Dog: Lice

General information

Ectoparasites are parasites that live on the exterior or surface of an animal. The common canine ectoparasites include fleas, ticks, lice and mites. They can transmit various diseases and cause hypersensitivity and skin disorders in animals. Some ectoparasites (mites and lice) spend their entire life on the dog while other ectoparasites (fleas and ticks) spend part of their life cycle in the environment. Fleas, ticks and mites are not species specific, meaning they can infest animals of different species.


Lice are ectoparasites that spend their entire 21 day life cycle on the dog. Dog lice do not infest other animals or people. There are two types of dog lice: Trichodectes canis chews on skin and the other Linognathus setosus sucks blood. Lice are flat, wingless, six-legged insects which can be seen with the naked eye. Adult lice lay eggs which are called nits which appear as white flakes attached to the hair shaft.

Abb. GSRB2VQG: Lice (Linognathus setosus), microscope.

Lice are an uncommon parasite in dogs in the United States. When lice are found on a dog, the dog is usually living in filthy, crowded conditions or is unhealthy from another disease.


Dogs acquire lice by coming into direct contact with other dogs infested with lice or by direct contact of lice and nit contaminated grooming equipment, bedding etc.

Cardinal symptom

Intense itching


Intense itching along with a scruffy, dry coat with areas of hair loss are the clinical signs of lice infestation. The blood sucking lice cause more skin irritation than the chewers because they break the skin. Very young puppies can develop life-threatening anemia from blood loss due to lice feeding on blood. These dogs will show signs of weakness, lethargy and pale gums.


Diagnosis is made by your veterinarian finding lice on your dog.


Because lice spend their entire life on the dog, they do not infest the environment as extensively as fleas and ticks and are easier to treat. The topical (spot-on) antiparasitic products are the preferred treatment for lice. An insecticide bath can also be used to quickly eliminate the adult lice. Treatment must be repeated to kill adult lice that have hatched from the eggs. Commonly, treatment is administered every 2 weeks for 3-4 treatments. All products should be purchased from your veterinarian. All bedding should be washed with hot, soapy water. Grooming equipment should be cleaned and disinfected after each use.


Prevention of lice in the form of monthly topical (spot-on) antiparasitics is recommended for dogs at risk. These monthly medications can be a combination of medications used to prevent tick, flea, mite, heartworm and endoparasite infections.


When applying the topical, spot-on medications, be sure to part the hair and apply the medication directly to the skin. Do not bath or allow your dog to swim for 2 days after application.

Update version: 4/24/2014, © Copyright by
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The information offered by enpevet Ltd. is intended solely for information purposes and and does under no circumstances replace a personal consultation, examination or diagnosis through a veterinarian. Thus, the information serves as an addition to the dialogue between pet owner and veterinarian, but can never replace the visit to the veterinarian. enpevet® would like to ask all users, whose animals have health concerns, to see a veterinarian as required. If you have any questions regarding the health of your animal, we recommend that you turn to your trusted veterinarian , instead of starting, changing or breaking off treatments on your own. The content of enpevet® cannot and should not be used for making your own diagnoses or for the selection and application of treatment methods.