl alcohol. Benzyl alcohol is a wicked ingredient despite also being considered “organic”. It is a solvent for inks, paints, lacquers and epoxy resins. You can even use it as a photo developer. It is also included in many flea and tick spot-on products. It poses a hidden danger, as one owner learned when his dog was treated with Advantage and his dog ended up stuck to the bottom of his crate due to benzyl alcohol in the product.

According to an FDA caution, benzyl alcohol should not be used on children under 6 months old as it can cause serious adverse reactions and even death. Toddlers are still developing their core systems, including neurological. They crawl on floors, hug on pets, sleep with pets and have a lot of hand-to-mouth contact, so they are especially in danger with topically applied flea and tick products and collars (as well as household cleaners) for exposure levels that can cause health issues and developmental problems.

3) Cats have a very hard time eliminating benzyl alcohol and with regular use, it becomes more and more toxic to them, building up in their bodies. Again, lack of access to cat-only studies is concerning. The MSDS refers only to rat studies and in many cases, because they are similar, the toxicity information for spinosad (Comfortis) was used instead. This might not normally be an issue except Comfortis is a dog-only product and dogs and cats are very different. Cats lack many enzymes that other mammals have to help them flush out and metabolize toxins.

4) According to Health Canada, spinetoram is almost fully metabolized by glutathione. Glutathione is in every cell in your body and other mammals. It is the most potent antioxidant known. Cats have very little glutathione and burn it up quickly. This is one reason they react so poorly to many things that other mammals can metabolize. Considering the lack of open toxicity studies specifically in cats, I can only conclude that it is very easy for a cat to have a toxic reaction to Assurity for Cats and that reaction may not show with the first dose, but possibly several doses later.

5) Comfortis, a tablet for dogs containing spinosad, has not been approved for cats. Spinosad is orally toxic to cats. Spinetoram, the ingredient in Assurity for Cats, is a partially synthetic form of spinosad. It is applied topically. Due to their grooming habits of self and other cats, there is a high risk that cats will ingest spinetoram, even when it is applied correctly. This risk increases in multi-cat households.

6) The EPA and Health Canada both refer to accepting toxicity studies for spinosad in lieu of studies for spinetoram because they are very similar in chemical structure. Again, spinosad is approved for use in dogs, not cats.

7) Assurity will be sold through vet offices only, which is not a requirement. Selling through vets in this case is a marketing move as it gives their product the appearance of being safer and they can charge a higher fee for their product. Sold through vet does not mean safer in some cases. Many vets attend conferences funded by companies like Elanco who pay "experts" to talk about their products.

8) Spinosad (in Comfortis) and spinetoram only work if a pest bites your pet and ingests the ingredient. This means that although Assurity for Cats is applied topically, it will go into the blood stream of your cat. If it was not absorbed through the skin, it would not work for use on a mammal for a 30-day time period.

9) From the Assurity for Cats website: "Spinetoram, the active ingredient in Assurity, kills fleas quickly on contact by targeting the fleas’ nervous systems, resulting in paralysis and rapid death." This description is deceiving. The product is supposed to work for an entire month, so that either means that your pet will be depositing residue in your home environment for 30 days by killing "fleas quickly on contact", building up with each application, or that it is absorbed and effective in the way other spinosyn pesticides are - through a flea biting your cat. While you are on the Assurity website, please download the label and read it.

10) If a flea has to bite your cat or dog in order to die, your cat or dog will still be at risk for flea dermatitis, an allergic condition caused by the saliva of a flea bite.

There are safer alternatives. Even the EPA suggests that pets are not treated monthly with pesticide flea and tick products, unless you live in a place where fleas are a year-round issue. They suggest that you only treat your pets when you have an outbreak and when all other methods have failed to contain it.

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Comments (7)

Thanks again VB. I appreciate all of the work you do to keep us informed.

Shirley Ross

No! to all pesticides being used on animals!

Sidney Cassidy Behnke

This is an interesting article...I do not think it is so good a product if the flea has to bite my babies

Annie Parini

For the past 12 years I have been a professional cat breeder...not a backyard breeder. Before I put anything on, or in my babies, I thoroughly research it...after talking to my vet first. Vets are not god, they are people. The research I have done so far on this product leaves me with cold chills. There is absolutely no way this product will be used in my Cattery. As soon as I complete my comment, I will be on the computer and phone contacting every one of my clients with regard to the high risk this product poses to their furkids. My clients heavily rely upon me to keep them in the loop of situations just like this one. And, as usual, I am right on top of things. Thank you, VB, for your wonderful research and commitment to all furkids and their 'pets' (us!)

Ranked #4 in Pet Health

Hi Annie! Thanks for spreading the word. Assurity is certainly a concern as are the "new" generic forms of Frontline (firpronil) including PetArmor. For more info you can check out the posts on - feel free to share any of his info or videos. Since writing this, I have received the "studies" used to give conditional approval to this product. It's even more frightening. If you would like a copy of them, please let me know. You have to get them from a Freedom of Information Act request.

Ali Kahn

My cat had snuck outside when being sat by a fiend. She dig a hole and laid in it and napped. She was infested literally wih fleas. The vet office gave her a bath and applied Assurity drops. No more fleas at all!! She has been very very comfortable since then. This information is concerning to me though. It has been 2.5 weeks and she is is great shape and not scrtaching and crying from the fleas. :)) She was in bad shape from those fleas, she was crawling with them. She is an old indoor girl and is currently happier then heck. So far no side effects thank God!!! I hope this stuff doesnt hurt any cute kitty cats out there. :(

Ranked #4 in Pet Health

Hi Ali - I am glad that your cat apparently shows no signs of adverse reaction to Assurity. A bath with Dawn would also have killed the fleas. That's Dawn Blue (regular stuff) and it should not be used regularly, but only in cases where it is an "emergency". I'd treat your yard with Food Grade Diatomaceous Earth & Beneficial Nematodes. There are links to ideas in the article. Sadly, your experience does not seem to be the norm. Of all the products covered it appears more adverse reactions happen with Assurity than I have seen in the past. This is just the feedback I have been given so far. Thanks for commenting & being a pet parent who cares!