Parasitic diseases

Parasites in Dogs - Types, Symptoms and Treatments

Josie F. Turner
By Josie F. Turner, Journalist specialized in Animal Welfare. July 26, 2022
Parasites in Dogs - Types, Symptoms and Treatments

See files for Dogs

Parasites are organisms that are able to colonize a host and feed at its expense. In the specific case of dogs, there are several parasitic agents that can cause disease. The symptoms associated with the presence of parasites in dogs vary greatly and depend mainly on the organs and tissues affected.

If you want to know more about parasites in dogs, do not miss the following AnimalWised article, where we talk about the types, symptoms and treatments of parasite in dogs.

  1. Types of parasites in dogs
  2. What is the difference between infection and infestation?
  3. Symptoms of parasites in dogs
  4. How are parasites spread in dogs?
  5. Are parasites in dogs contagious to humans?
  6. How are parasites transmitted in dogs?
  7. How to get rid of parasites in dogs?
  8. How to avoid parasites in dogs?

Types of parasites in dogs

There are a variety of parasites that can infect or infest dogs. Classification of these parasitic pathogens can be based on numerous criteria, but the most common method is to divide them into two groups based on the location they occupy in the host:

  • Ectoparasites or external parasites: They are located outside the body, i.e., on the skin and hair of the dogs.

  • Endoparasites or internal parasites: They are located inside the body and parasitize both in body cavities and in various organs and tissues.

Below, we will look in more detail at the most common ectoparasites and endoparasites in dogs.

Types of external parasites in dogs

Ectoparasites include a variety of parasitic arthropods that can be classified into two main groups:

  • The subclass Acari: This subclass includes ticks and mites.
  • The class Insecta: This class includes fleas, lice, sand flies, mosquitoes, and flies.

Types of internal parasites in dogs

The ectoparasites that infest dogs can be divided into two major groups:

  • Protozoa: these are microscopic single-celled organisms. This group includes flagellates (such as Giardia) and coccidia (such as Cystoisospora, Cryptosporidium, Neospora, Hammondia, Sarcocystis and Babesia).

  • Helminths: These are multicellular organisms that are usually visible to the naked eye in the adult state.

Within the helminths, there are also two well-distinguished groups:

  • Roundworms: known as nematodes (such as Toxocara, Toxascaris, Ancylostoma, Uncinaria, Strongyloides, Trichuris, Dirofilaria and Thelazia).

  • Worms or tapeworms: these include cestodes (such as Taenia and Echinococcus) and trematodes (such as Opistorchis, Alaria alata, and Paragonimus). Currently, trematodoses are very rare in dogs.

In this other article you will learn more about internal parasites, especially intestinal parasites in dogs.

What is the difference between infection and infestation?

Having learned about the different types of parasites most commonly found in dogs, it is important to clarify the difference between "infection" and "infestation".

In medicine, the term infestation is often used only for external ectoparasitic infestations, whereas the term infection refers to internal endoparasitic diseases.

Symptoms of parasites in dogs

Each species of parasite has a different biological cycle that involves infection of different organs and, in some cases, migration through different body tissues. Therefore, parasitic diseases can have very different clinical signs depending on which body tissues are affected.

If a dog has parasites, it is important to know what symptoms to look for. The most common clinical signs observed in parasitized dogs are:

  • Digestive signs: Diarrhea, vomiting, loss of appetite, bloating.
  • Cardio-respiratory signs: Cough, dyspnea, fatigue, exercise intolerance.
  • Dermatological signs: Itching, alopecia, scaling, erythema, pustules, scabs, etc.
  • Neurological changes: Circling, disorientation, pressing of the head, inability to use one or more limbs, sensitivity to touch and/or behavioral changes, seizures, and sudden or unexplained weakness and/or stumbling.
  • Other changes in the physical appearance: Weight loss and growth retardation.

At this point, it is critical to point out that not all parasite infections are accompanied by symptoms, but that dogs can sometimes remain asymptomatic. This is the case, for example, with giardiasis, in which adult animals can become asymptomatic carriers that are a source of infection for younger animals. Do not miss this other article about parasites in puppies to know more about this kind of parasite.

How are parasites spread in dogs?

The modes of transmission of parasites in dogs can be divided into two major groups:

  • Direct transmission: by direct contact between infected animals, by the fecal-oral route (when feces from infected animals contaminate the environment and water), by ingestion of infected tissues (especially from ruminants and rodents), by the lactogenic or transplacental route.

  • Indirect transmission: by vectors, such as ticks, sandflies and mosquitoes.

For parasitic infection to occur, dogs must necessarily come into contact with the infectious form of a parasite. In addition, there are a number of predisposing factors that favor the development of a parasitic infection. Some of the most important risk factors in dogs are:

  • Age: Young animals are more susceptible to parasites due to their immunological immaturity.

  • Hygiene deficiencies: environments with excessive humidity and poor cleaning and ventilation favor the survival of parasites in the environment.

  • Overcrowding: Communities (shelters, homes, farms, rehabs, etc.) that are poorly managed and where there is little hygiene control are conducive to transmission of this type of disease.

  • Stress and malnutrition: Both factors lead to immunosuppression, so dogs that are malnourished or constantly exposed to a stressful environment are more susceptible to parasitic infections.

  • Hunting habits: Meat and offal, especially from ruminants and rodents, can be a source of infection for hunting dogs.

  • Farm animals: Herding dogs are more susceptible to these infections because of possible contact with grass contaminated by farm animals.

  • Consumption of raw meat: A diet based on the consumption of raw meat and organs poses several health risks, including the transmission of parasitic diseases.

You might also be interested in this other article, where we talk about the most common blood parasites in dogs and how to prevent them.

Are parasites in dogs contagious to humans?

As we mentioned earlier, there are some parasites that are zoonotic. This means that they can be transmitted from dogs to humans. The most common are: Giardia, Cryptosporidium, Echinococcus, Toxocara and Leishmania.

Parasitic zoonoses can affect anyone, although there are certain populations that are particularly susceptible, such as:

  • Children
  • Immunocompromised people
  • Dog sitters
  • People who are professionally involved with dogs

To prevent these parasitic zoonoses, it is important to know how parasites are transmitted from dogs to people. Infection usually occurs:

  • By direct contact with parasitized animals.
  • By consumption of contaminated water or food from infected animals (oral-fecal route).
  • By another animal, such as a mosquito, which can transmit the infection from a parasitized dog to a susceptible person.

If you want to know more about zoonotic diseases, read this other article, where we cover the most common zoonotic diseases in dogs and how to prevent them.

How are parasites transmitted in dogs?

There are several differential diagnoses that can be made for each animal based on its symptoms and epidemiological situation. The most common methods of diagnosing parasites in dogs are:

  • Skin scrapings and trichograms: to diagnose external parasites.

  • Coprological analysis: by means of swabs, flotation or sedimentation techniques, which allow the detection of parasitic forms in the feces of dogs.

  • Other laboratory tests: such as immunodiagnosis (ELISA, immunofluorescence, etc.) and molecular diagnosis (PCR).

How to get rid of parasites in dogs?

Of course, parasitic diseases in dogs should be treated with antiparasitic drugs. Treatment should always be prescribed by a veterinarian, depending on the parasite species responsible for the infection. Currently, there are a variety of drugs against parasites in dogs, which can be administered by different routes (oral, parenteral, topical, otic, ophthalmic, etc.).

Etiologic treatment may be supplemented with supportive therapy as needed to alleviate symptoms and prevent complications. This supportive therapy may include:

  • Fluid therapy
  • Dietary treatment
  • Transfusions
  • Anti-inflammatory drugs

In addition, it is important to mention that some parasites favor the occurrence of secondary bacterial infections, such as hookworm or demodicosis. In these cases, it is important to perform a complementary antibiotic treatment.

Some intestinal parasites can also be treated with home remedies, however, you should always discuss this with your veterinarian and do not perform these treatments without professional supervision.

How to avoid parasites in dogs?

Antiparasitics can be used as prophylactic or preventive treatment. It is important to note that antiparasitics against parasites in dogs may vary due to the epidemiological situation in the region and the individual risks (e.g., hunting or consumption of raw meat) associated with each animal. For this reason, prophylactic deworming of dogs must be adapted to each animal and always prescribed by a veterinarian.

In general, prevention of parasites in dogs should include the following:

  • Protection against external parasites: through antiparasitic collars, pipettes, antiparasitic baths, sprays, etc.
  • Protection against internal parasites: through medications, usually administered orally. There are some medications for oral administration that are effective against both internal and external parasites.

In addition to pharmacological prophylaxis, it is important to prevent parasite infections through proper management of the dog's environment and habits:

  • Keep the dog's environment clean and dry.
  • Always provide fresh drinking water.
  • Provide safe food: cooked or previously frozen.
  • Avoid hunting habits and contact with dead animals.

Do not miss this other article where we describe in detail how to deworm a dog.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to Parasites in Dogs - Types, Symptoms and Treatments, we recommend you visit our Parasitic diseases category.

  • European Council for the Control of Parasitosis in Companion Animals. (2013). Control of intestinal protozoa in dogs and cats. ESCCAP guide nº6. Available at:
  • European Council for the Control of Parasitosis in Companion Animals. (2018) . Control of ectoparasites in dogs and cats . ESCAAP Guide nº3, Second edition. Available at:
  • European Council for the Control of Parasitosis in Companion Animals. (2021). Vermes control in dogs and cats. ESCCAP, Guide nº 01, Sixth edition. Available at:
Write a comment
Add an image
Click to attach a photo related to your comment
What did you think of this article?
Parasites in Dogs - Types, Symptoms and Treatments