External Dog Parasites: Fleas, Ticks, Lice, Mites

External parasites live on the outside of a dog’s body. According to the American Veterinary Medical Association (AVMA), many pets experience discomfort caused by external parasites, such as fleas, ticks, or mites, on their skin or in their ears at some point in their lives.

Local parasite threats may not be the same today as they were historically, making both internal and external parasite prevention even more important, cautions Dr. Heather Stockton Walden, president of the American Association of Veterinary Parasitologists and associate professor of parasitology at the University of Florida College of Veterinary Medicine. The national and global movement of people and their pets is one factor that helps facilitate the spread of canine parasitic disease. Other factors include urbanization and changes in climate and suitable host populations.

“Yearly prevention and annual visits with your veterinarian are the best safeguards for our pets,” Dr. Walden advises. “Since our pets can be sentinels for human disease, especially tick-borne disease, annual testing and prevention are essential.”

Fleas

Fleas are tiny wingless insects that feed on mammals, including dogs. They thrive in warm, moist weather and may be seasonal or active all year, depending on the region of the country. Fleabites make some dogs so miserable that they bite and scratch themselves raw. Fleas may cause young dogs to become anemic. Dogs can also become infected with tapeworm by swallowing fleas carrying tapeworm eggs.

Additionally, many dogs can develop an allergy to flea saliva, causing them to itch and scratch, often leading to a severe dermatitis. Even the bite of only one flea can trigger such a reaction.

Diagnosis

You may be able to see the dark fleas scurrying around on your dog’s skin. Their favorite spots include the base of the ears and the rump. Look closely in sparsely haired places, like the groin.

Another way to diagnose fleas is to part the fur and look for black specks the size of poppy seeds. These specks are flea feces, composed of digested blood. If you’re unsure whether you’re looking at “flea dirt” or just plain dirt, place some on a damp piece of white tissue. After a minute or so, a small red spot or halo will become apparent if it’s flea feces, since the blood rehydrates and diffuses into the tissue.

Transmission and Human Risk

Adult fleas are sensitive to body heat, breathing, and movement and will readily jump from one dog to another pet in your home. They breed and lay eggs in animal fur, pet bedding, carpet, and drapes. While flea season can vary from year to year, the Companion Animal Parasite Council (CAPC) produces a daily forecast of flea activity in the U.S.

Fleas prefer your pets but can also jump on humans, especially children who are closer to the ground where fleas lay eggs. In most cases, the bites only cause temporary itching. However, people may also swallow a flea carrying tapeworm eggs. Fleas feed on animal waste and may carry germs into open wounds.

Treatment and Prevention

Your best bet is to protect your dog from becoming infested with fleas in the first place by using a preventative product your veterinarian recommends. If you see evidence of fleas on your dog, it’s essential to get rid of them as quickly as possible, before the population grows.

Some additional methods to prevent a flea infestation include:

• Regularly washing bedding, rugs, and pet bedding
• Vacuuming floors and rugs, and empty vacuum bags outside
• Mowing your lawn frequently and don’t over-water — fleas thrive in moist environments
• Place garbage in sealed containers to keep rodents and wild animals away

Ticks

Ticks can cause a number of serious illnesses, as well as canine tick-borne diseases, including Lyme disease, Ehrlichiosis, and Rocky Mountain Spotted Fever. There are more than 800 species of ticks worldwide, and they all feed on the blood of mammals, birds, and reptiles. Ticks go through four life stages, which can take up to three years to complete. Once the eggs hatch, they must eat blood to survive.

Diagnosis

Ticks thrive in warm weather but can live year-round. Therefore, it’s a good idea to check your dog for ticks daily. They may be found anywhere on the body, especially around the neck, ears, muzzle, where legs meet the body, and between the toes. If your dog has a thick and/or dark coat, it may be easier to feel a tick than see one.

Transmission and Human Risk

Female ticks lay thousands of eggs in grass and bushes, and once they hatch, they wait for a warm-blooded host to walk by, crawl on, and attach. Ticks attached to the dog’s (or human’s) body will suck blood and can efficiently transmit any disease they’re carrying. Disease isn’t spread between dogs and humans; a direct bite from a tick is the only way to become infected.

The Kansas State Veterinary Diagnostic Laboratory reports that thousands of dogs and humans are infected with tick-borne diseases annually. That rate is climbing due to the increasing range of the various tick species, the encroachment of wildlife species into the traditional urban environments, and an increase in pet travel.

Treatment and Prevention

The CAPC reports that tick-borne diseases are advancing and recommends year-round use of products that kill and/or repel ticks.

Check your dog for ticks daily after they time outside, and whenever you see a tick, take it off immediately. The best way is to numb the tick with rubbing alcohol or petroleum jelly and pull it off with fine-point tweezers. Pull slowly and steadily out, and don’t twist the tick out as it may tear off the head. Also, never try removing a tick with your bare hands, as you could be at risk of infection from the tick’s blood entering any tiny cuts in your skin.

Lice

Lice are wingless insects the size of fleas that latch onto dogs and include canine sucking lice and canine chewing lice.

Diagnosis

An affected dog will scratch, bite, and rub the infested area of the body. Severe infestations may cause a matted, rough, or dry coat and hair loss, called alopecia, and anemia. One type of lice, Trichodectis canis, may also carry a tapeworm. If you part the hair on the dog, you may be able to see lice or eggs.

Transmission and Human Risk

Transmission can occur through direct contact with an infected dog or if the dog is groomed with equipment contaminated with eggs. The CAPC says lice are most prevalent in very old and debilitated dogs, dogs with compromised immune systems, and very young dogs. Dogs who aren’t treated with flea and tick preventatives are more susceptible to lice infestations.

The good news is that dog lice aren’t attracted to humans. Dog lice and human lice are different species. While dog lice may occasionally bite humans, humans won’t get an infestation as a result.

Treatment and Prevention

Lice eggs, called nits, are transparent, attach to the dog’s hair close to the skin, and can’t be dislodged with an ordinary shampoo. Your veterinarian will recommend a medicated shampoo or topical treatments to kill the lice.

Eggs continue to hatch for several weeks, so you should treat an infected dog again at a later time. You should also treat other dogs in the household, and wash any collars, brushes, combs, and bedding in hot, soapy water. Prevent lice infestations by using recommended flea and tick preventatives year-round.

Mites

Mites inhabit several areas of the dog, and the problems they cause are generally known as mange. There are two primary forms of mange in dogs: demodectic and sarcoptic, also known as scabies. Demodectic mange causes hair loss around the forehead, eyes, muzzle, and forepaws.

Diagnosis

The veterinarian may identify demodectic mange in a skin scrape taken from irritated areas of the dog’s skin. These mites appear as redness and scaly skin around the mouth and eyes, and are unlikely to be itchy. There may also be localized alopecia.

Transmission and Human Risk

These microscopic mites aren’t highly contagious, although mother dogs can pass them to puppies when they nurse. They haven’t been found to affect people. When an adult dog develops demodectic mange, the dog often has another medical condition compromising the immune system.

Treatment and Prevention

Many cases clear up on their own and don’t cause much itching, though some dogs may need special shampoos or oral medications. The CAPC reports that demodicosis has been considered a genetic predisposition, and some veterinarians discourage breeding affected animals. However, the hereditability of this type of infection is unclear.

Otodectes

Also known as ear mites, these are common in young dogs. Their entire life cycle, from egg to larvae to adult stages, occurs in the ear canal.

Diagnosis

Your dog may have mites if they shake their head and scratch their ears. You may also see a thick brown discharge. Excessive scratching can result in sores or broken blood vessels. A veterinarian can use an otoscope or a swab taken from a dog’s ear canal to see the mites moving around. These mites can also sometimes be found on the dog’s head or body.

Transmission and Human Risk

Ear mites are contagious and can travel from the ears of an infested dog to other dogs close by. It’s rare for people to be infested, but it has happened through close contact.

Treatment and Prevention

Your vet will treat your dog with medication, usually in the form of ear drops, and ear cleaning. All dogs and cats in the household should receive treatment. Cleaning your dog’s ears regularly can help prevent ear mites and allow you to spot them early.

Scabies or Sarcoptic Mange

This condition occurs when microscopic mites, which thrive in cool and tropical environments, burrow into a dog’s skin and cause intense itching. Scabies usually affects the ears, elbows, legs, and face. Hair loss, skin rash, and scabs are common. Dogs with long-term mange may develop seborrhea or oily dandruff, skin thickening, and open sores.

Diagnosis

The mites don’t always show up in skin scrapings. Scratching often causes visible crusty sores that can result in yeast or bacterial infections.

Transmission and Human Risk

Mites jump to other hosts through direct contact. Sarcoptic mange is highly contagious, and although it prefers dogs, wolves, coyotes, and foxes, it can also affect humans.

Treatment and Prevention

Veterinarians will prescribe medications to kill the mites, relieve itching, and heal the skin. Careful cleaning of the dog’s bedding and environment is also critical. Owners should treat all animals in the household and keep infected dogs separate from other animals.

Nasal Mites

These mites live on the dog’s mucous in the nasal passages and sinuses.

Diagnosis

Infested dogs may not show any symptoms, or they may shake their heads, cough, reverse sneeze, or have nasal discharge. The condition can also interfere with their sense of smell. The veterinarian will look for mites in mucus from the nose.

Transmission and Human Risk

This type of mite has only been found in dogs. Dogs can easily transmit nasal mites to other dogs through direct contact.

Treatment and Prevention

The veterinarian may prescribe an oral anti-parasite medication. The only known prevention is to keep any infested dog isolated from other dogs.

Cheyletiella Mites

Also known as hair-clasping mites, these cause “walking dandruff” on a dog’s head, back, and neck. They thrive on a dog’s skin, eating dead cells that protect the lower layers of the skin.

Diagnosis

The “dandruff” is visible on the dog, but dandruff also has many other causes. Veterinarians may take a skin scrape to examine the mites under a microscope. The CAPC says these mites can cause false positive results when dogs are tested for allergy to dust mites and suggests veterinarians rule out Cheyletiella spp. infestations before beginning allergy sensitization treatments.

Transmission and Human Risk

Although these mites are uncommon, they’re highly contagious because they’re very mobile and can spread to other dogs, cats, and humans, causing itchy red spots.

Treatment and Prevention

Dogs are treated by clipping long hair, using topical insecticides, and repeatedly giving medicated baths. Pet owners must treat all animals in the household, and wash all their bedding in hot water and detergent. Cleaning the house with products meant to eradicate fleas will eliminate an infestation. Prevention involves keeping your dog on a flea and tick preventative recommended by your veterinarian.

Frequently Asked Questions