An acute phase reaction was elicited in four horses to which Freund's adjuvant was administered intramuscularly. The localised inflammation was accompanied by changes in the plasma concentrations of copper, iron and zinc. The plasma copper concentration, the plasma ceruloplasmin copper concentration and the ceruloplasmin oxidase activity in the plasma steadily increased to a maximum 24 days after the administration of the adjuvant. At this time, the plasma copper concentration was 2.2 micrograms/ml, a 90 per cent increase over the baseline concentration. The ratio of the concentration of plasma ceruloplasmin copper to plasma copper remained constant, indicating that the non-ceruloplasmin bound copper component of the plasma is also an acute phase reactant in the horse. The plasma zinc and iron concentrations decreased to 59 per cent and 30 per cent of their respective baseline concentrations and the severity of the inflammation appeared to influence the plasma concentrations of each metal. Weak correlations between the plasma fibrinogen concentration and the plasma copper and zinc concentrations of 25 horses with plasma fibrinogen concentrations of 5 g/litre or greater indicated that a single measurement of plasma copper concentration is not useful in the diagnosis of non-specific inflammatory disorders of the horse. However, the results suggest that the plasma copper concentrations in serial samples may be used to monitor the resolution of inflammatory disorders in the horse.

Bracken fern (Pteridjum spp.) causes cancer of the oesophagus and the urinary bladder in cattle and sheep. Ptaquiloside (PT) is believed to b e the carcinogenic principle which alkylates DNA when activated to its unstable dienone form (APT) under alkaline conditions. In this report w e present evidence for the presence of PT-DNA adducts in the ileum of bracken fern-fed calves using the 3PP-postlabelling assay. H-ras mutations were also observed in the ileum using single strand conformation polymorphism (SSCP) technique. Mutations corresponding to adenine to pyrimidine transversions in the codon 61 of H-ras were identified b y the cycle sequencing method. In vitro DNA alkylation studies showed that APT alkylated H-ras primarily at the adenines. In addition, the rate of depurination of alkylated adenine was sequence dependent. Investigation of DNA template activity using a plasmrd DNA showed that DNA synthesis by T7 DNA polymerase was terminated b y the presence of all alkylated bases but certain apurinic sites allowed the DNAsynthesis to continue. These results suggest that initial alkylation of adenine b y PT in codon 61 followed by depurination and error in DNA synthesis lead to activation of H-ras proto-oncogene. o 1996 W~lq-L~ss, Inc

Sickness occurred in 3 of 4 horses within 24 h of being sprayed with an 0.025% w/v aqueous suspension of amitraz. The latter consisted of a portion of an amitraz aqueous suspension made up some 3 weeks previously, to which some freshly prepared spray fluid had been added. It seemed likely that the amitraz in the older solution had broken down to the highly toxic N-3, 5- dimethylphenyl N-methyl formamadine derivative and that this was in fact the main cause of the untoward effects observed. The horses displayed typical clinical signs of tranquillisation, depression, ataxia, muscular incoordination and impaction colic lasting up to 6 days. Subcutaneous oedema of the face occurred in one horse. The syndrome was accompanied by mild dehydration and acidosis. All horses survived after persistent symptomatic treatment including the giving of intravenous fluids, enemas, analgesics every 3 h, multiple doses of paraffin oil per os and dexamethasone intravenously. Following the eventual relief of constipation the horses scoured profusely for 24 h before their condition returned to normal.

Ochratoxin A was isolated from a culture of Aspergillus ochraceus grown on a cornmeal substrate. The mycotoxin was added to a grower ration for 14 kg young pigs at 2, 4, 8 and 16 mg/kg and fed to groups of 3 for periods ranging from 6 to 20 days. The highest dose rate group only became sick, with loss of appetite, weight loss, polydipsia, polyuria, proteinuria, glucosuria, elevation of serum creatinine, pale swollen kidneys, renal tubular degeneration and cortical fibrosis. The pigs on the 2 mg toxin/kg of diet appeared unaffected with only slight renal tubular degeneration present in one animal. Feeding diet contaminated with the intermediate doses of 4 and 8 mg toxin/kg diet lead to reduction of weight gain and/or reduced feed intake and feed conversion efficiency as well as mild renal lesions. Ochratoxin A has recently been reported on mould-affected grain in Queensland and some local strains of A. ochraceus in culture have been shown to be able to produce levels of ochratoxin A of up to 4000 mg/kg of substrate. Rare episodes of nephrotoxicity in pigs seen at slaughter in Queensland may thus be due to prior contamination of the diet with ochratoxin A.

Intravitreal cilia should be considered in penetrating eye injuries even in phakic eyes with no radiological evidence of IOFB, especially if associated with endophthalmitis. B-scan ultrasonography may aid detection of intravitreal cilia and thus alter clinical management.