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Intensive, Early Handling of Neonatal Foals: Mare-Foal Interactions Introduction Traditionally, horse managers and veterinarians have recommended moderation in handling foals during the neonatal period so as not to interfere with mare-foal bonding and the foal’s ingestion of colostrum. However, a specific early intensive handling procedure for foals has been developed and publicized as “imprint-training” (Miller, 1985; Miller, 1991). This procedure requires physical restraint of the foal while a highly regimented desensitization and sensitization procedure is performed immediately after birth. Presumably this procedure results in an imprinting of the foal to the human handler/s and purportedly provides an irreversible learning experience during a proposed critical period in development. By learning to submit to the handler within minutes or hours after birth, the foal should not be fearful of humans or of various specific new tasks that it is asked to perform throughout the rest of its life. Reasonable concern can be raised regarding the effects of such an intervention on the normal behavior of the mare and foal. The potential delay in nursing and the timely ingestion of colostrum is one concern. Delayed ingestion of colostrum in the presence of environmental microbial challenge could result in grave susceptibility to infections (Madigan, 1997) Intrusion by extensive human handling during the immediate post-partum period may interrupt normal mare-foal interactions, which may in turn interrupt effective bonding. Maternal behaviors observed in free-running mares include licking the neonate, vocalizations between the mare and foal, maintaining close physical and visual contact, and attention to fetal membranes (Tyler, 1972; Keiper and Houpt, 1984). These behaviors are all also observed in domestic mares. A survey study looking at domestic mares at parturition found that foal-rejecting mares were less likely than non-rejecters to exhibit the common maternal behaviors of licking and vocalizing towards the neonate (Juarbe-Diaz et al, 1998). The early interactions described above are suspected to play a role in ensuring accurate future recognition between the mare and foal, though a discrete imprinting or critical period for the foal has not been clearly identified. One interpretation of imprinting in foals is the observation or suggestion by several researchers of the “following response” in which foals navigate or attend to any large, usually slow moving, object, which would ordinarily be the dam (Crowell-Davis, 1985; Houpt, 2000; Keiper, 1985; Tyler, 1972). Rossdale (1967) suggested that latency period to successful first nursing might be interpreted as a culmination of whatever behaviors were necessary for successful imprinting to occur. Thus far, concerns that intrusion by human handlers during the immediate post-partum period may affect the ability of the mare and foal to bond properly, or instigate rejection by the mare, have not been clearly borne out. In a survey of foal rejection rates in a domestic horse population, the presence or number of human observers at the time of delivery did not seem to be associated with rejection (Juarbe-Diaz et al, 1998; Houpt, 2000) and mares facing extreme human intervention when a critically ill foal is born in or treated at a neonatal intensive care facility usually continue to pay attention to the foal and do not resist later nursing efforts by the foal (Pamela Wilkins, personal communication, 2001). However, anecdotal reports by veterinary practitioners still suggest that excessive human intervention can be associated with undesirable behaviors in the mare such as excessive protectiveness or some degree of foal rejection. Though intensive handling performed immediately post-partum is supposed to result in long term positive effects, it still remains to be determined if there are immediate, negative physiological or behavioral consequences, or even possibly benefits, for the neonate. This study was designed to quantify the effects of intensive early handling instituted immediately at birth, following the Miller “imprint-training” procedure, on specific mare-foal interactions, typical progress of the foal towards standing and nursing, and timely, effective ingestion of colostrum. Methods Subjects. Ten multiparous mares and their foals were observed over two breeding seasons; from each full sibling pair, one foal was assigned to the Control Group and the other to the Intensive Handling Group. Foals were randomly assigned to one group during the first year of the study, with the full sibling born the second year assigned to the opposite group. Mares were stabled in individual stalls in a barn from approximately 5:00 pm to 9:00 am and were turned out as a group in a 10-acre pasture during daylight hours. When in stalls, there were mares in adjacent stalls on at least one side and in stalls across the aisle way. The stalls had full wood plank walls with approximately ˝ inch spaces between planks. Mares within 2 weeks of 340-day gestation length were kept in a 12-foot by 18-foot foaling stall at night and were visually observed for signs of parturition at a minimum of once hourly. Lights were on in the stalls until approximately 10:00 pm and for the remainder of the night only aisle lights remained on. Once the mares were observed in Stage I of labor the lights in the stall were again turned on until the end of the post-foaling observation session. Delivery was attended in all cases and in some cases mild traction was used to assist the mare if deemed necessary by the foaling attendant. Intensive Handling Procedures. Control Group foals were handled minimally post-partum, which included only assistance breaking the umbilical cord and application of antiseptic to the umbilical stump. Intensive Handling Group foals were assisted similarly, followed immediately by the handling procedure. The dams were not restrained during the foal handling procedure and had access to hay (fed in one corner of the stall) and water at all times. A single handler restrained the foal and performed the procedure. For the first part of the handling procedure the foals were permitted to be in sternal or lateral recumbency. The following desensitization procedures were performed, each one continued for 30 repetitions or more, with the criteria for completion of each being cessation or absence of resistance by the foal:
On completion of this set of procedures, the foal was left unrestrained. Once the foal had stood on its own and was deemed reasonably stable on its feet, without regard for nursing status, the second part of the procedure was completed with the foal standing:
Data collection. An approximately 20 ml volume of colostrum was taken from the mare, prior to the foal nursing, for determination of specific gravity using a standard colostrometer. For both Control and Intensive Handling Group foals, blood was obtained by jugular venipuncture at 4 and 18 hours. Serum was frozen and at the completion of each foaling season sent to a commercial laboratory for IgG measurement using the radial immunodiffusion test. Behavior observations were completed for 4 hours on each mare and foal pair, with time 0 being immediately after expulsion of the foal (end of Stage II labor). Observations were made from continuous video recordings, using an event-recorder software application (The Observer, version 3.0, Noldus Information Technology Inc., Leesburg, VA, USA). The following behavior observations were made to describe the complete repertoire of activities of the mare and foal during the 4 hr observation period:
Data Summary and Statistics. From the behaviors observed, the following frequency, duration, and latency endpoints were derived: · Frequency: mare and foal vocalizations, foal nursing bouts, mare avoids foal, and mare shows aggression towards people, foal, or horse in adjacent stall · Duration: mare eating or drinking, mare lick foal, mare sniff or nudge foal, mare attend to fetal membranes, mare attend to people, foal search for teat, foal nurse, foal attend to people, and foal and mare in proximity · Latency: foal first stand and first nurse The differences between the Intensive Handling and Control Groups for all endpoints were determined using a paired t-test (Statistix 7, Analytical Software, Tallahassee, FL). Differences were considered significant at the p < 0.05 level. Results The two foaling seasons resulted in attended births of 8 pairs of full sibling foals that were included in the study. Therefore for the paired t-test there were 16 subjects or 8 subjects each in the Control and Intensive Handling Groups. The handling procedure carried out on the Intensive Handling Group began between 3 and 18 minutes following expulsion of the foal. Variation in starting time was due to latencies to rupture of the umbilical cord and in one case the behavior and position of the recumbent mare in relation to her foal precluded safe entry of the handler into the stall. The duration to complete both parts of the intensive handling procedure was from 38 to 66 minutes, with the mean being 48 minutes. The mares, being unrestrained while the foals were handled, did not interfere with the completion of any part of the procedure. All mares licked and sniffed their foals (permitted during the intensive handling procedure) and vocalized apparently towards their foals. Most, though not all, mares investigated fetal membranes or fluids on the floor of the stall independent of sniffing or licking the foal. Only one mare showed aggression towards the handler or towards the horse in the adjacent stall. Frequency of aggression by the mare towards the foal was low and was not observed in every mare. Aggressive behavior was of low intensity and included mainly kick and bite threats and nips. Likewise overt mare avoidance of the foal without aggression was low. A rather stereotypical stepping and circling away from the foal was performed by all mares and was so common that it was not included as an avoidance behavior. Attention paid to the handler by mares or foals was not seen in all subjects but was more frequent in the Intensive Handling Group likely due to more opportunity as a function of the design of the study. All foals vocalized. Some foals exhibited teat-seeking behavior directed at the wall, the air, and themselves and this was included in the analysis. The Intensive Handling Group mares spent a significantly decreased time eating and drinking and a significantly greater time sniffing their foals compared to the Control Group mares (Table 1). The Intensive Handling Group foals had a significantly longer latency to first stand. There was no significant difference between the two groups for the latency to first nurse.
Table
1. Behavior endpoints for
Control and Intensive Handling Groups. Colostrometer readings on pre-suckle mammary secretions from the first year were inaccurate due to instrument failure. During the second year of the study all mares had a colostrometer specific gravity reading of 1.040 or greater. The quantitative blood IgG measures using the radial immunodiffusion test have been completed only for year one of the study. The 4-hour samples ranged from <200 to 400 mg/dl and there appears to be no trend related to latency to first nurse or to Intensive Handling or Control Group status. The 18-hour samples ranged from 400 to 3600 mg/dl and also do not appear to follow a pattern regarding latency to nurse or group status. No foals showed clinical signs that might be associated with failure of passive transfer of antibodies. Discussion This study resulted in several specific endpoints differing between the Control and Intensive Handling Group mares and foals without apparent clinical effects on recognition between the mare and foal and viability of the foal with regards to progression towards nursing. Individual variation in the normal range of behavior of mares and foals as well as the robust nature of certain behaviors regardless of moderate levels of intervention could both account for a failure to find multiple differences between the groups using the endpoints that were derived. The difference between the Intensive Handling and Control Group mares for the sniffing and eating duration endpoints may suggest more attention was being paid to the foals that were being handled. Mares in the Intensive Handling Group spent less time eating and drinking and more time sniffing their foals than mares in the Control Group. Presumably while eating hay the mare is not as vigilant as when she is standing over or attending to (licking or sniffing) the foal, and generally the intensive handling procedure was not carried out in close proximity to the corner where the hay was fed. The mares used in this study were all multiparous and had been housed together and managed and handled similarly for at least 6 years. A known environment and consistent, gentle handling over this time may have contributed to their responses while their foals were handled immediately at birth; a similar study comprised of maiden mares or those in a more extensive management system may have yielded different results. This study did not clearly bear out the concern regarding a problematic slowing of the progression toward standing, nursing, and ingestion of colostral antibodies. It is interesting to note that, as one might expect, the intensively handled foals had a longer latency to first stand than their unhandled siblings yet their latency to nurse was not comparably delayed. However, the completion of the intensive handling procedure was of a shorter duration than that sometimes recommended in the “imprint-training” literature. The intensive handling of the foals was carried out in a manner deemed best to achieve the spirit and intent of the “imprint-training” procedure devised by Miller. The handling in this study in all likelihood could not have exactly replicated Miller’s procedure for at least two reasons: 1) at any point in time and depending upon the reference, parts of the procedure described by Miller are not consistent, and 2) the foals did not submit to the handling in a manner exactly reminiscent of that described or demonstrated by Miller in his writings and video productions. The Intensive Handling Group foals in this study were resistant to the procedure. Resistance to the handling procedure often appeared non-specific and more in response to restraint rather than to specific elements of the desensitization process, excluding the common resistance to desensitization of the nostrils. This issue of forced restraint recalls another concern voiced regarding the imprint-training procedure carried out immediately at birth: anecdotal reports by veterinarians of foals presenting with physical injuries and failure of passive transfer resulting from personnel aggressively restraining foals for a long duration. The handler in this study was experienced with foals and found the potential for trauma to the foals, as a result of the intervention, to be undesirable. Further work with the subjects in this study will investigate social and developmental behaviors of the foals and their compliance with specific handling and training procedures. Acknowledgements Supported by Project # 3817 of the PA Agricultural Experiment Station and the Department of Dairy and Animal Science at the Pennsylvania State University. This study was approved by the Institutional Animal Care and Use Committee at the Pennsylvania State University. The authors appreciate the help of the staff and students at the University Horse Farms and the generous advice and consultation from Dr. Sue M. McDonnell. References Crowell-Davis SL (1985) Nursing behaviour and maternal aggression among Welsh ponies (equus caballus). Appl Anim Behav Sci 14:11-25. Houpt KA (2000) Equine maternal behavior and its aberrations. International Veterinary Information Service http://www.ivis.org/advances/Behavior_Houpt/houpt-foal/chapter_frm.asp?LA=1, accessed May 15 2002. Juarbe-Diaz SV, Houpt KA, Kusunose R (1998) Prevalence and characteristics of foal rejection in arabian mares. Eq Vet J 30: 424-428. Keiper R and Houpt K (1984) Reproduction in feral horses: An eight-year study. American Journal of Vet Res 45: 991-995. Keiper RR (1985) The assateague ponies. Tidewater Publishers, Centreville, MD. Madigan JE (1997) Method for preventing neonatal septicemia, the leading cause of death in the neonatal foal. Proceedings 43rd Annual Convention of the American Association of Equine Practitioners, Phoenix AZ: 17-19. Miller RM (1985) Imprint training the foal. Blue Ribbon Equestrian Video Clinics. Palomine Productions, Westlake Village, CA. Miller RM (1991) Imprint training of the newborn foal. Western Horseman Inc., Colorado Springs, CO. Rossdale PD (1967) Clinical studies on the newborn thoroughbred foal i. Perinatal behaviour. Brit Vet J 123: 470-481. Tyler SJ (1972) The behaviour and social organization of the new forest ponies. Anim Behav Mono 5: 85-196. |
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