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Another favourite tube feed is to boil Jungle Oats 500 gram/day and split it into 3 - 4 meals per day. This will meet about 25% of the daily energy requirements of a 500 kg horse. Often a day or two of force feeding with Jungle Oats is all that is required to get a hypophagic horse to start eating normally. For this reason I have not exceeded the 500 gram dose.

Regardless of the diet used, the first day only one third of what is needed should be given. If no significant signs of diarrhea occurs, increase the amount by one third until the dailt requirements are met (usually after 3 days). Start by tube feeding every 2 - 4 hours, gradually increasing the volume and decreasing the frequency. However, tube-feed a hypophagic horse at least every 6 hours (4 X day). Do not exceed 6 litres of fluid per any feeding as a larger volume may be associated with reflux and signs of colic. Always check for the presence of fluid in the stomach before the next feed is given and if more than 50% of the previous feeding can be aspirated, discontinue the tube feeding.

Low fibre diets are often associated with diarrhea, but it is often mild and not associated with dehydration. It is not necessary to stop the tube feeding with mild diarrheas, but the horses should be closely monitored for signs of laminitis.

Feeding horses with specific disease

Introduction 

Most hospitalized do not need a special diet. They do not require the high amount of feed given to working horses. Most can be well maintained on a diet consisting of free choice, good quality hay. One to two kg of concentrated can be fed to these horses to help maintain appetite and adaptation to grain once the disease is cured.

For some specific diseases a specialized diet may speed up recovery and aid in the healing from the disease. Some specific examples are given below.

Hoof defects 

Hoof defects can occur from a multitude of causes and can be minimized with proper hoof care in consultation with your veterinarian and farrier.
Biotin supplementation may be helpful in enhancing the repair of hoof defects and preventing their recurrence. Horses with thin brittle hooves, cracks in the weight bearing border of the coronary horn with crumbling of the lower edges of the walls or open white lines may benefit from prolonged biotin supplementation. Biotin are widely marketed and a number of commercial products are available.

Bear in mind that it will take more than 6 months for the improvement to be noticeabl in the case of hoof cracks and more than 19 months in horses with white line disease. Thoroughbreds need 15 mg biotin per day and draft breeds twice as much.

Horses with stratum externum (on the outside) defects respond to biotin supplementation alone. Whereas, horses with stratum medium defects need calcium and protein too respond if they are on a diet deficient in these two nutrients. It is not possible to differentiate clinically between starum medium and externum defects.

Excess biotin intake by the horse has not been shown to be detrimental.

Recurrent airway disease 

Recurrent airway obstruction (COPD or heaves) is an allergic condition to fungal spores commonly found in hay and bedding. It is a disease of older (7 years and older), stabled horses characterized by chronic coughing, exercise intolerance, laboured breathing and nasal discharge. It is very common in South Africa and once the allergy develops it will remain present for the rest of the horse's life. It is a disease that can be controlled but not cured.

It is vital to changes a horses with Recurrent Airway Obstruction's environment and often it is essential to keep them outside and minimize exposure to the fungal spores. If a hay cube cannot be fed, the hay should be soaked in water at least 5 minutes before feeding. The same applies for dusty concentrates. Wet feed not immediately consumed should be replaced to prevent mouldy feed.

All feed should be fed close to the ground and not in a deep container so that dust particles will tend to fall away from the horse's nose and not be inhaled.
Straw, shavings and wood products should not be used for bedding and the best bedding (if the horse must be stabled) is river sand, which is more difficult to clean.

Diarrhea 

Horses with, or recovering from diarrhea should not be starved as lack of oral alimentation for more than 2 days will cause intestinal atrophy and loss of integrity which may delay the recovery even more and can result in septicaemia in young foals.

If the diarrhea is caused by small intestinal dysfunction, grain and concentrates should be withheld. Whereas, with a large intestinal dysfunction, concentrates can be fed but in small more frequent portions. Excess grain should be avoided because undigested starch will pass through the small intestine into the large bowel where fermentation may disrupt the normal large colon and caecal function and make the diarrhea worse.

Regardless of the cause of diarrhea, fibre ingestion is beneficial as a source of volatile fatty acids, which along with certain amino acids are the primary source of nutrition to the cells lining the intestine. Fibre may also stimulate intestinal segmental contraction (which will slow passage of ingesta) and add bulk to form faeces. Because of these benefits, horses with diarrhea should be fed a good quality hay.

If horses receive oral antibiotics, the may benefit from the oral administration of caecal contents, yogurt or a commercial probiotic to inoculate normal intestinal flora. This should only be done in conjunction with your veterinarian.

Sand induced diarrhea 

Sand induced diarrhea can be seen in horses taking in sand inadvertently with feed or purposely by some horses particularly foals. Inadvertent intake of sand is increased in horses on over grazed and sandy-soil pastures and when feed is consumed from the ground.

An insult to the gastrointestinal tract that alters motility may also prevent a horse from clearing normal small quantities of sand allowing it to accumulate and causing clinical signs of weight loss, diarrhea and in severe cases colic. The sand accumulate in the ventral portion of the large intestine, irritating the mucosa and causing diarrhea and weight loss. Sand accumulation can in some horses be heard on auscultation, seen in the sediment of a faecal emulsion or abdominal radiographs may in some horses be required to show up te sand.

Treatment includes feeding a soluble fibre containing psyllium (125 grams Metamucil given twice daily) together with a good quality hay and preventing additional intake of sand. Although the diarrhea may respond quickly to this treatment it may be necessary to give a longer course of treatment to clear all the accumulated sand. Give the treatment in consultation with your veterinarian. Bran, oil and other laxatives will have very little effect in clearing the sand. Having trace-mineralized salt mixed with equal parts of bone meal may prevent some (but not all) horses from consuming sand voluntary. A good deworming programme is also essential to prevent intestinal damage and altered gut motility.

Intestinal impaction 

Impaction of the large colon with ingested feed is one of the most common causes of colic and is characterized by dry, doughy contents. Colics caused by impactions are treated with analgesics and some form of laxative tubed by nasogastric tube. It is essential to keep food away from these horses until the impaction is passed.
To assist in preventing impactions, ensure proper dental care, supply fresh palatable water at all times, and make sure that the horse gets regular exercise and a diet consisting of good quality hay. Following the successful treatment of impaction make sure that the hay fed to the horse is not too high in fibre and not of a poor quality. Instead a low fibre highly digestible forage like growing grass or legumes will help in keeping the stool soft.

If necessary 90 - 120 gram of Epsom salt may be added to the daily diet.

Intestinal calculi 

Enteroliths cause impactions and colic and must generally be removed surgically. They form in the large intestine by mineral deposition around a nidus consisting of metal, cloth or nylon and most often consist of magnesium ammonium phosphate (struvite). Diets high in wheat bran and lucerne (and thus high in phosphorus, calcium, magnesium and protein) have been incriminated but not proven in the formation of enteroliths.

Some lucerne are high in magnesium and will also promote alkaline intestinal content, two factors implicated in the formation of struvite.
In areas where enteroliths are more common, they can be minimized by feeding a diet consisting of grass forage and grain and avoiding legumes and wheat bran (unless required).

Feeding apple cider vinegar may help as it will lower intestinal pH to below 6.6. The daily dose required is 110 ml per feeding of grain in a pony and twice as much in a 500 kg horse.

Large colon resection or dysfunction 

Horses with extensive large colon or ceacal resections should receive a diet high in protein (> 12%), phosphorus (0,4%) and low in fibre (less than 28%) to compensate for their decrease in apparent digestibility. A diet of this type can be provided by feeding a good weanling-type diet. In addition water must always be available as their needs for water is increased due to the small area of water absorption.

In horses with only left colon resection the intestinal function of the large colon will quickly return to normal and they will not require special diet modification.

Small intestinal resection or dysfunction 

The duodenum and the jejunum are the primary sites for digestion and absorption of starch, protein, vitamins and most minerals with the exception of phosphorus. The ileum is the primary site of fat and fat-soluble vitamin absorption. The large intestine can compensate to some extend for the lack of absorption of protein, carbohydrates and b group vitamins. With extensive small intestinal resection, a diet consisting of good quality forage and only small amounts of grain should be fed. Good quality lucerne and/or growing forage is the best. Calcium absorption is primarily from the proximal small intestine, but supplementation is not necessary if lucerne is included in the diet.

With ileum resection the parenteral administration of fat soluble vitamins A, D and E may be necessary.

Right dorsal colitis 

Right dorsal colitis is a specific inflamation of a small segment of the right dorsal colon associated with phenylbutazone administration. Clinical signs include weight loss, intermittent diarrhea and recurrent colic and is directly associated with the intake of roughage. This condition may be difficult to diagnose and will require very specific dietary management.

The aim is to fed a complete ration containing not more than 30% fibre. This can be achieved by feeding concentrates with milled lucerne (low bulk diet) to which 20% vegetable oil is added. The diet should be split in 5 - 6 smaller portions per day to decrease the mechanical and physiologic load on the colon. In those horses that start eating their bedding due to a fibre hunger, can be allowed to graze small amounts of green grass for short periods during the day.

Short chain fatty acids may aid in the mucosal repair of the large colon and including psyllium (Metamucil) in the diet for 4 - 6 months (125 gram per day in a 500 kg horse) will increase the short chain fatty acid ratio in the colon and promote healing.

Rectovaginal surgery or laceration 

Decreasing faecal volume, pressure and straining to defecate may be helpful following repair of rectovaginal laceration. This can be accomplished by feeding a diet low in fibre and high in energy. A complete peleted feed with 25 ml of oil/litre of pellets will accomplish this. If a complete peleted ration is not available, lucerne or green growing grass will also help to keep the faeces soft.

Hepatic dysfunction 

In horses with hepatic dysfunction the plasma concentration of branched chain amino acids (BCAA) leucine, isoleucine and valine may be decreased and that of aromatic amino acids (AAA) phenylalanine, tyrosine, tryptophan as well as ammonia is increasing leading to clinical signs of hepatic encephalopathy.
These alterations can be minimized by feeding a diet adequate to meet the energy and protein requirements but not excess protein and with a protein high in BCAA and low in AAA with a high BCAA:AAA ratio.

The diet should also be high in starch to limit the liver's need for glucose synthesis.

If the horse with liver disease is anorectic it should be tube fed as described previously. A diet that meets the requirements for hepatic disease can contain 0.5 kg mealies/100 kg body weight per day divided into 5 - 6 equal portions. A legume forage such as lucerne may be best due to the high BCAA:AAA ratio if the high protein content is tolerated by the horse (this can be determined by measuring the plasma ammonia level). If the plasma ammonia is to high a grass forage should be fed instead.

If the hepatic damage is severe or the course of the disease is more than a few weeks, a vitamin supplement containing vitamin A, D, E, K, thiamin (B1), riboflavin (B2), niacin, pantothetic acid, pyridoxine (B6), biotin, folacin, cobalamine (B12), and choline can be included in the daily feed.

Chronic renal failure 

Chronic renal failure occurs more commonly in older horses and is characterized by weight loss, high water intake, increased urine production due to an inability to concentrate urine. They will also have electrolyte disturbances (mainly a low sodium and chloride level in the plasma) and various degrees of anorexia caused by an inability to excrete metabolic waste products like urea and reabsorb electrolytes.

A diet for a horse with renal failure should be high in carbohydrates and low in protein (too decrease urea production), phosphorus and calcium. Excess calcium should be avoided as this is also excreted by the kidney in horses (this differ from other species). A diet low in calcium, phosphorus and protein can be provided by feeding a grass forage. Concentrates may be fed up to one half of the daily feed intake. Feeds to avoid include legumes like lucerne (too high in calcium and protein) and bran (too high in phosphorus).

A vitamin supplement containing vitamin A, D, E, K, thiamin (B1), riboflavin (B2), niacin, pantothetic acid, pyridoxine (B6), biotin, folacin, cobalamine (B12), and choline can be included in the daily feed to compensate for urinary loss of the b vitamins.

Salt and water should be available for free-choice consumption.

Urinary calculi 

Urinary tract calculi are not common in horses and if present are usually seen in the bladder of males (fillies can pass them through the relatively short urethra). Diet modification to decrease the urine concentration of calculi constituents and to alter the urine pH to make it unfavourable for calculi formation has been shown to an effective way of preventing calculi formation in horses. The dietary manipulation differs with the calculi composition which should be analysed before embarking on a course of diet supplements.

To prevent a recurrence of calcium carbonate a low-calcium diet and urinary acifiers should be fed. The diet should ideally meet but not exceed the daily requirements of phosphorus and calcium. This can be accomplished by feeding a mature hay - grain mixture with no added calcium. Early growth grass especially legumes are high in calcium and should be avoided.

Adding ammonium sulphate at 75 mg/kg to the diet will be sufficient to decrease the urine pH from 8 to 5 in a horse. Ammonium chloride will also lower the urinary pH, but is less palatable to the horse.
Urinary acidifiers may cause more harm than good in that they decrease the dietary cation-anion balance (Na+, K+; Cl-), which may increase the horse's calcium excretion in the urine.

Increasing the salt intake has been advocated to increase the urine production. However, increased sodium may enhance the reabsorption of calcium in the GIT and may not be beneficial in preventing calcium carbonate crystals in the horse.

Recurrent myopathy 

Recurrent myopathy or tying up is common in some Thoroughbred fillies, although it can also occur in other breeds and geldings. The relationship with carbohydrates and myopathy has been known for decades. By lowering the carbohydrate intake and supplementing with vegetable oils (250 ml per feeding) the incidence of tying up can be lowered in most horses with the problem.

Starvation 

Severe weight loss is a common sequel to chronic diseases and a number of diseases in the horse. Starvation per se occurs more commonly from late fall to spring and likely reasons include financial constraints, neglect or ignorance and very seldom cruelty. A horse with a long winter coat may look all right from a distance and the poor condition can only be appreciated by palpation of the spine and ribs. Fortunately most people notice and seek help if the starvation proceed to recumbency.

In horses with a condition score of 3 ( Transverse processes cannot be palpated but spinous precesses and ribs easily visible, tailhead prominent but individual vertebrae cannot be identified,) or more should be allowed free access to water and salt and a diet of both hay and grain (13 - 16% protein) divided in 4 - 5 feedings daily.

Once a horse is close to 40% below it's optimum weight it will become recumbent. Initially in sternal and later in lateral recumbency. Survival is unlikely once a horse reach 50% of it's optimal weight, regardless of the treatment. It takes a horse in good body condition at least 60 - 90 days without feed to become recumbent.
A chronically starved horse will have a long, dull coat that tends to mask the extensive loss in body condition. A horse recumbent due to starvation will have a condition score of 1 (Ribs, dorsal spinal processes and tuber coxae will be easily palpated and lack of muscle mass obvious). Most will die if they are unable to get up within 72 hours. Therefore, they should be assisted to get up manually or in a sling. Treatment should include intravenous and oral fluids without dextrose (they are usually hyperglycaemic).

If these horses are not eating they can be tube fed as described previously. If they are eating, provide frequent small amounts of grain (0,5 - 0,7 kg in a 500 kg horse) to which 10 - 20% vegetable oil is added. Start slowly and increase the amount gradually over a period of 3 - 4 days.

A vitamin supplement containing vitamin A, D, E, K, thiamin (B1), riboflavin (B2), niacin, pantothetic acid, pyridoxine (B6), biotin, folacin, cobalamine (B12), and choline can be included in the daily feed. If too much is fed too rapidly in a starved horse, acute laminitis, diarrhea and colic may occur, in which case, the amounts fed should be decreased.

Starved horses can attain their optimum body weight in 60 - 90 days.

Conclusion 
As you can see from this talk, it is important to adjust the sick horse's diet according the disease condition. By doing so, recovery will be enhanced and future problems may be avoided.

It is best to consult closely with your veterinarian on how to adjust the nutrition of the sick horse.

References

	Cohen N D et al 1995. The recognition and medical management of right dorsal colitis in horses. Veterinary Medicine: Equine Practice, July 1995: 687-692.
	Lewis L D. 1995. Sick horse feeding and nutritional support. From Equine Clinical Nutrition. Lea & Febiger, Baltimore, 389-419.
	Ralston S L 1990. Clinical Nutrition of adult horses. Veterinary Clinics of North America: Equine Practice, 6: 339-354.