Urine and tissue oxalate and hippurate levels in ethylene glycol intoxication in the dog.

Oxalate, hippurate and ethylene glycol were measured in dogs given 5 ml/kg ethylene glycol orally. Eight hours after administration, oxalate levels were 7.2-9.1 ppm in renal tissue and 10-100 ppm in urine. Hippurate was 40-90 ppm in urine. Ethylene glycol was 10-100 ppm in renal tissue and 5,300-27,000 ppm in urine. The above substances were measured in urine and renal tissue from normal dogs, dogs in non-toxic renal failure and clinical cases of ethylene glycol intoxication. Urine was analyzed for ethylene glycol by gas chromatography using direct injection. Ethyl ether extraction provided good recovery of ethylene glycol from tissues and blood. Results were confirmed by gas chromatography/mass spectrometry (GC/MS). Oxalic acid (CA oxalate) was extracted with acidic methanol, methylated and analyzed by GC. Results were confirmed by GC/MS. Hippuric acid (calcium hippurate) was extracted with acidic methanol and chromatographed by thin layer chromatography (TLC). Ultraviolet spectrometry and mass spectroscopy were used to confirm the results. High performance liquid chromatography (HPLC) and TLC with densitometry were used to quantitate hippuric acid.