Stallion Reproduction

Question 1

At what age should the testes be present in the scrotum?

Answer 1

2 weeks post-partum

Question 2

At what age does a stallion reach puberty?

Answer 2

12-24 months

Question 3

At what age is a stallion’s maximum reproductive capacity reached?

Answer 3

4 years

Question 4

At what age may a stallion’s fertility decline?

Answer 4

20 years

Question 5

What is it about equine testes that makes them prone to torsion?

Answer 5

Their horizontal orientation

Question 6

How can ejaculation be recognised in the stallion?

Answer 6

Cessation of thrusting, ‘flagging’ of the tail, palpation of urethral pulses in the ventral surface of the penis.

Question 7

What is the total duration of production of spermatozoa in the stallion?

Answer 7

49-55 days

Question 8

If semen quality is inaccurate, how long should you wait to retest for recovery in semen quality?

Answer 8

At least 60 days (takes 49-55 days to produce sperm)

Question 9

What is considered normal scrotal width in a stallion?

Answer 9

>80mm

Question 10

What is considered the normal progressive motility of stallion sperm?

Answer 10

>60%

Question 11

How would you measure a stallion’s basal hormonal concentrations?

Answer 11

Collect a blood sample every 30min for 6hrs

Question 12

What hormonal indications would you see in progressive testicular disease?

Answer 12

High FSH, low oestrogen and inhibin, progressive decline in testoosterone concentration with a rise in LH

Question 13

What sperm abnormality is present in this semen sample?

Answer 13

Detached heads

Question 14

What sperm abnormality is present in this semen sample?

Answer 14

Rolled heads

Question 15

What is abnormal about this sperm?

Answer 15

Coiled midpiece - aka ‘dag defect’

Question 16

What defect is present in these sperm?

Answer 16

Proximal cytoplasmic droplet

Question 17

What defect is present in this sperm?

Answer 17

Distal cytoplasmic droplet

Question 18

What defect is present in these sperm?

Answer 18

Coiled tails

Question 19

What defect is present in this sperm?

Answer 19

Distal midpiece reflex defect

Question 20

What can induce the distal midpiece reflex defect in normal sperm?

Answer 20

Prolonged contact with hypotonic solution

Question 21

What are your options for the diagnosis of cryptorchid stallions?

Answer 21

Basal and post stimulation testosterone. Oestrone sulphate. Anti-Mullerian hormone (not commercially available in Aus).

Question 22

What is paraphimosis?

Answer 22

Inability to retract the penis back into the prepuce.

Question 23

What are the general principle of treatment for paraphimosis?

Answer 23

1. Reduce swelling and inflammation and control pain
2. Return penis and any prolapsed prepuce to prepuce (if possible) or support the penis
3. Control infection
4. Isolate from mares

Question 24

What is priapsim?

Answer 24

Persistent erection without sexual arousal

Question 25

How do you treat priapism? (persistent erection)

Answer 25

Induction of detumescence. * cholinergic blocker * sympathomimetic

Question 26

What is phimosis and how would you treat it?

Answer 26

Inability to protrude penis completely from prepuce. Normal in foals. Surgical enlargement of the prepucial orifice.

Question 27

How do you treat EHV3 (equine coital exanthema)?

Answer 27

1. Sexual rest until lesions healed 2. Strict hygeine 3. +/- antibiotic ointment for secondary infection

Question 28

What is the most common testicular tumor found in stallions and how commonly do they metastasize?

Answer 28

Seminoma - rarely metastasize