Common causes of male dog infertility.

A complete breeding soundness evaluation is essential for assessment of the infertile male dog. Cryptorchidism, a sex-limited autosomal recessive trait, is more common as a unilateral condition. Azoospermia is an ejaculate consisting of seminal plasma but lacking sperm; repeated semen collections in the presence of an estrual bitch will rule out inadequate experience and lack of sexual stimulation. Both carnitine and alkaline phosphatase (AP) are produced in the epididymis; seminal plasma AP concentrations>5000 U/L indicate a normal ejaculate, whereas <5000 U/L is associated with incomplete ejaculation. Benign prostatic hypertrophy (BPH), the most common age-related condition in intact male dogs, is characterized by a sanguineous urethral discharge, hematuria, or hemospermia; diagnosis is based on prostatic enlargement and confirmed by a transabdominal biopsy. Although castration is recommended, valuable breeding dogs can be given finasteride. Prostatitis is more common in older dogs with BPH. Culture of the third fraction of the ejaculate or urine obtained by cystocentesis is indicated. Bacterial prostatitis is treated with antibiotics with high lipid solubility. Some dogs with bacterial prostatitis may develop prostatic abscesses (a medical and surgical emergency). Prostatic cysts are often asymptomatic. Approximately, 5-7% of dogs with prostatic disease have prostatic neoplasia, most commonly adenocarcinoma (it occurs in both intact and castrated dogs), which often metastasizes and has a very poor prognosis. Although a specific diagnosis can be made in many cases of male dog infertility, not all causes are amenable to treatment.