Clinical Biochemistry of Domestic Animals (Sixth Edition) - UMK ...

III. Nephrotoxicity
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suggested as a screening test for subclinical hepatic damage
in horses exposed to Crotolaria spp. ( Curran et al., 1996 ).
Hepatotoxic solanaceae include Cestrum parqui,
C. laevigatum, and C. aurantiacum . The toxin in these
plants has been identified as atractyloside.
Sawfly larvae (Lophyrotoma interruptus and Arge pullata
) infesting eucalyptus and birch trees in Australia and
Denmark, respectively, have been reported to induce hepatic
necrosis in cattle, sheep, and goats browsing foliage.
Terminalia oblongata , the yellowwood tree of
Australia, contains hepatotoxic tannins and pucicalagin,
which induces acute hepatic necrosis ( Kelly, 1993 ).
III . NEPHROTOXICITY
Acute nephrotoxicity ( Table 27-2 ) may initially
induce polyuria that is followed by oliguria or anuria.
Nephrotoxins affecting approximately 66% of the nephrons
will result in inability to concentrate urine to a specific
gravity greater than 1.030 in the dog, 1.035 in the cat, and
1.025 in the horse and cow. Chronic toxicity may result in
isosthenuria (constant urine osmolality in the range of glomerular
filtrate, 1.008 to 1.012).
The majority of urea is synthesized in the liver from
ammonia formed by protein catabolism or intestinal
absorption. Urea enters the vascular system and is distributed
throughout the total body water compartment
by passive diffusion. The urea concentration of blood
and glomerular filtrate is approximately equal. Urea passively
diffuses from the tubular lumen back to the blood.
Urine flow rate is inversely related to urea reabsorption.
Gastrointestinal secretion is inconsequential in monogastrics;
however, in ruminants up to 90% of urea in glomerular
filtrate may be reabsorbed and enter the rumen via
saliva for utilization in amino acid synthesis.
TABLE 27-2 Nephrotoxins
Nephrotoxin Disease Onset Geography Species Affected
Amaranthus retrofl exus (pigweed) Subacute US B, P
Antibiotics Acute to chronic Worldwide All
Cantharidin (blister beetle) Acute US B, Cp, E, O
Chlorinated hydrocarbons Acute Worldwide All
Ethylene glycol Acute Worldwide B, Cn, F, P
Fumonisin ( Fusarium moniliforme ) Acute to chronic Worldwide E, O, P
Gossypol (cottonseed) Chronic Worldwide B
Hemoglobin Acute All
Hypercalcemia Chronic Worldwide All
Isotropis spp. Acute AUS B, O
Lantana camara Chronic US, MEX, AUS, AFR B, E, O
Menadione Acute Worldwide E
Metals (Cd, Hg, Pb, Tl) Acute to chronic Worldwide All
Myoglobin Acute All
Ochratoxin ( Penicillium ochraceus ) Chronic Worldwide P
Oxalates Acute to chronic Worldwide B, Cp, O, P
Paraquat/diquat Acute Worldwide All
Petroleum Acute Worldwide All
Phenothiazine Acute Worldwide E
Phenylbutazone Acute Worldwide E
Phosphorus Acute Worldwide All
Pyrrolizidine alkaloids Chronic Worldwide B, Cp, E, O, P
Tannins ( Quercus spp., oaks) Acute Worldwide B, Cp, E, O
Terminalia oblongata (yellowwood) Acute to chronic AUS B, O
Abbreviations: B, bovine; Cn, canine; Cp, caprine; E, equine; F, feline; O, ovine; P, porcine.