Further studies on the diagnostic value of gamma-glutamyl transpeptidase and 5'-nucleotidase in cattle, sheep and horses

The distribution of 5'-nucleotidase (5'-NT) and gamma-glutamyl transpeptidase (gamma-GT) is similar in the tissues of the sheep, calf and horse, except that there is relatively less gamma-GT in calf liver than in the liver of the other two species. The liver lesion produced by the oral administration of chloroform is similar in the three species and is accompanied by the release of 5'-NT into the plasma of the sheep and calf but not of the horse. Conversely, gamma-GT is released into plasma of the horse but not of the sheep or calf. This difference is not related to the tissue distribution of the two enzymes. The kidney lesion in sheep produced by the intravenous administration of mercuric chloride is accompanied by a reduction in the rate of excretion of an injected dose of inulin and by an increase in the concentration of urea in plasma and in the activity of gamma-GT in plasma and urine. There was no increase in 5'-NT activity in plasma or urine.     

Observations on gamma-glutamyl transferase, 5'-nucleotidase and leucine aminopeptidase activities in the plasma of the horse

In 18 horses there was no effect of age or sex on plasma activities of gamma-glutamyl transferase (gamma-GT), 5'-nucleotidase (5'-NT) and leucine aminopeptidase (LAP). All the enzymes were equally stable after storage for one month at -20 degrees C and there was no significant difference between their activities in serum and plasma in clinically normal horses. The pattern of release of gamma-GT, 5'-NT and LAP into plasma was studied in 114 horses which had a variety of orthopaedic, gastrointestinal, cardiovascular and hepatic (necrosis, lipidosis, neoplasia and cirrhosis) conditions. A definitive diagnosis of hepatic disease was established by histological examination of the liver. gamma-GT and 5'-NT were leaked into plasma in hepatic disease and gamma-GT was the more sensitive indicator of liver damage. There was some evidence that gamma-GT and 5'-NT plasma activities may increase in hepatic necrosis as well as in biliary obstruction. LAP was insensitive and not hepatic specific in the horse.     

Enzymuria as an index of renal damage in sheep with induced aminoglycoside nephrotoxicosis

Acute nephrotoxicosis was induced in ewes by daily SC administration of gentamicin. Activity of 3 urine enzymes, gamma-glutamyltransferase (GGT), beta-N-acetylglucosaminidase (AGS), and beta-glucuronidase (GRS), were measured during the development of aminoglycoside nephrotoxicosis. Measurements from timed, volume-measured urine samples were performed on days 0, 7, and 8. Measurements from urine samples obtained without volume measurement (spot samples) were performed daily. Urine GGT and AGS activities were high 3 days prior to detection of high serum creatinine concentration and 1.5 days before the appearance of casts in the urine sediment; values consistently remained in the abnormal range until termination of the study. High urine GRS activity was inconsistent and transient; serum GGT activity did not change during the course of the study. Urine GGT and AGS activities expressed as total excretion per unit time and body weight, enzyme activity per unit volume, and as ratio of urine enzyme activity to urine creatinine concentration were strongly correlated. Urine GGT and AGS, but not GRS activities, are suitable indicators of renal tubular cell damage in sheep with aminoglycoside nephrotoxicosis. Urine GGT and AGS activities indicate cellular changes occurring several days prior to the first indications of renal functional change.     

Serum and urinary biochemistry and enzyme changes in ponies with acute renal failure

Serum and urinary biochemical changes were recorded in 5 ponies in which acute tubular nephrosis had been induced over 5 days with mercuric chloride and potassium dichromate. Serum osmolality, the serum concentrations of urea nitrogen, creatinine, sodium, potassium and chloride, and blood pH and blood gases were measured daily for 14 days or until humane euthanasia was performed. Levels of the same substances were quantitated daily in urine. In addition, routine urinalyses and determination of urinary gamma glutamyl transferase (GGT) activity were performed on each sample. Changes in the values of the urinary variables preceded alterations in the serum value of the same substance by at least one day. The first notable abnormality detected was in urinary GGT activities. These changes occurred up to 6 days before the detection of azotemia. It was concluded that acute equine renal injury could be diagnosed earliest with biochemical testing of urine. Measurement of urinary GGT levels represents a means by which proximal tubular disease in equidae could be diagnosed in its developmental stages.     

Clinicopathological features in ovine AA amyloidosis

This paper describes the clinicopathological findings in sheep with AA amyloidosis. Serum samples from 12 AA amyloid-affected sheep and urine samples from 5 of these ewes were analyzed. In sera, the most important alteration was reflected in hypoalbuminemia, high concentration in beta and gamma-globulins and high levels of serum BUN, phosphorous and potassium. Serum creatinine, cholesterol and calcium concentrations showed no alterations. Urinary analysis showed proteinuria and a high protein/creatinine ratio. In three urine samples, high activities of urinary enzymes gamma-glutamyl transferase (GGT), beta-glucuronidase (GRS) and N-acetyl-beta-D-glucosaminidase (NAG) were observed, their ratios with urinary creatinine being increased for GGT and NAG and decreased for GRS. In conclusion, important alterations in biochemical and urinary parameters were observed in ovine affected by systemic AA amyloidosis. Those related to the activities of urinary enzymes could constitute reliable parameters for assessing renal injury in ovine AA amyloidosis.     

Urinary excretion of immunoreactive sporidesmin metabolites in sheep in relation to factors influencing susceptibility to sporidesmin intoxication

AIM: To study the urinary disposition of orally administered sporidesmins A and D in sheep and identify factors influencing their kinetics, particularly the influence of breeding for resistance and susceptibility to sporidesmin, the mycotoxin responsible for the hepatogenous photosensitisation, facial eczema. METHODS: A competitive ELISA was used to monitor urinary output of immunoreactive metabolites after the intraruminal administration, to female Romney sheep, of either sporidesmin A or sporidesmin D, the nontoxic analogue. Preliminary characterisation of metabolites was carried out using HPLC with fractions monitored by ELISA. RESULTS: Maximum urinary excretion rates of immunoreactive metabolites occurred 2-8 h after dosing with sporidesmin D and 15-30 h after dosing with sporidesmin A. Sporidesmin D caused no liver injury, as detected by changes in serum enzyme activity, while the liver injury caused by sporidesmin A was greatest for the sheep with the highest cumulative output of metabolite. When sporidesmin D was administered in two separate doses to sheep bred for either resistance or susceptibility to facial eczema, the variability of metabolic output between sheep within groups was much less after the second dose. The mean urinary metabolite excretion was greater for the susceptible than the resistant sheep but the difference was not significant. Potentiation (caused by pre-administration of small doses of sporidesmin A) resulted in a more severe reaction to the dosed sporidesmin A. Urinary output of metabolite was less in the potentiated than in the unpotentiated sheep. When resistant and susceptible sheep were dosed with sporidesmin A after potentiation there was no difference between them in their cumulative totals or excretion rates of immunoreactive metabolites. However, the volume of urine produced by the susceptible sheep was lower and less variable than the resistant sheep and consequently the concentration of their urinary metabolites was higher. Preliminary ELISA examination of HPLC-fractionated urine from a sheep dosed with sporidesmin A indicated the presence of several metabolites of sporidesmin. CONCLUSION: Sporidesmin A and metabolites are rapidly excreted in urine but not as rapidly as sporidesmin D and its metabolites. Only minor differences between sheep bred for resistance and susceptibility were seen. Potentiation caused a more severe reaction to sporidesmin A and less urinary excretion of the sporidesmin and its metabolites. CLINICAL RELEVANCE: This work is part of a programme with the aim of identifying FE-resistant animals without the need for sporidesmin dosing.     

Some physiopathological features of experimental Homeria glauca (Wood & Evans) N. E. Br. poisoning in Merino sheep

Five Merino sheep were dosed 3 g/kg of dry, finely-milled Homeria glauca (Natal yellow tulp) plant material. An electrocardiogram was recorded and the arterial and central venous blood pressure, blood gases, haematological variables, plasma electrolytes (Na+, K+, Ca2+, Mg2+, Cl- and PO4(2-) ) and a variety of serum enzymes and chemical constituents were measured hourly until death (3 sheep) or until sheep were in extremis (2 sheep). Heart rate rose progressively as a result of sinus and, later, ventricular tachycardia. Systolic blood pressure rose, but there was little change in the mean and diastolic arterial pressures and central venous pressure. There was progressive hypoxaemia, hypercarbia and acidaemia with depletion of plasma bicarbonate. Haemoconcentration, hyperkalaemia and hypochloraemia were found along with rising serum creatinine and plasma glucose. Rises in serum enzymes indicated widespread tissue damage. Electrocardiographic recordings were being made at the moment of death in 3 of the 5 sheep. In these 3 sheep the cause of death was ventricular fibrillation.     

Effects of heparin, citrate, and EDTA on plasma biochemistry of sheep: Comparison with serum

The effects of various types of anticoagulants on plasma biochemistry were studied in man and various animals, but limited information is existing for sheep plasma biochemistry. Ten clinically healthy Baloochi breed of sheep were blood sampled in different tubes containing each anticoagulants and plain tube for harvesting plasma and serum. The concentrations of glucose, cholesterol, total bilirubin, urea, creatinine, total protein, albumin, calcium, inorganic phosphorus, and magnesium and the activity of aspartate aminotransferase (AST), alkaline phosphatase (ALP), creatine kinase (CK) and gamma glutamyl transferase (GGT) were measured. Except for the amounts of GGT, bilirubin and inorganic phosphorus, other measured parameters were significantly lower in citrated plasma than that of serum. For corrected citrated plasma significant differences were seen for the concentrations of glucose, creatinine, calcium and the activity of ALP.Most parameters did not show any difference, but significant increase was seen for albumin concentration when heparin was used as an anticoagulant. Using EDTA as anticoagulant caused a significant difference for the concentrations of some of the measured parameters in plasma except glucose, GGT, cholesterol, albumin, bilirubin, CK, and inorganic phosphorus comparing with serum.     

Effect of a hay and a grain diet on the bioavailability of ochratoxin A in the rumen of sheep

The role of the rumen and its contents in the detoxification of ochratoxin A (OA) was studied in sheep. The first experiment established that very little conversion of OA to alpha ochratoxin (O alpha) occurs systematically; 90 to 97% of the OA and metabolites was recovered as unaltered OA in the urine. Most of the small amount of O alpha recovered was also in the urine. In this experiment, two sheep were fasted and another two fed normally, but feed intake had no significant effect. In the second experiment, two sheep fed hay and two fed grain were dosed with OA at .5 mg/kg of BW into the rumen via a cannula. Recoveries, in urine and feces, accounted for 58 to 70% of the administered OA, but almost all (greater than 97%) was in the form of O alpha. About 76 to 92% of this O alpha was in the urine. Although excretion patterns and pharmacodynamics tended to differ with different diets, one of the sheep fed grain had very low intake and the results were equivocal. In the third experiment, eight sheep (four fed hay, four fed grain) were given a single intraruminal dose of OA (.5 mg/kg of BW). The disappearance of OA from the rumen and the corresponding formation of O alpha was much faster for hay-fed than for grain-fed sheep; the half-lives were .63 and 2.7 h for OA and .9 and 1.9 h for O alpha, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

SHEEP MORTALITIES ASSOCIATED WITH THE BLUE GREEN ALGA: NODULARIA SPUMIGENA

In 2 field mortalities studied, sheep died and showed haemorrhage and diffuse liver necrosis after drinking water from dams containing growths of the blue green algae Nodularia. Sheep dosed with water containing N. spumigena Mert 5, 9 and 18 days after collection from one of the farm dams developed pyrexia and leucopenia before death. At necropsy, these sheep showed extensive haemorrhage, accumulations of yellow fluid in body cavitis and acute hepatic necrosis. Guinea pigs dosed with the water 9 days after collection died and developed periacinar liver necrosis, but those dosed 12 days after collection did not.     

Effects of general anesthesia and surgery on renal function in healthy dogs

OBJECTIVES: To evaluate renal function in healthy dogs undergoing general anesthesia and ovariohysterectomy without concurrent IV administration of fluids. ANIMALS: 35 healthy client-owned dogs. PROCEDURE: Dogs were medicated with promazine hydrochloride (0.05 mg/kg of body weight, SC) approximately 45 minutes before induction of anesthesia with thiopental sodium (10 to 15 mg/kg, IV). Anesthesia was maintained with 2% halothane in oxygen. Ovariohysterectomies were performed by senior veterinary students under the direct supervision of a veterinary surgeon. Renal function was assessed (serum urea and creatinine concentrations, fractional clearance of sodium, urine alkaline phosphatase [ALP] and gamma-glutamyltransferase [GGT] activities, urine specific gravity, and enumeration of renal tubular epithelial cells in urine sediment) prior to and 24 and 48 hours after surgery. RESULTS: Duration of general anesthesia ranged from 80 to 310 minutes. Urine specific gravity and ALP activity and serum urea and creatinine concentrations did not change over time. Fractional clearance of sodium decreased 24 and 48 hours after surgery, whereas urine GGT activity and the ratio of urine GGT activity to urine creatinine concentration increased 24 hours after surgery, compared with presurgery values. Renal tubular epithelial cells increased in number in urine sediment from 11 of 35 (31.4%) dogs and 5 of 35 (14.3%) dogs 24 and 48 hours after surgery, respectively. However, this increase was not clinically relevant. CONCLUSIONS AND CLINICAL RELEVANCE: Intravenous administration of fluids to healthy dogs undergoing general anesthesia and elective surgery may not be necessary for maintenance of renal homeostasis.     

The ability of diamphenethide to control immature Fasciola hepatica in sheep at a lower than standard dose level

Groups of eight Welsh Mountain sheep were dosed with diamphenethide at the rate of 70 mg/kg bodyweight at either one, four, six or eight weeks after artificial infection with approximately 300 Fasciola hepatica metacercariae. Comparisons were made with similarly infected but undosed sheep and with sheep which were neither infected nor dosed. The good clearance of flukes up to six weeks of age (above 97 per cent on pooled data) was reflected in the plasma concentrations of the accepted liver damage marker enzymes glutamate dehydrogenase and gamma-glutamyl transpeptidase. Highly significant correlations were demonstrated between the numbers of flukes recovered, the plasma levels of these enzymes and haemoglobin and plasma albumin values. At 70 mg/kg, diamphenethide was shown to be able to control F hepatica populations of up to six weeks of age. The systematic use of diamphenethide at this dose level at intervals of up to six weeks during the period of metacercarial challenge should prevent ovine fascioliasis.     

Narthecium ossifragum (L.) huds. causes kidney damage in goats: morphologic and functional effects

We studied the effects of Narthecium ossifragum on goat kidneys. Twenty-five Norwegian dairy goats, 5 weeks to 4 months of age, were orally dosed with an aqueous extract from N. ossifragum. In experiment 1, we studied microscopic and functional changes in 12 animals that were euthanatized 2, 3, 4, 5, and 6 days after treatment. In experiment 2, we included ultrastructural studies on serial renal biopsies and urine analysis from five extract-treated animals and two controls. In addition, urine samples were collected from four dosed and two control goats. Ultrasonography revealed perirenal and retroperitoneal fluids. Microscopic changes were observed after 6 hours. The findings, most obvious in the inner cortex and the outer medulla, consisted of cytoplasmic vacuolization, interstitial edema, and focal necrosis of tubular epithelial cells. Ultrastructurally, the tubules had loss of microvilli, irregular cytoplasmic vacuolization, mitochondrial swelling with loss of cristae, and irregular but continuous basement membranes even with necrosis. In the glomeruli, there were occasional endothelial damage and shortening and swelling of the foot processes. Peritubular capillaries had breaks in the vessel walls and irregular endothelial cell edema, and the interstitium had marked edema. The functional lesions included elevated serum urea, creatinine, and magnesium concentrations, a slight decrease in serum calcium concentration, elevated urine protein and urine protein-creatinine ratio, and increased activities of urine alkaline phosphatase and gamma glutamyl transferase. Our findings indicate a fast-acting toxic principle inducing damage by both direct toxic and secondary ischemic effects.     

Facial eczema in goats: the toxicity of sporidesmin in goats and its pathology

Groups of six goats were orally dosed with sporidesmin at rates of 0.3, 0.6, 1.2 and 2.4 mg of sporidesmin per kg body weight and their responses up to 6 weeks later compared with those of sheep dosed at the same time. Clinical facial eczema and pathological lesions similar to those found in sheep were found in all the goat breeds, but at higher dose rates of sporidesmin than those which caused equivalent lesions in sheep. Saanens were the most susceptible goat breed, requiring 2-4 times as much sporidesmin as sheep to achieve similar effects. G4 and feral goats required 4-8 times the sheep dose of sporidesmin to obtain similar responses. Gamma-glutamyltransferase reached its highest serum levels after 20 days while glutamate dehydrogenase and aspartate aminotransferase reached their highest levels between 10 and 20 days. Alkaline phosphatase did not rise consistently to high levels in affected goats. The elevation in aspartate aminotransferase levels tended to be early and transient; glutamate dehydrogenase early and prolonged; gamma-glutamyltransferase late and prolonged, and'alkaline phosphatase late and minor. There was considerable individual variation in the time at which elevations occurred and the levels which enzymes reached. Cholesterol and bilirubin levels were high if liver injury was severe.     

Toxicity, pathophysiology and pathology in sheep following dosing of the nephrotoxic plant Nolletia gariepina (DC) Mattf

Ingestion of the plant Nolletia gariepina was confirmed as the cause of acute mortalities in cattle in the Kuruman area of the Northern Cape Province of South Africa. The aim of this trial was to investigate the toxic effects of this plant with respect to clinical signs, pathophysiology and pathology using the sheep as a model. At dosages of 1.5 g dried, milled plant material/kg body mass there were no detectable abnormal findings, while at dosages of 2.8-3.0 g/kg most of the animals died acutely. In subacutely affected sheep, depression, inappetance, teeth grinding, tachycardia, weak ruminal movements and recumbency were noticed. The most prominent pathophysiological changes observed, included a sharp rise in non-protein nitrogen substances in the plasma, remarkable decline in glomerular filtration rate, increase in sodium and potassium excretion, and a rise in urine gamma glutamyltransferase activity. Macroscopically a severe nephrosis was present in all the animals. The most important findings detected histologically were necrosis of the proximal convoluted tubular epithelium and large numbers of protein casts in the lumens.     

Distribution of 5'-nucleotidase and gamma glutamyl transferase activities in the tissues of the horse

In the horse, 5'-nucleotidase (5'-NT) activity is found mainly in homogenates of lung, kidney, small intestine, mammary gland, liver and pancreas. Lower activities are present in brain and muscle. Activity can be demonstrated histochemically in the glomeruli and tubules of the kidney, in the sinusoidal borders of the hepatocytes and the bile duct epithelium as well as in the blood vessels of all organs. There is no significant difference between the 5'-NT activity in serum and plasma of normal horses and of horses suffering from a range of orthopaedic conditions. Previous findings that gamma glutamyl transferase activity is greatest in kidney and high in liver and pancreas have been confirmed.     

Evaluation of a technique for measurement of gamma-glutamyltranspeptidase in equine urine

gamma-Glutamyltranspeptidase (GGT) activity in equine urine was measured, using an assay developed for use with serum and was found to be reproducible. The GGT activity was measured in samples prepared by serial dilution of exogenous GGT with equine urine, and the activity was determined to be linear between 21 IU/L and 407 IU/L. The behavior of exogenously added GGT was compared in equine serum and urine. The enzyme behaved similarly in both fluids. The GGT activity was measured in serum and urine samples after storage at -20, 4, and 25 C for 24 and/or 72 hours. Enzyme activity decreased after storage at all temperatures and times, but the decrease was greatest and most variable at -20 C. The urine GGT: urine creatinine ratio was calculated on serial urine samples collected over 24 hours. Although the urine GGT activity and creatinine concentration had significant variation, the ratio remained constant. The urine GGT: urine creatinine ratio was calculated from random urine samples collected from 27 clinically healthy adult horses and was found to be 10.52 +/- 4.78 (mean +/- SD).     

Experimental acute yellow-wood (Terminalia oblongata) intoxication in sheep

SUMMARY An aqueous suspension of air-dried, hammer-milled leaf of Terminalla oblongata (yellow-wood) was administered to sheep by gavage, as a single dose of 5 to 20 g (dry weight)/kg body weight. Doses of 15 g/kg, or more, caused depression, Inappetence, abdominal pain and reduced ruminal movements within 24 to 48 h and some sheep also showed dyspnoea, oplsthotonus and champing of the Jaws. Haematology and blood gas and acid-base measurements were unaffected. In sheep given a dose of 12.5 g/kg, or more, plasma osmolality, aspartate aminotransferase activity and potassium and bilirubin concentrations Increased while plasma total protein markedly decreased and plasma sodium concentration and alkaline phosphatase activity remained normal. Most sheep were necropsled 48 h after dosing. The liver showed zonal hepatocellular necrosis, the pattern of which varied with the dose given. No renal lesions were observed, although one sheep given a very high dose became azotaemic and hyperkalaemic. Hydrothorax, hydroperlcardlum and ascltes developed In sheep given doses of 15 or 20 g/kg.     

Photosenitization of sheep on kleingrass pasture

The clinical appearance and serum gamma-glutamyl transpeptidase (GGT) activity were studied in 5 groups of sheep (12 per group) on kleingrass (Panicum coloratum) pasture plots and in 1 group of sheep (10 animals) on native buffalograss (Buchlo? dactyloides) pasture. Eleven sheep (at least 1 from each group on kleingrass pasture plots) had elevated serum GGT activity. Seven of 11 sheep with elevated serum GGT activity developed signs of photosensitization. None of the sheep on buffalograss pasture developed signs of photosensitization or elevated GGT activity. The pathologic findings were similar in the sheep that had signs of photosensitization. Grossly, there was icterus and subcutaneous edema. The livers had tapeworms (Thysanosoma actinioides) in the bile ducts, were slightly swollen, and varied in color from yellow to ochre in severe cases of biliary system derangements. Microscopically, there was cholangitis.     

Urinary enzyme concentrations in healthy horses

Urinary concentrations of gamma glutamyl transferase (GGT), alkaline phosphatase (AP), aspartate aminotransferase (AsAT), and alanine aminotransferase (AAT) were measured in 32 healthy horses (16 geldings and 16 females) at the same time on 2 consecutive days. The subjects were divided into 4 ages groups, each comprising 8 horses (4 of each sex). In 10 of the geldings, urine was collected continuously for 72 hours, with catheterized samples being obtained at 0800, 1400 and 2000 hours, and an aliquot of the pooled urine being taken every 24 hours. Urinary enzyme activity was found to be unrelated to serum concentrations of the same enzymes. There was no diurnal variation in the activity of the urinary enzymes. Neither the sex of the horses nor their age influenced urinary enzyme activity regardless of whether it was expressed in absolute terms or in reference to creatinine excretion Normal values of GGT and AP were determined to be 3.3 +/- 3.0 IU/L, (2.5 +/- 3.4 IU/g Cr); and 10.2 +/- 4.0 IU/L (6.7 +/- 3.9 IU/g Cr) respectively. Neither AAT or AsAT were present in detectable levels. The mean urine creatinine concentration of all horses was 1.56 +/- 0.42 g/L with no significant age or sex variation being evident.