Intestinal obstruction in the horse. Physical signs and blood chemistry.

The research investigates the physical signs and changes in blood chemistry in horses with artificially induced intestinal obstructions in the duodenum, small colon, and a simulated twist of the ileum (volvulus). The study found that horses with duodenal obstructions presented the most severe symptoms and shortest survival times, with notable blood chemistry changes including acidosis and hyperkalemia.

Study Design and Methods

• The research involved artificially inducing obstructions in different parts of the horse’s intestine – the duodenum (the first part of the small intestine), the small colon (the last part of the large intestine), and creating a simulated volvulus of the ileum (a form of obstruction caused by twisting of the intestine).
• The researchers then monitored the physical symptoms of the horses and analyzed changes in their blood chemistry.

Findings: Duodenal Obstruction

• The physical symptoms of horses with duodenal obstructions were found to be the most severe. This was also the condition correlated with the shortest survival times, indicating that this type of obstruction is particularly dangerous.
• The horses’ blood showed an initial rise in pH (making it more alkaline), but this was followed by a condition called acidosis, where the blood becomes too acidic.
• Other changes in the blood included hyperkalemia (a higher than normal level of potassium), alongside reductions in bicarbonate (HCO3), sodium (Na+), and chloride levels (Cl-), all vital for normal bodily functions.

Findings: Small Colon Obstruction

• Horses with small colon obstructions exhibited milder physical signs compared to those with duodenal blockages.
• The blood tests for these horses were found to be normal, indicating that obstructions in this part of the horse’s intestine might not cause significant changes in blood chemistry.

Findings: Simulated ileal volvulus

• The simulated volvulus (twisting) of the ileum caused continuous colic (abdominal pain) in the horses.
• Blood tests revealed that these horses also experienced acidosis and hyperkalemia, together with continuous decreases in bicarbonate and chloride levels.

This study provides valuable insights into the physical and physiological impacts of different types of intestinal obstructions in horses, potentially guiding effective diagnostic and treatment strategies.