Category:Non-Burrowing Mites

• Live on the skin surface

• Feed on either skin scales and tissue or suck blood

Psoroptes

Chorioptes bovis

Otodectes cynotis

• Causes otodectic skin infestation

• Commonest mange of dogs and cats in the world

• Inhabits the inner ear

• Also found in the fox and the ferret

• Closed keratinous bars (apodemes) on ventral surface

• Life cycle takes 3 weeks

• Feeds on ear debris

Pathogenesis

• The majority of cats harbour the mites, however only a few show symptoms
  • Transmission occurs whilst kittens are suckling

• Common cause of otitis externa in dogs

• Brown waxy exudate produced

• Can lead to secondary infection

• Clinical signs are apparent
  • Head shaking
  • Ear scratching
  • Aural haematomata

Treatment

• Acaracidal ear drops
  • Massage base of ear to disperse drops after treatment

• Most treatments need to be repeated in 10-14 days to kill newly hatched mites

• Selamectin can be used as a spot-on treatment
  • Prolonged duration of action

• Treat all in-contact animals
  • These may be asymptomatic carriers

Cheyletiella spp.

• Surface mite of cats and dogs

• Also found on humans and rabbits
  • C.yasguri (dogs)
  • C.blakei (cats and humans)
  • C.parasitivorax (rabbits)

• Causes parasitic skin infestation

Recognition

• Waisted body

• Claw like palps on head

• Combs at ends of legs

Pathogenesis

• Highly contagious

• Mild pathogenesis

• Causes very scaly dermatitis

• Can be transferred to humans

Diagnosis

• Clinical signs
  • Excess scurf

• Brush scurf onto dark paper
  • 'Walking dandruff' as mites will move when present in large numbers

• Skin scrapings

• Hair pluckings from scaly areas
  • Eggs may be present

Dermanyssus gallinae

• Red mite of poultry

• Spends most of time off the host
  • Adults and nymphs visit poultry at night to feed

• Life cycle takes 1 week

• Adults can survive several months without feeding so reservoirs can build up

Appearance

• Spider like mite with long legs

• White or grey
  • Becomes red when engorged with blood after feeding

• Few hairs on body

• Hooks on legs

Pathogenesis

• Blood sucking mite

• Lesions usually found on the breast and legs

• Irritation, restlessness, decrease in egg production

• Anaemia can result if mites are present in large numbers

• Newly hatched chicks can rapidly die if infested

Treatment

• Acaricide

• Environmental treatment

• Remove wild bird nests

Ornithonyssus

• Also called the Northern mite or Northern feather mite

• Closely related to Dermanyssus

• Hairy

• Spends entire life cycle on the host

• Occurs in caged birds and poultry

• Causes feathers to become matted and severe scabbing can develop
  • Scabs particularly seen around the vent

• Decreases egg production

• Grey or black discolouration of feathers when large numbers of mites are present

Trombicula autumnalis

• Causes parasitic skin infestation

• Also called the harvest mite

• Not host-specific
  • Will parasitise any animal, including humans

• Only the larval stage is parasitic
  • Nymphal and adult stages are free-living in the soil

• Mite numbers are highest in late summer in temperate climates
  • Mite numbers are constant all year in tropical regions

Recognition

• Six legs

• Bright orange in colour

• Hairy

• No spiracles
  • Breath through cuticle

Pathogenesis

• Larvae insert mouthparts into skin and inject cytolytic enzymes

• Feed on partly digested host tissue

• Causes irritation

• Can cause a hypersensitivity reaction

• Mites found on head, ears and flanks of pets

• Mites found on face and limbs of grazing animals (depending upon host height)

Control

• Very difficult; try to restrict access of animals to 'hot-spot' areas

Treatment

• Fipronil spray applied to affected areas

Leporacarus

• Known as the rabbit fur mite

• Found on rabbits (domestic and wild) and on hares

• Common

• Clings to individual hairs

• Feeds on sebaceous secretions and skin debris

• Non-pathogenic

• May cause dermatitis in humans handling infected animals