Reproductive Disorders in the Stallion Flashcards
Which stallions should be selected for breeding?
- 75% pregnancy rate during one breeding season if can do 40 mares with natural cover and 120-140 mares with AI
- Eliminate stallions with genetic defects
- Alert owner about potential unsatisfactory breeders
Breeding soundness exam in stallions
- PE
- Testing (hereditary disorders and infectious disease)
- Testicular palpation and measurements
- Penis exam
- Semen collection and evaluation
- Testicular measurements
Semen collection and evaluation method
- 2 ejaculates one hour apart
- Total # of spermatozoa/ejaculate
What is the number of normal, progressively motile spermatozoa that we should get?
- At least 1 billion in the second ejaculate
Testicular measurements
- Total scrotal width
- Length, height, and width
- Volume
Common complaints in breeding stallions
- Visible abnormalities (cryptorchidism, penile lesions)
- Behavioral problems (poor libido or aggression and self-mutilation
- Impotentia coeundi
- Impotentia generandi (ejaculation failure, abnormal ejaculates with regards to color, concentration, viability, or morphology)
- Emergencies
When should both testes be in the scrotum?
- At birth
What is cryptorchidism?
- Incomplete descending of testicles at birth
Risk factors for cryptorchidism?
- Breed predisposition
Treatment of cryptorchidism
- Improve testicular descent?
- hCG
- GnRH
- Not effective
- Best recommendation is castration
Breeding cryptorchids
- Eliminated from breeding in several countries (not in the US)
How to differentiate between a cryptorchid and gelding with stallion behavior?
- Testosterone before and after hCG
- Estrogen
- Anti-Mullerian hormone
- Transabdominal or transrectal ultrasonography
Will AMH be higher in a cryptorchid or a gelding with stallion behavior?
- In a true cryptorchid or stallion
Transabdominal or transrectal ultrasonography suggestive of cryptorchid
- Normal development of accessory sex glands
- Presence of intra-abdominal testis
Categories of things that cause balanitis or balnoposthitis
- Viral
- Smegma accumulation (bacterial/fungal)
- Parasitic
Viral cause of balanitis
- EHV-3 or coital exanthema
What causes smegma accumulation in general?
- Bacterial/fungal complications
When are parasitic infections of the penis most likely?
- Summer (summer sores with Habronema larvae)
Diagnosis of parasitic causes of balanitis?
- Biopsy and clinical presentation
Treatment of parasitic balanitis?
- Topical
Prevention of parasitic balanitis?
- Fly control, hygiene, ivermectins
What are most tumors of the penis?
- Squamous cell carcinomas (75%)
- Also melanomas
- Cutaneous lymphoma and sarcoids less commonly
Diagnosis of neoplasia of the penis
- History
- Lesions
- Histopathology
Treatment of SCC in the penis
- Early on 5-FU and cisplatin
Treatment of melanoma of the penis
- Vaccines?
Surgical repair of tumors of the penis?
- Reefing or phallectomy
What are most common causes of paralysis of the penis?
- Mostly neurologic diseases
- Damage to sacral nerves
- Infectious disease
- Phenothiazine based tranquilizers (propionyl promazine)
- Exhaustion
- Starvation
- Trauma
Infectious diseases that can cause paralysis of the penis
- EHV-1
- Rabies
- Streptococcal purpura hemorrhagic
Symptoms of penile paralysis
- Flaccid penis, edema, excoriation
Treatment of penile paralysis
- Medical/physical management
- Phallectomy and urethrostomy if too late
Poor libido definition
- No response to a mare in estrus after a period of 10 minutes
- Don’t vocalize or have Flehmen response or erection
- No secondary behaviors
Male donkey libidinous behavior in general
- Takes longer
Causes of poor libido in stallions?
- Learning problems in young stallions or stallions retired from performance
Aggressive behavior signs in stallions
- Flank biting (abdomen, flank or hind limb while kicking and/or striking out, vocalizing in sharp squeals or barking grunts
Rule outs for aggressive behavior signs in stallions
- Painful conditions
- Behavioral problems
Management of aggressive behavior in stallions
- Address pain
- Physical device treatments to reduce self-mutilation (like cones)
- Provide motivation for a substitute behavior or strong distraction
- Diet change
- Odor masking preparations
- Medications
What diet for aggressive stallions?
- Only grass
Medications for aggressive stallions?
- Long-acting tranquilizers may work (fluphenazine)
- TCAs: imipramine, clomipramine
- Nutritional supplementation with L-tryptophan (serotonin precursor)
- Progesterone treatment
Risks of progesterone treatment in stallions when treating aggressive behavior
- Affects fertility long-term and testicular size
Impotentia coeundi problems
- Mounting problems
- Erection failure
Causes of erection failure?
- Complicated
- Look for painful lesions on the glans penis
- Abnormal vasculature
- Penile deviation
Abnormal vasculature causes of erection failure
- Compromised blood flow to the cavernosum body
Penile deviation from Stallion rings
- I guess it’s a thing
Diagnosis of causes of erection failure
- History
- PE
- Neurologic examination
- Contrast rads
- Penile ultrasound
Impotentia generandi
- Ejaculatory disorders
What’s included in ejaculatory disorders?
- Ejaculatory failure
- Incomplete ejaculation
- Retrograde ejaculation (rare)
- Premature ejaculation (rare)
- Urospermia
- Spermastasis (occluded or plugged ampullae)
- Poor semen quality (Azoospermia/oligozoospermia, teratozoospermia
Azoospermia
- No sperm
Oligozoospermia
- few sperm
Teratozoospermia
- Deformed sperm
Plan to work up ejaculatory disorders
- Complete physical examination
- Lameness and musculoskeletal examination
- Complete repro exam
- Use different collection methods
- Natural cover
- Videotape all sessions for review
- Use aids to facilitate ejaculation
- Attempt ex-copula induction of ejaculation
Aids to facilitate ejaculation
- Enhance sexual arousal (prolonged teasing, breeding chedule for maximum arousal, use mount mare in natural estrus, stable mount mare, minimal distraction in breeding shed, positive reinforcement)
- remove or reduce cause of pain or discomfort
- Increase stimulation of the penis by hot compress
- Enhance sexual arousal
- Lower ejaculatory threshold
- Induce ejaculation
Drugs to enhance sexual arousal
- GnRH, Diazepam
Drugs to lower ejaculatory threshold
- Imipramine
Drugs to induce ejaculation (ex-copula)
- Detomidine
- Imipramine
- Xylazine
- Imipramine + xylazine
Usual protocol for ex-copula induction of ejaculation
- Imipramine 2 hours before with xylazine 2 hours after that
- Ejaculation within 1-15 minutes
Volume and concentration with ex-copula ejaculation
- Volume decreased with high concentration
Management of true ejaculation failure?
- 100 mg imipramine 2 hours before collection
- Hot towels
How do we know if the horse has ejaculated or not?
- Pelvic thrust right before ejaculation
- Flag the tail after ejaculation
What % of ejaculatory disorders due to musculoskeletal system?
- ~50%
Examples of musculoskeletal disorders that can lead to ejaculatory problems
- Osteoarthritis
- Neurologic diseases
- Sore back
- Rhabdomyolysis
- Laminitis
- Aorto-iliac thrombosis
Management of stallions with musculoskeletal disease
- Control pain
- Enhance sexual arousal
- Ex-copula ejaculation
- Accommodate for musculoskeletal deficiencies
- One mount rule
What is the one mount rule?
- Find proper handling to achieve ejaculation with a single mount