Crib Biting Research Articles

Crib biting and equine gastric ulceration syndrome: Do horses that display oral stereotypies have altered gastric anatomy and physiology?

Equine gastric ulceration syndrome (EGUS) and crib biting (CB) are two separate conditions suffered by horses. Previous research has hypothesized causal relationships between these two conditions, whereby the behavior is driven by a requirement to stimulate saliva production to buffer gastric juice. However, to date, there is limited empirical evidence to support this notion. To identify if the anatomy and physiology of the equid stomach differed in CB horses and non–crib-biting (N-CB) controls a two-part experiment was conducted using cadaver stomachs. Twenty-four stomachs (CB: n = 12 and N-CB: n = 12) were collected from an abattoir. Duplicate 1.5 cm squared sections were taken from the fundic and pyloric mucosa for histology and H&E staining to identify gastrin (G)-producing cells. Slides were scored using an adapted four-point scale. A further 18 stomachs, (CB: n = 9 and N-CB: n = 9) were collected to test the pH of the mucosa and digesta from the fundic and pyloric regions. G cell concentrations were analyzed by Mann Whitney U-test. Stomach content pH was analyzed by one-way ANOVA and L.S.D post hoc. Relationships between digesta and mucosal pH were evaluated by correlation. In both parts of the study, there was no difference between the G-cell concentration (P > 0.05) and pH (P > 0.05) between CB and N-CB horses. There was a positive correlation between digesta and the mucosal surface of pyloric region in CB horses (R2 0.66, P < 0.001), but not in N-CB horses. These findings suggest, from cadavers, that CB and N-CB stomachs are not anatomically or physiologically different. It is plausible that there is no direct inherent link between CB and EGUS rather that both conditions are linked to environmental and physiological stress.

Crib Biting And Equine Gastric Ulceration Syndrome, Is There An Anatomical Link?

Crib Biting And Equine Gastric Ulceration Syndrome, Is There An Anatomical Link?

Acute-phase proteins, oxidative stress, and antioxidant defense in crib-biting horses

Abstract Crib biting is a common equine stereotypic behavior that has links to health problems and poor welfare. There is evidence that crib biters may be more sensitive to environmental stressors, and the aim of the present study was to test the hypothesis that crib-biting behavior in horses has a relationship with oxidative stress, antioxidant defense, or inflammatory proteins, as is observed in humans with various affective disorders such as depression and anxiety. Ten crib-biting horses and 10 age- and sex-matched healthy horses were used. Vital signs (heart rates, respiratory rates, and temperature) and blood samples were taken in 3 conditions; basal condition for crib biters (no stereotypic behavior observed for at least 30 minutes); crib biters during or directly after crib-biting periods (acute crib biting = crib biting for at least 15 minutes with no interruption longer than 2 minutes); non–crib-biting horses (control). Comparisons were made between crib biters and controls, and between crib-biters' basal and crib-biting values. No changes were observed in the vital signs. Total antioxidant capacity activity was significantly decreased in crib biters during the basal measurements relative to controls, and this was significantly decreased again during an episode of crib biting. Similar differences to those observed in total antioxidant capacity were also observed for the antioxidant enzymes superoxide dismutase, glutathione peroxidase, and catalase. Collectively, our data suggest that the antioxidant levels and antioxidant defenses against lipid peroxidation are reduced in crib biters, suggesting that oxidative stress plays a role in the pathophysiology of crib biting. In addition, our data suggest that further study on the role of oxidative stress in crib biting might be of benefit, particularly in the search for veterinary treatments or interventions for crib-biting horses.

A preliminary investigation into the effect of ad libitum or restricted hay with or without Horslyx on the intake and switching behaviour of normal and crib biting horses

In an attempt to reduce’fibre-belly’ and prevent obesity in horses many owners restrict access to hay in the stable. Such restrictions can lead to digestive disturbances and promote the development of stereotypic behaviours.The objectives of this experiment were to determine if ad libitum or restricted forage with or without the molasses based lick, Horslyx, would alter the behaviour in a group of normal and confirmed stereotypic horses.Two Randomised Block Design trials were conducted simultaneously. Group A consisted of 3 crib-biters and 1 normal horse, while group B contained 4 non-stereotypic (normal) horses. Horses were individually housed in 10×12 foot boxes and bedded on dust-extracted shavings with water available ad libitum. Diets were ad libitum hay, ad libitum hay+Horslyx, restricted hay, and restricted hay+Horslyx. For two days of each collection period every horse was individually observed, and an ethogram completed for ½h 3x/day=6 observation sessions for each horse. Switching behaviour and data for hay and lick intakes were averaged across the 5 days of collection and subjected to Friedman's non-parametric ANOVA with horse, diet and behaviour as fixed factors.Ad libitum or restricted forage or the presence of a Horslyx had no significant impact on horse behaviour. Crib-biting horses tended to consume less hay 8.81 (±3.60)kg/d and more Horslyx 1.10 (±0.38)kg/d compared with normal horses who consumed more hay at 11.72 (±4.59)kg/d and less Horslyx at 1.01 (±0.45)kg/d respectively, but there was no significant differences between the groups. Crib-biting horses switched behaviour (eating, licking, cribbing, drinking, and looking over the door resting) an average of 40 times more during the 30min observation sessions than normal horses. Crib-biting horses also licked the Horslyx 1.5 times more than normal horses.These results confirmed that stereotypic animals are addicted to the reward of the dopamine release, achieved by the action of crib biting, and are thus not influenced by ad libitum forage or access to a stable lick. The 4 fold increase in switching behaviour and additional licking by the crib-biting horses suggests an increased transmission of the neurotransmitter dopamine and in this regard licking may promote coping in certain environmental circumstances.The results of this study suggest that providing a lick in the stable for crib-biting horses gives them another activity to the normal forage consumption and resting actions and may provide another mechanism for dopamine release and thus enhance their ‘coping’ strategy when confined in stables.

The efficacy of capsaicin as an equine repellent for chewing wood

Capsaicin, a component of chili peppers, is a natural repellent for many mammals because of it being an irritant to the nasal and oral areas. We tested whether topical application of capsaicin in a commercially available product caused aversion to licking and chewing of wood by horses and hence might potentially prevent crib biting. Ten non–wood-chewing horses underwent 3 sequential trials involving the presentation of different treatments applied to a clean piece of wood (wooden block). Initially horses were exposed to molasses only, followed by equal proportions of molasses and the capsaicin product (Equi-Stop), and then a return to molasses only. The addition of capsaicin to molasses caused a significant reduction in the frequency of licking or chewing of a standardized wooden block and was associated with significant increases in behaviors that may be associated with equine irritation, including rubbing and head shaking, plus the nasal investigative behavior of flehmen response. The combination of both the reduction of licking or chewing of the wooden block and the increase in irritation and nasal investigation behaviors suggests that capsaicin may be an effective repellent for horses chewing wood. The significantly lower licking or chewing rates of wooden blocks coated with molasses only at the end of the trial sequence compared to that at the start suggests a learned aversion after exposure to capsaicin at least in some horses. This capsaicin-based product has the potential as a management tool for reducing the incidence of wood chewing and possibly crib biting in horses.

Assessment of modified Forssell’s myectomy success rate in the treatment of crib biting in horses

The objective of this retrospective study was to assess the success rate of Forssell’s modified myectomy – surgical treatment of crib biting on 33 horses of various breeds identified as stereotypical cribbers which were referred to the Equine Clinic in Brno between January 2001 and December 2010. The long term outcome was available for all horses. The overall success of the surgery without considering influencing factors was 61%. Thirteen horses (39%) returned to the stereotypical behaviour sooner or later after the surgery. In this retrospective study we confirmed the dependence of success of the surgery on the necessity of early treatment of the problem (up to 6 months after the appearance of initial signs), with the significance level of P = 0.037. Any connection between age, breed or sex, and positive outcome of the surgery were not confirmed during statistical evaluation. When the horses were diagnosed early enough, an 80% success rate in surgical treatment performed within 6 months from the initial signs of crib biting was recorded, which seems to be very promising. It can be concluded that surgical treatment of crib biting by modified Forsell’s myectomy is the recommended option in the therapy of this oral stereotype.

A preliminary report on estimating the pressures exerted by a crank noseband in the horse

The pressures applied to horses via restrictive nosebands are of growing concern to equitation scientists and horse sport administrators. They prevent the expression of normal behavior, may compromise blood flow, and even damage bone. This report describes an approach to estimate in vivo pressures applied to the dorsal and ventral aspects of a horse's nose via a so-called crank noseband. A load cell calibrated over a load range of 0-100 N was integrated into a commercially available crank noseband. These force values were combined with anatomical curvature data to estimate the pressure applied by the noseband to the underlying tissue at any point along the internal surface of the noseband using Laplace's law. Partial profiles of both dorsal and ventral aspects of the horse's nose, at a position corresponding to that of the noseband, were taken by contouring a flexible curve ruler to the nose. The ruler was stiff enough to retain the profile when removed from the nose, thereby allowing faithful transfer of the profile to paper for digitization. Once digitized, straightforward mathematical algorithms were used to provide an analytical expression describing each profile, to calculate profile curvature point by point, and, using measured noseband force values, to transform the curvature into a corresponding sub-noseband pressure profile. This process was used to study pressures applied when the horse chewed hay, chewed concentrate mix, and when it was cued to step backward. The calculated pressures ranged from 200 to 400 mm Hg; pressures that, in humans, are associated with nerve damage and other complications. As such, these preliminary data strongly suggest the need for more research in this domain. The current approach should inform some of the welfare concerns in ridden horses but should also be of use in studies of oral behaviors around foraging as well as crib biting and wind sucking.

Equine stereotypic behaviors: Causation, occurrence, and prevention

There are strong suggestions that equine stereotypies are connected to poor welfare and a suboptimal management and/or stabling environment. Different forms of equine stereotypic behaviors have been described. Crib biting, weaving, and box walking are considered the most prevalent. Several studies have been conducted to establish links between the underlying causes and potential function of such behaviors. Both experimental and epidemiological studies have indicated management factors specifically feeding practices, housing conditions, and weaning method as crucial in the development of stereotypies in stabled horses. Some neurological studies on equine stereotypy demonstrated some forms of central nervous system dysfunction as being associated with the performance of stereotypic behaviors. Different researchers hypothesized that the functional significance of stereotypies is that they reduce stress in captive environments and should thus be considered as a coping mechanism. In contrast, the owner's perspective is often that a stereotypic horse has a “stable vice” that needs to be stopped, and different kinds of methods have been developed to control or regulate stereotypic behaviors. However, if the stress-reducing hypothesis is correct, controlling stereotypic behaviors particularly by physical and surgical approaches without addressing the underlying causes is of great concern to the horse's welfare. Although there is ongoing uncertainty about the exact function, the growing knowledge about causation should be applied: under all circumstances prevention is better than cure.

Assessment of Gastric Ulceration and Gastrin Response in Horses with History of Crib-Biting

It was hypothesized that horses exhibiting crib-biting (CB) have a greater degree of gastric mucosal damage and higher serum gastrin response to concentrate feeding than non-crib-biting (NCB) horses. Eighteen mature horses, 9 CB and 9 NCB, were used to determine prevalence and severity of gastric mucosal damage and effect of concentrate feeding on circulating gastrin. Horses were maintained on pasture with free access to hay and fed a pelleted concentrate diet twice daily. Number of crib-bites and duration of cribbing bouts were recorded in a 24-hour period. Endoscopic examinations (EE) of the squamous mucosa were performed and gastric fluid sampled after 24 to 28 hour feed removal. Following EE, horses were returned to pasture for 72 hours. Blood was collected following 12-hour feed removal (0 minutes), and at 60 and 120 minutes after consuming 1 kg of concentrate. Mean number of crib bites in 24 hours was 1,558 ± 303 with CB peaking prior to and during the afternoon feeding (3:30 PM, P < .05). There were no differences in the number or severity of ulcers, prevalence of hyperkeratosis, or baseline gastric pH between CB and NCB. Serum gastrin concentration at 60 and 120 minutes was greater (P < .05) and tended to be greater (P < .06), respectively, in CB than in NCB horses following feeding of concentrate. Crib-biting behavior in horses maintained on pasture was not associated with gastric mucosal damage; however, consumption of concentrate feed resulted in greater serum gastrin concentration in CB horses.

Study of crib–biting and gastric ulceration and mucosal inflammation in foals

Crib–biting is a stereotypic behaviour performed by approximately 5% of captive domestic horses. Dietary factors have been strongly associated with the development of oral stereotypies and risk factors for crib–biting, identified in recent epidemiological studies, include feeding high concentrate and/or low forage diets (Waters et al., 2002). Experimental work has shown that such diets are likely to result in increased gastric acidity (Murray and Eichorn, 1996; Nadeau et al., 2000). We therefore propose that young horses initiate crib–biting in an attempt to produce alkaline saliva to buffer their stomachs when alternative opportunities for mastication are limited. The aim of this study was to determine whether there was an association between crib–biting behaviour and stomach condition in foals.Foals that had recently started to perform crib–biting were recruited into the study and compared with non–stereotypic foals. The stomachs of 15 crib-biting foals and 9 normal foals were examined using a video endoscope.

Meal frequency and stereotypic behaviour in stabled horses

Locomotor stereotypies such as weaving and nodding are commonly observed as pre–feeding activity in stabled horses (Cooper, McDonald and Mills, 2001), whilst oral activities such as crib–biting and woodchewing may be associated with the post–feeding period (McGreevy and Nicol, 1998) particularly in horses fed a low–fibre concentrate (Nicol et al., 2002). In this study, we investigated the effect of increasing the number of meals of concentrate whilst maintaining the same daily concentrate intake, on the behaviour of stabled horses with particular reference to stereotypic activities such as weaving and crib–biting. The study was carried out on a working equestrian yard with stables for up to 50 horses.A pilot study was used to record incidence of stereotypic behaviour and to select subjects for the main study. In this, the behaviour of 30 warm–blooded horses was recorded during their morning (0830h) and afternoon (1630h) concentrate meals. Each meal consisted of 0.5kg of a commercial feed, mixed with 1kg of soaked sugar beet pulp and 0.5kg of chopped hay and straw mixed in a bucket.