Page 961 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

936 CHAPTER 7

VetBooks.ir 7.17 renal failure. If proteinuria is substantial, the SG
of the urine may rise to, or exceed, 1.020 despite an
inability of the kidneys to concentrate urine. Urine
sediment is usually free of cells and casts unless
CKD is associated with pyelonephritis, in which
case RBCs, leucocytes, casts and bacteria may be
present. Bacterial culture of urine from a catheter-
ised sample should be performed in all suspected
cases of CKD.
Ultrasonographically, the kidneys tend to be
smaller and hyperechogenic compared with normal.
There may be a loss of distinction of the cortico-
medullary junction (Fig. 7.18). Cysts or nephroliths
may be visualised (Fig. 7.19).
Kidney biopsy may be helpful in the diagnosis
of pyelonephritis or a congenital abnormality, but
most findings are consistent with end-stage renal
Fig. 7.17 Excessive dental tartar in a horse with CKD. disease and rarely influence treatment or progno-
sis. Immunofluorescence testing of the biopsy sam-
ple may better define the aetiology of the disease.
neurological disorders, neoplasia, ruptured bladder Ultrasonographic guidance is preferred because of
and renal tubular acidosis. the risk of severe haemorrhage.

Diagnosis Management
Diagnosis of CKD is based on clinical signs and the Any underlying disease should be addressed and
persistence of isosthenuria and azotaemia. Palpation administration of nephrotoxic or potentially
p/r should be performed to evaluate the structure nephrotoxic drugs should be ceased if possible.
and size of the left kidney and ureters. The kidney Intravenous fluid therapy is indicated in acute exac-
is usually normal or small in size in cases of CKD, erbation of CKD, in azotaemic animals, for the
although, with neoplasia, infection or urinary tract treatment of underlying or concomitant disease or
obstruction, the kidney and/or ureters may be in dehydrated animals. Physiological saline (0.9%
enlarged. NaCl solution) is the fluid of choice although a bal-
Increases in blood urea and creatinine are present. anced electrolyte solution may be used if moderate
Normocytic, normochromic anaemia, as a result of to severe hyperkalaemia is not present. Intravenous
decreased erythropoietin production, may be iden- fluid therapy should replace fluid deficits and
tified. Hypoalbuminaemia, which may or may not account for maintenance requirements (65 ml/kg/
be associated with hypoproteinaemia, depending on day) and ongoing losses. If oliguria or anuria is
the serum concentration of globulins, may also be present, close observation is required during fluid
present. Hyponatraemia, hypochloraemia, hypercal- therapy to ensure that overhydration and resul-
caemia, hypophosphataemia and low plasma bicar- tant oedema do not ensue. Oliguria or anuria is
bonate concentration are associated with CKD, but uncommon; therefore, furosemide, mannitol and/
are variable. Excessive urinary losses of electrolytes or dopamine are rarely indicated. They are more
lead to variable electrolyte disturbances, which can often indicated in acute exacerbation of CKD and
be expressed as metabolic acidosis or, less frequently, are discussed under AKI.
metabolic alkalosis. Fractional clearance of electro- Peritoneal dialysis may sometimes be helpful in
lytes may be normal. relieving severe azotaemia. The procedure is labour-
Isosthenuria (SG 1.008–1.012) in the presence of intensive and usually has only a short-term benefit.
azotaemia or dehydration confirms the presence of Recovery of infused fluid is often difficult.