ASK THE NUTRITIONIST

Ask the Nutritionist ANNA PESTA, PH.D., EQUINE TECHNICAL SOLUTIONS, PURINA ANIMAL NUTRITION SPECIAL ADVERTISING SECTION ? Ask the Nutritionist is a monthly column featuring questions answered by PhD equine nutritionists and sponsored by Purina Animal Nutrition. Have a nutrition question you want to see featured? Email Marie Rosenthal. For clinics looking for specific nutritional advice, visit purinamills.com/ask-an-expert.

What role does nutrition play in both the recovery from acute kidney failure and management of chronic kidney failure?

ACUTE KIDNEY DISEASE

Acute kidney injury or acute renal failure (ARF) can occur at any age in otherwise healthy horses. It’s caused by injury from nephrotoxic medications or environmental toxins, or it may develop secondary to another issue that has caused low blood volume.

Most horses with ARF have very poor appetites and, due to metabolic effects of low energy intake, exhibit hyperglycemia and hypertriglyceridemia. This decreased intake, combined with impaired amino acid uptake, leads to muscle catabolism. Therefore, the primary nutritional goal for supporting horses through recovery is to limit protein and energy-wasting by simply keeping them eating.

Provide a variety of palatable feedstuffs, especially green grass, to encourage voluntary intake. If that fails, it may be necessary to provide enteral nutrition through a slurry of blended feed, like Purina® Equine Senior® feed, or a balanced preparation, such as Wellsolve® Well-Gel® horse supplement. If the horse exhibits electrolyte imbalance and is wasting sodium and chloride in the urine, offer saltwater (a 0.45% NaCl solution) in addition to plain water. You also can topdress feed with plain, loose salt (10 g NaCl per 100 kg BW per day).

CHRONIC KIDNEY DISEASE

Most commonly, chronic kidney disease (CKD) is discovered during an evaluation for unexplained weight loss. However, in performance horses, the first signs may be as subtle as a poor coat or decreased performance. Your goal is to improve and maintain body condition and to manage blood urea nitrogen (BUN) levels for as long as possible. As with acute cases, appetite is often a significant challenge and recommendations for intake of certain nutrients must be balanced with the need for energy intake. At a certain point, it is more important that the horse eats rather than worrying about what they eat!

Renal diets have been used with positive results in small animals for decades, but recommendations for equine diets are still evolving. Protein intake does not need to be as restricted as recommended in the past, but it needs to be managed to meet—and not greatly exceed—NRC requirements. Protein should be monitored through BUN to creatinine ratio (values over 15 mg/dl or below 10 mg/dl indicate excessive or inadequate protein intake, respectively).

Green pasture is the preferred diet foundation. If hay is fed, grass hay is best due to lower protein and calcium content. Feed alfalfa if it is all the horse will accept because it may stimulate the horse’s appetite for grass hay. Quality forage, plus a vitamin and mineral supplement, can be an appropriate diet. More commonly, though, caloric intake is a challenge and supplementation with concentrates is necessary. Oats have been long favored due to their nutrient profile and palatability, but a low-protein, textured feed such as Purina® Omolene® 100 feed is a balanced and complete alternative. Fat supplementation also can help meet energy requirements in horses without severe hyperlipidemia. There are positive data in other species to support the benefits of omega-3 fatty acids and antioxidants (another benefit of pasture, which is a good source of both).

Horses with CKD have disturbed calcium regulation, and the goal is to meet, not exceed, dietary requirements for calcium and phosphorus. Salt supplementation has been controversial. It may increase voluntary water intake, but the potential further damage to kidney function may negate this benefit in advanced cases. Finally, small amounts of forced exercise can help stimulate appetite and prevent muscle wasting. Incorporate exercise into management plans where appropriate.

Creatinine is an important marker for the current status and prognosis of horses with CKD. When it is low to moderate, the primary nutritional consideration may be as simple as ensuring water intake. But when creatinine is high (>5 mg/dL), long-term emphasis should be on supporting body condition to maintain quality of life as long as possible.

Contact a Purina PhD nutritionist for a complimentary consultation through Purina Customer Service, 800-227-8941 or send us a message at www.purinamills.com/ask-an-expert.

UPCOMING TOPICS October: Reproduction: Stallion needs November: Reproduction: Mare needs

Have a question you want to see featured? Send them to modernequinevet@gmail.com.

Reference and suggested additional reading: Schott, H. C. 2013. Urinary Tract Disease. In: Equine Applied and Clinical Nutrition, Ed. R. J. Geor, P. A. Harris, and M. Coenen. Saunders Elsevier, St. Louis, MO.

ABOUT THE AUTHOR Dr. Anna Pesta, PhD, is a nutritionist on the Equine Technical Solutions Team at Purina Animal Nutrition. She is a lifelong equestrian and actively competes her off-the-track Thoroughbred in three-day eventing.