SPORTS MEDICINE THE EXHAUSTED HORSE SYNDROME Poor race performance syndrome Synchronous diaphragmatic flatter www.drghanem.co.nr
THE EXHAUSTED HORSE SYNDROME Exhaustion is a result of brief maximal exercise or protracted (prolonged) submaximal exercise. www.drghanem.co.nr
produces severe metabolic lactic acidosis With maximal exertion in racehorses, there is rapid depletion of readily available muscle energy stores (creatine phosphate, ATP) produces severe metabolic lactic acidosis www.drghanem.co.nr
minimal changes in acid‑base status or lactic acid concentration. With protracted submaximal or endurance exercise, energy is supplied by aerobic metabolism of both fatty acids and carbohydrates minimal changes in acid‑base status or lactic acid concentration. www.drghanem.co.nr
Etiology and pathogenesis occurs mostly during summer season, when the temp. and humidity are elevated. www.drghanem.co.nr
high-intensity short exercise. 2 types of exercise The syndrome is associated with 2 types of exercise and high-intensity short exercise. prolonged submaximal exercise: www.drghanem.co.nr
High-intensity short exercise: rapid depletion of the phosphagen pool of muscle cells (creatine phosphate and ATP) and accumulation of lactate Accumulation of lactate reduces the muscle pH from normal (7.0 – 7.1) to 6.3 or lower Inactivation of muscle metabolizing enzymes, thus reducing the availability and production of ATP Interfering with Ca availability by actomyosin, reducing the contractile efficiency. www.drghanem.co.nr
Prolonged submaximal exercise 1- Sweating large volumes of fluid may be lost via this route producing dehydration and reduction of exercise performance Horse sweat is hypertonic, and sodium and chloride are the major ionic constituents the major signs resulting from the loss of sodium and associated fluid are due to decreased circulatory function and poor organ perfusion . Loss of potassium ions in the sweat may occur and contribute to the exhaustion but usually transient because of the compensatory release from other cells. Oxygen with Ca in Mitochondria required for oxidative phosphorylation of ADP to ATP so reduction of oxygen or calcium produce exhaustion www.drghanem.co.nr
Prolonged submaximal exercise 2- Depletion of intramuscular glycogen store during prolong submaximal exercise contributes to increasing the exhaustion www.drghanem.co.nr
Profuse sweating www.drghanem.co.nr
Clinical signs There are variations in the severity of signs of exhaustion in individual horses. All affected horses will have elevated rectal temperatures and pulse and respiratory rates, and variable dehydration on arrival. The most reliable quantitative guides to impending exhaustion are pulse and respiratory recovery rates. The pulse and respiratory rates take 30 minutes after rest and must return to acceptable levels, usually 60 to 70 per minute and 40 per minute, respectively. Severely affected horses are usually severely depressed with little interest in food or water despite apparent dehydration. Pulse pressure and jugular distensibility are often markedly decreased. Capillary refill time is prolonged and cardiac irregularities. Muscle cramps (lactic acid) and spasms are often evident. Diminution or absence of intestinal sounds. www.drghanem.co.nr
Diagnosis Case history Clinical Signs Lab Diagnosis Hyponatremia Hypochloremia Metabolic acidosis (lactic acidosis) Hemoconcentration www.drghanem.co.nr
Treatment --- step 1 1 Horses manifesting depression and persistently elevated pulse and respiratory rates as their only problems Respond to rest, cooling out, and access to salt, clean feed, and water. If there is no improvement in 30 minutes, they should receive fluids orally or intravenously. www.drghanem.co.nr
The rectal temp. should return to normal within 15-30 Min cold water is applied by a hose, sprayer, sponge, or towels over the large vessels of the distal extremities, head and neck, and over the jugular veins. . Treatment Step 2 2 The rectal temp. should return to normal within 15-30 Min Cautions ! Use an open area with free circulation of air, in a breeze or in front of a fan. Avoid pouring very cold water over the large muscle masses to avoid inducing muscle spasms Cold alcohol leg wraps are also useful in dissipating heat www.drghanem.co.nr
severe exhaustion requires prompt and vigorous fluid therapy Treatment --- step 3 3 severe exhaustion requires prompt and vigorous fluid therapy Restoration of effective circulating blood volume by IV injection of saline (provides Na+ and Cl-). Correction of electrolyte deficits by IV saline with addition of K+. The use of non-steroidal anti-inflammatory drugs is controversial because they may produce toxicity in dehydrated, volume-depleted horses. However, they may be used after rigorous fluid therapy for their anti-inflammatory, analgesic and anti-pyretic effect. Provision of readily metabolizable energy as glucose www.drghanem.co.nr
Questions www.drghanem.co.nr