03 - nodular skin disorders

Question 1

what are the three main differential dx for these lesions?

Answer 1

infectious causes

neoplasia

sterile inflammatory causes

Question 2

(bacterial causes)

(abscesses)

1-4. what 4 bacteria

5. tx?

Answer 2

corynebacterium pseudotuberculosis (zoonotic concerns)

strep equi

clostridium spp.

staph spp.

5. lance abscess, abx

Question 3

(bacterial causes)

(ulcerative lymphangitis)

1. same bac as abscesses
2. secondary to what?
3. Cx?
4. dx?
5. tx?

Answer 3

2. wound contamination
3. sudden onset of leg edema, multiple nodules that ulcerate and drain
4. cyto, culture and sens
5. systemic abx

Question 4

(fungal causes)

(sporotrichosis)

1. caused by what?
2. what form most common in horse?
3. tx = cyto, histo, culture
4. tx = ?

Answer 4

1. sporothrix schenkii (zoonotic!)
2. cutaneolymphatic
3. sodium iodide

Question 5

(fungal causes)

(pythiosis)

1. not truly a fungal organism
2. very pruritic lesions
3. requires what to factors to invade damaged skin?
4. dx?
5. very difficult to treat

Answer 5

3. warm temp and moisture

(usually gulf coast states)

4. histo, PCR

Question 6

(viral causes)

(aural plaques)

1. lesions affecting the inner surface of the pinna caused by what?
2. dx by appearance
3. cosmetic defect - currently no effective tx

Answer 6

1. the papilloma virus

Question 7

(parasitic causes)

(demodicosis)

1. rare in horses
2. what causes?
3. affects where on horse?
4. dx with scrapings, look for underlying cause, currently no effective tx

Answer 7

2. demodex equi
3. face and neck and shoulders

Question 8

(parasitic causes)

(cutaneous habronemiasis - summer sores)

1. aberrant parasite that occurs only in horse
2. habronema muscae, habronema majus, drscha megastoma
3. what happens with larvae?
4. lesions form as a result of what?

Answer 8

3. go to deep layers of skin rather than going to stomach as usual
4. hypersensitivity rxn

Question 9

(parasitic causes)

(cutaneous habronemiasis - summer sores)

(cx)

1. seasonal
2. occur where?
3. ulceration with granulation tissue, variable pruritis
4. tx?

Answer 9

2. medial canthus of eye, male genitalia, lower extremitiess
3. corticosteroids for lesion size, prevent reinfection with fly control

Question 10

(allergic and immunologic causes)

(urticaria)

1. extremely common
2. what kind of hypersens?
3. many causes idiopathic
4. other causes = drugs, allergens, insects
5. dx = Cx, histo to rule out vasculitis
6. tx?

Answer 10

2. type 1
3. corticosteroids, antihistamines, avoid inciting cause

Question 11

(allergic and immunologic causes)

(angioedema)

1. rare in the horse
2. what type hypersens?
3. unknown mech
4. nonpruritic nodules
5. dx = histo
6. tx?

Answer 11

2. type 1
3. avoid insects, intralesional corticosteroids, surgical excision

Question 12

(allergic and immunologic causes)

Question 13

(neoplastic causes)

Question 14

(neoplastic causes)

(sarcoid)

1. most common neoplasm seen in horse
2. locally agressive - any mets?
3. cause not completely understood - what virus has been implicated?
4. age?

Answer 14

2. no
3. bovine papilloma virus
4. occurs at any age

Question 15

(neoplastic causes)

(sarcoid)

1. dx?
2. tx?

Answer 15

1. histo
2. many therapies attempted (laser, cryo, chemo, various topicals)

vx not successful

aldara (imiquimod)!!!

Question 16

(neoplastic causes)

(SCC)

1. ulcerative or proliferative tumor
2. solar induced
3. locally invasive - mets?
4. tx?

Answer 16

3. slow to mets
4. radical surgical excision

various radiation or cryo options

Question 17

(neoplastic causes)

(melanocytic tumors)

1. what horses moslty?
2. many are malignant and will mets
3. tx?

Answer 17

1. older gray horses
2. sx excision, cryo, cimentidine,