Mites

PARASITES ARACHNIDA

Astigmata Introduction

Mites are one of the most successful and divers vertebrate group. The species of veterinary importance are parasitic, although a few non-parasitic mites are also important, such as orbatid and forage mites.

Mites are very small, on average under 0.3mm in length and for this reason often go unnoticed. They spend the majority of their life cycle on the host and cause mange.

The taxonomy of mites is complex as there are over 8 families. In this article the families are split according to their location on the host into sub-surface (burrowing) and surface (non-burrowing) mites.

Burrowing Mites

Sarcoptes

• In scabies

Knemidocoptes

• K. mutans
  • Scaly leg in poultry

• K. pilae
  • Scaly leg in psittacines

Demodex

• Demodex in demodicosis

Notoedres

• Notoedres cati in notoedric skin infestation

Non-Burrowing Mites

Psoroptes

• In psoroptic skin infestation

Psoroptes cuniculi

• Parasite of rabbits
• Epizootiology
  • Common among conventional rabbits; transmitted via contact.
• Clinical
  • The ears are painful and itch intensely; affected rabbits shake their heads and scratch their ears. The inner surfaces of the pinnae are covered with brown, scaly, fetid material, and the skin beneath is raw. Mites are grossly visible.
• Pathology
  • Histologically, there is chronic erosive and proliferative eosinophilic dermatitis. The mites are non-burrowing and thus are found only in the exudate, not in the tissue.
• Diagnosis
  • Appearance; examination for mites (low magnification).
• Control
  • Infestations are difficult to eliminate from a colony, although ivermectin is said to be effective.

Chorioptes bovis

• In skin infestation

Otodectes cynotis

• in otodectic skin infestation

Cheyletiella sp.

• Cheyletiella yasguri
• In skin infestation

Trombicula

• In skin infestation