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

Evaluation of Gastric pH and Gastrin Concentrations in Horses Subjected to General Inhalation Anesthesia in Dorsal Recumbency

The prevalence of gastric disorders in high-performance horses, especially gastric ulceration, ranges from 50 to 90%. These pathological conditions have negative impacts on athletic performance and health. This study was designed to evaluate changes in gastric pH during a 24 h period and to compare gastrin concentrations at different time points in horses undergoing general inhalation anesthesia and dorsal recumbency. Twenty-two mixed-breed mares weighing 400 ± 50 kg and aged 8 ± 2 years were used. Of these, eight were fasted for 8 h and submitted to 90 min of general inhalation anesthesia in dorsal recumbency. Gastric juice samples were collected prior to anesthesia (T0), and then at 15 min intervals during anesthesia (T15-T90). After recovery from anesthesia (45 ± 1 min), samples were collected every hour for 24 h (T1 to T24) for gastric juice pH measurement. During this period, mares had free access to Bermuda grass hay and water and were fed a commercial concentrate twice (T4 and T16). In a second group (control), four non-anesthetized mares were submitted to 8 h of fasting followed by nasogastric intubation. Gastric juice samples were then collected at T0, T15, T30, T45, T60, T75, and T90. During this period, mares did not receive food or water. After 45 min, mares had free access to Bermuda grass hay and water, and gastric juice samples were collected every hour for four hours (T1 to T4). In a third group comprising ten non-fasted, non-anesthetized mares with free access to Bermuda grass hay and water, gastric juice samples were collected 30 min after concentrate intake (T0). In anesthetized mares, blood gastrin levels were measured prior to anesthesia (8 h fasting; baseline), during recovery from anesthesia, and 4 months after the anesthetic procedure, 90 min after the morning meal. Mean values of gastric juice pH remained acidic during general anesthesia. Mean pH values were within the physiological range (4.52 ± 1.69) and did not differ significantly between time points (T15-T90; p  >  0.05). After recovery from anesthesia, mean gastric pH values increased and remained in the alkaline range throughout the 24 h period of evaluation. Significant differences were observed between T0 (4.88 ± 2.38), T5 (7.08 ± 0.89), T8 (7.43 ± 0.22), T9 (7.28 ± 0.36), T11 (7.26 ± 0.71), T13 (6.74 ± 0.90), and T17 (6.94 ± 1.04) (p  <  0.05). The mean gastric juice pH ranged from weakly acidic to neutral or weakly alkaline in all groups, regardless of food and water intake (i.e., in the fasted, non-fasted, and fed states). Mean gastric pH measured in the control group did not differ from values measured during the 24 h post-anesthesia period or in the non-fasted group. Gastrin concentrations increased significantly during the post-anesthetic period compared to baseline (20.15 ± 7.65 pg/mL and 15.15 ± 3.82 pg/mL respectively; p  <  0.05). General inhalation anesthesia and dorsal recumbency did not affect gastric juice pH, which remained acidic and within the physiological range. Gastric juice pH was weakly alkaline after recovery from anesthesia and in the fasted and fed states. Serum gastrin levels increased in response to general inhalation anesthesia in dorsal recumbency and were not influenced by fasting. Preventive pharmacological measures are not required in horses submitted to general anesthesia and dorsal recumbency.

Investigating the gastrointestinal physiology of mature horses with and without a history of cribbing behavior in response to feeding a digestive support supplement

Cribbing, a stereotypic oral behavior observed in horses, involves placing incisors on a fixed object, arching the neck, pulling against the object, and emitting an audible grunt. This behavior has been associated with gastrointestinal (GI) dysfunction and gastric ulceration. In this randomized crossover study, we investigated the impact of a GI support supplement (SPL) on the GI environment and physiology of four cribbing (CB) and four non-cribbing horses (NCB). Mature Quarter Horses, acclimated to individual stalls for 16 hours daily with paddock turnout in pairs for 8 hours per day, were randomly assigned to receive either the SPL or placebo for 21 days, followed by a 2-week washout period. Fecal and gastric samples were collected for pH determination and blood samples were analyzed for serum cortisol and gastrin levels. Endoscopic examinations assessed gastric ulcer severity, and cribbing frequency and bouts were recorded via video surveillance. Data were analyzed using a mixed-model ANOVA. Results showed no differences in fecal and gastric pH between cribbing statuses. However, an interaction between supplementation and cribbing status was observed for squamous mucosa ulcer scores (P=0.003). There were no differences in glandular mucosa ulcer scores, serum cortisol, serum gastrin, and crib-bite count between CB and NCB horses or between supplementation groups. Crib-bout duration did not differ with supplementation, but differences were found between periods (P<0.05) and hour ranges (P<0.001). Our findings suggest that the GI support supplement may not effectively address cribbing behavior or alter the GI environment in NCB or CB horses.

Influence of weaning management on gastritis incidence in foals

This study evaluated the incidence of gastritis in foals subjected to different weaning management methods. Sixteen crossbreed foals [230±35 kg], were enrolled in an experiment with a randomized block design. After weaning, foals were housed in either individual pens or a group pen. Gastritis in the foals was evaluated through gastroscopy. Data were submitted to analysis of variance by the non-parametric Friedman test at 0.05 significance level. Before weaning, gastritis was observed in 87.5% of the foals, and the scores for the number of gastric lesions were 2.10 and 1.56 for foals housed in group and individual pens, respectively. After weaning, the scores for the number of gastric lesions were 1.75 and 1.25 for foals housed in group and individual pens, respectively. For the intensity of gastric lesions, the average scores observed before weaning were 3.31 and 1.37 for foals housed in groups and individual pens, respectively. After weaning, the scores for the intensity of gastric lesions were 1.93 and 1.00 for foals housed in group and individual pens, respectively. The intensity of the gastric lesions decreased when comparing foals prior to weaning and after weaning, regardless of the management system (P<0.05). The number of lesions was not significantly different but tended to decrease after weaning. Differences in plasma cortisol concentrations were observed between samples collected on the weaning date and after weaning (P<0.05). No differences were detected in plasma gastrin concentration. In conclusion, gastritis in foals can be observed before weaning, which contributes to a decreased gastric lesion incidence.

Genetics of Equine Behavioral Traits

Behavior is a valuable quantitative trait in the horse because of its impact on performance, work, recreation, and prerequisite close interactions with humans. This article reviews what is known about the genetics of behavior in horses with an emphasis on the genetic basis for temperament traits, neuroendocrine function, and stereotypic behavior. The importance of using modern molecular genetic techniques to the study of equine behavior and recommendations for future research are also discussed. Ultimately, these studies enhance the understanding of the biology of behavior in the horse, improve handler and rider safety, and benefit horse welfare.

Common Feeding Practices Pose A Risk to the Welfare of Horses When Kept on Non-Edible Bedding

During the evolution of the horse, an extended period of feed intake, spread over the entire 24-h period, determined the horses' behaviour and physiology. Horses will not interrupt their feed intake for more than 4 hours, if they have a choice. The aim of the present study was to investigate in what way restrictive feeding practices (non ad libitum) affect the horses' natural feed intake behaviour. We observed the feed intake behaviour of 104 horses on edible (n = 30) and non-edible bedding (n = 74) on ten different farms. We assessed the duration of the forced nocturnal feed intake interruption of horses housed on shavings when no additional roughage was available. Furthermore, we comparatively examined the feed intake behaviour of horses housed on edible versus non-edible bedding. The daily restrictive feeding of roughage (2 times a day: n = 8; 3 times a day: n = 2), as it is common in individual housing systems, resulted in a nocturnal feed intake interruption of more than 4 hours for the majority (74.32%, 55/74) of the horses on shavings (8:50 ± 1:25 h, median: 8:45 h, minimum: 6:45 h, maximum: 13:23 h). In comparison to horses on straw, horses on shavings paused their feed intake less frequently and at a later latency. Furthermore, they spent less time on consuming the evening meal than horses on straw. Our results of the comparison of the feed-intake behaviour of horses on edible and non-edible bedding show that the horses' ethological feeding needs are not satisfied on non-edible bedding. If the horses accelerate their feed intake (also defined as "rebound effect"), this might indicate that the horses` welfare is compromised. We conclude that in addition to the body condition score, the longest duration of feed intake interruption (usually in the night) is an important welfare indicator of horses that have limited access to roughage.

Therapeutics for Equine Gastric Ulcer Syndrome

Equine gastric ulcer syndrome (EGUS) is an umbrella term used to describe ulcers in the nonglandular squamous and glandular mucosa, terminal esophagus, and proximal duodenum. Gastric ulcers in the squamous and glandular regions occur more often than esophageal or duodenal ulcers and likely have a different pathogenesis. At present, omeprazole is accepted globally as the best pharmacologic therapy for both regions of the stomach; however, the addition of coating agents and synthetic prostaglandins could add to its effectiveness in treatment of EGUS. Dietary and environmental management are necessary for prevention of recurrence.