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External Dog Parasites: Are They Dangerous? (List of 6 Parasites)

External parasites, as the name implies, parasitize the skin of a host, such as dogs or humans. A dog’s external parasites can often be transmitted to humans. Most parasites can transmit various diseases to their hosts. For these reasons, prevention is crucial.

Dogs are magnets for parasites. Many of these parasites can parasitize the skin of your pet. Few dog owners are aware of the importance of regular application or administration of antiparasitic products.

These treatments are essential for both pet and human health – many external and internal parasites are transmitted from pets to humans and vice versa.

In this article, you will find out about the most important external parasites in dogs and what to look for.

Are External Parasites Dangerous for Dogs?

External parasites such as ticks can endanger your dog’s life. They can transmit diseases that can be fatal to dogs, such as Lyme disease or babesiosis. The rest of the external parasites are not as dangerous, but can still lead to medical complications.

The organisms that can parasitize your dog externally can be split into two categories: mites and insects.

MitesTicks, ear mites, Demodex, and sarcoptic mange (scabies).
InsectsFleas and lice.

Many of these parasites can be transmitted from pets to humans, causing severe illnesses.

Although fleas and scabies are more visible and uncomfortable, they are considered the least dangerous parasites.

You can get rid of fleas relatively easily. They do not stay long on the human body because we wash and change our clothes frequently. It is more difficult to remove them from our homes.

Scabies is very unpleasant but, if treated in time, does not cause major problems for dogs and humans.

Fleas can also transmit internal parasites to dogs which can infect humans. If we do not wash our hands after petting our dog, we can ingest tapeworm eggs. Children are the most at risk if basic hygiene rules are not followed.

The most dangerous external parasites for dogs and humans are ticks. These mites can transmit various diseases, which may require hospitalization. Some of these diseases can be deadly if not treated in time.

Are External Parasites Dangerous for Dogs

Most Common External Dog Parasites


Mites are eight-legged arthropods that are part of two major orders: Acariformes and Parasitiformes. They live on plants, in water, in soil, or on animals.

Mites date back millions of years. Fossils of Parasitiformes were found in amber specimens dating to the Cretaceous (~100 million years ago).[1]

They have various dimensions, from microscopic sizes (0.04 inches) to 0.25 inches[2]. Mites do not jump or fly. They disperse by walking and accessing locations in the immediate vicinity. 

Some mites climb on grass and extend their legs into the air, then cling to a suitable passing host. Others are carried away by the wind.[3]

Parasitic mites use their hosts to spread through to other hosts through direct contact. Some are found permanently on animals. When a host has a low immune system, mites can develop excessively, leading to illness (demodex). Others climb onto the animal to feed, like ticks.

red mite


There are many species of ticks, but only a few parasitize dogs. Ticks can transmit dangerous diseases to pets, which can be fatal if not diagnosed and treated in time.

Ticks mostly parasitize mammals and birds, but they can also be found on bees[4]. They are active from March to October but can be found all year round in warmer regions.

Ticks that parasitize dogs are part of the family Ixodidae. These are hard-bodied ticks[5]. They are vectors for a variety of tick-borne diseases.

There are four harmful species of hard-bodied ticks that can transmit diseases to dogs:

  • Black-Legged Tick (Ixodes spp.) – Lyme disease, babesiosis, bartonellosis, and anaplasmosis
  • Brown dog tick (Rhipicephalus sanguineus) – Rocky Mountain spotted fever and Hepatozoonozis canis
  • Lone star tick (Amblyomma americanum) – Ehrlichiosis
  • American dog tick (Dermacentor variabilis) – Ehrlichiosis

All of these diseases can lead to severe health complications if not diagnosed and treated in time. 

Contact your veterinarian if your dog begins to show certain symptoms after you have removed or noticed a tick on your pet.

Related: What Do Ticks on Dogs Look Like?

What Is a Tick

Tick Infestation Symptoms in Dogs

A dog with ticks may have the following symptoms:

  • Licking and biting at various areas of its body.
  • Itching and scratching.
  • Red and inflamed skin at the feeding site.
  • Pale mucous membranes in massive infestations.

Your dog may start scratching excessively when infected with ticks. The tick can tickle your pet when it walks through its fur to find a place to feed.

Ticks can make a dog yelp when it cuts its skin to insert the feeding tube. Tick saliva acts as an anesthetic, but it can also be irritating, causing local allergic reactions in some dogs.

These external parasites can also be felt with your fingertips when you pet your dog. Make sure you check your dog for ticks after walks.

Fed ticks (engorged) feel like a mole or bump, while unfed ones are flat and feel like skin scabs.

Ear Mites

The most common mites that parasitize pets’ ears are ear mites (Otodectes cynotis). They have a three-week life cycle and feed on oils and earwax located in your dog’s ear canal. They can cause inflammation and irritation in the ear. This is easily cured with proper treatment.

Ear mites are extremely contagious. They can be transmitted not only from dog to dog but between different species of pets (dogs to cats). Puppies are particularly sensitive to ear mites.

These parasites live on the surface of the ear canal. The pathology of this infestation is manifested by the accumulation of a dark brown viscous substance (modified earwax), in moderate or excessive amounts. Ear mites are very tiny and can only be seen under a microscope.

Ear mites can lead to severe skin or ear infections and inflammations if left untreated. Some dogs lose their hearing and balance due to a massive infestation of these mites.

Symptoms of Ear Mites in Dogs

You can tell your dog has ear mites by the way they behave. Symptoms of this parasite manifest in different ways:

  • Excessive scratching, especially around the ear
  • Self-mutilation
  • Head shaking
  • The presence of a dark brown secretion in the ear canal
  • Local inflammation
  • Some dogs may lose their hearing

The presence of ear mites can also be accompanied by a strong, unpleasant smell.

ear mite
Image Source

Demodex Mites

Demodicosis is a disease that occurs as a result of the proliferation of Demodex mites in the skin. They are part of the normal flora of dogs. A low immunity can lead to the multiplication of demodex and infection.

Demodex mites are part of the normal microfauna of skin tissue. They are transmitted from mother to newborn from the earliest days of life.

Demodicosis, also known as red mange, can be both in a juvenile stage (occurs in puppies) or adult stage (occurs in adult dogs).

In Europe, the most affected dog breeds of juvenile demodicosis are Mops, English bulldog, Dobermann pinscher, and terriers[6]. The West Highland white terrier breed mainly develops demodicosis in adulthood.

In addition to a weakened immune system, other risk factors for juvenile demodicosis include:

  • Pyoderma
  • Internal parasitism
  • Poor nutrition
  • Estrus (heat)
  • Debilitating chronic diseases
  • Coccidiosis

In adult demodicosis, the main risk factors are represented by:

  • Chemotherapy
  • Neoplasms
  • Hypothyroidism
  • Hyperadrenocorticism
Demodex Mites
Image Source

Demodicosis Symptoms in Dogs

Demodicosis comes in two forms: localized or generalized.

In the localized form, the most common symptoms are:

  • Hair loss (usually located on the head and forelimbs).
  • Mild erythema and crusts.

In more severe forms, multiple areas of hair loss may be present with a tendency to merge and advance to other regions. In regions with alopecia, lumps or granulomatous tumor-like dermatitis can be observed.

Scratching is generally reduced and is mainly due to bacterial overgrowth.

The generalized form is one of the most severe dermatological problems in dogs, and can lead to the death of your pet. 

This form of demodicosis is manifested in several ways:

  • Erythema
  • Alopecia
  • Crusty skin patches

With the development of a large number of mites inside the hair follicle, the follicle loosens, allowing the penetration of bacteria.

As the disease progresses, severe, exudative, and granulomatous inflammation occurs. Over time the skin becomes blackish and thickened due to persistent irritations.

Scabies (Sarcoptic Mange)

Sarcoptic scabies, caused by the parasite Sarcoptes scabiei var canis, is the most common mange in pets. Females make tunnels in the skin to lay eggs. Sarcoptic mange spreads easily between animals through direct contact.

This highly contagious parasite is found in dogs around the world. Although these mites prefer dogs, humans and other animals that come in contact with an infected dog can also become infected.

The parasite enters the body and digs galleries in the skin layer using its pedipalps and hooked legs. This causes intense itching in the affected area.

Symptoms of Sarcoptic Mange in Dogs

Not all dogs show symptoms when infected with sarcoptic mites. Symptomatic dogs can show severe sudden itching. This itching is caused by sensitivity to mite droppings.

The infested skin will erupt with small, solid swellings that appear after scratching. These swellings often lead to thick, crusty wounds.

Wounds first appear on the abdomen, chest, ears, elbows, and feet. If the disease is not diagnosed and treated in time, the lesions can spread to the rest of the body.

Sarcoptic scabies
Image Source


Fleas are external parasites that feed on blood. They can negatively impact the lives of our pets. They can transmit diseases such as bartonellosis, plague, or tapeworms.

In addition to causing a dog to itch and scratch intensely, fleas can also cause local or generalized allergic reactions. Dogs exposed to repeated and long-lasting flea bites can become allergic to flea saliva.

One in seven dogs is infected with fleas[7]. They multiply rapidly, with a single female laying up to 50 eggs a day (2,000 eggs in a life cycle). Due to the rapid multiplication, fleas can easily infest your home.

What Are Fleas

Symptoms of Fleas on Dogs

Dogs with fleas start to scratch intensely out of nowhere. The itching can greatly affect your dog’s well-being and reduce its quality of life. Sometimes the itching is so severe that neither your dog nor you can sleep.

Red, inflamed areas of skin can appear as a result. You can also notice small red bumps or pimples on your dog’s skin. These are caused by flea bites.

Another sign of fleas on dogs is hair loss, especially on the abdomen, legs, and base of the tail.

Contact your veterinarian if your dog shows any of these symptoms.

About Iulia Mihai (DVM)

Dr. Iulia is a certified veterinarian with more than 10 years of experience in the field. With extensive knowledge of diet, care, and medication, she helps Misfit Animals provide readers with accurate knowledge on technical topics.

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