VPA 221: Veterinary Entomology and Acarology (1+1)

EFFECT ON THE HOST - D. CANIS

• Injury to host occurs when mites puncture with their stylet like chelicerae the epithelial cells lining the hair follicles and glands to feed on the cell contents
• The host response in most cases leads to thrombosis of internal infestations
• Pustules initially seen on abdomen, neck, legs, also feet, face and thigh regions
• Dogs have repulsive mousy odour / rancid odour
• Itching is less
• In dogs both forms are seen
• Clinical signs evident in dogs less than 1 year old- presumably immuno deficient
• 1^st appear as mildly erythematous patch above eyes and corners of mouth, associated typically with hair loss- then spreads to forelegs, trunk
• Most resolve without treatment
• Death occurs in severely infected animals
• In generally predisposed or immuno depressed animals and in case of secondary infection, it develops into chronically severe, moist, purulent dermatitis - "Pustular Demodicosis” - unpleasant odour - rancid/mousy
• If generalized, there is intense redness, tenderness of skin which easily bleeds-Death occurs  in heavily infested animals
• Mild and moderate hypertrophy of the affected epithelia
• In some cases marked hypertrophy and cell destruction occurs
• Opening of hair follicle and ducts of glands are blocked
• Dermal papule formation and nodules
• Hair loss-secondary bacterial infection-inflammation, pruritus and pustule formation (Staphylococcus)
• Lesions occur on face and head and then spread-if untreated, death due to emaciation and toxaemia occurs