The Stallion

Question 1

1. Puberty in the colt.
2. Sexual maturity in the colt.

Answer 1

1. from 14m.
2. from 4-5y.

Question 2

Pasture breeding.

Answer 2

Lower value mares and stallions and in semi-feral populations.
Less knowledge of exact dates.
Less disease control/monitoring.
Stallion turned out w/ a group or single mares.
- serves those in oestrus twice daily.
- difficult to bring in new mares as shifts herd dynamic.
- limited numbers of mares per season.
- may have preferred mares.

Question 3

In hand breeding.

Answer 3

ALL TB breeding.
- mare screening strongly encouraged.
- covering certificates show dates.
- follows mare management and ovulation prediction w/ US scanning.
Care w/ handling:
- several handlers required.
- risk of injury to handlers, mare and stallion.
Maximum of 3 covers per day.

Question 4

Artificial insemination.

Answer 4

Pleasure and competition horses.
Collect semen by training stallion to mount dummy.
- Or mare in oestrus and diverting penis at last minute (more potential to go wrong/spread disease).
- W/o intromission potential for stallion to catch disease is less but still potential for transmission by stallion.
- Health certificate paper for semen strongly encouraged (HBLB).

Question 5

1. Stallion breeding soundness exam.
2. Stallion vaccinations.

Answer 5

1. General heath - vac status.
   Gross exam.
   Bacteriological screening.
   Virology for venereal pathogens.
   - some exotic and notifiable.
   Semen evaluation.
2. Influenza.
   Tetanus.
   EHV.
   Consider EVA.
   Strangles?

Question 6

Gross exam of stallion.

Answer 6

Testicular palpation.
- thin skinned scrotum.
- symmetrical.
- firm.
- tail of epididymis caudal.
- non painful.
- appropriate size – 10x6x5cm TB.
Penis.
- straight.
- capable of erection.
- no masses (think SCC on geldings).
Sheath.
- no discharge.
- no smell.

Question 7

Bacteriological swabs of the stallion…
1. Low risk stallions.
2. High risk stallions.
3. What needs to be swabbed?
4. What can be done to help acquire samples?
5. Sending samples.

Answer 7

1. Low risk stallion - 2 negative sets of swabs >7d apart.
2. High risk stallion - 2 negative sets of swabs >7d apart AND screen 4 mares post mating.
3. • Urethral orifice.
     - Urethral fossa.
     - Prepuce.
     - Pre-ejaculatory fluid.
4. Teasing.
5. For CEMO, Klebsiella and Pseudomonas screening same as mares:
   - swabs sent in Amies Charcoal Medium.
   - culture w/in 48hrs at Approved Laboratory.

Question 8

What if culture is CEMO positive?

Answer 8

• Stop mating, teasing and collection and insemination of semen immediately.
• Isolate and treat infected horse(s).
• Arrange swabbing of any at-risk horses.
• Inform all O’s of mares booked to stallion, incl. any that have already left the premises.
• Disinfect all equipment used for breeding procedures.
• Inform people to whom semen from stallion has been sent.
• Inform national breeders’ association.
• Arrange for one straw of every ejaculate stored semen from infected and at-risk stallions to be tested by a lab. If a straw is infected, all straws of that ejaculate should be destroyed.
• Any at-risk pregnant mare bust be foaled in isolation, placenta incinerated, foals swabbed 3 times at intervals of >7d before 3m old. Culture all these swabs aerobically and microaerophilically:
  – filly foals –> swab clitoral fossa.
  – colt foals –> swab inside penile sheath and around tip of penis.
• Do not resume any breeding activity until freedom from disease confirmed in all infected horses.

Question 9

Treatment of bacterial venereal pathogens.

Answer 9

Topical cleaning of penis.
- 50% acetic acid (Pseudomonas).
- 0.2% HCl (Pseudomonas).
- 5.25% sodium hypochlorite (Klebsiella).
- Dilute iodine solution.
- Dilute chlorhexidine (CEMO).
- Silver sulphadiazine creams.
If horse healthy and no infected penis.
- Soapy water.
- Sheath cleaner (lanolin and castor oil).
- Consider frequency (5-6 monthly should be sufficient).
Topical antimicrobial agents:
- Polymixin – 90% Pseudomonas sensitive.
- Neomycin – 90% Klebsiella sensitive.
- Enrofloxacin – CEMO / Pseudomonas.
- Nitrofyrazone – CEMO.
Inoculate w/ broth from normal stallion to re-colonise w/ normal bacteria:
- Coagulase -ve staphs.
- Alpha haem streps.
- Coryneforms.
- Plan 5d treatment and then install broth on d6 and 8.
?Systemic ABX.
- TMPS BID for 10d (CEMO).

Question 10

1. Why may stallion be EVA seropositive?
2. Notifiable?
3. Common?
4. Importation of what is not permitted?

Answer 10

1. • Previously vaccinated.
     - Historical infection.
     - Active infection.
2. Yes.
3. Rare in UK, endemic in Europe.
4. Semen from shedder stallions.
   Shedder stallions.

Question 11

1. EVA clinical signs.
2. Transmission of EVA.
3. Course of EVA disease.

Answer 11

1. Predilection for MMs – conjunctivitis.
   Malaise, d+ and colic.
   Cough, dyspnoea.
   Urticarial rashes, oedema (scrotum, eyelids, ventral oedema).
   Abortion in mares.
2. Droplet infection through resp. tract.
   Virus present in nasal secretion, urine, blood, faeces, semen.
3. Symptomatic, treatment aids spontaneous recovery over 1m.
   30% of stallions shed virus in semen for life – CASTRATE!

Question 12

Other pathogens.

Answer 12

EHV1.
EHV-3 Coital exanthema.
Strep equi equi.
Equine infectious anaemia (EIA).

Question 13

1. EHV-3 clinical signs.
2. Dx of Strep equi equi.
3. Another name for EIA.
4. EIA notifiable?
5. EIA common?
6. Transmission of EIA.

Answer 13

1. Warts.
2. ELISA, GP Lavage, PCR, culture.
3. Swamp Fever.
4. Yes.
5. Rare in UK.
6. Biting flies, fomites, transplacental, possible but uncommon via semen.

Question 14

1. What does CEMO usually cause in the stallion?
   – where is it normally residing?
2. AI from the stallion perspective.

Answer 14

1. Pyospermia.
   – accessory sex glands.
2. Semen collection.
   Remove gel fraction.
   Assessment of semen.
   Extend semen.
   Processing/fractioning.
   Chilling/freezing.
   Post thaw assessments.

Question 15

1. What is semen damaged by?
2. Semen collection general principles.

Answer 15

1. light, water, rubber, cold.
2. Avoid toxic lubricants.
   Avoid contamination w/ water.
   Avoid allowing sample to become cold.
   Keep out of light.
   If analysis to be delayed, do not store at body temperature, store at room temperature.
   Extend semen before chilling.

Question 16

Artificial vagina.

Answer 16

AV temps and fills vital and stallion specific.
Estimate penis size and choose appropriate AV and degree of filling.
Filled w/ warm water (38 degrees) in closed unit.
Lined, lubricated and insulated.

Question 17

On semen collection, how is ejaculation confirmed?

Answer 17

Flagging of tail.
Cessation of thrusting.
Urethral pulse.
Disinterest.
Fluid collection in the vessel.

Question 18

1. Why is the gel fraction removed?
2. How is the gel fraction removed?

Answer 18

1. Gel reduces sperm motility.
   Gel reduces longevity.
   Interferes w/ staining.
   Makes pipetting of semen difficult.
2. Filtration.
   - filter at entry to collection vessel.
   Suction.
   - Pipette off.
   Centrifugation.
   - Need cushion gel for sperm before spinning.

Question 19

1. What is sperm output affected by?

Answer 19

1. Age.
   Season (40% increase during natural breeding season).
   Frequency of ejaculation (1st almost double the second).
   Testicle size.

Question 20

Normal semen.

Answer 20

• Colour of dish water.
• Volume 15-100ml.
• Conc. 50-700 x 10^6 sperm per ml.
• Total sperm 4-8 x 10^9 per ejaculate.
• Motility 60-80% progressive motility.
• Morphology 60% live normal sperm.

Question 21

1. Semen assessment.
2. Staining?
3. Differentiating dead from alive sperm on microscope.

Answer 21

1. Gross morphology.
   Number - conc. and volume.
   Motility - progressively motile %, objective (automated), subjective (warm slide microscope).
2. Nigrosin (background) and Eosin (membrane).
3. Dead are more dull as pick uo stain differently.

Question 22

Cooled semen extension.

Answer 22

Extend before cooling.
1:1 -1:3 ratio semen : extender.
Once cool, keep cool until inseminate.
Extenders:
- milk or egg based.
- trial each stallion w/ different types.

Question 23

Frozen semen extension.

Answer 23

Cushion then centrifuge.
Dilute into cryoprotective solution.
Cool to 5C.
Freeze in liquid nitrogen.
Individual variation between stallions in performance.
- Trial different extenders.
- Some semen just doesn’t freeze well.

Question 24

Semen processing.

Answer 24

0.5ml straws.
- 2-5 straws may make up one dose.
- Depends on sperm conc. and progressive motility.
E.g.:
- 200-250 million sperm per ml.
- 8 x 0.5ml straws per dose.
- 800 million-1 billion sperm per dose.
- At 30% progressive motility, this exceeds recommended minimum of 200 million progressively motile sperm per dose.

Question 25

BEVA minimum standards for semen.

Answer 25

Fresh semen. - progressively motile w/ normal morphology >50%. Chilled semen. - >500 x 10^6 progressively motile sperm/dose at AI. - >1 billion sperm at collection. Frozen semen. - >30%PM sperm. - >200 x 10^6 PM sperm.

Question 26

AI male perspective.

Answer 26

Cooled semen. - allow to warm in mare. Frozen semen. - Fast thaw 30 sec at 37C. - Cut crimped end. - Place in insemination device cut end first. - Depress stylet, pushes bung along straw. - Repeat. Equipment in contact w/ semen should be: - rubber free. - warmed to 37C. - dry. - dark.

Question 27

What if semen quality is poor?

Answer 27

Semen evaluation. US. Urethroscopy. Further tests: - testicular biopsy. - testicular FNA cytology. - cytology.

Question 28

Pertinent question -- any recent illness?

Answer 28

Has the stallion had any fever in the preceding few months? - ANY cause of fever will reduce sperm production. - It can take a few months for fertility to increase. -- spermatogenesis takes 57d. - There is nothing you can do to help it other than give it time. - Some studs argue that there is a link between NSAIDs and fertility and they are reluctant to use them. -- give fever proven to cause infertility and NSAIDs may, can you argue that prompt treatment should be more effective?

Question 29

Normal US of testes.

Answer 29

Echogenic capsule. Hypoechoic parenchyma. - bright echogenic stippling. - central vein. 10x6x5cm normal size for TB stallion. vol= 0.52 x h x w x l. - Daily sperm output = 0.024 vol -1.26. -- billion sperm/day.

Question 30

US of abnormal testes.

Answer 30

Generalised changes in testicular echotexture. - Often representing cellular infiltration. -- fibrosis (degeneration). -- haemorrhage. -- oedema. -- inflammation / infection. Focal changes in testicular echotexture. - neoplasia. - cysts. - spermatocoele.

Question 31

1. Testicular biopsy complications. 2. Methods of testicular biopsy. 3. Outcomes for Dx.

Answer 31

1. Reduced sperm count for weeks-months. Inflammation. Haematoma. Adhesions. Increased testicular pressure. Immune reaction against sperm. Decreased testicle size. 2. FNA. Trucut style biopsy. Open biopsy. 3. Neoplasia. - Sertoli cell. - Seminoma. - Leydig cell. - Teratoma. Degeneration -- age.

Question 32

Heamospermia.

Answer 32

- Reduction in fertility w/ whole blood in ejaculate. -- probably caused by reduced sperm motility dur to sperm agglutinating w/ RBCs. - Aetiology: -- urethritis: --> bacterial. --> urolith. -- Accessory gland infection. -- Penile laceration / trauma w/ urethral rent. - Dx -- cytology. - Tx -- Systemic ABX and NSAIDs for primary condition. -- Rest --> no covering/collection.

Question 33

Urospermia... 1. Aetiology. 2. Dx. 3. How is fertility affected? 4. Tx. 5. Management changes to collection.

Answer 33

1. Cystitis or cauda equine syndrome. 2. Obvious colour and smell, pH 9, Urea and creatinine, microscopically CaCO3 crystal. 3. Sperm motility drastically affected. 4. Treat underlying disease. 5. Serve when bladder empty. Immediately extend, centrifuge and re-suspend in extender.

Question 34

Pyospermia... 1. Aetiology. 2. How does it affect fertility? 3. On cytology.

Answer 34

1. Infection of accessory sec glands -- rare. Seminal vesiculitis: - Klebsiella. - Pseudomonas. - Streptococcus. - Staphylococcus. - Brucella abortus. 2. Reduces sperm longevity. 3. PMN and bacteria.

Question 35

Fractioned ejaculates.

Answer 35

1st jet = bulbourethral gland secretions. 1st-3rd jets = sperm rich fraction, fluids from testes, epididymis and ampullae. Remaining jets (approx. 9 in all): - sperm poor fractions. - fluids from seminal vesicles and prostate glands. Identify source of blood/pus/bacteria and remove gel.

Question 36

Endoscopy -- urethroscopy (and cystoscopy).

Answer 36

Under standing sedation. Using standard endoscope designed for equine upper respiratory tract. <8mm diameter, 1-2m length. Lubricate tip. Air distension. Normal appearance: - pale pink mucosa. - longitudinal folds. Use to ID source of: - blood (haemospermia.haematuria). - pus. - visualise uroliths.