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Examination of tissues obtained from thoroughbred horses showed that the 'intestinal' phosphatase activity could be differentiated from other phosphatases by analysis at a pH of 9-5 and inhibition with 15 mM L-phenylalanine. A simple method for the measurement of 'intestinal' phosphatase in heparinised plasma or serum is described. Application of the technique to serum or plasma from normal and diseased horses indicates that the increase in the activity of 'intestinal' phosphatase is associated with cases showing clinical, biochemical and haematological evidence of intestinal damage.

The time of onset of permanent insensibility, subsequent to incision of the major blood vessels of the neck, was studied in eight one-week-old calves. Insensibility was determined from the study of electroencephalograms (EEG). Apart from one animal in which insensibility first occurred within 34 s, the first indication of insensibility did not occur until between 65 and 85 s. All animals subsequently showed evidence of periodic resurgence of possible sensibility for up to 123 to 323s after slaughter. Such resurgences were seen to be preceded by a respiratory gasp. The EEG did not become isoelectric until between 132 and 336 s. Involuntary movements of the animal and the presence of corneal and palpebral reflexes persisted for up to 300 s after slaughter. It is suggested that the marked increase in the time for insensibility to occur after slaughter in calves, compared with sheep and lambs, is due to a greater contribution of blood to the brain by the vertebral arteries in calves., (Copyright © 1982. Published by Elsevier Ltd.)

The relationship between paired plasma and serum viscosity measurements and plasma proteins, including fibrinogen, were compared in 106 horses with both normal and abnormal serum protein levels. There is a highly significant positive correlation between serum viscosity and total serum proteins and total globulin levels. The difference between plasma and serum viscosity correlated well with clottable fibrinogen concentration. Albumin levels showed a negative correlation with plasma and serum viscosity, globulins and fibrinogen. Simultaneous estimation of serum and plasma viscosity improves the diagnostic value of the latter test without appreciable increase in cost or time and should prove useful for screening large numbers of samples for the presence or absence of abnormal levels of globulins and, or, fibrinogen.

Using methylene blue boli, injected via an intracardiac catheter, the blood supply to the brain in two one- to 10-day-old calves and three adult sheep was studied during and after severance of the common carotid arteries and jugular veins. Passage of dye through cerebral vessels could not be observed in the exposed cerebrum of sheep after bilateral severance of major blood vessels. When vessels were severed on one side only, the passage of dye was noted for at least 53 seconds. In calves, after bilateral severance, sequential boli of dye could be detected passing through the cerebral vessels for more than 100 seconds. These results provide an explanation and support for the belief that there are major differences in the onset of insensibility between sheep and calves subsequent to severance of the common carotid arteries and jugular veins. The differences in blood supply to the brain which were demonstrated could be accounted for by differences in the blood supply to the brain by the vertebral artery in sheep and cattle. The effects of slaughter on the blood supply to the eye are discussed as a possible explanation of the disparity between results of studies in this general field which have used retinal responses in their investigations and those which have not.

Polyacrylamide gel electrophoresis (PAGE) and enzyme-linked immunosorbent assay (ELISA) were employed to investigate the epidemiology of typical and atypical rotavirus infections in five piggeries. Of 152 faecal samples examined, 46 (30 per cent) were positive by ELISA for group A rotavirus. Rotaviruses with electrophoretic patterns resembling groups A, B and C were detected. At least two and up to five different rotavirus electrophoretypes (typical and/or atypical) were detected in each of the five piggeries. Out of 152 faecal samples examined, 28 (18 per cent) contained rotaviruses with group A electrophoretypes, 9 (6 per cent) with group C but only 1 with Group B. Six samples contained both group A and group C rotaviruses. No common electrophoretypes of group A or C rotaviruses were detected in these five piggeries. The PAGE technique was also used to analyze group A rotavirus isolated sequentially from another piggery over a three year period. A single electrophoretype was found during the first two years, but in the third year a different electrophoretype was detected.

The occasions, position and relative concentration of LDH iso-enzymes in the blood tissues of the thoroughbred horse were determined. Locomotor muscles possess a high concentration of LDH 5 whereas non-locomotor muscles have a low concentration of this iso-enzyme.

Epidemiological aspects of infection with leptospires of the Ballum serogroup in black rats (Rattus rattus) and brown rats (Rattus norvegicus) are described. Rats inhabiting a variety of habitats were investigated and isolates identifed as belonging to the Ballum serogroup were obtained from 21 of 61 black rats (34%) and 63 of 243 brown rats (26%). The high level of endemic ballum serogroup infection in these species reported here has not been described in other countries. A statistical relationship was shown between the prevalence of infection in brown rat populations and population density but this was not evident for black rats. Epidemiological data indicates that the black rat is a maintenance host for leptospires of the Ballum serogroup in New Zealand. The brown rat does not appear to be an efficient maintenance host for these leptospires, however endemic infection can be maintained in high-density populations inhabiting synanthropic foci. An hypothesis of 'competitive exclusion' (preferential maintenance of a particular serovar by a host species) is introduced with regard to leptospiral infection in brown rats. It is concluded that the establishment and maintenance of an endemic focus of leptospirosis is dependant on: introduction of a particular serovar; a suitable host; and a suitable host habitat. Within a maintenance population direct transmission appears to be more important than indirect transmission via the environment.

A serological survey of leptospirosis among more than 1000 meat inspectors, from meat works throughout New Zealand, revealed a serological prevalence at a minimum serum dilution of 1:24, of 10.2 percent. Eighty-five percent of serological reactions were to serovars pomona and tarassovi. A highly significant correlation was demonstrated between the serological prevalence of these serovars and the inspection of pigs. Evidence is provided to substantiate the use of titres as low as 1:24 as an indication of previous leptospiral infection. Forty-two inspectors reported medical evidence of previous clinical infection with leptospirosis. Analysis of those who still exhibited a serological response and their individual case histories, indicated that detectable titres of leptospirosis can exist for up to 10 years.

Samples of dust, faeces and effluent were collected from a piggery and examined for group A rotavirus, using a commercial ELISA test, electron microscopy and inoculation of MA-104 cells. Rotavirus antigen was demonstrated in samples collected from farrowing and weaner rooms but not from fattener and sow houses. Rotavirus antigen was also detected in samples collected from a weaner room which had been free of piglets for three months. A cytopathic porcine rotavirus (British isolate SW20/21) was kept at room temperature for four months; it survived with titres reduced by 2 log10. These observations suggest that the environment of commercial piggeries is an important source of rotaviral infection for young piglets.

Antibody titres to Streptococcus suis type 2 were measured with an enzyme linked immunosorbent assay (ELISA) in four occupational groups in New Zealand. No veterinary students, 9% of dairy farmers, 10% of meat inspectors and 21% of pig farmers were seropositive to S. suis type 2. The development of antibody to S. suis type 2 was associated with occupational contact with pigs or their meat products. Subclinical infection with S. suis type 2 appears to occur in humans and the antibody produced is of only short duration. The annual incidence of subclinical infection and seroconversion in pig farmers may approach 28%. Thus S. suis type 2 may be one of the most infectious potentially zoonotic agents present in New Zealand, although very rarely resulting in clinical disease.

A method is described for the measurement of haptoglobin in equine serum using the peroxidase activity of the haemoglobin-haptoglobin complex. The problems of interference with Fe2+ and Fe3+ ions are described. Normal values for haptoglobin in 629 blood samples from thoroughbreds in training are presented showing a log normal distribution with a 5 per cent to 95 per cent range of 0.42 to 1.7 g/litre. There was no consistent alteration in haptoglobin concentration throughout the season in spite of a change in red cell size and total bilirubin concentration. It is concluded that the measurement of haptoglobin is useful in the detection of frank haemolytic states but is insufficiently sensitive to detect mild red cell destruction. The test, after further investigation, might be used as an adjunct to the current batch of blood tests employed to assess liver function.

Equine placental extracts show phosphatase activity with a pH optimum between 4.5 and 6. The enzyme shows heat stability to 45 degrees C and electrophoresis on cellulose acetate demonstrates the presence of two bands of activity. Histochemistry confirms the presence of phosphatase activity in the placental villi. Assay of plasma samples from pregnant mares showed no increase in phosphatase activity through pregnancy under conditions of test.

Methods were developed for the measurement of superoxide dismutase (SOD), diamine oxidase (DAO) and caeruloplasmin oxidase in the blood of thoroughbred horses. These enzymes were measured in 178 normal thoroughbreds stabled throughout the United Kingdom. The relationships between the activities of SOD, DAO and caeruloplasmin oxidase and the blood concentrations of their associated trace metals (copper, zinc and manganese) were studied in 52 of the thoroughbreds. Trace metals were measured by electrothermal atomic absorption spectrophotometry. No relationships were found between the activities of erythrocyte SOD and serum/whole blood copper, zinc and manganese, or serum DAO and serum copper or zinc concentrations. Caeruloplasmin oxidase in equine blood was found to be correlated to serum copper concentration, r = 0.695 (P less than 0.001) over the normal range. Samples from thoroughbreds with trace metal deficiency or toxicity were not available for study. The observed normal ranges for the activity of these enzymes are as follows: SOD: 50 to 200 units per ml whole blood between 5 and 95 percentiles; DAO: 0.1 to 28.5 units per litre (means = 14.8, SD 7.1) and caeruloplasmin oxidase; 11.6 to 35.8 units per ml (means = 23.7, SD 6.0). For numerical simplicity, the activity of DAO is given in units per litre, compared to units per ml for caeruloplasmin oxidase and SOD.

Three fully conscious lambs, two adult sheep, five calves and one young bull were slaughtered by bilateral severance of the carotid arteries and jugular veins while standing. The calves and bull exhibited apparently coordinated body movements for much longer than the lambs and adult sheep. Other signs assumed to be associated with cerebral hypoxia, such as clonic convulsions and pupillary dilation, occurred earlier in the sheep than in the cattle. Although there is no single definitive method for assessing the onset of insensibility in animals during slaughter, it is believed that these findings support previous more objective encephalographic studies which indicated that there are clear cut differences between sheep and cattle.

Selenium and gamma-glutamyl transferase activity has been measured in the serum of clinically health thoroughbreds. The thoroughbreds, whose performance was reported to be unsatisfactory, had consistently low concentrations of selenium and high activity of gamma-glutamyl transferase in the serum when compared with those whose performance was as expected. Vitamin E levels in the serum showed no such difference. The only other biochemical and haematological abnormality was lower serum phosphate concentrations in the unsatisfactory group. These results suggest that low concentrations of selenium in the serum may be associated with subclinical hepatic insufficiency in the thoroughbred.

The time of onset of permanent insensibility, subsequent to incision of the major blood vessels of the neck, was studied in sixteen adult sheep and five one-week-old lambs. Insensibility was determined from the study of electroencephalograms (EEG) and interpretation was based on the amplitude and pattern of fast wave signals of a transhemispheric bipolar derivation. In both adult sheep and lambs, conscious at the time of slaughter, insensibility occurred within 2 to 7 s and EEG traces became isoelectric between 10 and 43 s. In sheep which were lightly anaesthetised at the time of slaughter, EEG traces became isoelectric between 18 and 70 s after incision of the major blood vessels of the neck. In one sheep which was slaughtered by severance of the carotid artery and jugular vein on one side of the neck only, the onset of insensibility was delayed for 29 s. In the majority of animals, the electrocardiogram (ECG) continued to show a normal pattern for more than 10 min after slaughter. There was an initial rise in blood pressure in the first 5 to 7 s and it remained elevated for a further 10 to 20 s. The results of this work are discussed with reference to definition of death appropriate for statutory purposes and the implications for the humane slaughter of sheep., (Copyright © 1982. Published by Elsevier Ltd.)