ectoparasites in dogsEctoparasites in dogs

Ectoparasites, also known as external parasites, encompass a diverse array of parasitic arthropods.

Taxonomically, they belong to the sub-class Acari, which includes ticks and mites, and to the class Insecta, comprising fleas, chewing and sucking lice, mosquitoes, flies, and phlebotomes (sand flies).


Fleas (Siphonaptera) are blood-sucking insects that are wingless, laterally flattened, and commonly found on mammals and birds.

The adult stages exclusively reside on the host, while the eggs and immature stages, comprising the majority of the flea population in an infested environment, are found in the surroundings.

Fleas are prevalent parasites among cats, dogs, and other small mammals in multi-pet households as companion animals. Additionally, fleas can serve as vectors for various pathogens.


Ticks infesting dogs and cats are classified under the family Ixodidae, specifically categorized as hard ticks. Female hard ticks undergo a substantial increase in weight, up to 120 times, as they engorge with blood before laying eggs.

When fully engorged, a female tick, such as Ixodes, can measure approximately one centimeter in length, resembling a small bean.

Ticks are pervasive across nearly all of Europe, with numerous species exhibiting diverse biology and geographical distribution. Among them, Ixodes ricinus is widely spread, except in northern Scandinavia.


Sucking and chewing lice are insects that are flattened dorso-ventrally and wingless. They directly damage the skin of affected animals, and sucking lice have the potential to cause anaemia. The dog chewing louse, Trichodectes canis, also serves as an intermediate host for the tapeworm Dipylidum caninum.

In Europe, the lice of significance on dogs and cats fall under the suborders Anoplura (sucking lice) and Ischnocera, a subgroup of chewing lice formerly classified as Mallophaga.

Lice exhibit high host specificity, with two primary species on dogs being Trichodectes canis and Linognathus setosus. Chewing and biting lice are not zoonotic. Their feeding mechanisms vary by species: chewing lice feed on skin debris, while sucking lice, except for L. setosus with its elongated head, possess piercing mouthparts to feed on blood. The other species found on dogs and cats are chewing lice, characterized by typical broad heads.

Sand Flies / Phlebotomes

In Europe, only sand flies belonging to the genus Phlebotomus hold veterinary significance, particularly well-documented in the Mediterranean region.

The intricate biology of phlebotomines remains largely unknown, but their critical role as vectors for protozoan parasites, specifically of the genus Leishmania, is well-established. Leishmania infantum, transmitted by sand flies, poses a significant threat as it causes leishmaniosis, a severe disease in dogs that serve as the primary reservoir hosts for this parasite in Europe.

Notably, Leishmania infantum can also affect humans, presenting a public health concern, especially for children and immunodeficient adults.

To mitigate the risk of canine leishmaniosis in endemic areas, preventive measures against phlebotomine sand fly bites are recommended. These include minimizing dog exposure to sand flies, such as avoiding bringing pets to leishmaniosis-endemic regions altogether. If that is not possible, keeping animals indoors after dusk in these areas is advisable.

Furthermore, the use of insecticides with repellent properties against phlebotomines is recommended. Regular application of these compounds throughout the risk season has proven effective in significantly reducing the risk of dogs acquiring L. infantum infections. The complete development of sand flies takes approximately 6–8 weeks during the summer.

Mosquitoes (Culicidae)

Globally, there are over 3,500 identified mosquito species. Although primarily a nuisance for both animals and humans, mosquitoes play a crucial role as vectors for various significant pathogenic organisms.


Demodectic Mange Mites

Canine demodicosis primarily results from Demodex canis, commonly known as the follicle mite. Female mites measure up to 0.3 mm in length, while males reach up to 0.25 mm.

In the realm of canine skin fauna, Demodex mites are typically present in small numbers on many dogs without evident clinical signs, residing exclusively within hair follicles and, in severe cases, infiltrating sebaceous glands. These mites cannot survive away from their hosts. Newborn puppies typically acquire mites from their mothers through direct contact within the first few days of life, often without displaying clinical signs of infestation.

Female mites lay eggs that mature into eight-legged, slender, cigar-shaped adults within approximately 3–4 weeks. Canine demodicosis, commonly known as demodectic mange and caused by D. canis, is a prevalent skin disease, especially in young dogs. Puppies usually acquire mites through direct skin contact during nursing, leading to initial infestation and lesions on the upper lip, eyelids, nose, forehead, and ears.

Over time, mites may spread across most of the body. Demodex spp. are host-specific mites and do not infest other animal species, including humans, being considered normal commensals. Demodex gatoi is an exception, considered contagious, with increased populations linked to concurrent diseases or immunosuppression.

The immunopathogenesis of demodicosis is not fully understood, and often, an underlying cause is not identified. However, long-term corticosteroid treatment, chemotherapy, and underlying cancer or endocrinopathic diseases have been associated with demodicosis in individual adult animals. Consequently, thorough evaluation for potential underlying causes is recommended in dogs and cats displaying signs of the disease.

While specific immune deficiencies haven’t been identified in affected dogs, some studies suggest that cellular immunity may be compromised in individuals developing demodicosis.

Sarcoptic Mange Mites

The genus Sarcoptes is home to a single species, Sarcoptes scabiei, responsible for causing highly pruritic and contagious sarcoptic mange in a broad array of mammalian hosts. While strains have evolved to be largely host-specific, with occasional infestations in other mammals, this phenomenon accounts for the zoonotic transmission from dogs to their owners. This condition is well-recognized in both human and veterinary medicine, commonly referred to as scabies in humans.

Sarcoptes scabiei (var. canis) specifically causes canine sarcoptic mange. Adult mites feed superficially on the skin, creating small burrows and feeding pockets. After mating, the female mite burrows deeper into the upper layers of the epidermis, feeding on fluid and debris resulting from tissue damage. Within these tunnels and side tunnels, the female lays eggs over several months. The development from egg to the adult stage spans 2–3 weeks.

Transmission to new hosts occurs through direct or indirect contact, primarily by the transfer of larvae from the skin surface. Sarcoptes scabiei var. canis can be highly prevalent in fox populations, particularly in urban areas in the UK or central Europe, where the transmission of mites from foxes to dogs has been observed.

S. scabiei can survive for a few weeks away from hosts, making contaminated bedding or grooming equipment potential sources of infestation. Infestation by host-adapted strains of S. scabiei between different host species typically results in a temporary infestation. Clinical disease in humans after contact with affected dogs is quite common.

Otodectic Mange Mites

Ear mites, scientifically known as Otodectes cynotis, are a source of aural irritation and discomfort in dogs, cats, and ferrets, potentially affecting one or both ears. In rare instances, these mites may induce dermatitis across the animal’s body.

The entire life cycle of these mites transpires on the host, with transfer between animals—such as from dogs to cats or cats to ferrets—likely occurring through close contact. Eggs mature into adults within approximately three weeks. Unlike Sarcoptes or Notoedres mites, Otodectes mites can endure in the environment for several weeks.

Ear mites can manifest in any age group of cats or dogs but are more prevalent in puppies and kittens, with a higher frequency in cats than in dogs. Otodectes cynotis, being surface dwellers, may appear as small, mobile, white spots in the external ear canal. Infestation typically accompanies a brown, waxy discharge.

While some animals, particularly cats, may tolerate ear mites without displaying clinical signs, others may exhibit pruritus, ear scratching, rubbing, and self-inflicted trauma. Erythema in the pinna and ear canal may occur, and secondary bacterial or fungal infections often exacerbate symptoms.

Fur Mites

Cheyletiella spp. mites have the potential to infest dogs, cats, and rabbits. While some individuals may tolerate the infestation well, it can cause irritation and discomfort in others. These mites can also feed on humans, leading to localized dermatitis.

Distinct species infest dogs and cats: Cheyletiella yasguri affects dogs, while Cheyletiella blakei infests cats.

The entire life cycle, from egg to larva, nymph, and adult stages, takes about three weeks on the host. Female mites, however, can survive for up to ten days in the environment. Transfer from host to host occurs readily and rapidly, especially between animals in close contact.

Cheyletiellosis is frequently observed in kennels, and young and weak animals appear to be more susceptible to infestation.

Harvest Mites (Chigger Mites)

Harvest mites are responsible for inducing trombiculosis. Two species contributing to this condition in dogs and cats are Neotrombicula (formerly Trombicula) autumnalis and Straelensia cynotis. Trombicula larvae, which represent the only parasitic stage, can also infest humans.

The adult mites deposit their eggs in decomposing plant matter, and within a few days, these eggs hatch into larvae. Characterized by a distinctive orange color and measuring about 0.2–0.3 mm in length, only the larvae exhibit parasitic behavior. In temperate climates, larvae become active during dry, sunny conditions, typically between July and October, hence the term “harvest mite.”

These larvae climb onto vegetation, awaiting passing hosts. Importantly, there is no transfer from one animal to another. After attaching themselves to hosts, they feed for a period of 5–7 days on enzymatically liquefied tissue, epithelial secretions, or blood. Subsequently, they detach and continue their development as free-living stages on the ground. The life cycle may span 50–70 days or more.

Harvest mites exhibit resilience to adverse climatic conditions, with female mites capable of living for over a year. In regions with a temperate climate, typically, there is one generation per year, while in warmer areas, they may complete more than one cycle annually.

Canine Nasal Mites

The life cycle of Pneumonyssoides (Pneumonyssus) caninum, a infrequently encountered parasite remains incompletely understood. It is hypothesized that these mites are permanent residents of the nasal cavities and paranasal sinuses, particularly the ethmoid region, exclusive to dogs. The adults are visible to the naked eye, with females reaching a length of 1–1.5 mm and a width of 0.6–0.9 mm.

The primary mode of transmission is believed to be through direct contact between dogs, considering the active movements of the larvae that can be observed in the nostrils of affected animals. Although indirect transmission in cages and kennels and via fomites such as bedding cannot be ruled out, as these parasites can endure for up to 20 days away from the host.

Remedies for dogs that can help against some ectoparasites

Andiroba oil against ticks

Margosa extract against parasites

Geraniol tick repellent

Dimeticone tick repellent