Stallion

Question 1

What breeds are predisposed to cryptorchidism?

Answer 1

• Quarterhorse
• Percheron
• ASH
• ponies

Question 2

What’s the idea behind hCG/GnRH stimulation in diagnosing cryptorchidism?

Answer 2

Give stim→ if there’s testicular tissue there,
you stim Leydig cells to make testosterone,
& you have a significant increase from before your injection to an hour/90 min after

• usually you want at least a 2x increase w stimulation*
• to* conclude that there is in fact testicular tissue

Question 3

T or F:
Stallions are among the species that make the most estrogen in their testes.

Answer 3

true.

basal estrone sulfate is a good test for diagnosing cryptorchidism

Question 4

T or F:
If you take baseline AMH in a suspected cryptorchid,
the animal with testes should produce higher than baseline [AMH].

Answer 4

• *True;**
• AMH is probably the best of the tests, but it’s still not perfect.*

Question 5

What’s the most common testicular neoplasia of young horses?

Answer 5

teratoma

esp cryptorchids

Question 6

If you have a white, soft tumor, what is it most likely to be?

Answer 6

seminoma

mature stallions; may be malignant

Question 7

If you have a white, firm tumor, what is it most likely to be?

Answer 7

sertoli cell tumor

rare

Question 8

What is the morphological description/brief pathogenesis of testicular degeneration?

Answer 8

Acquired atrophy of seminiferous tubules

• oligozoospermia: dec. # of sperm
• asthenozoospermia: dec. sperm motility
• teratospermia: abnormal morphology
• {eventually}… azoospermia: zero sperm…

Question 9

So you’re suspicious that this stallion has testicular degeneration. You know that to definitively diagnose, you need a biopsy. How should we fix the testicular tissue?

Answer 9

Bouins Solution

Fixes tissue w.miminum shrinkage

- as opposed to formaldehyde -
which can cause seminiferous tubule shrinkage
& then we can’t differentiate if the shrinkage is from
the formaldehyde or testicular degeneration

Question 10

What is a varicocele?

Answer 10

Dilation of the pampiniform plexus vessels
incompetent testicular vein

What other species gets this?
*rams: get it the neck of the scrotum is bigger than the testes & the testes literally touch the ground. Those rams make perfectly quality*

Question 11

What “anatomic propensity” may be associated w.testicular torsion?

Answer 11

long proper ligament of testis or epididymal ligament

Question 12

If a horse has testicular torsion that happened more than 6 hours ago, can you just untwist? Why or why not?

Answer 12

NO

ischemia repercussion injury
{breakdown of Blood-testes-barrier, creation of Abs,
& potential attack on the other testes}

Question 13

Inguinal hernias are most common in…?

Answer 13

Foals!
{newborns}

sometimes you can just roll them over & shake them
but most often they have to go to surgery & have the inguinal ring tightened up

Question 14

What is phimosis? Paraphimosis?

Answer 14

Phimosis: penis gets trapped inside prepuce & cannot be extended

Paraphimosis: penis is extended & cannot be retracted

Question 15

When treating priapism, what do we use & how/where do we administer it?

Answer 15

Benztropine mesolate {8mg IV} right into the corpus cavernosum

or terbutaline/clenbuterol

Question 16

What is this lesion pretty typical of?

Answer 16

EHV-3
when closes/heals, leaves depigmented skin

Question 17

What’s the most common penile neoplasia?

Answer 17

SCC

Question 18

What is “Ampullar spermiostasis”?

Answer 18

Sperm come passively thru the tract, w/out ejaculation,
& they sit, pack, and create a blockage in the ampullae

Question 19

T or F:
[ALP] in semen is a good test to confirm suspected unilateral ampullar spermiostasis.

Answer 19

False

unilateral won’t help us;
we still need the ALP from the testis on the other side

Question 20

What can we use to chemically induce ejaculation in the stallion, followed 2 hours later w/xylazine?

Answer 20

Imipramine

Question 21

Testicular degeneration in the stallion can be monitored w.hormone profiles over 3 consecutive days. What hormones would we see elevated? Decreased?

Answer 21

• Increased: FSH
• ​Decreased: inhibin + estrogeny

Question 22

If we test for testicular degeneration in the stallion, we can use a GnRH response test and evaluate the hormone profile. What would we expect in a test positive?

Answer 22

• increases: Testosterone
• LH stays the same…