Objective—To determine whether there is a relationship
between species-specific mitochondrial DNA
(mtDNA), especially canine and feline mtDNA, and
detectable amounts of pentobarbital in previously
analyzed dog food samples.
Sample Population—31 dog food samples previously
analyzed for pentobarbital (limit of detection, 1 µg/kg).
Procedure—Polymerase chain reaction (PCR) analysis
was performed on dog food samples by use of
PCR primers specific for either canine, feline, equine,
bovine, porcine, ovine, or poultry mtDNA.
Results—PCR amplicons specific for feline or canine
mtDNA at a 0.007% (70 µg/g [wt/wt basis]) or
0.0007% (7 µg/g) level, respectively, were not found
in the 31 dog food samples. Most of the 31 dog food
samples had a PCR amplicon on PCR analysis when a
PCR primer set capable of simultaneously detecting
mtDNA of cows, pigs, sheep, goats, deer, elk, and
horses was used. Results of PCR analysis by use of
primers specific for bovine, swine, sheep and goat, or
horse mtDNA revealed amplicons specific for bovine
or swine mtDNA only in 27 of the 31 samples.
Analysis of the remaining 4 samples failed to yield
amplicons for any mammalian mtDNA. Pentobarbital
was detected in 2 of these 4 samples. Results of PCR
analysis correlated with the stated ingredient list for
most, but not all samples.
Conclusions and Clinical Relevance—Because
canine and feline mtDNA were not found in a set of
retail dog food samples, these results indicate that
the source of pentobarbital in dog food is something
other than proteins from rendered pet remains. ( Am J Vet Res 2004;65:99–103)
Objective—To determine whether renal crystals can be experimentally induced in animals fed melamine or the related triazine compound cyanuric acid, separately or in combination, and to compare experimentally induced crystals with those from a cat with triazine-related renal failure.
Animals—75 fish (21 tilapia, 24 rainbow trout, 15 channel catfish, and 15 Atlantic salmon), 4 pigs, and 1 cat that was euthanatized because of renal failure.
Procedures—Fish and pigs were fed a target dosage of melamine (400 mg/kg), cyanuric acid (400 mg/kg), or melamine and cyanuric acid (400 mg of each compound/kg) daily for 3 days and were euthanatized 1, 3, 6, 10, or 14 days after administration ceased. Fresh, frozen, and formalin-fixed kidneys were examined for crystals. Edible tissues were collected for residue analysis. Crystals were examined for composition via Raman spectroscopy and hydrophilic-interaction liquid chromatography–tandem mass spectrometry.
Results—All animals fed the combination of melamine and cyanuric acid developed goldbrown renal crystals arranged in radial spheres (spherulites), similar to those detected in the cat. Spectral analyses of crystals from the cat, pigs, and fish were consistent with melamine-cyanurate complex crystals. Melamine and cyanuric acid residues were identified in edible tissues of fish.
Conclusions and Clinical Relevance—Although melamine and cyanuric acid appeared to have low toxicity when administered separately, they induced extensive renal crystal formation when administered together. The subsequent renal failure may be similar to acute uric acid nephropathy in humans, in which crystal spherulites obstruct renal tubules.