Colic, Equine - contd.
Diagnosis of colic is often established on clinical signs and symptoms alone. Determination of the underlying disorder, its severity, and appropriate treatment requires a thorough physical examination and occasionally procedural tests.
Examination may reveal increases in pulse and respiratory rates in the affected horse. A pulse rate greater than 60 beats per minute indicates severe disease and a guarded prognosis. Absence of peristalsis, or gut sounds, is not favorable for recovery. The mucous membranes may be poorly perfused in horses with diminished cardiovascular function and shock.
A peritoneal tap, or abdominocentesis, enables sampling of abdominal fluid via a needle or catheter inserted through the abdominal wall. This fluid is normally clear. A sample that is off-color, has blood in it, or contains feces indicates the need for surgery. The character of the white blood cells present and the level of protein in the fluid are important markers of the severity of the underlying disorder. Abdominocentesis is indicated for severe, recurrent, or chronic cases of colic.
Examination of aspirated fluid through a nasogastric tube will help to characterize the problem and evaluate the severity of the disorder. The stomach fluid retrieved can be evaluated for pH and color. Normal gastric fluids are acidic in character; an elevated, or alkaline, pH suggests a backflow of intestinal contents that may indicate some obstructive process. Gastric lavage fluids that are brown in color or resemble coffee grounds may contain blood, suggesting the possibility of gastric ulceration. Retained fluids often smell foul.
An elevated packed cell volume, or PCV, of blood indicates dehydration and poor perfusion. When PCV is elevated, the fluid fraction of blood has been reduced, thereby raising the relative level of red blood cells. Colicky patients that have a markedly elevated PCV are seriously ill, and have a poorer prognosis.
Rectal palpation is a useful adjunct to physical examination and laboratory testing. This exam permits the clinician to evaluate by feel the organs in the posterior section of the abdominal cavity. Palpation allows the veterinarian to detect distension or the presence of impaction, displacement or torsion of the intestines. When peritoneal inflammation is present, the surface of the intestines may become roughened, which is detectable by palpation. The presence or absence of feces and the character of the feces will be evident. Equine patients may resist rectal examination or strain excessively. Sedation, local anesthesia or nose twitching may be elected to permit safe examination and avoid the complication of a rectal tear.
