ARTHROPODS INSECTS
FLEASSUCKING AND CHEWING LICEPHLEBOTOMESMOSQUITOES
Ctenocephalides canis - dog flea Ctenocephalides felis - cat flea Felicola subrostratus Linognathus setosus - canine sucking louse Trichodectes canis - dog chewing louse Phlebotomus spp. Culicidae spp.

Ectoparasites - Insects

FLEAS

Fleas are significant vectors of various infections including pathogens and zoonotic infections. See ESCCAP Guideline 5: Control of Vector-borne diseases in Dogs and Cats. For more information on endoparasite control see ESCCAP Guideline 1: Endoparasites: Worm Control in Dogs and Cats. For further information about dermatophytic fungi see ESCCAP Guideline 2: Superficial Mycoses in Dogs and Cats.

Ctenocephalides canis - dog flea

Distribution:

Common throughout Europe.  More dog related, the predominant species in some countries e.g. Ireland, France and Greece.  Vector for a number of parasites including the small intestine tapeworm Dipylidium caninum as well as Bartonella spp..

Clinical signs:

Infestation is highly variable depending on the frequency of exposure, duration of infestation, presence of secondary infections and the degree of hypersensitivity.  Non–allergic animals may have few clinical signs and allergic animals can show pruritus, alopecia, broken hairs, papules and erythematous macules with crusts.  Moist dermatitis is typically seen in the dorsal lumbar and tail region.  Lesions can extend to thighs and abdomen.  Secondary pyotraumatic dermatitis, pyoderma and seborrhoea are commonly seen.  In chronic cases the skin shows thickening of the dermis with acanthosis, hyperkeratosis and lichenification.  Additionally, in young, old or debilitated animals, heavy infestations will cause anaemia.

Diagnosis:

Low numbers of fleas may remain undetected.  Combing the coat facilitates the collection of flea faeces and collected material can be combed onto damp white tissue where black spots of faeces can be detected surrounded by a red ring of undigested blood.  A combination of the presence of fleas or flea faeces can confirm the diagnosis of flea allergy dermatitis (FAD).  There are a number of allergy tests, with no single test being the gold standard, which may assist.  Diagnosis can be further complicated as FAD–affected dogs are more likely than non-FAD dogs to be atopic or have other allergies (e.g. food allergy).

Ctenocephalides felis - cat flea

Distribution:

Common throughout Europe.  Vector for a number of parasites including the small intestine tapeworm Dipylidium caninum, Bartonella spp. and Acanthocheilonema reconditum.

Clinical signs:

The flea bite gives rise to inflamed skin weals and repeated bites result in flea bite allergy where lesions will arise on the back, ventral abdomen and inner thighs of the cat.  Repeated scratching will produce areas of alopecia or moist dermatitis.  Flea allergy dermatitis (FAD) is one of the most common dermatological conditions, often associated with intense pruritus and reddening of the skin.

Appearance:

The dark brown-black fleas are wingless with females 2.5mm in length and the shorter males 1.0mm long.

Diagnosis:

Raised weals on the skin and by combing the coat “flea dirt” – reddish black faecal pellets will be revealed.  High levels of infestation can lead to anaemia particularly in the young.  Scratching and biting of infected areas by the dog or cat results in FAD where the skin is covered by small brown crusty papules.  Repeated licking, chewing and biting of the flea bite sites leads to hair loss, self-induced trauma and secondary infection.  Other symptoms include restlessness, irritability and weight loss.

SUCKING AND CHEWING LICE

Lice are dorso-ventrally flattened wingless insects. They cause direct damage to the skin of affected animals and sucking lice can cause anaemia. The dog chewing louse Trichodectes canis, can also act as an intermediate host for the tapeworm Dipylidium caninum. Lice are highly host-specific with two main species on dogs Trichodectes canis and Linognathus setosus, and only one species Felicola subrostratus on cats. The entire life cycle is spent on the host. Adult chewing and sucking lice lay individual eggs, called nits, and cement these to hair shafts. The entire life cycle takes approximately 4 - 6 weeks.

Felicola subrostratus

Distribution:

All over Europe but rare, more common in stray cats.  The only species of louse that commonly occurs on cats.

Clinical signs:

Infestations found on the skin, face, pinnae and back resulting in a dull ruffled coat with scaling, crust and alopecia.

Diagnosis:

These lice are coloured beige or yellow with brown bands.  Adults are 1–1.5mm in length.  Eggs are laid on the fur and hatch in 10-12 days with adult stage reached in 2–3 weeks.  Diagnosis from lice or eggs (nits).

Linognathus setosus - canine sucking louse

Distribution:

All over Europe rare except in Scandinavia where it is the predominant ectoparasite with chewing lice.

Clinical signs:

Skin lesions such as excoriation, military dermatitis or urticaria-like lesions and even necrotic skin lesions have been described.  May cause anaemia in heavy infestation.

Diagnosis:

Primarily found in the head and neck areas and commonly under the collar.  Long eared dog breeds such as spaniel, basset and Afghan hounds are particularly susceptible.

Trichodectes canis - dog chewing louse

Distribution:

Sporadic over most of Europe except Scandinavia where lice are the predominant ectoparasite.

Clinical signs:

A harmful ectoparasite of dogs particularly in puppies and old or debilitated dogs.  Intense pruritus, scratching, biting, sleeplessness, nervousness and a matted coat are typical of T. canis infestation.  Damage to the skin from scratching can result in inflammation, excoriation, alopecia and secondary bacterial involvement.

Diagnosis:

Commonly found on the head, neck and tail attached to the base of hairs and feeding on tissue debris.  Often congregates around body orifices or wounds seeking moisture.  Diagnosis from lice or eggs (nits).

PHLEBOTOMES

In Europe only sand flies of the genus Phlebotomus are of veterinary importance and are well described in the Mediterranean region. Little is known about the complex biology of the phlebotomes but they are extremely important as vectors of protozoan parasites of the genus Leishmania infantum. L. infantum is transmitted by sand flies and leishmaniosis is a serious disease of dogs which are the main reservoir hosts. Leishmania infantum also affects humans and is a public health hazard for children and immunodeficient adults in particular. Refer to ESCCAP Guideline 5: Control of Vector-borne Diseases in Dogs and Cats.

Phlebotomus spp.

Distribution:

Phlebotomes are widely distributed in the Mediterranean area preferring semi-arid and savannah regions.  Distribution tends to be patchy.

Clinical signs:

The bites from these flies are painful, give rise to weals.  Preferred areas where biting occurs are the ears, eyelids, nose, feet and tail.

Diagnosis:

Unlikely to be seen as they are very small.  Crepescular, around evening and dawn females feed on host blood.

Culicidae spp.

Distribution:

There are more than 3,500 species worldwide and whilst a nuisance for animals and humans they are of great significance as vectors of several important pathogenic organisms.  Parasites transmitted by mosquitoes include Dirofilaris immitis, Dirofilaria repens and Acanthocheilonema spp..   Refer to ESCCAP Guideline 5: Control of Vector-borne Diseases in dogs and cats.