Transendoscopic laser surgery to correct nasopharyngeal obstruction caused by head flexion in horses.

OBJECTIVE: To determine outcome after transendoscopic laser fenestration of the median septum and removal of the salpingopharyngeal fold of the guttural pouch on nasopharyngeal obstruction caused by poll flexion in Warmblood horses. STUDY DESIGN: Clinical study. ANIMALS: Horses (n = 9). METHODS: Nine horses with a history of performance insufficiency and respiratory noise during poll flexion were examined. On endoscopy, an often asymmetric dorsoventral obstruction of the nasopharynx occurred during poll flexion. Left lateral radiographs were taken in neutral, extended, and flexed head positions showed that mean nasopharyngeal diameter during poll flexion was significantly smaller than in healthy horses. Transendoscopic laser fenestration of the median septum between the guttural pouches was fenestrated and on the worst affected side, resection of the salpingopharyngeal fold was performed for correction. Three days after surgery a follow-up examination including an exercise test, endoscopy, and radiology was performed in 7 horses. RESULTS: Mean ± SD nasopharyngeal diameter based on radiographic measurements had increased significantly by 64% from 1.67 ± 0.49 to 2.58 ± 0.61 cm (P = .01) and the respiratory noise was reduced or eliminated in 7 horses. Six months after surgery, a beneficial long-term effect on performance was confirmed by an owner interview in 8 horses. CONCLUSIONS: Transendoscopic laser surgery offers a promising low-risk treatment option for horses suffering from nasopharyngeal obstruction caused by poll flexion.

In vitro studies on intestinal calcium and phosphate transport in horses.

Transepithelial transport mechanisms play a key role in regulating the absorption and secretion of calcium (Ca(2+)) and inorganic phosphate (P(i)) in the gastrointestinal tract. Although intestinal disorders with imbalances in macromineral homeostasis are frequently observed in horses, available data on intestinal Ca(2+) and P(i) transport are limited. The aim of the present study was to characterize the intestinal Ca(2+) and P(i) transport functionally by using the in vitro radioisotope tracer technique with Ussing chambers and to identify components involved in Ca(2+) transport at both mRNA and protein level. Among the different intestinal segments, the duodenum showed significant and highest active Ca(2+) absorption. The findings from RT-PCR and Western blot analysis suggest that the epithelial Ca(2+) channel TRPV6, the cytosolic calcium binding protein calbindin-D(9K) and the plasma membrane calcium ATPase PMCA may be involved in active transcellular Ca(2+) transport. Regarding the P(i) transport, the results indicate significant active P(i) secretion in the jejunum, but the contributing mechanisms remain unclear. A significant inhibiting effect of ouabain as an antagonist of the basolateral Na(+)/K(+)-ATPase on the serosal-to-mucosal P(i) transport suggests a pivotal role of Na(+) in jejunal P(i) transport in the horse.

Effect of head and neck position on pharyngeal diameter in horses.

Dynamic nasopharyngeal collapse with upper airway obstruction is an important cause of exercise intolerance in performance horses. Its underlying pathophysiology is not fully understood. We hypothesize that head position affects pharyngeal diameter, and thus head position may be a contributing factor to nasopharyngeal obstruction. Fifteen adult healthy horses were subjected to endoscopy and radiography at rest. The pharyngeal diameter was measured at nine different head and neck positions. The effect of sedation and breathing cycle on the pharyngeal diameter was determined, and the relationship between the head angle and the pharyngeal diameter was analyzed. There was a significant influence of head and neck position on pharyngeal diameter, with head position having the major effect (P < 0.001); neck position was less important, but still significant (P < 0.05). The smallest pharyngeal diameter was found at the dorsal, flexed position, which is a clinically important head position in dressage horses. The largest pharyngeal diameter was found at the extended midway position. At each head level, the pharyngeal diameter decreased with flexing the head and it increased with extending the head. The head angle was not associated with pharyngeal diameter, and neither sedation status nor breathing cycle significantly affected pharyngeal diameter. A decrease in pharyngeal diameter will limit the airflow through the upper respiratory tract, and it may result in turbulence with subsequent dynamic collapse. Head and neck position should therefore be considered a possible contributing factor in horses with suspected nasopharyngeal dysfunction.