Equine Sarcoid & Melanoma

Question 1

__________ is the most common tumor in the horse

Answer 1

Sarcoid

Comprises 20% of all equine tumors (90% of all skin tumors)

Question 2

What is the etiology of equine sarcoid?

Answer 2

Papova virus

Related to bovine papilloma virus​

Question 3

What is the sex predilection for equine sarcoid?

Answer 3

No sex predilection

Question 4

Equine sarcoid can occur anywhere on the body, but where does it occur most commonly?

Answer 4

Limbs

• 45% of sarcoid cases
• Hindlimbs > forelimbs
• Above tarsus/carpus > below tarsus/carpus

Question 5

What are the four forms of equine sarcoid?

Answer 5

Verrucous, Fibroblastic, Mixed, Occult​

Question 6

What form of sarcoid is shown here?

Answer 6

Verrucous sarcoid​

Question 7

What form of sarcoid is shown here?

Answer 7

Fibroblastic sarcoid​

Question 8

T/F: Benign neglect may be a therapeutic option for equine sarcoid

Answer 8

True

Considered for small tumors that are not causing discomfort, or impeding use

Question 9

T/F: Surgical excision is considered the most effective therapeutic option for equine sarcoid

Answer 9

False

No single approach to therapy has proved universally successful

Question 10

T/F: Most sarcoid lesions that are surgically excised recur within three years

Answer 10

True

Most recur within 6 months

Question 11

What cryogens are used for cryosurgery to remove equine sarcoid?

Answer 11

Liquid nitrogen, nitrous oxide, Freon​

Question 12

What is the average healing time for equine sarcoid after cryotherapy?

Answer 12

2.4 months​

Question 13

T/F: Most cases of equine sarcoid recur after cryotherapy

Answer 13

False

70% of cases are reported free of recurrence

Question 14

Concerning sarcoids, which statement is most accurate?

• The rate of recurrence is less than 10% following resection
• Immunotherapy is the treatment of the choice
• They occur most commonly in the flank area
• They are locally invasive, do not metastasize, and recur commonly
• They commonly become fibrosarcomas following cryotherapy

Answer 14

They are locally invasive, do not metastasize, and recur commonly​

Question 15

T/F: Sarcoids are nonmetastatic skin tumors

Answer 15

True

Question 16

T/F: The four categories of sarcoids are based on the gross appearance. Sarcoids are the most common skin tumor of the equid.

Answer 16

True​

Question 17

Brachytherapy (CCDP) for treatment of equine sarcoid involves injection of what anti-neoplastic agent into the tumor?

Answer 17

Cisplatin

• Treatment usually includes a series of 4 intratumoral injections of cisplatin given at 2 week intervals. The overall cure rate is 93%
• MOA: Inhibition of DNA synthesis

Question 18

Xxterra® is a caustic agent used as immunotherapeutic treatment of equine sarcoid.

In a general sense, what does it do?

Answer 18

Changes the antigenicity of the sarcoid

• The body recognized the cells as foreign and produces antibodies
• Apply Xxterra® to the sarcoid and place a bandage over it for 4 days

Question 19

How do you definitively diagnose equine sarcoid?

Answer 19

Histopathology​

Question 20

It is difficult to differentiate between benign and malignant melanoma in horses. In aged gray horses, melanoma is more likely to present:

Answer 20

Benign​

Question 21

It is difficult to differentiate between benign and malignant melanoma in horses. In non- gray horses, melanoma is more likely to present:

Answer 21

Malignant​

Question 22

Melanoma lesions may be solitary or multiple. Where do they most commonly occur?

Answer 22

Perineum or ventral surface of the tail

Question 23

What H-2 receptor antagonist has been proposed for treatment of melanomas in horses?

Answer 23

Cimetidine

Question 24

T/F: Light-skinned cattle are more commonly affected with melanoma than dark-skinned cattle

Answer 24

False

Dark-skinned cattle are more commonly affected