Brand: COMFORTIS ®
INDICATIONS: DOGS and CATS
PARASITES CONTROLLED* (spectrum of activity): Fleas
USA and other countries
- Dogs, 3.3 to 4.9 lbs. ≈ 1.5 to 2.2 kg bw: 1 tablet with 90 mg spinosad (equivalent to 60.0 to 40.9 mg/kg spinosad)
- Dogs, 5 to 10 lbs. ≈ 2.3 to 4.5 kg bw: 1 tablet with 140 mg spinosad (equivalent to 60.9 to 31.1 mg/kg spinosad)
- Dogs, 10.1 to 20 lbs. ≈ 4.6 to 9.1 kg bw: 1 tablet with 270 mg spinosad (equivalent to 58.7 to 29.7 mg/kg spinosad)
- Dogs, 20.1 to 40 lbs. ≈ 9.2 to 18.1 kg bw: 1 tablet with 560 mg spinosad (equivalent to 60.9 to 30.9 mg/kg spinosad)
- Dogs, 40.1 to 60 lbs. ≈ 18.2 to 27.2 kg bw: 1 tablet with 810 mg spinosad (equivalent to 44.5 to 29.8 mg/kg spinosad)
- Dogs, 60.1 to 120 lbs. ≈ 27.3 to 54.4 kg bw: 1 tablet with 1620 mg spinosad (equivalent to 59.3 to 29.8 mg/kg spinosad)
- Dogs, >120 lbs. ≈ >54.4 kg bw: administer the appropriate combination of tablets
- Cats, 2 to 4 lbs. ≈ 0.9 to 1.8 kg bw: 1 tablet with 90 mg spinosad (equivalent to 100.0 to 50.0 mg/kg spinosad)
- Cats, 4.1 to 6 lbs. ≈ 1.9 to 2.8 kg bw: 1 tablet with 140 mg spinosad (equivalent to 73.7 to 50.0 mg/kg spinosad)
- Cats, 6.1 to 12 lbs. ≈ 2.9 to 5.4 kg bw: 1 tablet with 270 mg spinosad (equivalent to 93.1 to 50.0 mg/kg spinosad)
- Cats, 12.1 to 24 lbs. ≈ 5.5 to 10.9 kg bw: 1 tablet with 560 mg spinosad (equivalent to 101-8 to 51.4 mg/kg spinosad)
EU and other countries
- Dogs, 1.3 to 2.0 kg ≈ 2.9 to 4.4 lbs. bw: 1 tablet with 90 mg spinosad (equivalent to 69.2 to 45 mg/kg spinosad)
- Dogs, 2.1 to 3.0 kg ≈ 4.5 to 6.6 lbs. bw: 1 tablet with 140 mg spinosad (equivalent to 66.7 to 46.7 mg/kg spinosad)
- Dogs, 3.1 to 3.8 kg≈ 6.7 to 8.4 lbs. bw: 1 tablet with 180 mg spinosad (equivalent to 58.1 to 47.4 mg/kg spinosad)
- Dogs, 3.9 to 6.0 kg≈ 8.5 to 13.2 lbs. bw: 1 tablet with 270 mg spinosad (equivalent to 69.2 to 45.0 mg/kg spinosad)
- Dogs, 6.1 to 9.4 kg≈ 13.3 to 20.7 lbs. bw: 1 tablet with 425 mg spinosad (equivalent to 69.7 to 45.2 mg/kg spinosad)
- Dogs, 9.5 to 14.7 kg ≈ 20.8 to 32.4 lbs. bw: 1 tablet with 665 mg spinosad (equivalent to 70.0 to 45.2 mg/kg spinosad)
- Dogs, 14.8 to 23.1 kg≈ 32.5 to 50.9 lbs. bw: 1 tablet with 1040 mg spinosad (equivalent to 70.3 to 45.0 mg/kg spinosad)
- Dogs, 23.2 to 36.0 kg≈ 51.0 to 79.4 lbs. bw: 1 tablet with 1620 mg spinosad (equivalent to 69.8 to 45.0 mg/kg spinosad)
- Dogs, >36 kg≈ >79.4 lbs. bw: administer the appropriate combination of tablets, ensuring a dose of 45-70 mg/kg bw
- Cats, 1.2 to 1.8 kg ≈ 2.6 to 4.0 lbs. 1 tablet with 90 mg spinosad (equivalent to 75.0 to 50.0 mg/kg spinosad)
- Cats, 1.9 to 2.8 kg ≈ 4.1 to 6.2 lbs. bw: 1 tablet with 140 mg spinosad (equivalent to 73.7to 50.0 mg/kg spinosad)
- Cats, 2.9 to 3.6 kg 6.3 to 7.9 lbs. bw: 1 tablet with 180 mg spinosad (equivalent to >62.1 to 50.0 mg/kg spinosad)
- Cats, 3.7 to 5.4 kg≈ 8.0 to 11.9 lbs. bw: 1 tablet with 270 mg spinosad (equivalent to >73.0 to 50.0
- Cats, 5.5 to 8.5 kg12.0 to 18.7 lbs. bw: 1 tablet with 425 mg spinosad (equivalent to >77.3 to 50.0
- Cats, >8.5 kg ≈ >18.7 lbs. bw: administer the appropriate combination of tablets, ensuring a dose of 50-75 mg/kg bw
* Can be slightly different in some countries: read the product label!
- LD50 (acute oral) in rats: n.a. for the tablets. >3600 mg/kg for the a.i. spinosad
- Estimated Hazard Class according to the WHO: not applicable for veterinary medicines
Suspected poisoning? Read the article on spinosad safety in this site.
WARNING !!!: Never use on cats tablets approved only for use on dogs, and vice-versa. Never use on cats or small dogs tablets approved for large dogs. Learn more about tablets and their safety.
You may be interested in the following articles in this site dealing with the general safety of veterinary products:
- Safety for humans
- Safety for domestic animals
- Safety for the environment
- Hazard classifications of pesticides
Risk of resistance? YES, low in fleas, mainly the cat flea, Ctenocephalides felis
So far there are no reports on flea resistance to spinosad. However, fleas have developed resistance to several other insecticides (e.g. carbamates, organophosphates and pyrethroids) and are certainly capable of becoming resistant to spinosad as well. Experience shows that prolonged and uninterrupted use of any insecticide on fleas (including spinosad) bears the risk of resistance development.
Alternatives to prevent resistance through product rotation:
- Carbamates (F+T*), e.g. carbaryl, propoxur
- Indoxacarb (F*)
- Insect Development Inhibitors (F*), e.g. lufenuron, methoprene, pyriproxyfen
- Isoxazolines (F+T*), e.g. afoxolaner, fluralaner, sarolaner
- Macrocyclic lactones (F*), e.g. selamectin
- Neonicotinoids (F*), e.g. dinotefuran, imidacloprid, nitenpyram
- Organophosphates (F+T*), e.g. chlorpyrifos, coumaphos, diazinon, fenthionn, etc.
- Phenylpyrazoles (F+T*), e.g. fipronil, pyriprole
- Pyrethroids (F+T*), e.g. cyphenothrin, cypermethrin, deltamethrin, etofenprox, flumethrin, permethrin, etc. toxic to cats!
*F = effective against fleas; T = effective against ticks.
These alternative products may not be available in all countries, or may not be available as tablets.
Resistance of fleas to carbamates, organophosphates and pyrethroids is not uncommon in several countries, including the USA.
Are the active ingredients of this product ORIGINAL* or GENERICS**?
- Spinosad: GENERIC (introduced in the 1990s)
*Meaning that they are still patent protected and generics are not yet available
**Meaning that they have lost patent protection and may be acquired from manufacturers of generic active ingredients other than the holder of the original patent.
COUNTRIES where this product is marketed: USA, the EU, Canada, Australia, etc.
GENERIC BRANDS available? So far not available in most countries.
Click here to learn more about GENERIC vs. ORIGINAL drugs.
COMFORTIS is ELANCO's original once-a-month flea tablet brand with spinosad for dogs and cats. Although ELANCO had acces to spinosad since the 1990s, a spinosad-based flea product was introduced only around 2010.
Spinosad is a broad-spectrum insecticide of natural origin introduced in the 1990s (by ELI-LILLY). It is moderately used in pets, rather scarcely in livestock and moderately in agricultural pesticides. It has a systemic mode of action, i.e. after oral administration it gets into the blood of the pet and reaches the fleas during their blood meal. It kills the fleas very fast. Administered about every 4 weeks it controls established flea infestations and prevents flea population development in the pets environment, but only if all the dogs and cats in the same household are treated against fleas.
Systemic products (tablets for oral administration, injectables) have several general advantages over topical products (spot-on, insecticide-impregnated collars, shampoos, soaps, sprays, powders, etc):
- They do not contaminate the pet's hair coat: avoiding contact with the pets after administration is not necessary for children or adults.
- The active ingredient reaches the parasites through the blood, everywhere in the pet's body, whereas topical products may leave some body parts (e.g. the ears, between the legs, etc.) insufficiently protected.
- Efficacy is independent from exposure to dirt, sun, shampooing, washings, rain, baths, dirt, etc., whereas topical products can be washed away, or broken down by sunlight, etc.
But they have also a few disadvantages:
- The parasite has to bite and suck blood first before it is killed or sterilized.
- Orally administered products (tablets, suspensions, pastes, etc.) may be vomited and treatment needs to be repeated.
- Administration of tablets may be less convenient than administration of spot-ons.
- The choice of products for oral or injectable administration is smaller than for topical administration.
For an overview and a list of the most popular pet antiparasitics for flea, tick, lice and/or mite control click here.
This article IS NOT A PRODUCT LABEL. It offers complementary information that may be useful to veterinary professionals and users that are not familiar with veterinary antiparasitics.
Information offered in this article has been extracted from publications issued by manufacturers, government agencies (e.g. EMEA, FDA, USDA, etc.) or in the scientific literature. No guarantee is given on its accuracy, integrity, sufficiency, actuality and opportunity, and any liability is denied. Read the site's DISCLAIMER.
In case of doubt contact the manufacturer or a veterinary professional.