Also see Breeding Soundness Examination of the Male Breeding Soundness Examination of the Male . The breeding soundness examination should begin with a thorough history, including information regarding libido, mating ability, number of mares bred, pregnancy rates, prior illness or injury, and any medications administered. A general physical examination should be performed, noting lameness Overview of Lameness in Horses Lameness is defined as an abnormal stance or gait caused by either a structural or a functional disorder of the locomotor system. The horse is either unwilling or unable to stand or move normally... read more (particularly of the back and hindlimbs) and heritable conditions that may affect breeding ability or desirability as a sire.
The penis and prepuce should be free of lesions. The testes and epididymides should be evaluated for size, shape, and consistency. The testes should be freely movable within the scrotum and have a total scrotal width >8 cm. The length (L), width (W), and height (H) of the testicles can be determined using calipers or ultrasonography to calculate the volume of each testicle using the equation: 0.523 (L × W × H) = testicular volume. The stallion's daily sperm output can then be predicted by the equation: total testicular volume × 0.024 – 0.76 = daily sperm output. The internal genitalia, inguinal rings, and aorta and iliac vessels are evaluated by palpation and ultrasonography per rectum. Various semen collection and evaluation techniques and criteria can be considered for determination of breeding soundness Breeding Soundness Examination of the Male classifications.
Swabs of the external genital tract (penile fossa and the urethra before and after ejaculation) can be obtained and submitted for aerobic culture to detect the presence of possible pathogens. If consistent heavy growth of potential pathogens such as Pseudomonas aeruginosa, Klebsiella pneumoniae, or Streptococcus zooepidemicus is seen on aerobic culture of swabs of the penile fossa or urethra and there is a history of repeated infection in mares bred, it may be necessary to breed by artificial insemination using semen extender containing an appropriate antibiotic to which the isolated organism is sensitive. If natural service is required, semen extender containing that antibiotic may be infused into the mare’s uterus before servicing.
Stallions found to have an overgrowth of P aeruginosa on the external genitalia (penis, prepuce) may benefit from a once-daily rinse of the penis and prepuce using a dilute acid solution prepared by mixing 10 mL 38% HCl (concentrated) with 4 L of water. Rinsing should be repeated daily until P aeruginosa is no longer isolated. Stagnant water should be removed from the stallion's environment.
If a heavy growth of K pneumoniae is isolated from the stallion's penis and prepuce, a daily rinse of the penis and prepuce may be considered using a dilute bleach solution prepared by mixing 45 mL 5.25% sodium hypochlorite (bleach) with 4 L of water. This rinsing should be performed daily for 1–2 weeks and then discontinued for 4 days, after which swabs should be taken from the penile fossa and preputial fold for aerobic culture. Treatment can be repeated if needed. Stagnant water and sawdust bedding should be eliminated from the stallion's environment.
If Taylorella equigenitalis Contagious Equine Metritis Contagious equine metritis (CEM) is an acute, highly contagious venereal disease of horses (and experimentally of donkeys) characterized by a profuse, mucopurulent vaginal discharge and early... read more is present, the stallion should not be used for breeding. The isolation of T equigenitalis requires special culture conditions; the organism will not grow in routine aerobic cultures. Stallions with lesions of coital exanthema Equine Coital Exanthema should not be used for breeding until skin ulcers are completely healed.
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Also see pet health content regarding routine health care for horses Routine Health Care of Horses In addition to properly feeding and exercising your horse, other aspects of general care are needed to keep your horse healthy throughout his or her life. These include routine veterinary care... read more and the breeding and reproduction of horses Breeding and Reproduction of Horses Mares reach puberty at about 18 months of age and undergo an estrous, or heat, cycle. Mares go into heat repeatedly during the breeding season, which usually continues while day length is long... read more .