(08) - Equine Insect Hypersensitivity

Question 1

1. What is the most common cause of pruritus in horses?
2. It is usually a seasonal problem but, it can be year-round in warmer places.
3. Is it recurrent?
4. Is the predisposition to develop hypersensitivity to insect bites hereditary?

Answer 1

1. Insect hypersensitivity
2. The disease is a recurrent one and it becomes progressively worse with age.
3. yes

Question 2

1. Is primarily what type of hypersensitivity? can also be what?

Answer 2

1. It is primarily a Type I (immediate, IgE mediated) hypersensitivity. However, a Type IV (delayed, cell
   mediated) also play a role

Question 3

1. The condition is rare or non-existent in horses of what age?
2. It typically affects how many animals out of a stable or pasture?
3. What are the initial signs?
4. What regions are classically affected?
5. Lesions can be generalized.

Answer 3

1. less than one year of age
2. one - supporting its allergic nature
3. Pruritus and crusted papules (As the disease progresses excoriations, alopecia, lichenification, pigment disturbances, a “rat tail” and a “buzzed off” mane are seen)
4. Base of the tail, rump, back, withers, crest, poll and ears are classically affected. However,
   ventral distribution with or without involvement of the mane and tail can also be seen.

Question 4

1. Diagnosis of insect hypersensitivity is usually based on history and clinical findings. what support the presumptive diagnosis?

Answer 4

1. Biopsy

results and intradermal testing

Question 5

1. The primary objective in treating insect hypersensitivity dermatitis is avoidance of exposure to insects
2. When avoidance is not practical or the offending agent is not known, what therapy can be instituted?
3. What can be tried when avoidance of the allergen is impossible and systemic glucocorticoid
   therapy is contraindicated; however, its therapeutic value is unknown?

Answer 5

2. antihistamines and/or systemic glucocorticoid

3. Immunotherapy