CHAPTER 192 Examination of the Foal with Colic
Unfortunately, horses can be affected by colic from the first day of life until the last. Evaluation and treatment of acute abdominal pain in foals is somewhat different from that in adult horses because of their size, pain tolerance, and the types of diseases foals acquire. The purpose of this chapter is to attempt to differentiate the medically manageable foal with colic from the foal requiring surgery. This discrimination is especially important in foals because of their predisposition for adhesion formation following abdominal surgery. The decision to treat medically or surgically is resolved by synthesizing information concerning the foal’s history, results of diagnostic tests, and, most important, the physical examination.
PHYSICAL EXAMINATION
Thoracic auscultation should be performed on the right and left sides of the thorax to evaluate the heart and lungs. Mean heart rate is 100 beats per minute during the first 30 days of life and decreases to 60 to 70 beats per minute by age 2 to 3 months. A high heart rate may be a response to pain, excitement, hypovolemia, or endotoxemia. Bradycardia is rare but may be detected in foals with uroabdomen if they are hyperkalemic ([K+] greater than 5.5 mEq/dL). These foals are also prone to developing cardiac arrhythmias. Cardiac murmurs may be normal in foals up to 3 to 5 days old and are usually caused by blood flow through a patent ductus arteriosus. Such murmurs may sound like continuous machinery–type or systolic murmurs. Innocent flow murmurs can be heard in some foals, but these are restricted to the left heart base and are usually less than grade 2/6. Fever and anemia can also result in cardiac murmurs. The lungs should be ausculted on the right and left sides and over the trachea. Borborygmus heard within the thorax is normal because of the shape of the diaphragm and is not indicative of diaphragmatic hernia.
DIFFERENTIAL DIAGNOSIS
Differential diagnoses for neonatal foal colic include meconium retention (see Chapter 187, Meconium Impaction), enterocolitis (see Chapter 191, Inflammatory Bowel Diseases in Foals), uroabdomen and ruptured bladder, and congenital lesions.