Page 545 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

520 CHAPTER 2

VetBooks.ir between handler and examiner is essential. It can management guidelines to optimise pregnancy
rates. The BSE includes: accurate animal identifica-
be helpful to stand the stallion against one wall to
limit his movement during the examination. The
libido; bacterial culture of the urethra and semen;
examiner approaches slowly but confidently from tion; a complete physical examination; evaluation of
the left side at an angle to the shoulder, and moves evaluation of semen for pH, total sperm numbers,
alongside the stallion until reaching the left flank. It sperm motility, morphology and longevity; and
is helpful to run the left hand or arm over the stal- examination of the external reproductive organs.
lion’s neck and back as one moves toward the stal- Additional tests that may be warranted during the
lion’s flank, so the stallion is aware of the examiner’s BSE include examination of the internal reproductive
location. The examiner should never surprise the organs, endoscopy of the urethra and measurement
stallion with movements or grasping of genitalia, of motility after semen cooling or freezing. Results
as the most likely response will be a forceful kick must be recorded clearly and permanently.
with the hindlimbs. Many stallions squeal and kick After the BSE, stallions are classified as satisfac-
out behind when the scrotum or penis is palpated or tory, questionable or unsatisfactory. Classification
washed. With training, most stallions become accus- guidelines are listed in Table 2.3. Results of the BSE
tomed to routine examination without difficulty. are not a guarantee of fertility or infertility and
must not be represented as such. Occasionally, stal-
INTRODUCTION lions with apparently adequate results may achieve
poor pregnancy rates. In such cases, additional
Guidelines for evaluation of breeding sound- diagnostics, including evaluation of breeding man-
ness in stallions are published by the Society for agement, and additional sperm staining and func-
Theriogenology (www.therio.org). The primary tion assays are required to diagnose the problem.
purpose of the breeding soundness examination In contrast, stallions classified as questionable may
(BSE) is to select stallions that are expected to achieve adequate pregnancy rates, especially when
achieve pregnancy rates of at least 70% when bred to bred to a limited number of mares. It is important
40 mares by natural service or 120 mares by artificial to remember that the BSE predicts fertility based on
insemination (AI). A second purpose of the BSE is findings from a single day. Semen quality is expected
to diagnose causes of reduced fertility and develop to change over time depending on factors such as

Table 2.3 Classification criteria for stallion breeding soundness evaluation (Society for Theriogenology)

Satisfactory classification
• Good libido.
• Penis anatomically normal and free from inflammatory lesions.
• Bacterial culture does not result in pure growth of a single organism.
• Bacterial culture under correct conditions is negative for Taylorella equigenitalus (contagious equine metritis).
• Equine infectious anaemia (Coggins) test is negative.
• Two scrotal testes are present.
• Testicles and epididymides are of normal size, shape and texture.
• Total scrotal width is >8 cm.
• At daily sperm output, the second of two ejaculates collected 1 hour apart contains a minimum of 1 billion progressively
motile morphologically normal sperm.
Questionable classification
• At or below standard on two or more of the criteria above.
Unsatisfactory classification
• Uni- or bilateral cryptorchidism.
• Equine infectious anaemia (Coggins) test positive.
• Carrier of known genetic disease (e.g. combined immunodeficiency disease of Arabian horses).