• A BSE is important if one hopes to use a dog for stud purposes. This will establish that the dog produces spermatozoa that move normally, in normal quantities with normal morphological characteristics. It will show that he has a normal penis, can probably copulate normally and has normal testes and epididymides and no apparent prostatic disease. A BSE should also establish that a dog is free from brucellosis Brucellosis. A positive screening test should always be followed by a more specific confirmatory test. 
  • An annual BSE test is advised for valuable, proven stud dogs; early recognition of problems provides the best chance for successful therapy.
  • A BSE should also establish that a dog has a sound disposition and is free of obvious heritable defects. This includes conformational defects and breed specific inherited diseases, most commonly orthopedic, cardiac, ophthalmologic and metabolic. The veterinarian's role in this respect has to be informative and not judgemental; great diplomacy will be required in some cases.
  • Imported dogs: a BSE should begin with a screening test for brucellosis; a positive screening test should be followed by more specific confirmatory testing. 
  • Semen collection for evaluation should be performed before the physical examination or any diagnostics are undertaken, so as not to impact the dog's libido.

Semen evaluation

  • The characteristics of normal semen Semen: evaluation are:
    • 3 components:
      • a) First fraction (pre-sperm).
      • b) Second fraction (sperm-rich).
      • c) Third fraction (post-sperm).
  • Volume variable from 1-2 ml to more than 60 ml, depending on how much third fraction is collected. Therefore, the concentration is extremely variable as well. Sperm output is less variable; from about 200 million to about one billion. The second fraction is 0.5-2.0 ml maximally.
  • At least 70% should be progressively motile when examined under high power on a prewarmed (35-37°C) slide. Also, when examined within a bubble under a coverslip under high dry power, at least 65% should have normal morphology. When the semen has been stained (Nigrosin eosin or similar) at least 60% should have normal morphology.
  • There should be no or only occasional inflammatory cells and no red blood cells unless benign or cystic prostatic hyperplasia Prostate: benign hyperplasia and hypertrophy is present. With these conditions, sperm cells can be difficult to visualize, but have normal morphology and motility. Occasional epithelial cells can be present. Bacteria and inflammatory cells may be urethral in origin and not problematic; this is supported by normal semen characterisitics otherwise.

Evaluation of the penis, prepuce, testes, epididymides, and prostate gland

  • The penis should be able to be extruded from the prepuce without difficulty (preputial orifice normal in size) and should be free of mucosal lesions. No penile frenulum should be evident.
  • Both testes should be present in the scrotum, cryptorchidism Testicle: cryptorchidism; even unilateral cryptorchidism is unacceptable and heritable.
  • The testes should be palpated for normal turgor Testicular degeneration and irregularities that may indicate neoplasia Testicle: neoplasia or current or past inflammatory disorders. They should also be compared with one another and if possible with age/breed matched cohorts for evidence of hypoplasia Testicular hypoplasia or atrophy. Although unusual in dogs, examine the scrotum for inguinal herniation Inguinal hernia as well. The left and right epididymides should be palpated carefully and compared with one another for symmetry.
  • There should be no pain on palpation of either the prostate Prostate gland: clinical examination, testes or epididymides.
  • Ultrasound of the prostate Ultrasonography: prostate, bladder Ultrasonography: bladder and urinary tract, testes Ultrasonography: testes and epididymi is indicated if abormalities are detected on the physical examination or with semen evaluation. 

Male reproductive tract morphologic disorders

  • The heritability of the following disorders is not known.


  • Definition: inability to extrude the penis from within the prepuce. This can occur if the dog develops an erection while the penis is still ensheathed in the prepuce, most commonly with inexperienced stud dogs during semen collection. This can occur with a non-erect penis if the preputial orifice is too small, a developmental problem, or if stenotic secondary to chronic inflammation. A small preputial orifice can require surgical intervention; care must be taken not to enlarge the orifice excessively or paraphimosis can result.


  • Definition: inability to return the penis within the prepuce . This occurs most commonly after manual semen collection without adequate use of (non-spermicidal) lubrication at the base of the penis; during detumescence the skin at the preputial orifice can roll inwards preventing normal return of the penis into the prepuce. This can be exacerbated by a long hair coat. Occasionally, this occurs after a natural breeding with an outside tie (no copulatory lock). Rarely this occurs after natural breedings due to a comparatively small preputial orifice. It can be iatrogenically produced if preputial orifice revision results in an opening that is too small or too large.

Persistent frenulum

  • The frenulum attaches the pediatric penis to the internal, ventral aspect of the preputium and normally regresses under the effect of androgens at puberty. If persistent, the frenulum causes the erect penis to flex ventrally, interfering with the ability of the stud dog to accomplish a natural breeding . Surgical correction is indicated .

Fracture of the os penis

Neoplasia of the male reproductive tract