Reproductive Disorders of the Stallion

Question 1

Semen collection and evaluation

Answer 1

 2 ejaculates one hour apart
 Total number of
spermatozoa/ejaculate
 Total number of normal
progressively motile spermatozoa
should be at least 1 billion in the
second ejaculate

Question 2

Cryptorchidism

Answer 2

• Testes should be in the
scrotum at birth
• Breed predisposition
• Treatment
 Improve testicular descent???
– hCG
– GnRH
 Castration
– Eliminated from breeding in
several countries (Not in the
USA)

Question 3

Differential diagnosis between cryptorchid and

gelding with stallion behavior

Answer 3

Endocrine
• Testosterone before after
hCG stimulation test
• hCG: 6000-10000 IU IV
• Testosterone increase 2
to 3 fold after 2 hours
• Estrogen
• Anti-Mullerian Hormone
Transabdominal or
transrectal ultrasonography
• Normal development of
accessory sex glands
• Presence intraabdominal
testis

Question 4

Penile lesions: Balanitis / Balanoposthitis

Answer 4

• Viral
 Coital exanthema (EHV-3)
• Smegma accumulation
 Bacterial / fungal
complications
• Parasitic
 Summer sores (Habronema
larvae)

Question 5

Treatment of parasitic balanitis

Answer 5

 Diagnosis (biopsy)
 Topical treatment
 Prevention:
– Fly control
– hygiene
– Ivermectins

Question 6

Neoplasia

• Type of neoplasia

Answer 6

 Squamous cell carcinomas
 Melanomas
 Other
– Cutaneous lyphosarcoma
– Sarcoids

Question 7

dx of neoplasia; tx

Answer 7

• Diagnosis
 History
 Lesions
 Histopathology
• Treatment
 SCC: early 5 F-U, cisplatin
 Melanoma: vaccines?
 Surgery: reefing, phalectomy

Question 8

Paralysis of the penis - causes

Answer 8

 Damage to sacral nerves
 Infectious diseases: EHV-l, Rabies,
Streptococcal- associated purpura
hemorrhagica
 Phenothiazine-base tranquilizers
(propionyl promazine)
 Exhaustion
 Starvation
 Following trauma

Question 9

clinical signs of penis paralysis

Answer 9

 Flaccid penis, edema, excoriation

Question 10

treatment of penis paralysis

Answer 10

 Medical/physical management if
early detection, penile amputation if
too late

Question 11

Poor libido

Answer 11

• No response to an
estrous mare after a
period of 10 minutes
• No secondary behaviors
• Donkey may take a lot
longer
• Consider learning
problems in young
stallions or stallions
retired from performance

Question 12

Aggressive behavior- Self-mutilation

Answer 12

• Flank-biting (abdomen, flank or hind limb while kicking and/or striking out
vocalizing in sharp squeals or barking grunts)
• Rule out
 Painful conditions
 Behavioral problems

Question 13

Aggressive behavior- Self-mutilation - management

Answer 13

 Address pain
 Physical device treatments to reduce self-mutilation
 Provide motivation for a substitute behavior or a strong distraction
 Diet change (grass and grass hay only without any grain or richer forage)
 Long-acting tranquilizers such as fluphenazine may be effective
 Tricyclic anti-depressants such as imipramine and clomipramine have
been found clinically useful
 Nutritional supplement l-tryptophan, the precursor of serotonin, has been
clinically effective in reducing self-mutilation
 Progesterone treatment (affects fertility)
 Odor masking preparations

Question 14

Impotentia coeundi

Answer 14

• Mounting problems

* Erection failure

Question 15

Erection failure

Answer 15

• Erection: a complex
process
• Look for painful lesions
on glans penis
• Abnormal vasculature
 Compromised blood flow
to the cavernosum body
• Penile deviation
 Old lesions of “Stallion
rings”

Question 16

Impotentia generandi

Answer 16

• Ejaculatory disorders
 Ejaculation failure
 Incomplete ejaculation
 Retrograde ejaculation (rare)
 Premature ejaculation (rare)
 Urospermia
 Spermastasis (occluded or plugged ampullae
syndrome)
• Poor semen quality
 Azoospermia/oligozoospermia
 Teratozoospermia

Question 17

Aids to facilitate ejaculation

Answer 17

• Enhance sexual arousal
• Remove or reduce cause of pain or discomfort
• Increase stimulation of the penis: hot compress at the
base of the penis
• Enhance sexual arousal (GnRH, Diazepam)
• Lower ejaculatory threshold (Imipramine)
• Induce ejaculation

Question 18

50% of ejaculatory

disorders are atributed to what?

Answer 18

musculoskeletal problems 
• Osteoartritis
• Neurologic diseases
• Sore back
• Rhabdomyolysis
• Laminitis
• Aorto-iliac thrombosis

Question 19

Management of stallions with musculoskeletal

disease

Answer 19

• Control pain
• Enhance sexual
arousal
• Ex-copula ejaculation
• Accommodate for
musculoskeletal
deficiencies
• One-mount rule
 Find proper handling to
achieve ejaculation with
a single mount

Question 20

• Azoospermia

Answer 20

 Complete testicular degeneration
 Orchitis
 Testicular hypoplasia
 Epididymal blockage (bilateral)

Question 21

• Oligozoospermia

Answer 21

 Testicular degeneration
 Incomplete ejaculation (sperm
accumulator)
 Retrograde ejaculation

Question 22

Azoospermia / Oligozoospermia due to testicular

degeneration - factors

Answer 22

 Age
 Anabolic steroids
 Altrenogest
 Testicular trauma/infections
 Fever

Question 23

testicular

degeneration clinical findings

Answer 23

 Small testes / asymmetry
 Increase spheroids in
ejaculate
 Increased sperm
abnormalities
 Low motility

Question 24

Sperm Agglutination/accumulation: Diagnosis

Answer 24

• Very high concentration
• Presence of epithelial cells
• Clumping
• Transrectal ultrasonography
 Enlarged ampula of the vas
deferens

Question 25

“Plugged or occuluded ampullae”: Treatment

Answer 25

• Ampullae
massage
• Oxytocin, PGF2
alpha before
breeding
• Frequent
ejaculation
 1 x to 2 x per day
for 10 days

Question 26

Hemospermia

Answer 26

Glans penis
 Surface of the penis
 Urethra
– Urethritis
– Urethral rents
 Internal genitalia
– Seminal vesiculitis
• Timing of bloody discharge
• Quantity
• Diagnosis
 Clinical evaluation
 Transrectal ultrasonography
 Endoscopic evaluation of the
urethra and accessory sex glands

Question 27

Hemospermia - Treatment

Answer 27

• Antimicrobials
• Sexual rest
• Urinary antiseptics
• Sub-Ischial
urethrotomy
• Management during
the breeding season
 Fractionated ejaculate
 Collection into extender
 Chemical ejaculation??

Question 28

Urospermia clinical signs

Answer 28

Clinical signs
– Large volume ejaculate
– Change in color
– Urine odor
– Sediment
– Poor motility

Question 29

Urospermia dx

Answer 29

•Diagnosis
–Evident (odor color)
– Azostix®
– Determination of creatinine
(>2g/dl)
–Urea (>30 mg/dl)

Question 30

urospermia causes

Answer 30

– Cauda equine neuritis
– EHV-1
– Sorghum and sudan grass
– Severe pain
– Urolithiasis
– Generalized neoplasia

Question 31

Urospermia - Treatment

Answer 31

• Diuretics: Furosemide (250 mg IV) (Lowe, E.V.J. 2001,
Thoroughbred stallion)
• Catheterization of the bladder and imipramine (Turner et al 1995)
• No improvement with furosemide or imipramine in 3 cases
(Sepulveda et al, Reprod. Dom. Anim 1999)
• Management: Fractionation of ejaculate, “washing”
• Flavoxate hydrochloride (bladder wall relaxation)
• Bethanechol chloride (improves coordination of the bladder
sphincter and detrusor function)

Question 32

Seminal vesiculitis (Pyospermia)

Answer 32

• Infertility
 Normal breeding behavior or
reluctance to breed
 Poor semen quality
• Straining and posturing
after breeding
• Inflammatory cells in
ejaculate, +/- microscopic
hemospermia

Question 33

Seminal vesiculitis Dx/Tx

Answer 33

• Culture:
Catheterization and
massage
• Treatment
• Direct flushing
• Antibiotic infusion
• Systemic antibiotics
• NSAIDs
• Management:
 Minimum contamination
breeding
 AI (direct collection in
extender, fractionate