SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
Horses in CRF are typically anemic and hypoproteinemic with hematocrits in the
range of 20-25%. The combination of azotemia and urinary specific gravity (S.G.) in
the isosothenuric range (1.008-1.019) is pathognomonic for CRF.
Azotemia is a very common finding, however the magnitude of the azotemia is not
necessarily indicative of the duration of the disease process. Many cases of
compensated or effectively managed CRF are characterized by SUN concentrations
of 30-50 mg/dl and serum Cr concentrations of 3-5 mg/dl.
The most common findings in horses with CRF are hyperkalemia (usually mild),
hypochloremia and hyponatremia. The severity of electrolyte disturbances in CRF
varies with the severity of the disease and the patient’s appetite and diet.
Horses in CRF are sometimes hypercalcemic and hypophosphatemic.
Hypercalcemia is most commonly seen in horses fed alfalfa. A change to grass hay
frequently leads to normo- or even hypocalcemia.
Urinalysis
The urine of horses with CRF is invariably isosothenuric. Isosthenuria, however, is
not always associated with renal failure. If isosothenuric and mild elevations in either
SUN or Cr, but not both, exist, a water deprivation test may be indicated to assess
whether or not the animal is able to concentrate urine. Use of this test should be
judicious. Ideally, S.G. and SUN or Cr concentration should be monitored together
and the test is discontinued if concentrations of either of the serum variables begin to
increase without an appropriate increase in S.G. Generally, a water deprivation test
lasts no longer than 8 hours.
Proteinuria in CRF is usually due to glomerulonephritis. This is frequently associated
with hypoproteinemia, hypoalbuminemia, and dependent edema.
Therapy
Because of the progressive loss of nephron function, the aim of therapy in CRF is to
prolong life rather than to completely resolve the condition. Death or euthanasia is
usually inevitable although horses have survived for 12-18 months. General
principles are to provide sufficient fluid, electrolytes and nutritional support. Water
should be available at all times and salt absent. The intake of salt should be
restricted if edema is evident, even if the horse is hyponatremic. Clients should be
well informed regarding the nature of the disease and the need to carefully manage
the animal’s condition. Sometimes a weekend without close supervision is all that is
required to provide an acute exacerbation of the condition, with the associated
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