Cats infected with feline lice


How common is it?
Is it contangious to children or dogs?
Does the Lyme dip only kill the lice or does it also kill the eggs and larva?
What is the life cycle of cat lice?
Will canine Frontline Plus kill feline lice? The packaging states kills "chewing lice".
What advice, recommendation or precautions should we give to the potential foster home? They are in ISO now.
Now that they have been Lyme dipped can they safely be sent for spay/neuter?
What is the best way to treat the remainder of the cats on the property? We are waiting to find out how many are friendly vs feral. They all need spay/neuter. All live outdoors.
What is the best way to rid the "living area" of the problem?

Answer Date: 
August 14, 2012

Feline lice is a rare finding and usually associated with neglected cats or those living in poor husbandry conditions.  It is very contagious between cats, so if there is one infected cat, there is a good chance the others are infected as well.  Luckily, lice are species-specific so dogs and people are safe from contracting them.

Lime sulfur dip is very effective in killing nymphs and adults, but not reliable in killing eggs.  Lice have an incomplete life cycle (unlike  fleas that have a larval and pupal stage), where the eggs (nits) hatch  into nymphs (mini-adults), which then go through several molts to become  adults.  The complete life cycle is about 3-4 weeks depending on the  environment, and occurs on the animal. I don't know of any insecticide  that will effectively penetrate the eggs, so repeating treatments every 2  weeks for a total of 2-3 treatments is recommended.  Precautions that a  foster home should take is to have their resident cats on monthly flea  control (Advantage, Frontline, Revolution, etc.).  As long as there are  no underlying medical conditions (e.g., anemia caused by lice infestation), a lime sulfur treated cat is okay for surgery. Lucky for  us, lice are susceptible to pretty much anything that fleas are  susceptible to, including Frontline.  Frontline spray (as well as Top  Spot and Plus) is a very effective way to get rid of lice.  This may be  an option for the remaining feral cats.  You don't necessarily have to  touch the cat, but if you can get close enough to spray it, it will  help.  As far as the environment, anything that can be tossed in the  laundry, should be.  Otherwise, just treating the cats every two weeks  should take care of the infestation, as long as the cats are not  re-infecting each other. Another option may be placing flea collars on  the affected cats if you can get it on them.  I am not a huge fan of  flea collars or using pyrethrin-based products on cats, but if the cats  keep the collars on long enough (2+ weeks) to kill off the lice and  newly hatched nymphs, this will take care of the problem too.  If you  must use an environmental product, use one that is targeted towards  fleas and that is safe for cats.

Cristie YJ Kamiya, DVM, MBA
Resident, Koret Shelter Medicine Program
Center for Companion Animal Health
UC Davis School of Veterinary Medicine