The gut sounds we are listening for are quite specific. An ileocaecal sound is the strongest evidence of good gut function. We hear this when the fluids cascade out of the small intestine into the caecum. Other sounds that relay evidence of a healthy gut relate to the propulsion of ingesta along the gut from the front of the horse to the back. Gas tinkling is not evidence of health. When no propulsive sounds are heard then the condition is called ileus.

Horses with ileus are often colicky but can be just depressed. They are always dehydrated and low in vital electrolytes. This is an emergency situation that requires large amounts of "spiked" fluids. Fluids are spiked with calcium and potassium to hasten recovery. If enough fluids are given early then the condition is reversible. Endurance vets believe that ileus may be the precursor to rotation of the bowel which is only reversible with surgery.

Currently the evidence is that the quality of gut sounds is related to redistribution of blood flow and electrolyte depletion. They are not related to how much that a horse has eaten. Exercise causes the blood to be redistributed to the muscle for work and the skin for cooling. The gut misses out even more during prolonged exertion. At gate into hold rides some horses come off track so quickly that redistribution of gut blood flow and hence vital sounds has not had time to occur. This is in marked contrast to the standard half-hour recovery horses that should be displaying good gut sounds. This is why we call for represents at many gate into hold rides. The horses that have sufficiently recovered will have evidence of returning gut function.

In addition to redistribution of blood flow, gut sounds are reduced by electrolyte depletion and fluid loss . Every endurance horse loses significant amounts of sweat. This creates the dehydration and electrolyte imbalance (especially calcium and potassium ). Calcium and potassium are both essential for nerve and muscle function. Significant losses will cause the return of gut sounds to be prolonged. They also lose potassium via urine . If the potassium is not replaced by diet, that is if the horse hasn't been eating well prior to the ride then they may have started the ride already low in potassium. Obviously heat, humidity, speed and fitness all determine the rate of fluid loss. As losses become significant the horse has difficulty giving blood flow back to the gut in order to allow adequate blood to working muscles (to deliver energy, oxygen and remove lactate) , skin (for sweat production) and more essential organs (brain, kidney, liver etc ).
Thus gut sounds will only return to normal when the horse has stopped working and cooled down and taken up enough fluids to allow blood distribution to the gut .

This is facilitated in the fit horse by basic strapping. Cool the horse with large quantities of water. This relieves the demand placed by the skin vessels on the blood flow and some of the saving is channeled to the gut. Walk between washes to allow lactate to come out of muscles prior to the walk up to be vetted . Then when the skin and muscles are happy the blood can return to the intestinal vessels and the gut is happy too. At this stage you can feed your horse. Do not feed a horse that has only partially recovered as this will load the circulation and elevate the heart rate.

Are gut sounds improved by feeding prior to vet check? The are marginally increased by feeding the horse that is fit enough to have recovered quickly , thus restoring the blood flow to the gut promptly. At a gate into hold it is pointless feeding the horse prior to vetting , there simply isn't time. The horse with a healthy gut will eat and the presence of food stimulates movement of the intestinal wall. However a horse does not have poor gut sounds because it is not eating. If a horse is reluctant to eat then there is something wrong. In the horse that has just come off track then dehydration and electrolyte depletion are the likely culprits. Often good active gut sounds are heard in unfed horses as their gastrointestinal tract is never totally empty due to the reserves in the large intestine and caecum. And if the gut is not moving due to exhaustion, fluid and electrolyte loss or heart rate is still elevated then feeding is not the answer.

How does the heart rate get affected by feeding? The heart rate of the endurance horse will be affected by many factors. When the horse comes in off track the demand for blood flow is high so heart rate will be high. If the horse is cooled and had been ridden so as to reduce the lactate levels then and there is no pain or excitement then heart rate will drop. Feeding creates a demand for blood to return to the gut provided the skin and muscle are satisfied with their share. The increase in blood flow to the gut in a fed horse will create demand on the heart and heart rate is elevated. If your horse recovers to well below the cut off then you can risk a few beats elevation as a trade off for an early start on recharging the batteries.

How can I improve on the gut sound rating ABCD? Those that have understood this article so far will know the answer to this already. Gut sounds will always be lower at Gate into Hold but they can be improved upon. The ways to help increase gut score are
1. have your horse fit enough to cope with the ride at that distance and humidity, terrain etc.
2. ride your horse within the limits of its stage of conditioning
3. Come into the check point steadily to reduce lactate burden and hence speed recovery
4. Strap the horse well with cold water, monitor the heart rate as you slosh. Humid conditions often require iced water. Get the blood out of the skin into the gut. If the horse is already cool then reduce the volume of water. You will feel cold long before your horse well. I have seen 99 understrapped horses for every over strapped horse. Iced water does not cause cramping if used correctly.
5. Supplement with adequate electrolytes.
6. Feed good quality roughage before the ride to hold water in the gut and create a buffer against depletion.

Happy Riding,

David Brown BVSc MACVSc