Age and other factors like season and breed are often associated with sperm quality and fertility in domestic animals. Even though many studies assessed the relationship between the age of the male and sperm parameters, the effects have not been comprehensively evaluated. Changes in semen quality from pubertal (young) to adult and old age were identified in the bull, ram, buck, boar, dog, and stallion, respectively. The review discusses the association between male age and semen volume, the total number of spermatozoa per ejaculate, sperm concentration, motility, morphology, sperm cell function, sperm DNA integrity, oxidative stress, and antioxidant activity in these species of animals. Generally, semen characteristics improve to a certain age, which declines as the animal ages. Only a few studies evaluated the impact of advanced age or employed advanced functional sperm assessment methods to assess age-related changes in sperm quality and male fertility. Such studies in the dog or stallion, for instance, may contribute to advancing knowledge in human-assisted reproductive techniques used in patients of advanced paternal and maternal age.

Contents: Over the last 10–15 years, long‐acting GnRH agonists have become widely available. In the field of small animal reproduction, most recent studies have focused on the use of two compounds developed under the form of subcutaneous implants: azagly‐nafarelin and deslorelin. Only the latter has been commercially available for use in male dogs, first in Australia and New Zealand, then in several countries of the European Union since 2008. Although officially marketed for male dogs, this compound has also been studied in bitches and more recently in queens. Some published papers or recent presentations at congresses – still unpublished – have focused on the use of GnRH agonists implants in females.

Hypo-osmotic swelling test (HOST) is used to assess the functional integrity of sperm plasma membranes in many species. The primary aim of this study was to test a simplified HOST procedure for the evaluation of feline semen. The second objective was to check if sperm abnormalities can influence the results of this test. Urethral semen was collected from 19 male, domestic cats. In Exp. 1, HOST was performed in different media (50 mOsm/kg fructose or distilled water), temperature (37 °C or room temperature) and time (5 and 30 min). In Exp. 2, the potential effect of sperm abnormalities on HOST results was assessed by observing individual normal and abnormal spermatozoa microinjected into droplets of distilled water. The results showed no differences between the HOST results performed in different media, temperature and time. Viable abnormal spermatozoa were able to swell under hypo-osmotic conditions in the same manner as normal ones, except spermatozoa with distal droplets, which showed a higher frequency of ‘despiralization’. In conclusion, HOST can be reliably performed at 0 mOsm/kg for 5 min at room temperature, which may contribute to a wider use of this test under clinical environments. Viable abnormal spermatozoa are able to swell under hypo-osmotic conditions; therefore, their presence in the ejaculate would not bias the results of HOST when total coiling is calculated.