Equine pelvic flexure impaction. A model used to evaluate motor events and compare drug response.

The study reveals how impaction at the pelvic flexure in ponies can be induced and the effects of drugs such as xylazine and flunixin on alleviating these conditions. The research also examines the alterations in the blood flow to the colic arteries during colic episodes and after administering the mentioned drugs.

Research Methodology

• Researchers developed pelvic flexure fistulas in eight Shetland X ponies, each weighing approximately 160kg. The fistulas were formed with a diameter of 2.5cm.
• An impaction was created at the pelvic flexure 25 times in these ponies by causing a partial obstruction with a 1 litre rubber rebreathing bag fixed at the fistula site.
• Two ponies had blood flow probes implanted on their dorsal and ventral colic arteries — the right colic artery and the colic branch of the ileocolic artery.
• Researchers measured intraluminal pressure changes at eight different sites in the large colon during episodes of colic and also following the administration of flunixin or xylazine.

Findings

• Episodes of colic – characterized by behaviors like pawing, anxiety, anorexia, and attempts to lie down during impaction – corresponded with longer, louder sounds upon auscultation and multiple contractions.
• The drugs flunixin and xylazine provided relief from these clinical signs for a period of approximately 30-60 minutes.
• Xylazine caused a halt in intraluminal pressure changes for about 30 minutes. Flunixin also provided relief but did not significantly affect the intraluminal pressure changes.
• During episodes of colic, the average arterial blood flow through the colic arteries doubled.
• The administration of flunixin during colic episodes did not affect the elevated blood flow. However, when xylazine was administered during a colic episode, the blood flow decreased.

Implications

• The study provides valuable insights into how the drugs flunixin and xylazine can provide temporary relief from colic symptoms induced by impaction at the pelvic flexure.
• The comparison of the effects of these two drugs on factors such as intraluminal pressure changes and blood flow during colic episodes offers vital information for veterinarians to make effective decisions regarding treatment.
• A clear understanding of the changes in blood flow and intraluminal pressure during colic episodes will help in developing appropriate therapeutic strategies and interventions for equine colic.