Treating Dog Lice

Reviewed, Edited and Updated by Veterinarian:  Dr. Omer Ahmed, DVM
April 24, 2024

Types of Dog Lice: Chewing and Sucking Varieties

Lice are flightless insects, also termed ecto-parasites (external parasites), which infest domestic animals and humans. These are host specific parasites, which depend upon the skin debris to feed and by sucking blood from the skin. Based on feeding pattern, lice are thus divided in to two different types; biting or chewing lice and blood-sucking lice, which is a function of their head shape.

• Chewing or Biting Lice: The chewing or biting lice belong to Anoplura order, while blood sucking lice are part of the Mallophaga order. Trichodectes canis and Heterodoxus spiniger are two common chewing or biting species of lice, The H spiniger type is found in the tropics and rarely in North America. These lise use their large mandible to grasp dot hair. Chewing lice are hosts for canine tapeworm.
• Sucking Lice: Linognathus setosus is the only blood sucking specie of lice, which infests pet dogs and causes clinical symptoms. These types of lice have a narrow head, with a mouth engineered to suck fluids or blood. Trichodecetes canis can also serve as a intermediate host for tape-worms in dogs. It's important to note that dogs cannot get human lice, emphasizing the host specificity of lice infestations. These lice are widely found in subtropical and tropical areas in South and North America, Asia, India and Africa. Sucking lice are more common in dogs with long hair.

Life Cycle and Transmission of Lice

Lice are typically host specific. They cannot fly and usually cause no problems for accidental hosts, such as cats or humans. These are transmitted by direct, physical contact only and only adult or advance larval stages of canine lice can be transmitted from one dog to another. These are wingless parasites, therefore they cannot fly and physical contact is necessary for their transmission. Common places/means of transmission are parks, walking trails, beddings and grooming instruments. It's important to understand the stages of the louse life cycle, particularly that it takes most lice about three to four weeks to develop from nit (egg) to a reproductively capable adult, which underscores the need for timely intervention and treatment.

The life cycle of dog lice is complex.

From the egg stage to the adult lice laying new eggs, the complete life cycle of a dog louse takes approximately 3 to 6 weeks to complete.

Egg Laying and Hatching

Female lice lay several eggs, also known as nits, on a daily basis throughout their lifespan of around 30 days. These eggs are firmly cemented to the dog's hair follicles near the skin's base. The eggs then hatch in 1 to 2 weeks, releasing the young lice.

Developmental Stages

After hatching, the young lice go through three distinct developmental phases before reaching adulthood. This process takes an additional 2 to 3 weeks

Adult Lice

The fully mature adult lice measure between 1 to 1.25 millimeters in length. They have a yellowish to tan coloration with distinct dark markings on their bodies.

Lice Symptoms

Lice cause discomfort to the infested dog. The first signs include scratching, rubbing and biting of infested areas. The dog's coat will appear dry, rough and dull. Nits or eggs are sometimes mistaken for dandruff, and appear like white specks of sand. Itching and severe irritation are other notable signs, which cause stress and discomfort. The hair shaft may appear matted in heavy infestation. Sucking lice also causes small wounds, which may get infected. Thus stress, discomfort and small wounds can trigger other underlying disorders, such as secondary microbial skin infections. Symptoms usually appear on the head and ears as well as the rear, shoulders and neck.

Blood sucking dog lice may cause anemia if they infest a dog in greater numbers; puppies are particularly more prone to anemia, since they have a less developed immune system and the skin is relatively immature. Clinically, a dog with a lice infestation appears stressed, dull and with severely dry and scruffy coat. Canine lice otherwise do not cause much damage to the health of your dog.

Diagnosis

Diagnosis is purely based upon clinical examination, hygienic history, and examining the dog's hair for signs of lice infestation. Shaking the dog's hair can help distinguish lice from dandruff, a crucial step in accurate diagnosis. Adult lice can be isolated from the base of the dog hairs, while eggs are usually glued with the hairs, which is why the hair can feel greasy. In order to diagnose, the pattern is observed. For example, parting the hairs often reveals lice, where chewing lice appears active and blood-sucking lice usually moves slowly. If the veterinarian needs to confirm the type of dog lice, adult lice and/or eggs may be examined under microscope.

Treatment to Effectively Treat Lice in Dogs

Dog lice treatment or management of an infestation is usually done with the help of sprays, dips, bathes, and thorough cleaning of the skin. Using flea combs to remove live and dead lice from the dog's coat is an effective step in the treatment process. Therapeutic elimination is necessary for proper treatment and several anti-parasitic drugs can be used for this purpose. Dislodging with fine-toothed combs usually doesn’t help much, because it’s a tedious process and also it doesn’t kill lice that have hatched.

These therapeutic agents that treat lice, such as pyrethrins, permethrin, lindane, rotenone, methoxychlor, diazinon, malathion, or coumaphos are commercially available in different formulations such as sprays, lotions, dips, dust, and shampoos, with various therapeutic levels. Using flea shampoo in the treatment can help kill nymphs and adults, though it won't eradicate the eggs. Application of anti-parasitic/anti-lice preparation requires repeated doses in 10 – 14 days, because all canine lice nits are usually not killed in a single application.

A veterinarian should prescribe anti-parasitic drugs, and owners should follow the instructions of the veterinarian and before application clearly read the instructions on the label. One over-the-counter option is BioSpot Pyrethrins Dip for Dogs.

In severe infestations, i.e., in case of secondary microbial infections, a veterinarian might prescribe antibiotics as well.

Clearing the environment and surroundings with the help of different anti-parasitic sprays and washing the bedding and belongings of pets is essential in preventing canine lice infestation and transmission. Similarly, the infested dog should be kept separate from others. It's also important to clean and replace grooming tools to prevent reinfestation.

Products such as Frontline Plus will control dog lice as well as other parasites.

Preventive Measures

To keep your dog safe from lice, it's essential totake preventivemeasures. Hereare some tipsto help you preventlice infestations inyour dog:

• Regular Grooming: Brush and bathe your dog regularly to help detect and prevent lice infestations. Use a flea comb to check for lice and their eggs, especially in areas where they are commonly found.
• Pet Hygiene: Keep your dog's living environment clean by washing their bedding and cleaning their living spaces regularly. This can help prevent lice from infesting your dog.
• Avoiding Contact with Infested Animals: Be cautious about your dog's interactions with other animals that may be infested with lice, as lice can spread through direct contact.

Environmental Control

Since lice can survive in the environment for a short period, it's crucial to control the environment to prevent lice infestations:

• Cleaning and Disinfecting: Clean and disinfect your home and any areas your dog frequents. Use specific cleaning agents effective against lice to ensure a thorough clean.
• Laundry: Wash your dog's bedding, collars, and any fabric they have been in contact with regularly. Use hot water and high heat drying cycles to kill any potential lice or eggs.

Recognizing and Managing Recurrence in an Infested Dog

ILice infestations can recur, so a section on this topic would be beneficial:

• Monitoring: Explain how to regularly check the dog for signs of lice after an initial infestation has been treated.
• Follow-up Treatments: Discuss the importance of follow-up treatments as prescribed by a veterinarian to ensure all lice and nits are eradicated.
• Long-Term Strategies: Offer strategies for long-term prevention, including routine veterinary check-ups and maintaining a schedule for preventative treatments.

Myths and Misconceptions

Addressing common myths and misconceptions about dog lice can help pet owners better understand the condition:

• Human Transmission: Clarify whether dog lice can be transmitted to humans or other pets, such as cats.
• Home Remedies: Discuss the effectiveness and safety of home remedies or over-the-counter products that are not specifically designed for dogs.

When to Consult a Veterinarian

Knowing when to seek professional help is crucial for your dog's well-being:

• Severe Infestations: Describe the signs of a severe infestation that would require immediate veterinary attention.
• Treatment Failure: Advise on what to do if the lice do not respond to initial treatments or if the dog has an adverse reaction to any treatments.
• Health Complications: Inform about potential health complications that can arise from lice infestations, such as skin infections or anemia, and the importance of veterinary intervention.

Resources

Merck Veterinary Manual (2023 edition) 

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