Question:

Hello,

 

How can a person get rid of lice in feral cats? Obviously Frontline® is not an option since they cannot be handled.

 

The feral cat colony is about 25 cats. Should their environment be sprayed with an insecticide? If so, which one?

 

Thank you very much.

 

Answer:

Thank you for your question and for caring for these cats!

 

Lice infestations are typically seen in debilitated or otherwise stressed cats who have been exposed to lice from other cats. Due to the widespread use of monthly flea and tick preventatives that are also effective against lice (e.g. Revolution® (selamectin) and Frontline® (fipronil)), lice infestations are otherwise uncommon in cats and dogs. Diagnosis is commonly made by visualization of lice or their eggs (nits) in the hair coat. The lice that affect cats, Felicola subrostrata, are of the chewing variety. Fortunately, cats are not at risk of becoming anemic from their infestation; chewing lice feed on dead skin and do not feed on the blood of the host. Severe lice infestations can cause extreme itch, restlessness, intense scratching, and hair loss. There is no evidence that the cat louse carries and transmits other diseases. Failure to treat the infestation is not life-threatening, but treatment is ideal when feasible. Lice are specific to their host, so there is no risk of a cat passing them to dogs or humans. Lice can easily, however, be spread from cat to cat.

 

The life cycle of the louse is about 30 days and is carried out entirely on the host animal. Females lay multiple eggs daily which take 1-2 weeks to hatch into nymphs; nymphs molt twice before becoming adults. Lice will die in a few days if separated from the host.

 

Unfortunately, treating unsocialized community cats for lice is challenging in a few ways. There are many topical products which are effective in treating lice infestations. However, as you point out, they require being able to handle the cats; they also require multiple administrations to clear an infestation. Another challenge in treating community cats is that the legality of treating unowned cats may differ by state in terms of what is required for a valid veterinarian-client-patient relationship. If any of the cats require spay/neuter, an appropriate product (e.g. Revolution® (selamectin) or Frontline® (fipronil)) can be applied and any nits on the coat removed while they are under anesthesia.

 

These products are effective at killing adult lice, but do not have any activity against eggs. Since it takes 1-2 weeks for eggs to hatch, it is therefore important to repeat treatment every 2 weeks for a total of 4 treatments to eliminate newly hatched nymphs, which gets back to the challenges associated with treating unsocialized cats- you will likely only have one chance to treat them (or no chance if they are already sterilized). Removing the nits, while tedious, can increase the chances that a one-time treatment may be successful. Unfortunately, without treating all cats in the colony (an unlikely prospect), cats will continue to infect each other.

 

Regarding your second question, since lice do not survive for a long period of time off the host, treatment of the environment unfortunately plays little role in controlling the infestation. Control requires treatment of the cats themselves.

 

I’m sorry there are no easy answers to your question! Your best chance at controlling the lice may be limiting the colony population through spay/neuter efforts and treating cats as they come through for surgery. Since lice infestation is more common in dense populations of debilitated cats, gradually reducing the colony size through spay/neuter and adoption of socialized cats would also likely be helpful. Thankfully, lice are not life threatening and cats can often have a good quality of life despite them.

 

For more reading about lice in cats:
https://www.uwsheltermedicine.com/library/resources/cats-infected-with-feline-lice
https://www.uwsheltermedicine.com/library/resources/what-is-the-best-course-of-treatment-for-lice-on-kittens

 

Thank you again for your dedication to these cats. Please let us know if we can be of further assistance.

 

Kimberly Perley, VMD
Maddie’s Shelter Medicine Intern 
University of Wisconsin – Shelter Medicine Progeam
Dane County Humane Society
www.uwsheltermedicine.com
www.facebook.com/UWShelterMedicine