Fleas and Mites

By | October 5, 2014

Some cats and dogs are extremely sensitive to fleas; an afflicted cat will chew off large swatches of fur – and even skin in some cases.

Mites of various types can also cause chewing, allergic reactions, and hair loss.  They include Sarcoptes scabiei canis (mange; the human form of scabies is caused by a different subspecies of mite), Cheyletiella blakei (aka walking dandruff) which infects cats and can transiently infect humans, and ear mites (otodectes).

When alternative controls prove to be inadequate, rather than use one of the ubiquitous – but environmentally very toxic – over-the-counter flea treatments (e.g. Advantage or Frontline, topicals  applied to the back of a cat or dog’s neck), instead use Comfortis (pill) or Revolution (topical), veterinarian prescribed medications.  (See the information below for purchasing Comfortis and Revolution online from CanadaPetCare.com.)

A series of two or three treatments, one every four weeks; combined with a cleaning of bedding, carpets, and other furniture that could harbor flea eggs is typically sufficient for indoor cats.  Flea activity peaks during the warmer weather, especially in sandy or dusty environments.  Unless you have a super-sensitive cat, you can wait to see an indication of flea activity before starting a treatment series.  Signs include increased scratching, a flea, and flea droppings – small black crumbs that in water dissolve into blood.  Periodically comb your animals with a flea comb to look for fleas and droppings.

The active ingredients in Advantage II are Imidacloprid,  and Pyriproxyfen.  Imidacloprid is environmentally unfriendly (ex. it’s very toxic to honeybees when applied as an insecticide); the environmental impact of Pyriproxyfen has not been well-studied.  Fipronil, the active ingredient in Frontline, is likewise environmentally unfriendly.

Spinosad, the active ingredient in Comfortis, is reportedly environmentally friendly and is approved by numerous nations for use in organic agriculture.

Selamectin, the active ingredient in Revolution, is not clearly environmentally friendly or unfriendly; it is not used in agriculture.  Dogs without the MDR-1 gene defect and cats are not sensitive to the killing action of Selamectin; when applied in the correct dosage Revolution is considered safe.  Particular caution should be taken when using Revolution on Collies and other breeds more likely to carry the MDR-1 gene.  Selamectin is toxic to fish and aquatic invertebrates.

See 1-800-Pet-Meds for a comparison of Advantage II, Comfortis, and Revolution.  All three kill but do not repel fleas.  Advantage kills flea eggs and larvae while Revolution prevents the development of eggs and larvae into adult fleas; Comfortis does not impact the flea eggs and larvae.  Revolution also kills ticks and treats and controls ear mites and sarcoptic mange.

In the last few years, some flea populations have developed resistance to Advantage and Frontline (but not to Comfortis or Revolution).  Further, some cats may be super-sensitive to Advantage and/or Frontline – most likely they are reacting to the feel of the liquid.  (My Tokinese went completely bonkers when I treated him with Advantage; he has no issue with Revolution.)

Since the treatments kill fleas in the animal’s environment as well as on the animal, in a multi-cat or dog household (or in a feral cat colony), you don’t necessarily need to treat all of the animals.  Hold off treating pregnant, very young, ill, sensitive, or very skittish animals.  Instead treat the other animals and watch for signs of fleas.

Revolution kills flea eggs and mites so it takes a little bit of time to disrupt the fleas’ reproductive cycle.  Comfortis kills fleas right away but doesn’t do much about mites.

Online Canadian pharmacies are much more cost-effective suppliers of Comfortis and Revolution than most local vets.  The Comfortis tablets are fairly large (for a cat or a small dog); they should be fed to the animal after a meal.  Per my feline test subjects, the tablets are not very tasty.  (It probably doesn’t help that the tablets are beef or pork flavored, proteins that my three aren’t used to eating – because those are inappropriate proteins for felines.)  Comfortis tablets for small dogs, denoted by an orange striped box, are the appropriate dosage for most adult cats.  Revolution comes in single-dosage applicators sized and mixed for a particular range of cat or dog sizes.

CanadaPetCare.com is my source for Revolution and Comfortis.  You might want to start with the Comfortis (less expensive and more environmentally benign) and then switch over to Revolution as needed.  The Comfortis formulation is the same for cats and dogs; the color of the packaging denotes the dosage per pill.  So it’s more cost effective to buy the pills for large dogs and then cut them down to the appropriate dosage.  The next to largest size (light blue label) is currently on sale for $0.075 per mg – 6x 810 mg doses – that’s $61 for 18 doses for 6 to 12 lb cats or 10 to 20 lb dogs.

Cats dosage:
weight    Comfortis
in lbs    in mg
2 – 4     90
4.1 – 6   140
6.1 – 12  270
12.1 – 24 560

Dogs dosage:
weight – Comfortis – package – $ per mg (Feb 2017)
in lbs     in mg       color
3.3 – 4.9 90 – yellow – $0.51
5 – 10     140 – pink – $0.4
10.1 – 20 270 – orange – $0.23
20.1 – 40 560 – teal – $0.12
40.1 – 60 810 – light blue – $0.075 (special price)
60.1 – 120 1620 – brown – $0.093

(dosage table from https://www.comfortis.com/)


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