Direct and induced phototransformation of mecoprop [2‐(4‐chloro‐2‐methylphenoxy)propionic acid] in aqueous solution

Mecoprop was irradiated under various conditions of pH, oxygenation and wavelengths in order to study the reactions involved in the phototransformation. Four main photoproducts were identified: 2‐(4‐hydroxy‐2‐methylphenoxy)propionic acid ( I ), o‐cresol ( II ), 2‐(5‐chloro‐2‐hydroxy‐3‐methylphenyl)propionic acid ( III ) and 4‐chloro‐o‐cresol ( IV ). When the anionic form of mecoprop was irradiated between 254 nm and 310 nm (UV‐C or UV‐B), I was the main photoproduct. At 254 nm its formation initially accounted for more than 80% of the transformation. It has not previously been reported in the literature. The reaction results from a heterolytic photohydrolysis. Product II accounted for only a low percentage of the transformation. The stoichiometry was different with the molecular form: the main photoproduct, III , resulted from a rearrangement after a homolytic scission. Products I, II and IV were also formed as minor photoproducts. Some other minor photoproducts were also identified. In contrast, IV was the main photoproduct under sunlight irradiation or when solutions were irradiated in near‐UV light (UV‐A). This wavelength effect is attributed to the involvement of an induced phototransformation; IV is also the main photoproduct when the phototransformation is induced by Fe( III ) perchlorate or nitrite ions. In usual environmental conditions the excitation of the molecular form is negligible and the phototransformation is mainly due to induced photoreactions. © 2000 Society of Chemical Industry     

Gastrointestinal perforation in five dogs associated with the administration of meloxicam

Objective: Five canine cases of gastrointestinal (GI) perforation and septic peritonitis associated with the routine use of meloxicam are reviewed. Series summary: Selective cyclooxygenase‐2 (COX‐2) non‐steroidal anti‐inflammatory drugs (NSAIDs) are being used more extensively and routinely for acute and chronic pain as well as for perioperative management of pain. These medications are safe and effective but can be associated with known GI and renal side effects. The patients in this case series had no significant concurrent illness, were not on any concurrent medication known to potentiate the ulcerogenic effects of NSAIDs, and in most cases did not display clinical signs that were apparent to the owners until the time of perforation. New or unique information provided: Despite the preferential selectivity for COX‐2, newer NSAIDs still carry the risk of GI performation. The incidence of GI perforation may be increased with inappropriate dosing regimens, with use of non‐veterinary products and in animals that are at high risk for toxicity. Early signs of toxicity may include alteration in appetite, and subtle signs of nausea during treatment. Warning owners to monitor their pet for vomiting, melena, and hematemesis may not be sufficient to avoid the potential disastrous consequences of GI ulceration.     

Metabolic aspects of the toxicology of diazinon. I. Hepatic metabolism in the sheep,cow, pig,guinea-pig,rat, turkey,chicken and duck

The phosphorothionate insecticide diazinon was incubated with liver microsomes from the sheep, cow, pig, guinea-pig, rat, turkey, chicken and duck. Metabolism by liver slices of most of these species was also examined. Hydroxydiazinon, isohydroxydiazinon, dehydrodiazinon, their oxons and diazoxon were identified and determined quantitatively or semi-quantitatively. An eighth metabolite was tentatively identified as the 6-aldehyde analogue of diazinon. Yields and rates of production of these metabolites varied greatly between species. Production of oxons was not generally correlated with susceptibility to diazinon poisoning, although it was lowest in the least susceptible animal, the sheep. The degradation of oxons by liver slices was too slow to explain the low toxicity of diazinon to the mammals. The relative importance of hepatic and extrahepatic metabolism in determining toxicity to vertebrates is discussed.     

Calving rate following fixed time insemination after a 12-day progesterone treatment in dairy cows, beef cows and heifers.

Farm trials were carried out to determine if cows and heifers could be inseminated on a fixed time basis following a 12-day treatment with progesterone coils and an injection of 5 mg oestradiol benzoate and 200 mg progesterone at the start of treatment. The retention rate of the coils was significantly higher (P less than 0.05) when a 5.5 cm diameter was used compared with a diameter of 7.0 cm. Calving rate was similar in treated cows bred at a detected oestrus, at 56 + 74 hours after treatment or at 56 hours after treatment and injection of 100 microgram gonadotrophin releasing hormone 20 hours previously and in control cows bred at oestrus. Fertility to the first repeat oestrus was also similar in treated and control cows. Significantly (P less than 0.05) more synchronised cows calved following fixed time AI compared with the calving rate in control cows inseminated for a 24-day experimental period. In beef suckler cows, calved at least 50 days, and dairy heifers weighing over 280 kg, calving rate was similar in treated animals bred at 56 and 74 hours after treatment compared to calving rate in control animals bred at oestrus.     

Prion protein gene polymorphisms in pedigree sheep in Ireland

The development of clinical signs of scrapie in sheep has been linked to polymorphisms in the prion protein (PrP) gene. The most important polymorphisms appear to be at codons 136, 154 and 171. The objective of this study was to investigate polymorphisms at these codons in five native (Belclare, Galway, Wicklow Cheviot, Donegal Blackface Mountain and Mayo Blackface Mountain) and five imported (Texel, Bleu du Maine, Rouge de l'Ouest, Vendéen and Charollais) sheep breeds in Ireland. A total of 13 genotypes were found. The percentage of the most resistant genotype AA(136)RR(154)RR(171)varied from 1.8 per cent in the Vendéen breed, 3.1 per cent in Donegal Blackface Mountain, 10.0 per cent in Texel, 11.1 per cent in Wicklow Cheviot, 12.9 per cent in Belclare, 22.0 per cent in Charollais, 25.6 per cent in Mayo Blackface Mountain, 33.3 per cent in Galway, 46.4 per cent in Bleu du Maine to 62.5 per cent in Rouge de l'Ouest. The results indicate that a significant amount of variation exists between the breeds analysed in this study.