Chapter 8 BREEDING MANAGEMENT OF THE WARMBLOOD STALLION
NUTRITION
Vitamin and mineral supplementation of the breeding stallion beyond National Research Council requirements is not necessary and will not improve semen quality.1
A common problem in breeding stallions is excessive weight. Horse owners commonly increase feed intake, particularly grain, during the fall and winter to offset the nutritional demands of cold weather. Feed intake, again, may be increased at the onset of the breeding season. However, many of these stallions are kept indoors during the winter and may even be blanketed. These nutritional changes are usually unwarranted and predispose the horse to laminitis. It is recommended that stallions be weighed each month. An ideal weight for the horse should be determined and maintained with minimal fluctuation. The feeding program should be closely associated with an exercise program. Recent evidence would suggest that feeding docosahexaenoic acid (DHA)–enriched nutraceuticals would have a significant effect on the quality of fresh, cooled, and frozen stallion semen 2
PREVENTIVE HEALTH CARE
Parasite Control
The stallion should be dewormed at regular intervals based on farm needs. No adverse effects from anthelmintics, such as pyrantel pamoate,∗ fenbendazole,† ivermectin,‡ or moxidectin,§ have been noted in stallions. A frequently used interval for deworming horses is 8 weeks, with the dosage based on the horse’s weight. Continuous, daily feeding of pyrantel pamoate¶ has also been safely used in breeding stallions. Periodic examination of fecal specimens should be performed to monitor the efficacy of specific deworming compounds and intervals between treatments.
Dental Examinations
Dental examinations should be conducted on all stallions once per year, or as needed, for each horse. Floating and other dental procedures should be performed as needed to maintain normal mastication and dental arcade alignment. If tranquilization is needed to safely conduct dental examinations and procedures, promazine tranquilizers should not be used due to risk of penile paralysis.3,4
Vaccinations
Equine arteritis virus can be spread from stallions to mares via respiratory secretions and the semen.5,6 Approximately 30% of horses previously exposed to equine viral arteritis (EVA) continue to shed EVA virus in their semen. Some of these stallions continue to shed the virus in semen for life. EVA virus infection can cause upper respiratory infections and abortion. The virus from shedding stallions can be passed to seronegative mares during live cover or artificial insemination with fresh, cooled, or frozen semen. Therefore, it is recommended that all stallions to be used for live cover breeding or in an artificial insemination program be serologically tested for exposure to EVA virus before the onset of each breeding season. Stallions that are serologically positive to EVA virus should have an aliquot of semen submitted to an approved diagnostic laboratory to determine the presence or absence of EVA virus in the semen. If the stallion has EVA virus in his semen, he should not be used to breed seronegative mares. Seronegative mares, however, can be safely bred to a virus-shedding stallion following EVA vaccination of the mare. The seropositive stallion that does not shed EVA virus in his semen can be safely used to breed seropositive or seronegative mares without risk of inducing viral infection in the mare.
Seronegative stallions can and, in most cases, should be vaccinated against EVA (e.g., Arvac, Equine Arteritis Vaccine, Fort Dodge Animal Health, Ames, Iowa) before the onset of the breeding season and given boosters annually.5