Lice are easy to identify: They are wingless, flat, six-legged insects which attach to a host's hairs. Unlike ticks, which are actually arachnids (related to spiders), lice are light in color and more or less oval in shape. Lice lay their eggs on the shafts of a host's hair, and the resulting babies (called nits) look very much like dandruff. Untreated lice infestations can lead to skin issues and bald patches (from excessive scratching), and they have been known to transmit diseases. Lice do feed off the blood of their hosts; in cases of severe infestation of small puppies or kittens, blood loss can lead to shock or death. It's important to know that lice can be avoided and treated, and, as a result, infestations are relatively rare among American pets (though they are common among feral dogs and cats).
What Are Lice in Dogs and Cats?
Lice are parasites that can infest any animal with hair; it's very important to know, however, that each species of animal is only infected by their own special species of lice. If a stray louse from another species does find its way onto a dog or cat or even a person, it will not remain there.
Both dogs and cats do sometimes get lice, although lice are not one of the more common parasites diagnosed. They are most common in animals that live in poor conditions without proper sanitation. Dogs can get two different types of lice: Trichodectes canis and Linognathus setosus. Cats get only one type: Felicola subrostrata.
Pet lice are either bloodsuckers or chewers. The lice that chew live on a pet's dead skin, which is irritating to the pet, and is why they scratch. Bloodsucking lice do what their name implies: suck the animal's blood. Both types of lice carry diseases and can lead to tapeworms. Untreated lice can cause fur loss from your pet's scratching.
Symptoms of Lice in Dogs and Cats
The most common symptom of a lice infestation is extreme itchiness. Most pets infested with lice will suddenly start scratching themselves, sometimes to the point of irritating their skin.
Upon closer inspection, it's possible to see lice among a pet's hairs. Lice are light-colored and slow moving (fleas, by contrast, are dark and fast-moving, while ticks are dark and immobile). Because lice lay their eggs on the shafts of pet hairs, it's also possible to see their empty eggshells which look very much like dandruff. If the white flakes are sticky and hard to remove from the hair, they are almost certainly lice eggs.
Causes of Lice
Lice are transmitted when two animals are close enough to one another for the parasites to leap to another host. This can occur in kennels, pet stores, pet adoption centers, pet "daycares," or even at pet shows or dog parks. While poor sanitary conditions and crowding are one source of lice infestations, so too are more upscale settings such as agility events or group walks.
If you notice your pet scratching and suspect lice, take it to a veterinarian to be sure it's not something more serious, and to make sure it's lice and not fleas (which require slightly different treatment). Your veterinarian should be able to recommend an over-the-counter spray, shampoo, or spot treatment for your pet's lice.
There are many products that kill and repel lice; they include shampoos containing pyrethrins or organophosphates. On-the-spot insecticides like imidacloprid (Advantage) and Selamectin (Revolution) can also be effective for either cats or dogs. It's important to note, however, that while permethrin-containing products can be helpful in treating dogs, permethrin is toxic to cats. Thus, if your home includes both dogs and cats, be sure to let your vet know—and avoid any treatment containing permethrin.
While pharmaceuticals are very effective, another safe, nontoxic option is a lime-sulfur dip. While it may have a few side effects (such as the smell of sulfur and a short-term yellow tinge to your pet's fur) it works quite well. Dips should be repeated each week for up to six weeks. It's also helpful to use a fine-toothed flea comb to remove dead lice and sticky nits from your pet's fur.
If you have a pet with lice and more than one animal lives in your house, keep the infected animal away from the others during the course of treatment. It's likely you'll end up treating all your dogs or cats since lice spread fairly easily. During treatment (about four weeks) keep pets away from other animals; that means avoiding pet shows, agility events, pet daycares, and other communal pet settings.
Dispose of any bedding, brushes, or cloth toys that a pet infected with lice has used, and if possible, have any furniture they use frequently, such as chairs or rugs steam cleaned.
How to Prevent Lice in Dogs and Cats
There is no way to absolutely prevent lice infections, but the following can reduce the likelihood of a problem:
- Keep your pets in clean locations, and make sure bedding is washed and/or changed on a regular basis.
- Avoid allowing skin-to-skin contact with animals from outside your home.
- If you do take your pet to pet shows, agility events, daycares, or obedience schools, check on the setting ahead of time to be sure it's clean and well managed.
- If you take your pet to a groomer, check to be sure grooming equipment is properly cleaned between clients.
- Consider using an on-the-spot treatment which can reduce the likelihood of lice infestations.
Are Pet Lice Contagious to People?
Lice are a common parasite, especially for school-aged children. Often, the family pet gets blamed for the infestation. But can your family really get lice from your family pet?
People do not get lice from dogs and cats. Nor do dogs and cats get lice from people. Lice are species specific parasites. The lice that infect people only infect people. The lice that infect dogs only infect dogs. The lice that infect cats only infect cats. Human lice need human blood to survive; dog lice need dog blood and so on.
People are susceptible to three different types of lice: head lice, body lice, and pubic lice. The head louse is known as Pediculus humanus capitis. The body louse is called Pediculus humanus corporis and is also sometimes referred to as the clothes louse. The pubic louse is Pthirus pubis, though you may hear it referred to as a "crab" as well. All three types of lice are only passed from person to person, though, and none can be acquired from the family dog or cat or any other family pet.
If your child has head lice, your dog, cat, or other pets in the household are not at risk of catching the lice or its hatching eggs. And while lice are not common in dogs and cats, the lice that live on dogs and cats are not able to live on humans.