Equine Male Reproduction

What are the seven primary parts of the equine male reproductive tract?

Scrotum, testes, epididymis, spermatic cord, accessory sex glands, penis, and prepuce.

Which asymmetrical sac holds the equine testicles?

The scrotum.

What structure divides the equine scrotum into two separate compartments?

The median raphe.

Which scrotal layer contains large numbers of sebaceous and sweat glands?

The skin (outermost layer).

What tissues compose the tunica dartos layer of the scrotum?

Muscular and fibro-elastic tissue.

Which scrotal layer contracts and relaxes to regulate testicular temperature in response to the environment?

The tunica dartos.

What is the primary function of the scrotal fascia?

It is loose connective tissue that allows the testicles to move freely within the sac.

The tunica vaginalis in the scrotum is continuous with which body cavity lining?

The peritoneum.

Which scrotal layer is composed of fibrous tissue and divides the testis into lobes?

The tunica albuginea.

What is the defining characteristic of a 'closed' castration?

The tunica vaginalis remains closed during the procedure.

What is the defining characteristic of an 'open' castration?

The tunica vaginalis (peritoneum) is exposed or opened.

What is the primary clinical advantage of a closed castration?

It reduces the chances of peritoneal infection.

What is the primary risk associated with an open castration?

Increased risk of peritonitis.

Where specifically is the surgical incision made for an equine castration?

1-2cm paramedian (away from the median raphe).

Why is it illegal to remove only one testicle during a castration?

Both testes must be removed because the horse remains a stallion (cryptorchid) otherwise.

What are the five most common complications of equine castration?

Edema, infection, heavy bleeding, omental prolapse, and intestinal herniation.

What is the cause of a scrotal hernia (as opposed to a castration complication)?

Severe inguinal ring opening during breeding that allows intestines to escape into the scrotum.

What is the typical width range of firm, oval-shaped equine testes?

9-13cm

What two factors primarily influence the size of equine testicles?

Season and the age of the animal.

Why is testicular size a useful indicator for a stallion?

It correlates with the amount of sperm produced and breeding potential.

Which cells in the testes are responsible for sperm nourishment and development?

Sertoli cells.

Which cells in the testes secrete hormones for secondary sex characteristics?

Leydig cells.

What is the clinical term for the failure of one or both testes to descend into the scrotum?

Cryptorchidism.

What is a 'high flanker' in equine medicine?

A horse with abdominal cryptorchidism (testicle remains in the abdominal cavity).

What is a 'low flanker' in equine medicine?

A horse with inguinal cryptorchidism (testicle remains in the inguinal canal).

Name two equine breeds where cryptorchidism is most commonly found as a heritable problem.

Quarter Horses and Saddlebreds

(also Percherons and Standardbreds).

What are the two primary surgical approaches for treating cryptorchidism?

Ventral abdominal incision (linea alba) or laparoscopy.

What are the three anatomical parts of the epididymis?

Head, body, and tail."

Which part of the epididymis serves as the site for sperm storage prior to ejaculation?

The tail.

What are the four primary functions of the epididymis regarding sperm cells?

Transport, maturation, concentration, and protection.

What four components are contained within the equine spermatic cord?

Ductus deferens, testicular vessels/nerves, lymphatic vessels, and the cremaster muscle.

How much cooler must equine testes be relative to the body for proper function?

3-5℃ less than body temperature.

Which muscle within the spermatic cord helps change testicular position for thermoregulation?

The cremaster muscle.

What is the function of the pampiniform plexus?

It is a heat-exchange mechanism where cooled veins coil around warm testicular arteries.

Which accessory sex gland is responsible for sperm storage just before the pelvic urethra?

The ampulla of the ductus deferens.

What is the primary function of the equine prostate gland?

Providing alkaline secretions to the semen.

Name the four accessory sex glands in the stallion

Ampulla, vesicular gland, prostate, and bulbourethral gland."

The stallion has a _ type of penis.

Musculocavernous

What are the three main anatomical regions of the equine penis?

Glans, body, and root.

Which dorsal erectile tissue is surrounded by the tunica albuginea in the penis?

Corpus cavernosum.

Which erectile tissue specifically surrounds the urethra?

Corpus spongiosum.

What is the function of the retractor penis muscle?

It pulls the penis back into the prepuce after erection or urination.

What structure in the glans penis is the common site for the accumulation of 'beans' (smegma)?

The urethral sinus.

What is the clinical term for the inability to retract the penis into the prepuce?

Paraphimosis.

Which surgical procedure involves creating a new opening for the urethra in the perineal region?

Perineal Urethrostomy.

What is 'smegma' in the context of equine penile health?

Secretions and dead skin cells that can harden into 'beans' within the urethral sinus.

Which specific artery provides the main blood supply for the equine testes and is a risk for bleeding during castration?

The testicular artery.