External Dog Parasites

External parasites

External parasites are defined as harmful animals on or in the skin such as fleas, lice, mites, ticks, and maggots. These animals usually create a terrible itch, but also bald spots, skin infections and even anemia.


Fleas are the most common parasites in dogs. This 3.5 mm insect feeds on the blood of their host. The two most common are the cat flea (Ctenocephalides felis) and dog flea (Ctenocephalides canis). Cat Fleas are also a risk for dogs.

Flea life cycle
Flea life cycle” by doyourownpestcontrol licensed under CC BY 2.0

Fleas are motile brown, black bugs and they jump on their host to suck blood. Since fleas are good at hiding, you find them mostly in densely hairy parts of your pet. They suck blood up to 20 times the volume of their stomach, and separate it almost immediately, so it is is quite the pest. The droppings look like black grains, and they give a reddish brown stain if they are placed on a wet tissue (undigested blood).

Another fact is that fleas almost never voluntarily leave their host and moreover, fleas multiply rapidly. Female fleas lay more than 100 eggs per day. The eggs fall to the ground and thus contaminate a whole area, and within ten days the larvae hatch. They feed on the excreta of the adult fleas. Larvae are barely observable to the naked eye and also, they hide in warm places on the floor, for example, small cracks and crevices of the parquet. The larva develops 1 to 3 weeks in a cocoon which offers ideal protection. The flea then waits patiently for the next host such as dogs, cats, and humans. The flea can survive up to 140 days in its cocoon. When a new host is walking or lying near the flea, it will adhere to the warm coat.

The most common symptom a flea cause is itching. In particular, on the back, at the flanks, and at the tail base. Your dog may also be allergic to fleas; this is caused by the saliva of the flea, which is injected as the flea sucks blood because of the itching the dog will lick, bite or scratch to try to get some relief which can cause a serious skin problem. Young puppies can have some many fleas that ultimately can cause severe anemia causing them to die.

Finally, humans can also experience the fleas themselves. The bites leave itchy bumps on the skin of our arms and legs. When your dog is infected with fleas, it is necessary to direct your dog to be treated with a product that kills the fleas. In severe cases, the area is treated with a special spray. Good vacuuming is always recommended since 90% of the fleas are not on your dog. Also, remember that fleas can develop in the winter thanks to the central heating. As always, prevention is better than cure. Treat your dog with flea preventative treatment, so fleas do not become a problem.


Ticks are blood-sucking parasites that are waiting for their prey passing into the grass and twigs. After a blood meal, they can grow in size up to 200 times larger. They can cause inflammation or abscesses at the site where they attach and infect people with Lyme disease or borreliosis. This disease is accompanied by fever, loss of appetite, swelling of the lymph nodes and stiff joints.

The life cycle of a dog tick
The life cycle of a dog tick

The dog can also become infected with Lyme disease. However, the susceptibility of infection in dogs is a lot lower than in humans and Lyme disease is essentially quite rare in dogs.  Dogs in forested areas run a higher risk of coming into contact with ticks. They can also be infested with ticks in your yard or the park. Adult ticks are found in woods and tall grass. When passing a warm-blooded animal (dog, cat, sheep, hedgehog, mouse, and human) the tick falls on the hoist and sucks the blood.

They are often found at the front of the animal and are usually female ticks. Females can be identified easily as they are 3x larger than the males. blood parasites can transfer Babesia and Ehrlichia. Babesia is caused by a parasitic organism which the red blood cells and is also transferred to a germ Ehrlichia which monocytes (a type of white blood cell) parasite. Should you take your dog abroad, talk to your vet about what steps you can take. Ticks need about 24 hours to find a suitable location on the body of a hoist to suck blood. It is therefore important that the tick is killed during this period and thus does not get the chance to transmit disease.


unlike fleas, lice on pets are rare, they are white-yellow in color, crawl slowly through the hair and can be seen with the naked eye. Most anti-flea also work against ticks.


mites are so small that they must be identified with a magnifying glass or microscope. Mites live on or in the skin, and every type requires its own approach to kill.

Skin Scabies (Sarcoptes)

These mites burrow deep into the skin. This type is contagious to other dogs and cats, but also for people and gives a large amount of painful itching. It is treatable with washing or by injection.

Ear mites

ear mites are also itchy, causing the dog scratching at the ears or shaking a lot. They are grainy black and white and recognizable with the microscope. Ear mites are treated with ointment over a number of days. The inside of the ear should be cleaned with a damp cotton wool.

Cheyletiella (Cheyletiella Dermatitis)

This mite feeds on dead skin, which gives the image of “rose.” This parasite also causes itching. Their bites look like red bumps that cause itching.

Tiny Mite(demodex)

This form is most common in dogs during the first year of life. There is little or no itching and is difficult to control. They create bald spots on the head, neck or legs and also form spots on the body and inflame the skin.  The treatment consists of giving your dog a bath for 4 to 6 weeks every day with a mite killing shampoo or administering drugs for an extended period.

Harvest mites (Trombicula)

Harvest mites are small orange-red mites which are visible to the naked eye. Harvest mites are especially visible between the toes, on the feet and the ears of the dog. They also create itching and irritation. The treatment consists of washing the dog with an anti-parasitic shampoo, but usually, no treatment is necessary because the mite in the dog disappears.


Maggots prefer skin folds and thick coats, especially if they are covered with diarrhea, urine or wound fluid longhaired dogs are most at risk. The maggots (larvae), which hatch from eggs, eat their way deep under the skin in the flesh and can cause a large wound and poor health. Quick action is essential by keeping the coat clean and cut the hair off.