equine derm

Question 1

most common causes of bacterial folliculitis

Answer 1

Staphylococcal spp and Corynebacterium spp

• CS - alopecia, crusts, epidermal collarettes, non itchy, but still sensitive on palpation

Question 2

Onchocerca spp

Answer 2

• CS - diffuse patchy alopecia on ventral midline and face, ** bulls eye** lesions in center of forehead

** resulting dermatitis = hypersensitivity to microfilarial antigen –> accumulation of microfilaria in the eye can also lead to conjunctivitis + uveitis

Tx - (onchocerca mircofilaria ) - ivermectin , repeat in four months

( adult filaria ) - not killed by ivermectin , but resolve within 6-12 months

Adult filaria –> live in calcified nodules in the ligamentum nuchae and produce microfilaria thet migrate to the ventral midline, face, neck, and chest

Question 3

Culicoides spp

biting midges - no see ums

Answer 3

• carry onchocera microfilaria, but don’t cause the same problems
• CS - sweet itch, very pruritic warm weather dermatitis that is also secondary to hypersensitivity
• can incidentally find microfilaria on skin biopsies in asymptomatic horses

Tx - corticosteroids, antihistamines +/- abs to prevent infection

• shampoos won’t help