Parasites are organisms capable of colonizing a host and feeding at its expense. In the specific case of dogs, there are multiple parasitic agents capable of causing disease. The symptoms associated with the presence of parasites in dogs are highly variable and depend mainly on the affected organs and tissues.
Types of parasites in dogs
There is a wide variety of parasites capable of infecting or infesting dogs. The classification of these parasitic agents can be made based on numerous criteria, although the most common is to classify them into two groups based on the location they occupy in the host:
- Ectoparasites or external parasites: they are found outside the body, that is, on the skin and hair of dogs.
- Endoparasites or internal parasites: they are found inside the body, parasitizing both body cavities and different organs and tissues.
Next, we are going to talk more in depth about the most frequent ectoparasites and endoparasites in the canine species.
Types of external parasites in dogs
Ectoparasites include a wide variety of parasitic arthropods belonging to:
- The subclass Acari: This subclass includes ticks and mites.
- The class Insecta: this class includes fleas, lice, sandflies, mosquitoes and flies.
The importance of ectoparasites in dogs lies in the following points:
- Cause skin lesions.
- They can produce a pathological immune response, as occurs in allergic dermatitis to flea bites.
- They can act as vectors of different diseases, since they are capable of transmitting other pathogenic agents by stinging or biting their host.
- They can be zoonotic, that is, they can be transmitted to people.
Types of internal parasites in dogs
Endoparasites that affect dogs can be classified into two large 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: they are multicellular organisms that can generally be seen with the naked eye in their adult state.
Within the helminths, there are two well-differentiated groups:
- Roundworms: known as nematodes (such as Toxocara, Toxascaris, Ancylostoma, Uncinaria, Strongyloides, Trichuris, Dirofilaria and Thelazia)
- Worms or flatworms: include the cestodes (such as Taenia and Echinococcus) and the trematodes (such as Opisthorchis, Alaria alata and Paragonimus). Currently, flukes are very rare in dogs.
Also, internal parasites are important because:
- They can cause different diseases depending on the organ or organs they affect.
- They can induce a pathological immune response, such as in some cases of heartworm disease.
- They can be zoonotic, that is, they can be transmitted to people.
What is the difference between infection and infestation?
Now that we know the different types of parasites that are most common in dogs, it is worth clarifying when to speak of “infection” and when of “infestation”.
Although there are different opinions, the most commonly used criteria are:
- Talk about infection for internal parasites and infestation for external parasites.
- Or, talk about infection only for microscopic parasites (ie protozoa) and infestation for all others.
Symptoms of parasites in dogs
How to know if a dog has parasites? Each parasitic species has a different biological cycle that involves the infection of different organs and, in some cases, migration through various body tissues. Therefore, parasitic diseases can be accompanied by very diverse clinical signs, depending on the body tissues that are affected.
To detect a parasitic disease it is essential to know what the symptoms of a dog with parasites are. The most common clinical signs that are usually observed in parasitized dogs are:
- Digestive signs: diarrhea, vomiting, anorexia, bloating (accumulation of gas in the intestine), etc.
- Cardio-respiratory signs: cough, dyspnea, fatigue, exercise intolerance.
- Dermatological signs: itching, alopecia, scaling, erythema (redness), papules, pustules, scabs, etc.
- Weight loss or stunted growth.
- Dehydration.
- Anemia.
- Fever.
- Neurological disorders.
At this point, it is important to mention that not all parasitic infections are accompanied by symptoms, but sometimes dogs can remain asymptomaticThis is the case, for example, of giardiasis, in which adults can become asymptomatic carriers that are a source of infection for younger animals. Do not miss this other article on Parasites in puppies.
How are parasites spread in dogs?
The routes of transmission of parasites in dogs can be classified into two large groups:
- Direct transmission: by direct contact between infected animals, through the oro-faecal route (when the feces of infected animals contaminate the environment and water), by ingestion of infected tissues (especially from ruminants and rodents), by lactogenic or transplacental route.
- Indirect transmission: via vectors such as ticks, sandflies, and mosquitoes.
For a parasitic infection to occur, dogs must come into contact with the infective form of a parasite In addition, there is a series of predisposing factors that favor the establishment of a parasitic infection. Some of the most important risk factors in the canine species are:
- Age: young animals are more prone to parasites due to their immune immaturity.
- Hygiene-sanitary deficiencies: Environments with excess humidity and poor cleaning and ventilation favor the survival of parasites in the medium.
- Overcrowding: communities (shelters, residences, hatcheries, rehalas, etc.) poorly managed and with little sanitary control favor transmission of this type of disease.
- Stress and malnutrition: both factors cause immunosuppression, which means that dogs that are malnourished or continuously subjected to a stressful environment are more predisposed to parasitic infections.
- Hunting Habits: meat and offal, especially from ruminants and rodents, can be a source of infection for hunting dogs or with hunting instinct.
- Farm Animals: Sheepdogs are more prone to these infections due to possible contact with grass contaminated by livestock.
- Raw meat consumption: Diets based on the consumption of raw meat and organ meats pose a variety of he alth risks, including transmission of parasitic diseases.
Do parasites in dogs spread to humans?
As we have already mentioned, there are some parasites capable of being transmitted from dogs to people. Some examples are Giardia, Cryptosporidium, Echinococcus, Toxocara (produces larva migrans), and Leishmania.
Parasitic zoonoses can affect anyone, although there are certain population groups that are particularly sensitive, such as:
- Kids.
- Immunocompromised people.
- Dog handlers.
- People whose work activity is carried out with dogs.
To prevent these parasitic zoonoses, it is essential to know how parasites are transmitted from dogs to people. Contagion usually occurs:
- By direct contact with parasitized animals.
- By consumption of contaminated water or food from infected animals (oral-faecal route).
- Vectorial: a vector (such as a tick or mosquito) can transmit the infection from a parasitized dog to a susceptible person.
How to detect parasites in dogs?
Based on the symptoms and the epidemiological situation of each animal, it is possible to establish a list of differential diagnoses. However, to reach the definitive etiological diagnosis, it is necessary to carry out complementary tests:
- Skin scrapings and trichograms: for the diagnosis of external parasites.
- Coprological analysis: using smears, flotation techniques or sedimentation techniques, which allow the detection of parasitic forms in dog feces.
- Other laboratory tests: such as immunodiagnosis (ELISA, immunofluorescence, etc.) and molecular diagnosis (PCR).
How to eliminate parasites in dogs? - Treatment
Of course, parasitic diseases in dogs should be treated with antiparasitic drugs Therapeutic treatment should always be prescribed by a professional veterinarian depending on the parasitic species responsible for the infection. Currently, there is a wide variety of medications for parasites in dogs, which can be administered by different routes (oral, parenteral, topical, otic, ophthalmic, etc.).
The etiological treatment can be complemented with a supportive therapy when necessary, in order to alleviate the symptoms and avoid complications. This supportive therapy may include:
- Fluidotherapy.
- Dietary management.
- Transfusions.
- Anti-inflammatory drugs, etc.
In addition, it is important to mention that some parasites favor the appearance of secondary bacterial infections, such as hookworm or demodicosis. In these cases, it is important to establish a complementary antibiotic treatment.
How to avoid parasites in dogs?
In the previous section we talked about the therapeutic treatment (ie curative) of parasitic infections. However, antiparasitic drugs can also be used as prophylactic or preventative treatmentIt is worth mentioning that the prophylactic treatment against canine parasites may vary depending on the epidemiological situation of the region in which the animal lives and the individual risks of each individual (for example, risks associated with hunting or diet based on of raw meat). For this reason, prophylactic deworming of dogs must be adapted to each animal and must always be prescribed by a veterinary professional
In general, the prevention of parasites in dogs should include:
- Protection against external parasites: through antiparasitic collars, pipettes, antiparasitic baths, sprays, etc.
- Protection against internal parasites: through drugs generally administered orally. There are some oral drugs that are effective in preventing both internal and external parasites.
Don't miss this other article in which we detail How to deworm a dog. In addition to pharmacological prophylaxis, it is important to prevent parasitic infections through correct management of the dog's environment and habits:
- Keep the dog's environment clean and dry.
- Always supply drinking water.
- Supply safe food: cooked or previously frozen (at -20ºC, at least 4 days).
- Avoid hunting habits and contact with dead animals.
Now that you know what parasites are like in dogs, how to treat and prevent them, establish an adequate deworming schedule and keep your dog free of them.
