TICKS

Ixodidae or hard ticks are endemic throughout almost all of Europe, and there are more than 12 different species with varying biology and geographical distribution. Commonly found ticks are Ixodes ricinus, Rhipicephalus sanguineus and Dermacentor reticulatus. The main importance of ticks is their role as vectors of pathogenic agents which cause a range of tick-borne diseases (TBDs). Tick-borne diseases are detailed in ESCCAP Guideline 5: Control of Vector-borne diseases in Dogs and Cats.

Dermacentor reticulatus – marsh tick

Distribution:

Europe – from the Atlantic coast to Kazakhstan.  Vector in dogs for Babesia canis.

Appearance:

Ticks are white with variegated brown splashes.  Adult females are 3.8–4.2 mm unfed and 10 mm when engorged.

Ixodes ricinus

Distribution:

A three-host tick widely distributed in Europe except in northern Scandinavia.

Clinical signs:

Can be found all over the body but the main predilection sites are the non-hairy and thin skinned areas such as the face, ears, axillae, interdigital, inguinal and perineal regions.  Heavy infestations may lead to anaemia.  The tick bite wound may become infected or a micro abscess may develop as a reaction to the mouthparts if the tick is forcibly removed leaving the mouthparts embedded in the skin.  Attached engorged female ticks measuring up to 1 cm long are easily seen.

Diagnosis:

Usually by identifying the tick on the animal.  It is more difficult to detect the small larval and nymphal stages than the males (rarely found in the case of Ixodes) and the engorged adult females.  Females can increase their weight up to 120 times as they engorge with blood prior to egg laying; when fully engorged a female tick can measure around 1 cm long and appears like a small bean hence their being called the "castor bean tick".  There are different names in different countries.

Rhipicephalus sanguineus – brown dog tick, kennel tick

Distribution:

Primarily a tick of southern Europe and warmer climates.  More prevalent during spring and summer but may feed all year round.  In northern European countries R. sanguineus will not normally survive outdoors but may complete its life cycle inside kennels and houses.

Clinical signs:

On dogs the tick is often found in the ears and between the toes.  Immature stages prefer the hair of the neck.

Appearance:

These ticks are yellow, reddish or blackish brown in colour.  Size is highly variable and the engorged females can be 12 mm in length.

DEMODECTIC

The mites of cats and dogs are host specific with few exceptions. The most prevalent significant mange mites are Demodex canis, found in dogs and Demodex cati in cats.

Demodex canis – the follicle mite

Distribution:

Throughout Europe.

Clinical signs:

Slight loss of hair on the face and forelimbs in early infection which may spread over the entire body.  A common feature is the absence of pruritus.  Lesions first appear on the muzzle, face, periorbital region and forelimbs. Demodex spp. are viewed as normal commensals and increased populations are associated with intercurrent disease or immunity.

Diagnosis:

Take deep samples of the skin to confirm the presence of larvae and nymphs.  Various methods including plucking hair, dry scrape or biopsy.  Scrapings can be achieved by taking a fold of skin, applying a drop of liquid paraffin, and scraping until capillary blood appears.

Demodex cati

Distribution:

Throughout Europe.  Rarer as a cause of disease in cats than D. canis is in dogs.

Clinical signs:

Erythema, papules and thickened skin crusts, alopecia.

Diagnosis:

Deep scrapings by taking a fold of skin, applying a drop of liquid paraffin and scraping until capillary blood appears.

SARCOPTIC

The genus Sarcoptes contains a single species Sarcoptes scabiei which gives rise to sarcoptic mange. There are variants i.e. var. canis.

Sarcoptes scabiei var. canis – canine sarcoptic mange mite

Distribution:

In fox and dog populations particularly in urban areas of central Europe, rarely cat.

Clinical signs:

Ears, muzzle, elbows and hocks are predelection sites but in severe infestation lesions may extent over the whole body.  Initial lesions are visible as erythema with papules followed by crust formation and alopecia.  Intense pruritus is characteristic and can lead to self-inflicted traumatic lesions.

Diagnosis:

Intense itching particularly at the ear edge and when rubbed it elicits a scratch reflex in 90% of dogs.  Clinical diagnosis can be confirmed by the examination of several superficial skin scrapings although the sensitivity of this may be as low as 20%.  The diagnostic yield is greatly increased by the application of mineral oil to large areas of affected skin before scraping.  Also can be diagnosed by blood test.

Zoonosis:

Yes but normally self-limiting and different to variant causing scabies in humans.  Very severe form "Norwegian mange".

Notoedres cati – cat notoedric mange closely resembling Sarcoptes

Distribution:

Throughout Europe but sporadic e.g. very rare in UK.

Clinical signs:

Intense pruritus, erythema, skin scaling, greyish yellow crusts.  Loss of hair and scratching leading to excoriation of the skin, inflammation and secondary bacterial infection.

Diagnosis:

Occurs in clumps in the skin and initially found around the head and ears.  Diagnosis may be based on the intense pruritus, the presence and location of lesions and the rapid spread to kittens if present.  Confirmation by recovery of mites from the skin scrapings.

Zoonosis:

Yes, transient dermatitis can occur in humans.

Otodectes cynotis

Distribution:

Throughout Europe Ear mites, Otodectes cynotis, cause aural irritation in dogs, cats and ferrets.

Clinical signs:

Can occur in any age group of cats and dogs but more commonly in kittens and puppies.  Seen as small, motile white spots in the external ear canal and typically accompanied by a brown waxy discharge which look like coffee grounds.  There may be a history of pruritus with ear scratching or rubbing.  The pinna and ear canal may be erythematous.

Diagnosis:

Use of an otoscope will reveal mites in the external ear canal accompanied by the characteristic brown ear wax discharge.  The ear canal may be inflamed and examination may be painful for the animal.  Use a cotton swab to collect wax and debris from the ear canal and roll the swab onto a slide to examine under low (x40) magnification.

FUR

Cheyletiella spp. mites can infest dogs, cats and rabbits

Cheyletiella blakei – cat fur mite

Distribution:

Throughout Europe.

Clinical signs:

Gives rise to mild eczema-like skin conditions and pruritus.  Many skin scales are shed into the fur giving a mealy appearance.  Presence of moving mites in the skin debris has given rise to the term "walking dandruff".

Diagnosis:

In the presence of excessive scurf or dandruff on the catCheyletiella should be considered in the differential diagnosis.  Comb out scurf onto dark paper to observe movement of the mites in the debris and examine under low-powered microscope.

Zoonosis:

Yes, as for dogs and readily passed on to humans.

Cheyletiella yasguri

Distribution:

Throughout Europe.

Clinical signs:

Skin scales are shed into the fur giving it a powdery or mealy appearance.  There is very little skin reaction.  In the rare severe cases, which involve most of the body surface, crusts are formed.

Diagnosis:

Look for "moving dandruff" as they are almost visible with the naked eye.  Appear as small moving dandruff amongst skin scales.

Cheyletiella yasguri – dog fur mite

Distribution:

Throughout Europe.

Clinical signs:

Often found in young animals in good physical condition and may be more prevalent in short-haired breeds of dog.  Very little skin reaction or pruritus and in rare severe cases involving much of the body surface crusts are formed.

Diagnosis:

A positive diagnosis may be associated with a history of persistent skin rash in the owner’s family.  Characteristic of the dermatitis caused by infection is that many skin scales are shed giving the skin a mealy or powdery appearance.

Zoonosis:

Yes, readily transferred to humans where it can give rise to severe localised irritation and intense pruritus.

Straelensia cynotis – causing the emerging disease straelensiosis

Distribution:

Straelensiosis has been reported in southern France, northern Spain and Portugal in the last decade.

Clinical signs:

Cutaneous lesions affecting dorsal areas of the body are common including maculae that may progress to erythematous, alopecic nodules and papules.  In contrast to neotrombiculosis the degree of pruritus varies from case to case; straelensiosis appears to be primarily non-pruritic, with pruritus only appearing when there is a secondary infection.  Typically the infection is very painful.

Diagnosis:

Is through observation of the typical six-legged larvae usually present in dilated hair follicles of biopsies from affected skin.

HARVEST

Responsible for the condition called trombiculosis. The two species that cause trombiculosis in dogs and cats are: Neotrombicula(syn. Trombicula) autumnalis and Straelensia cynotis.

Neotrombicula (Trombicula) autumnalis

Distribution:

Throughout Europe where the larvae become active in dry sunny conditions particularly between July and October hence "harvest mite".  Localised occurrence e.g. in the UK can be found in Cotswolds, Malvern Hills and Edinburgh.

Clinical signs:

Cutaneous lesions are usually found in ground-skin contact areas such as the head, ears, legs, feet and ventral areas.  The lesions are highly pruritic.  Macroscopically they are very peculiar due to the bright orange colour of groups of the larval mites.  Severe hypersensitivity reactions have been observed in cases of repeat infestation.

Diagnosis:

Gross observation of the lesions, together with the time of year and a possible history of the dog having been in the countryside.  The parastic larval mites can be seen without magnification.

Pneumonyssoides (Pneumonyssus) caninum

Distribution:

Particularly prevalent in Scandinavia.

Clinical signs:

Are varied depending on the parasite burden, from an absence of any signs to severe cases of nasal discharge, sneezing, fatigue and head shaking.  In very severe cases purulent rhinitis and sinusitis may occur.

Diagnosis:

The inaccessible localisation makes in vivo diagnosis difficult and except in rare cases the presence of nasal mites is detected postmortem.  Nasal discharge, collected using a catheter for retrograde nasal flushing, can be examined under a microscope, although this is considered to be of limited diagnostic value.  Observing the mites in their predilection sites using nasal endoscopy is feasible.

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