SAEVA Proceedings 2018 4. Proceedings | Page 120

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 115