Diagnosis and Treatment of Kidney Diseases in Horses
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American author Roger Kahn once wrote, "Boxing is smoky halls and kidneys battered until they bleed." Horses don't typically engage in behaviors that batter each other's kidneys; however, there are many causes of both acute and chronic kidney damage worth "boxing around" when faced with a sick horse.
"Acute kidney injury usually develops in horses as a complication of another disease process, or as a side effect from medications, or exposure to toxins (see sidebar at left)," relayed Hal Schott II, DVM, PhD, Dipl. ACVIM, professor of equine medicine at Michigan State University's College of Veterinary Medicine during his presentation at the 12th Congress of The World Equine Veterinary Association, held Nov. 2-6, 2011, in Hyderabad, India.
Acute kidney injury is the current term for compromised renal function that is often reversible if treated appropriately. Clinical signs of horses with acute kidney injury can be as nonspecific as anorexia and lethargy or more obvious as little to no urine production.
Horses that survive an acute episode can recover fully or might have persistent kidney damage that is considered irreversible chronic kidney disease (CKD). In early or less severe cases of CKD, increased drinking and urination could be the only signs noted. As CKD progresses horses suffer weight loss and often have decreased exercise capacity, a dull hair coat, and mild edema (swelling) between their forelimbs. Because the kidneys aren't filtering the blood properly when affected by CKD, waste products can build up in the circulation causing tartar buildup on horse's teeth and ulcers in the oral cavity, stomach, and intestines.
"Unfortunately, horses with chronic kidney disease do not have a favorable long-term prognosis, but they can live comfortably with supportive therapy for several months or even a few years," said Schott.
Such therapies include:
- Maintaining body condition (feed grain, fat, and protein while maintaining a neutral nitrogen balance)--the best diet is high quality pasture grass;
- Supplementing with omega-3 fatty acids;
- Decreasing calcium intake (by feeding grass hay instead of alfalfa); and
- Routinely monitoring creatinine blood levels (a measure of the "health" of the kidney) as well as electrolyte concentrations and acid-base balance.
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Other causes of chronic kidney disease are seen in foals or young horses and include renal hypoplasia (incomplete kidney development) or dysplasia (improper kidney development) and polycystic kidney disease (development of numerous cysts in the kidneys).
Regardless of the cause, once a horse's blood creatinine levels exceed 5 mg/dL, the condition tends to accelerate and the horse's life expectancy is generally limited to a few months.
A full summary of Schott's presentation will be available for free on the
International Veterinary Information System.