Musculoskeletal pain and ex-copula ejaculation
Key words: stallion, equine, pain, ejaculate, ex-copulaStallions may fail to mount and ejaculate because of severe musculoskeletal pain. In this case, a 3-year old Standardbred stallion was unable to copulate because of severe degenerative joint disease in both stifle joints:
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The owner was advised against breeding because of potential heritability of conformational defects. Nevertheless, the option to attempt to collect semen from the stallion was adopted.
Several fruitless attempts were made to collect semen by standing collection (non-mounted collection) using a tease mare and an artificial vagina. Therefore a system was prepared for ex-copula semen collection. This consisted of a ring of polyethylene tubing (joined with a plastic tubing connector) attached to a plastic sleeve with cable ties. The hand of the sleeve was removed and the sleeve was shortened. A conventional filter and "Whirl-pak" was attached to collect the semen. The apparatus was suspended beneath the preputial opening using tail bandages as shown here:
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A tricyclic antidepressant imipramine (total dose 1,5 g per os) was used to obtain ejaculation, followed 2.5 hours later with 350 mg of xylazine. These are both tricyclic compounds, known for their ability to produce erections and in combination, ejaculation, more reliably than when used alone.
As shown here, related tricyclics are also known to produces partial erection and in some cases, even priapism (pathologically prolonged erection).
The stallion attained partial erection and a small ejaculate was produced:
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This ejaculate contained 1.1 billion spermatozoa (most normal ejaculates contain between 3.5 to 12 billion in our experience) and almost all of the sperm had loose-heads. The motility of the sample was zero.
On the afternoon of that same day, the stallion was given 500 mg of flunixin meglumine intravenously. After a one hour, and in the presence of a mare in estrus, the stallion mounted a phantom after several attempts and ejaculated a substantial, normal ejaculate with excellent motility.
This case demonstrated that a single ex-copula ejaculate may not be an accurate reflection of semen quality. Also, appropriate analgesia may be helpful in these cases.
