Management of breeding stallions is crucial to equine reproduction. The longevity of the breeding career is the ultimate objective, whether the stallion is used for natural cover or for semen collection and artificial insemination. Stud farm veterinarians should be aware of the techniques used to evaluate testicular function and the diagnostic approach to testicular disorders in cases of emergency. This paper presents the clinical methods used to evaluate testicular health, including palpation, ultrasonography, biopsy, and fine-needle aspiration. The discussion of testicular disorders is broken down into four categories: congenital disorders (cryptorchidism, monorchidism, and testicular hypoplasia), differential diagnosis of scrotal enlargement, differential diagnosis of causes of progressive testicular enlargement, and differential diagnosis of testicular asymmetry or reduction in size with an emphasis on testicular degeneration. The sudden increase in testicular size is often accompanied by severe clinical signs and is a major cause for referral of stallion for surgery. Testicular disorders are illustrated with clinical cases seen by the authors.

Llamas and alpacas are important production animals in South America, with increasing interest in other parts of the world. Poor reproductive efficiency combined with several unique anatomical and physiological reproductive features offer challenges in the diagnosis and treatment of infertility in camelids. This review presents an approach to the clinical investigation and common causes of infertility and subfertility in the male and female. The selection of males for breeding should be made based on complete evaluation to eliminate congenital and possibly hereditary disorders. Common disorders of the male reproductive system include testicular hypoplasia, testicular and epididymal cysts and testicular degeneration. Semen evaluation presents some challenges owing to the viscous nature of the ejaculate in these species. Females should be screened for congenital genital defects before breeding. Causes of subfertility in the female are dominated by ovarian and uterine disorders. A systematic clinical approach and the use of endometrial biopsy and advanced techniques, such as laparoscopy, allow early identification of these disorders. Further research is needed for continued understanding of the reproductive pathological processes in these species.

This comprehensive review explores the complex processes of reproduction, pregnancy establishment, and pregnancy diagnostic methods in cattle, sheep, goats, swine, horses, and camelids. It provides an overview of the history of pregnancy detection and an in-depth exploration of the physiology of pregnancy in livestock. The detection of conceptus tissue and fluids, conceptus-produced hormones, and maternal responses to conceptus signals, crucial for pregnancy diagnosis, are also discussed in detail, as are emerging methods for pregnancy diagnosis in livestock species. Overall, this review emphasizes the direct impact of pregnancy diagnosis and efficient pregnancy management for profitability of livestock enterprises.

Alpacas have a high incidence of congenital reproductive tract abnormalities, including ovarian hypoplasia/dysgenesis. Diagnosis of this condition is often challenging. The present study describes the clinical, ultrasonographic, and histologic features of ovarian hypoplasia/dysgenesis syndrome in 5 female alpacas. Additionally, serum AMH levels were compared between female alpacas diagnosed with ovarian hypoplasia/dysgenesis and a group of reproductively sound females (n= 11). The syndrome was suspected based on the presence of an infantile uterus and lack of ovaries by ultrasonography and laparoscopy. All females had normal female karyotype (n= 74 XX), but one presented a minute chromosome. The ovaries from these cases showed 3 main histological classifications: hypoplasia (n= 2), dysgenesis (n= 2), and dysplasia (n= 1). Serum AMH levels in affected females were significantly lower (P< 0.05) than those of reproductively sound control females. In conclusion, Serum AMH level may be helpful in the rapid diagnosis of ovarian hypoplasia/dysgenesis syndrome in alpacas. Furthermore, this syndrome in alpacas presents a variety of histological features. Different mechanisms may be involved in the derangement of ovarian differentiation. Further studies are needed to elucidate the causes of the syndrome.

Steroid response to human Chorionic Gonadotropin (hCG) administration has been used in various species to study testicular function and for diagnostic purposes. In this study, two experiments were conducted to determine serum testosterone concentration response to administration of hCG and its correlation with testicular weight. In the second experiment the relationship between age, testosterone and estrogen response to hCG, and testicular histometry was in pre-pubertal and post-pubertal male alpacas. For experiment 1, males in two age groups (2 to 3 years, n = 9) and (4 to 7 years; n = 15) received 3,000 IU hCG IV, 36 to 48 h before castration. Serum testosterone concentration was determined before (T0), 1 h (T1), 2 h (T2), 8 h (T8), and 24 h (T24) after administration of hCG. Basal concentrations of serum testosterone was significantly different (P < 0.01) between age groups. Serum testosterone concentrations increased over time and doubled 2 h after treatment. The highest change (250 to 300% increase from T0) was observed at 8 h (3.5 ± 0.3 ng/ml). A significant correlation (P < 0.01; r = 0.64) was found between serum testosterone concentration and total testicular weight. For experiment 2, 60 males ranging in age from 6 to 60 months were used. Serum testosterone and estrogen was determined in samples taken just prior to and 2 h after administration of 3,000 IU hCG. Basal serum testosterone concentrations were very low (≤0.1 ng/mL) until 9 months of age then increased steadily with age. There was a significant variation amongst males within the same age group. Serum testosterone concentration increased by 2- to 4-fold 2 h after hCG injection (P ≤ 0.05). Males in the 13 to 14 months of age group had the highest rise. Estrogen concentration increased in response to hCG administration and was detected only in males with high testosterone. We conclude that administration of 3,000 IU of hCG IV can be used reliably to detect testicular tissue and study its steroidogenic activity. The response is correlated with testicular weight and Leydig cell number. Testicular growth and sensitivity to LH stimulation increases between the ages of 13 and 14 months. The aromatizing ability of Leydig cells increased significantly in post-pubertal male alpacas.