How to Manage Foal Rejection

Foal rejection is an uncommon but important problem that can adversely affect the well-being of equine neonates. Various methods are available for managing and overcoming foal rejection. These include physical and/or chemical restraint, behavior modification, and hormone therapy. Surrogation is utilized when a foal’s dam experiences severe illness, death, or outright rejection of the foal, all of which can prevent her from raising her foal. Methods commonly used to treat foal rejection are also used to graft foals onto surrogate mares. Authors’ address: Claiborne Farm, PO Box 150, Paris, KY 40362; e-mail: cscoggin@claibornefarm.com.

1. Introduction

While relatively uncommon, foal rejection is a serious condition that can adversely affect the health and welfare of an equine neonate. Consequences can be costly and labor intensive for the human caretakers and they can cause untoward and sometimes fatal injuries to the foal. Foal rejection can be seen in all breeds of horses, with the highest rate reported in Arabians (5.1%), followed by Paint Horses (1.9%) and Thoroughbreds (<1%).¹  Another important consideration is that a mare that has previously rejected her foal is at an increased risk of doing so again.²

Normal Maternal Behavior

Most signs of normal maternal behavior are fairly easy to recognize. Nickering at and licking and nuzzling of the foal are commonly seen traits. A dam will shield her foal from humans and other horses and she will often stand over her foal while it is recumbent. More subtle signs include the mare stepping a hind leg back to offer greater exposure to the udder and gently nudging the foal as it is searching for a teat. These motherly instincts are thought to develop from various sensory, tactile, and mental stimuli. Stimulation can occur with olfactory recognition of fetal fluids and membranes, physical contact, nursing, and visual exchanges with the foal. These actions—along with other factors that might not be readily apparent—help foster normal attentive and protective maternal behavior. 

Endogenous hormones are important for developing a female’s instincts and ability to care for and nurture her offspring. The neuropeptide oxytocin seems to be important in developing proper maternal behavior. Oxytocin is synthesized in the hypothalamus and released from the posterior pituitary gland. While commonly thought of as an ecbolic agent whose primary target tissue is the myometrium of the uterus, oxytocin has been demonstrated to have effects within the central nervous system. Indeed, its importance in stimulating maternal behavior has been described in humans,³ lab animals,⁴ and farm animals.^5,6 In addition, progesterone and estrogen may also play a role in the development of maternal behavior. For example, a preliminary study showed lower serum concentrations of these hormones in rejecting mares compared to nonrejecting mares.¹ Lactation —an important milestone in the immediate postpartum period—is mediated through a multitude of hormones, including the aforementioned sex hormones and oxytocin, as well as growth hormone, prolactin, dopamine, and insulin-like growth factor 1. Consequently, knowledge of the hormonal events involved in maternal behavior, lactogenesis, and milk letdown can become important when identifying causes for and managing cases of foal rejection. 

Abnormal Maternal Behavior and Foal Rejection

Abnormal maternal behavior and foal rejection can be perplexing and, at times, disturbing to witness. Mares may kick, squeal, or chase their foal, while others may simply seem indifferent to or become elusive from their foals. Different forms of foal rejection have been previously described by Crowell-Davis and Houpt.⁷ In our practice, we typically see two types of foal rejection. The first is aggressive rejection, which is typified by overt violence and hostility towards the foal. Signs include biting, kicking, and savage attacks. The second is avoidance rejection and is characterized by disinterest of the mare and/or evasion from the foal. For instance, the mare may walk away from the foal when it attempts to nurse or fail to display any interest in the foal, especially when the two are removed from eyesight of each other. A salient point regarding these classifications is that they are not mutually exclusive; indeed, variations of the two can occur depending upon the circumstances and individuals involved in each case.

In some cases, the cause for foal rejection is readily apparent. For example: the mare could be young and/or inexperienced; she could have previously rejected a foal; she could feel anxious or nervous around the foal due to a change in environment or management; she could have poor milk production secondary to a disease process; she could have produced an abnormal or sick foal; or the scent of the foal could have been altered through drugs, such as dimethyl sulfoxide (DMSO), which could interfere with olfactory recognition.² All of these instances can disrupt bonding time or hamper the natural progression of motherly behavior, thereby leading to foal rejection.

Other times, the reasons for rejection are not so clear. The clinician must obtain a thorough history and perform a careful physical examination of the mare and foal to decide if there are any issues that may be contributing to the abnormal behavior. Watching the pair interact can be useful for determining certain behavioral cues that might be contributing to rejection. It also behooves the clinician to carefully evaluate the management practices of the farm to ascertain whether changes in the environment have led to maternal aggression or avoidance.

One factor that is sometimes overlooked, yet highly important, is that of maternal pain. Pain can be secondary to either normal physiologic processes or certain disease conditions. Examples of the former include pain arising from postpartum uterine contractions or discomfort from a sore udder due to an aggressively nursing foal.² Examples of the latter include musculoskeletal injury, such as laminitis or osteoarthritis, and systemic illness, such as metritis associated with retained fetal membranes or gastroenterocolitis. Identifying the source of pain underscores the importance of performing a thorough physical examination, while proper management of the pain can result in a successful outcome for all parties involved.

The safety and health of the foal should be of primary concern when dealing with cases of foal rejection. As such, the foal should be immediately removed from a mare that displays overt aggression towards the foal. If necessary, the foal should be administered at least one pint of good quality colostrum through a nasogastric tube for passive transfer of immunoglobulins and nourishment. Alternatively, or in addition, intravenous plasma can be used to provide adequate passive transfer. Subsequent feedings can be performed every two to three hours with the mare’s own milk (provided she is tractable for harvesting milk), goat’s milk, or a commercial foal milk replacer formula^a from a pan, bottle, or indwelling nasogastric feeding tube. Supportive care, in the form of intravenous fluids, and prophylactic administration of broad-spectrum anti-microbials may also be administered at the discretion of the clinician to prevent or treat dehydration and sepsis.

2. Materials and Methods

Strategies that can be employed to treat and manage foal rejection include physical restraint, behavior modification, pharmaceutical intervention, and surrogation. Depending on the circumstances and individuals involved, these strategies can be used alone or in conjunction with one another. Also, farm management practices and available resources may preclude the use of some of these strategies. The clinician must thus work in cooperation with the owner or caregivers to determine which strategies could be useful, as well as which ones are feasible with respect to their experience and wherewithal.

Success in establishing normal maternal behavior or adequate surrogation can be determined by using at least three subjective markers. The first marker is the mare’s response following removal of the foal from eyesight. If the mare whinnies, becomes anxious, or attempts to follow the foal, then these are good indicators of the mare’s acceptance of and bonding with the foal. The second marker is leaving the mare and foal free from restraint in a stall or small enclosed area and observing their interactions. [...]