b'YOUR GUIDE TO THE 2017 AAEP CONVENTION SPONSORED BYminute). Anesthetized late-term pregnant women, on the other hand, have a de-creased residual respiratory volumetheUrine Trouble: Freezing Contaminated Semen amount of air remaining in the lungs atUrospermia, or urine in semen, is one of the most frequent ejaculate dysfunctions in the end of respiration. stallions. Because urine can have toxic effects on sperm and cause inflammation in the Similar changes would be expectedmares uterus, it can diminish semen quality and conception rates. Sometimes, however, in anesthetized pregnant mares in lateall veterinarians have to work with are contaminated semen samples. So, when is it okay to gestation, particularly when they arefreeze that ejaculate for future use?positioned in dorsal recumbency (lyingRobyn Ellerbrock, DVM, Dipl. ACT, a PhD candidate at the University of Illinois at Urbana-on their back), he said. Champaigns Department of Veterinary Clinical Medicine, in Urbana, sought to find out how What scientists do know more abouturospermia affects semens freezability for artificial insemination use. is how sedation and anesthesia impactIn her study, she took 64 semen samples from eight light-breed stallions and subjected pregnancy in horses. each to varying levels of urine contamination. Group 1 was the control, with no contami-In one study researchers administerednation. Group 2 was 20% urine (considered low), and Group 3 was 50% urine (high). the sedative detomidine to 10 pregnantPre-freezing, Ellerbrock confirmed that the contaminated semen had significantly higher pH, mares weekly from Day 14 to 60 of gesta- urea, and creatinine levels (which all affect semen quality) and significantly lower sperm tion and then monthly until foaling. Onemotility, or movement.mare aborted on Day 167 of gestationAfter centrifugation (to separate the sperm from the seminal plasma before freezing), and another was euthanized after devel- however, she said the urea and creatine values had lowered and motility had increased. She oping a large colon torsion (twist). Sixthen performed gradient centrifugation, a technique often used with poor-quality semen, of the eight live foals born were normal,and found that it increased sperm viability. There were no motility differences at this point while the other two suffered from torti- between Groups 1 and 2, while Group 3s motility remained lower than Groups 1 and 2.collis (abnormal neck twisting) and bilat- Post-freezing and thawing, sperm viability was significantly lower in Group 3 than the eral upward fixation of the patella (a stifleother two groups, Ellerbrock said.Ejaculate with less than 20% contamination might be suitable for cryopreservation, she condition). Still, he said, the authorssaid. Highly contaminated samples may benefit from gradient centrifugation after traditional concluded that there were no specificcentrifugation. Its worth your while to take the extra step if faced with an ejaculate that adverse effects of the detomidine. absolutely needs to be cryopreserved.Alexandra BeckstettHowever, he acknowledged that all known anesthetic techniques have the potential to decrease cardiac output, depress arterial pressures, and causeResearchers havent performed ex- surgery had a lower foaling rate than respiratory depression (slow and ineffec- tensive studies evaluating the effects ofmares pregnant for greater than 40 tive breathing), which could lead to fetalanesthesia on pregnant mares undergoingdays at surgery, he said.acidosis (abnormally high blood acidity),elective surgeries, Hubbell said, so veteri- Based on this research, Hubbell sug-hypoxia (inadequate oxygen supply),narians must use findings from studiesgested that if pregnant mares must under-and hypercarbia (abnormally high bloodon mares anesthetized on an emergencygo general anesthesia, the safest window carbon dioxide levels). basis. Some examples of results include:is from Days 40 to 220 of gestation.The largest retrospective study ofThe decision to anesthetize a pregnant anesthetic morbidity and mortality inmare is made on a case-by-case basis, horses shows that mares in the thirdHubbell said. Factors to consider include trimester were at increased risk, withthe general health of the mare, her age (an two of 16 mares dying of anestheticincreased anesthetic risk on its own), the complications, he said; anticipated duration of the procedure, and Based on results from a series of stud- any previous history of foal loss. In most ies, researchers concluded that intrave- cases the risk of anesthetizing the mare nous agents resulted in fewer cases offor surgery must be weighed against the fetal acidosis and hypoxia than inhaledrisk of leaving a condition untreated.hanesthetics;I n four studies in which researchers evaluated colic surgerys effects onefoaling rates, Hubbell said foaling rates Visit TheHorse.com/AAEP2017for surviving mares were 80%, 79.4%, 66.7%, and 53.8%; and Common and Uncommon Ovarian Abnormali- One study examined the relationship MATHEA KELLEY between the timing of colic surgeryties, TheHorse.com/40224The safest window for pregnant mares to under- and gestational age, finding that maresManaging Umbilical Remnant Complications in go anesthesia is Days 40 to 220 of gestation. pregnant 16 to 39 days at the time ofFoals, TheHorse.com/40225A36 TheHorse.com/AAEP2017 AAEP Wrap-Up THE HORSEMarch 2018'