Lice in Dogs

Symptoms of lice infestation in dogs can include one or more of the following:

• Itchiness
• Scratching, rubbing and/or biting at skin
• Restlessness
• Skin redness, irritation
• Dry coat
• Matted fur
• Hair loss – often around neck, ears, upper back, groin and rectum
• Anemia – more often seen with severe infestation
• Lethargy, weight loss, poor development in severely infested pups

Types

There are two species of lice that infest dogs:

• Trichodectes canis

  : The chewing louse. These insects grip the host’s fur with their large, wide mouthparts and chew the dead skin cells of the dog host. This species is found throughout the world and can serve as a vector for the canine tapeworm.

• Linognathus setosus

  : The sucking louse. These insects grip host hair with their claws and have narrow mouthparts for sucking blood through the skin. This species is found throughout the world and can be more common in long-hair breeds and colder climates.

A pet owner may notice itchiness, restlessness, fur loss, or other symptoms mentioned above as an initial sign of possible lice infestation. The owner or groomer may see adult lice on the skin or the eggs of lice, “nits,” on the pet’s fur. Adult lice can be 1-2.5mm in length and look like spots of dirt on the skin. Nits look more like white sand granules stuck along the hair shaft. Lice can be difficult to notice until a full infestation has developed.

The type of infestation is diagnosed by a veterinarian by examining a sample of fur or scraping of the skin for nits and adult lice under the microscope. Chewing lice are identified by their large mouthparts used for chewing and grasping fur. Sucking lice are identified by their narrow mouthparts and slightly more developed claws.

Diagnosis is based on reported clinical symptoms and visual identification of lice or nits. Most lice in an infestation will be found under clumped or matted fur or along the head, neck, shoulders, groin and tail. Lice seek out moisture and will often locate themselves near skin abrasions or the anus.

Infestation with lice can be treated fairly easily. Once your pet has been diagnosed with pediculosis, the veterinarian will supply you with instructions for treating the infestation and preventing further infestation. It is important to remember that merely bathing your pet will not rid it of a lice infestation. Lice hold tight to the skin and hair and will not be removed or killed with soap and water.

There are numerous shampoos, sprays and powders effective in killing lice. The effective ingredient may be:

• Lime-sulfur
• Pyrethrin
• Pyrethroid

Flea treatments are also effective in preventing and treating a lice infestation. Some products that may be recommended by the veterinarian include:

• Fripronil
• Imidacloprid
• Selamectin

Clumped or matted fur may require shaving. Shaving will expose the skin and ensure that lice are put in contact with the insecticidal treatment.

Because of the life cycle of the parasite, it may be necessary to treat your pet more than once with topical shampoos, powders or sprays. Adult females live approximately 4 weeks and lay eggs daily. Nits hatch within 1-2 weeks. The nymph becomes an egg-laying adult within 2-3 weeks.

The initial treatment will kill the adult lice. However, nits are not susceptible to insecticides and will remain on the pet. Treatment every 1 to 2 weeks for at least 4 weeks should be sufficient to kill all hatched nymphs.

Certain dogs, pregnant dogs and young puppies can be susceptible to insecticides. Be sure to follow the veterinarian’s instructions on treatment. Keep the treatment products in a safe place away from children and pets and wear gloves when applying them. Although people cannot get dog lice, remove and wash your clothing immediately after treating your furry buddy. Wash all towels used in the process as soon as you complete each treatment session.

Affected pets should be quarantined and have no contact with other dogs until the full treatment regimen is complete.

To prevent reinfection, throw away or clean any place where your pet spends time. Carpets, floors, rugs, furniture and outdoor surfaces should be cleaned thoroughly. Throw away or wash all pet bedding. Lice survive only 3-7 days off of the host, so unwashable items can be packed in sealed plastic bags for 4-6 weeks (allowing time for all eggs to hatch and die). Clean all grooming brushes, combs, crates, leashes, collars and dog apparel.

Dogs severely infested with sucking lice may require supplementation with iron, vitamins and minerals to address anemia (low red blood cell levels). Most monthly flea treatments will prevent future lice infestation.