Chapter 15 - Miscellaneous

Question 1

At which body sites do eosinophilic granulomas most commonly occur in horses?

Answer 1

Back, withers and neck

Question 2

In horses, what does the skin and hair coat overlying an eosinophilic granuloma look like?

Answer 2

Normal

Question 3

What can older lesions of eosinophilic granuloma in horses be mistaken for?

Answer 3

Calcinosis circumscripta or mast cell tumours

Older lesions show marked dystrophic mineralisation

Question 4

What histopathological finding can suggest that close clipping has caused an eosinophilic granuloma to develop?

Answer 4

Free hair shafts within a lesion

Question 5

In horses, eosinophilic granuloma nodules with large areas of necrosis is suggestive of which diseases?

Answer 5

Habronemiasis
Pythiosis
Zygomycosis
Injection reactions
Arthropod bites
Mast cell tumours

Question 6

Which inflammatory cell predominates on cytology of unilateral papular dermatosis in horses?

Answer 6

Eosinophils

Question 7

Can unilateral papular dermatosis in horses spontaneously resolve?

Answer 7

Yes, within several weeks to six months

Question 8

Which disease in horses is characterised by exfoliative dermatitis, ulcerative stomatitis, wasting, and infiltration of epithelial tissues by eosinophils, lymphocytes and macrophages?

Answer 8

Multisystemic eosinophlic epithelioptropic disease

Question 9

What are the histopathological findings of linear alopecia in horses?

Answer 9

An early infiltrative lymphocytic mural folliculitis with variable outer root sheath oedema, to a later lymphohistiocytic mural folliculitis.

Epithelioid cells and multinucleated histiocytic giant cells are prominent in chronic lesions and apoptotic keratinocytes and eosinophils may be found in the wall of the hair follicle. Complete follicular destruction can occur.

Question 10

What can Sudan stains highlight on cytology in cases of panniculitis?

Answer 10

Extra- and intracellular lipid droplets

Question 11

Equine sarcoidosis spares the mane and tail, true or false?

Answer 11

True

Question 12

What are the clinical signs of nodular auricular chondropathy in horses?

Answer 12

Firm, raised, non-moveable, non-pruritic, non-painful papules and nodules within the pinnal cartilage, often near the tips. Single or multiple. Do not progress.

Question 13

True or false, sebaceous adenitis and scleroderma (morphea) have been reported in horses.

Answer 13

True

Question 14

Equine anhidrosis is believed to result from a conditioned insensitivity of sweat glands to what?

Answer 14

Epinephrine

Question 15

What are the clinical signs of chronic anhidrosis in horses?

Answer 15

A dry hair coat, excessive scaling, and partial alopecia of the face and neck. May be pruritic, PU/PD, reduced appetite and loss of body condition. The skin can become inelastic.

Question 16

Name five differential diagnoses for the reaction pattern of pastern dermatitis.

Answer 16

Bacterial folliculitis/furunculosis Dermatophilosis
Spirochetes
Dermatophytosis
Chorioptic mange 
Trombiculiasis 
Pelodera dermatitis 
Vaccinia
Primary irritant contact dermatitis 
Allergic contact dermatitis Photosensitization
Trauma
Vasculitis
Pemphigus foliaceus
Chronic progressive lymphedema

Question 17

Name five differential diagnoses for coronary band disorders?

Answer 17

Pemphigus foliaceus
Vasculitis
Photodermatitis
Multisystemic eosinophilic epitheliotropic disease 
Sarcoidosis
Vesicular stomatitis 
Epidermolysis bullosa 
Erythema multiforme 
Ergotism
Selenosis
Vitamin A deficiency
Zinc-responsive dermatitis Dermatophilosis
Dermatophytosis
Hepatocutaneous syndrome 
Coronary band dysplasia (dystrophy)

Question 18

A young horse with a hard nodule on the stifle and histopathological findings of multinodular deposition of mineral separated by variable degrees of fibrosis and granulomatous inflammation is most likely to have what?

Answer 18

Calcinosis circumscripta