Motor neuron degeneration in a horse.

A 9-year-old Quarter Horse mare was examined because of progressive weight loss, weakness, muscle atrophy and tremors, and behavioral change. Selenium and glutathione peroxidase assays, blood lead analysis, erythrocyte transketolase analysis, pseudorabies and Borrelia burgdorferi serology, electromyography, and CSF analysis were performed. Motor neuron degeneration was diagnosed by microscopic examination of neural tissues. The cause of the disease was not substantiated, but several possibilities were excluded via diagnostic testing. Diagnosis of motor neuron degeneration in horses may be made from an accurate history, thorough neurologic examination, and ancillary testing. In particular, antemortem diagnosis may be based on finding scattered angular atrophy of predominantly type-1 or of type-1 and -2 skeletal muscle fibers in frozen sections of muscle biopsy specimens.

Ameliorative effects of reduced food-borne fluoride on reproduction in silver foxes.

Reduction of ingested fluoride in a skulk of silver foxes resulted in the reduction of fluoride burden, decreased neonatal mortality and increased kit production during a two breeding and whelping season period.

Identification and quantitation of trenbolone in bovine tissue by gas chromatography-mass spectrometry.

Identification and quantitation of trace amounts of trenbolone in bovine tissue by capillary gas chromatography-mass spectrometry-selected-ion monitoring (GC-MS-SIM) has been developed. Three-phase liquid-liquid extraction using a mixture of water-acetonitrile-dichloromethane-hexane was utilized for the sample extraction from tissue. Target compounds were extracted from the tissue into the acetonitrile layer. The residue from this extraction was then subjected to solid-phase extraction by C18 and silica gel disposable cartridges using methanol-water and benzene-acetone as eluents. To overcome extensive matrix interferences, preparative reversed-phase high-performance liquid chromatographic separation was used with an octadecyl-bonded column using methanol-water as mobile phase for sample clean-up prior to GC-MS analysis. A structural analogue of trenbolone, 19-nortestosterone, was chosen as the internal standard for quantitation by GC-MS. The sample was co-injected with N,O-bis (trimethylsilyl) trifluoroacetamide-1-(trimethylsilyl) imidazole (95:5, v/v) for flash heater derivation. Identification and quantitation were simultaneously carried out by SIM of characteristic ions of the trimethylsilyl derivatives of trenbolone and 19-nortestosterone. The limit of detection for trenbolone and epitrenbolone was 0.5 ppb in muscle and liver tissue. A comparison of sensitivity and specificity between GC-MS under electron ionization in addition to positive- and negative-ion chemical ionization conditions using methane reagent gas is also discussed.

Background lead levels in dairy cattle: updated values for 1986.

Lead poisoning continues to be a problem in cattle. The toxicologic significance of blood lead levels requires the differentiation of background blood lead from toxic levels. A ten-fold variation of background blood lead levels reported in previous studies has prompted us to conduct our own survey. Our results indicate significantly lower background blood lead levels in New York State cattle analyzed in 1986 than in those levels previously reported elsewhere.

Fluoride intoxication in dairy calves.

Chronic fluoride intoxication in dairy cattle, caused by feeding fluoride contaminated commercial feed, was previously described in a dairy herd. Dental fluorosis and a catastrophic decrease in milk yield were the foremost findings. In calves born to the fluoride intoxicated cows, congenital fluorosis was manifested by brown discoloration of enamel, enamel hypoplasia, brown mottling of bone, severe retardation of cartilage cell differentiation, atrophy of osteoblasts, osteopenia, atrophy of bone marrow cells, serous atrophy of bone marrow fat and severely stunted growth.

Toxic effects of food-borne fluoride in silver foxes.

Chronic ingestion of excessive amounts of fluoride from commercial fox food is associated with agalactia in vixens resulting in the starvation deaths of large numbers of kits in three fox herds. Evidence of infectious disease or poor management could not be found and a causal relationship between fluoride and high kit mortality is suggested.

Milk production of cows fed fluoride contaminated commercial feed.

A commercial feed concentrate and a mineral mix with excessive amounts of fluoride were introduced into a Holstein dairy herd with an average milk production well above national standards. Milk production decreased drastically, and during the following 6 years the deficit in milk production in the herd ranging from 52 to 120 milking cows was 1.5 million Kg (3 1/4 million lbs.). The tolerance levels set by the National Academy of Sciences for fluoride ingestion by lactating cow were found to be inadequate.

Toxic and protective constituents in pet foods.

An analytical survey of mutagens, nitrosamines, polychlorinated biphenyls, toxic elements, and gamma-emission, as well as the toxicologically protective constituents zinc, selenium, and vitamin C, in 48 pet foods was conducted. Aside from high concentrations of fluoride and iodide in some samples and the expectedly higher concentrations of mercury and selenium in certain cat foods containing fish, the samples were notably free of the other toxic constituents. Direct-acting and promutagens and nitrosamines were not detectable in any of the samples. gamma-Emission was very low in all of the foods. Polychlorinated biphenyls were only detected in one cat food.