These four products are the newest entrants in our unending flea and tick-control wars.
They also offer a potential new treatment for both demodectic and sarcoptic mange. That is because all these parasites (as well as ear mites) depend on a "bug" (arthropod) nervous system that is quite different from the one you and I and furry pets share - but quite similar to that of a flea. (ref)
If your dog has been diagnosed with sarcoptic or demodectic mange, these newer medications might be a better option than the products veterinarians have had available until now. That is particularly true if your dog is sensitive to ivermectin or reacts poorly to amitraz (Mitaban®) dips.
NexGard® (afoxolaner), Bravecto® (fluralaner), Symparica® (sarolaner) and Credelio® all contain similar related compounds called isoxazolines. These compounds are distant relatives of fipronil – the active ingredient in Frontline®. Of the four, NexGard has been on the market the longest (since 2013). So owner feedback on that medication is largest.
I believe that there is currently a caution on the label on these products that they be used with special care (if at all) in pets with a history of seizures or neurological abnormalities. I would also be cautious about using any of them in dogs under 6 months of age. I believe that Bravecto® has or had that on their label. They have also been reported to occasionally cause itching and hair loss in cats. Never apply any of them in greater amounts than suggested on their product inserts. Read those inserts here: (NexGard®, Bravecto®, Symparica®, Credelio®)
At the bottom of this article, I listed the current reports on the effectiveness of these medications in curing demodectic and sarcoptic mange. But I would like to caution you as your read those articles that they were all paid for or performed by the companies making the products. That is generally not the best way to obtain unbiased information about something you are considering buying or using. Unfortunately, that's all we've got. Simparica® is, according to its maker, Zoetis, the most potent (effect last the longest ?). Merck, the maker of Bravecto disputes this saying their product offers up to 12-week protection against fleas and ticks. (ref) So basically, the articles were funded as part of company marketing campaigns.
The makers report that side effects are uncommon and generally mild and the FDA, in their review, accepted that. (ref) The tests on these medications' ability to kill fleas and ticks and the occurrence of side effects were run on laboratory beagles. So they may not be indicative of what might occur in the general dog population. In pet owner trials, when side effects occurred, they included, vomiting, dry flaky skin, diarrhea and decreased appetite. But most owners reported that no side effects occurred during the rather brief period that the studies lasted. In company studies, more serious side effects were confined to dogs receiving higher than the suggested dose.
Some topical flea/tick medications (like Imidacloprid/Advantage®) kill fleas on contact. These three oral chew tablets do not. The fleas have to “drink” the chemicals as it circulates in the pet’s body fluids. So dogs with fleabite allergies (allergies to flea saliva) may not be rid of the fleas before itching and skin damage begins.
None of the studies I know of compare the effectiveness of these three products to more traditional topical or oral products that have been on the market for a long time. That might lead one to conclude that they are no more effective against fleas and ticks than the older ones. Running that sort of comparative study would not be that difficult and if the manufacturers thought their new products out performed the old ones, they would almost certainly have run them by now.
If you got to this page because you are trying to control fleas and ticks on your dog and the products that you are using now are working well for you, I see no reason for you to change (You might be advised to do so because bigbox stores like Walmart now compete with veterinarians by offering topical fipronil products [ref]).
But if you got here because of a mange problem, that's another story. Sometimes, a sarcoptic mange problem can be hard for veterinarians to entirely rule out in an itchy dog. In those cases, incorporating a few months of one of these three products - even if atopic allergies are the more likely cause - might be good insurance.
There are other factors to consider. I personally prefer using products that remain on the skin and hair coat rather than that permeate the pet's entire body - if topically-applied products are controlling parasites satisfactorily. But some pet owners feel more comfortable knowing that topical insecticides are not on the skin and hair of the pets they snuggle up to and that no product residues are being spread around their home environment. These chews might be better for them. Other owners have pets that resist or fear the odor of topical flea/tick control products. There are also a number of pets that show skin irritation and hair loss at the points where some topical flea/tick drops are applied. Elderly pet owners and others might just appreciate this oral, less hassle approach.
I would not give these products to pregnant or breeding dogs until we have more information on what effects they might have on the offspring. I know there are veterinarians giving Simparica to pregnant breeder dogs in an attempt to keep them from producing puppies with demodectic mange. That might be successful. However, dogs that produce litters that are prone to long-term demodectic mange have defective immune systems. I find it quite cruel and unethical to breed them or for veterinarians to encourage dog breeders to do so. (ref)
Simparica has added a cautionary statement to their website :
“Simparica may cause abnormal neurologic signs such as tremors, decreased conscious proprioception [= foot placement] , ataxia [~wobbly] , decreased or absent menace , and/or seizures.”
Here are some articles describing these product's use in eliminating mange:
You can send me an email telling me of your experiences using these three products and I will post them here anonymously. I am particularly interested in the good (or not so good) things that happened when the products were used, that stop when the products were discontinued and that begin again when the products were again used. I would also like to know if you found them more effective against fleas and ticks than topically applied products or collars.