Developed by the University of Kentucky Equine Section, Department of Animal Sciences; Reviewed by Kathy Anderson, Horse Extension Specialist, University of Nebraska
A breeding soundness exam of a stallion includes not only examination of various seminal characteristics, but also, the evaluation of the stallion’s physical condition and his ability to perform in the breeding shed. The physical examination should include evaluation of the locomotor system, including muscular, skeletal and neurological factors, as well as the stallion’s visual function. The most reliable measure of fertility in a stallion is the pregnancy rate he obtains when bred to mares of normal fertility under ideal management.
Most stallions selected for evaluation include those about to be, or recently, purchased, those about to enter the breeding season, those suspected of reduced fertility and young stallions being considered for their first breeding season. The evaluation of the stallion for potential breeding soundness consists of 4 parts:
- General physical examination
- Examination of external reproductive organs
- Examination of internal reproductive organs
- Semen collection and evaluation
General Physical Examination
In evaluating a stallion’s physical condition, pay close attention to his ability to approach and to successfully mount the mare. Any condition (conformational or otherwise) that adversely affects his ability to mount mares should be noted and corrected before he develops psychological problems and refrains from breeding. Most of these conditions will involve the musculoskeletal system of the back and hind limbs. Chronic conditions like osteoarthritis of any of the hind limb joints, chronic laminitis and bursitis may hinder his ability to cover mares. If problems become acute and cause enough pain, the stallion may become uninterested in breeding.
If a stallion has poor body condition, that may indicate inadequate nutrition or improper management. Because poor body condition of stallions may have detrimental effects on semen quality, do not evaluate such stallions for breeding soundness until the condition has been corrected and at least 60 days have passed. This will allow for spermatogenesis and sperm transport to reflect the stallion’s improved condition.
Examine the conformation of the stallion and note any conformation defects. Seriously consider whether stallions with severe conformation defaults should be allowed to breed. The Society for Theriogenology’s manual for clinical evaluation of a stallion lists the following conditions as being genetically controlled:
- Cryptorchism
- Combined immunodeficiency
- Parrot mouth
- Hemophilia
- Cataracts
- Wobbler syndrome
Any stallion found to have any of these conditions should be considered ineligible as a sire. Include an ophthalmologic examination in the physical examination. Close observation of the handling of a stallion may be necessary to differentiate between decreased libido and improper handling or mistreatment. Note any unsoundness in a stallion and consider its degree and severity when evaluating that stallion as a potential sire.
