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Colic is one of the most common diseases in horses. During treatment, the animal is exposed to several stressors which are known to promote gastric mucosal alterations. According to the literature, Equine Gastric Ulcer Syndromes (EGUS) occur with a prevalence of 53-93 %, depending on use and breed. Frequently, affected animals develop very unspecific indications or no symptoms at all. This thesis aims to investigate the prevalence of EGUS in horses with colic, the impact of colic on EGUS and if and to which extent colic results in gastric ulcers. In a prospective study, 30 horses were examined, which were hospitalized due to colic symptoms in the Clinic for Horses of the Freie Universität Berlin. In addition, a control group contained ten horses, which were taken to the clinic for another medical reason. The patients were between 3 and 32 years old and were kept in open stabling or boxes with several hours outdoor access on a paddock daily. Gastroscopies were conducted two times at intervals of tree days. Based on the assumption described in the literature, lesions in the gastric mucosa develop within 48 hours after occurrence of a noxa. Therefore, the first examination was performed on day 1 approximately 12-17 hours after hospitalization in order to figure out the initial state of gastric mucosa. At the same time a detailed anamnesis was documented and blood samples were taken. The second gastroscopy took place on day 4 after hospitalization and the results of these two examinations were compared. The diagnosis of the stomachs was evaluated based on the scoring system of MAC ALLISTER, which was modified by LUNDBERG and recommended by the Equine Gastric Ulcer Council. This system assigns the gastric findings to four severity grades individually for both Pars nonglandularis and Pars glandularis and considering number and severity of the lesions. In this study, a significant deterioration of the gastric findings was observed within three days. Horses that had shown intact gastric mucosa on day 1 developed lesions till day 4 and the findings in horses that had shown alterations in the gastric mucosa already on day 1 deteriorated significantly till day 4. The Pars nonglandularis was affected more often than the Pars glandularis. On day 1, in 54 % of the colic patients lesions in the Pars nonglandularis were detected and additionally in 19 % in the Pars glandularis while only 27 % showed no lesions. On day 4 after appearance of first colic signs, in 38 % of colic patients the Pars nonglandularis and in 54 % both mucosa components were affected, whereas only 8 % of horses still did not show any lesions. Within the three days, the severity of the clinical findings increased significantly too. Thus, 55 % of the colic patients were assigned grade I and II on day 1 for the Pars nonglandularis and 14 % grade III. At that time, the Pars glandularis was only marginally affected: 15 % of patients obtained grade I and 4 % grade II, respectively. On day 4 after hospitalization however, 53 % of the colic patients showed light and moderate lesions in the Pars nonglandularis of grade I and II and 40 % showed severe lesions of grade III and IV. The scoring of the Pars glandularis resulted in 42 % of the patients grade I and II, and in 12 % in grade III.
In contrast, in the control group 70 % of the horses had no gastric lesions. The remaining showed lesions of grade I and II and no changes in the findings in the Pars nonglandularis from day 1 to day 4 could be observed. Interestingly, the increase in the number and severity of lesions in the Pars glandularis was observed to be significantly higher in the group of the surgically than of the conventionally treated horses. However, due to the small group of surgically treated horses this new result requires further evidence.
No correlation could be found between the clinical findings and the concentrations of the blood characteristics hematocrit and total protein. The number of leucocytes correlated with the clinical findings on day 1. Horses with lesions showed higher numbers than those without lesions. Nevertheless, these numbers did not exceed the reference range reported in the literature. The measurements of the gastrin concentration did not show any abnormality or effect of gastric ulcers. In contrast, the concentration of the acute phase protein haptoglobin increased from day 1 to day 4 by a factor of 1.53 which is a clear indication of an inflammation. Therefore, haptoglobin is a useful blood parameter for the evaluation of the course of the inflammation. Already on day 1, the concentration of serum amyloid A was observed to be above the reference range reported in the literature which proves an acute inflammation in interrelation with colic diseases.
The present study shows that colic in combination with hospitalization may result in EGUS and increase the severity of existing lesions of the gastric ulcer significantly. Further studies should focus on the question whether these lesions require medical treatment. Spontaneous remission of mild lesions may be expected once the horse is back in its habitual environment, no longer stressed and fed regularly, but further evidence is needed. Longer existing EGUS and severe lesions (grade ≥III) very likely require rehabilitation or prophylactic administration of ulcer protective drugs. In this context, a third gastroscopy would be interesting once the horse is back in its habitual environment. It could provide indications about spontaneous remission and rehabilitation requirements of lesions in gastric ulcer caused by colic disease and hospitalization of the horse.