HOW-TO SESSION: LIFE STAGE MANAGEMENT Mare


It is desirable to maintain a 12-month foaling inter- val, which is achievable in mares first rebred on their foal heat (average interval to conception in these mares is 25 days).7 During this period the mare must recover physically from parturition; in- volute her uterus sufficiently to receive an embryo; re-establish cyclicity at approximately 21-day inter- vals; initiate and increase lactation to meet the rap- idly accelerating nutritional requirements of the foal; and consume feed sufficient to meet all of these demands while conceiving at a subsequent breeding in a timely fashion. However, whereas time of first post foaling ovulation ranges from 7 to 15 days, pregnancy rates in mares ovulating 10 days or more post foaling are greater. Voluntarily not breeding on foal heat by waiting until the second post-partum estrus (around 30 d post foaling) inevitably leads to delayed conception, and eventual foregoing of a breeding season to allow earlier breeding the follow- ing year. This lost opportunity significantly affects the lifetime economic return on the broodmare, without reducing ongoing maintenance and oppor- tunity costs. Mating over multiple cycles to achieve pregnancy increases costs; however, this is small compared with the potential future sales revenue of offspring. This repeated attempt at establishing pregnancy, however, will delay the foaling date and potentially decrease the sale price of the yearling.8,9 Live foaling rate per season has been reported


as 80%.1 To achieve this or better, veterinary expenditure is shown in economic models to be a relatively small proportion of the total outlay for a broodmare owner, and performing the necessary rational veterinary procedures to improve overall health and particularly reproductive efficiency are prudent expenditures.4 Lactation is a nutritionally demanding time for


the mare. Insufficient intake to meet the require- ments of lactation results in the loss of body reserves to maintain foal growth,10 and can reduce reproduc- tive performance.11 In one study of fat supplemen- tation prior to and following parturition, mares supplemented showed shorter post-partum inter- vals and fewer cycles per pregnancy, and their foals had higher initial weight gains compared with con- trol mares and their foals.12 The preferred body condition score for mares foaling and entering early lactation to enhance breeding efficiency has been determined to be 5/9.11


3. Examination of the Foal


Gross appearance of the foal is affected by in utero events (Appendix 1). Prematurity occurs when a foal is delivered before the expected gestational length, often after a seemingly uneventful preg- nancy. Their relative immaturity as indicated by short soft hair coat, flaccid ears and lips, small skel- etal size, and tendinous laxity. Dysmature foals present with an elongated haircoat, erupted incisor teeth, abnormal mentation, a comparatively small


skeletal size, and tendinous laxity similar to a pre- mature foal; however, they experience a prolonged gestation. Placental insufficiency is considered a contributing factor. Postmaturity is where an oth- erwise-normal foal results from a prolonged gesta- tion, being of a more appropriate skeletal size but with a decreased muscle mass. As in utero resi- dence increases, skeletal growth continues taxing placental function, precipitating a relative placental insufficiency. Disturbances of in utero maturity of the foal pre- dispose the foal to orthopedic, pulmonary, neurolog- ical, and infectious pathologies. At birth, a foal is approximately 10% of its mature


body weight, reaching 30% by 3 months of age. The most rapid period of growth occurs close to parturition meaning any nutritional or physiological checks at this time may have significant effects.13 Managerial influence on foal growth is mediated via broodmare health and nutrition governing milk pro- duction. Failure to thrive or loss of body weight is an indication of an underlying disease process caus- ing reduced feed intake, inappetence, or catabolism. Examination of the foal begins with a good history


of events at the time of delivery and in the immedi- ate few days afterward. The neonatal foal seeks to achieve sternal recumbency within minutes of birth.14 The majority of foals stand within 1 hour of delivery, with pony foals requiring less time and larger breeds taking up to 2 hours (range, 15–165 min).14 Compromised neonates tend to remain re- cumbent longer. Initial attempts to stand are poorly coordinated in all foals; however, once stand- ing the foal rapidly develops an appropriate posture and moves freely in search of the mare. At the time of foal heat evaluation, the foal should seem coordi- nated and move freely. Within 5 to 10 minutes of birth the suckle reflex is present. Foals actively seek to suckle, and even the recumbent foal makes suckling motions into the sur- roundings. Most foals suckle the mare within 2 hours of birth (breed and size variations) with greater than 3 hours considered an abnormal find- ing.14 At foal heat, the foal should be regularly and vigorously suckling the mare, without loss of milk from the mouth or nares.


Checklist for Examination


Behavior and Activity Level Foals are inquisitive but quickly develop a strong avoidance of handling, seeking shelter on the far side of the mare. If recumbent, the healthy foal is easily roused and quickly seeks the mare for suckling.


Head


The head and face should appear symmetrical. Mucous membranes should be pink and moist. The forehead and nares should be free of milk stain- ing. Eyes should be free from discharge, with clear


AAEP PROCEEDINGS  Vol. 62  2016 453


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