Metabolic changes and induction of hepatic lipidosis during feed restriction in llamas.

OBJECTIVES: To determine whether feed restriction induces hepatic lipidosis (HL) in llamas and to evaluate the metabolic changes that develop during feed restriction. ANIMALS: 8 healthy adult female llamas. PROCEDURE: Llamas were fed grass hay at a rate of 0.25% of their body weight per day for 13 to 28 days. Llamas were monitored by use of clinical observation, serum biochemical analyses, and ultrasound-guided liver biopsies. RESULTS: All 8 llamas lost weight and mobilized fat. Five llamas developed HL, including 4 that were nursing crias. During the period of feed restriction, mean serum concentration of bile acids and activities of aspartate aminotransferase (AST), sorbitol dehydrogenase (SDH), and gamma-glutamyl transferase (GGT) were significantly higher in llamas that developed HL, compared with llamas that did not. Mean insulin-to-cortisol concentration ratios were lower in llamas with HL before and up to 7 days of feed restriction, compared with those that did not develop HL. CONCLUSIONS AND CLINICAL RELEVANCE: HL in llamas may be induced by severe feed restriction, particularly in the face of increased energy demand. Llamas with weight loss attributable to inadequate dietary intake may develop biochemical evidence of hepatopathy and HL. Increases in serum concentration of bile acids and activities of GGT, AST, and SDH may indicate the development of HL in llamas and identify affected animals for aggressive therapeutic intervention.     

Evaluation of ornithine carbamoyl transferase and other serum and liver-derived analytes in diagnosis of fatty liver and postsurgical outcome of left-displaced abomasum in dairy cows

OBJECTIVE: To evaluate postsurgical outcome in dairy cows with left-displaced abomasum (LDA) with regard to severity of fatty liver and assess the usefulness of preoperative determination of serum ornithine carbamoyl transferase (OCT) activity, bile acids concentration, and other variables for evaluating liver function during the postsurgical convalescence period. DESIGN: Prospective study. ANIMALS: 68 Holstein cows. PROCEDURES: Blood and liver biopsy specimens were obtained during standing LDA surgery. Liver tissue was examined histologically and classified by severity of fatty change. Serum activities of liver-derived enzymes and concentrations of total lipids, triglycerides, bile acids, glucose, beta-hydroxybutyric acid, bilirubin, and nonesterified fatty acids were determined. RESULTS: Most cows with LDA and cows with severe fatty liver were detected within the first month after calving. Postsurgical outcome was related to severity of fatty liver. All cows that died had severe fatty liver. Serum activities of OCT, aspartate aminotransferase, and glutamate dehydrogenase and serum total bilirubin concentration were sensitive indicators of fatty liver. Serum bile acids concentration was not an accurate indicator of fatty liver. CONCLUSIONS AND CLINICAL RELEVANCE: Postsurgical outcome of cows undergoing surgery to correct LDA was related to fatty liver severity. Assessment of serum activities of OCT, aspartate aminotransferase, and glutamate dehydrogenase and serum total bilirubin concentration is recommended for diagnosis of fatty liver in dairy cows with LDA, whereas determination of bile acids concentration is not. The strong correlation between OCT activity and degree of hepatocellular damage supports use of this enzyme for assessing severity of fatty liver and predicting postsurgical outcome in cows with LDA.     

Purification of a protein from serum of cattle with hepatic lipidosis, and identification of the protein as haptoglobin.

A protein that has 2 subunits with molecular weight of 35,000 and 23,000 was detected in serum of cattle with hepatic lipidosis (fatty liver). The protein was purified from serum obtained from a cow with fatty liver, and was identified as haptoglobin, which is known to have hemoglobin-binding capacity and to be an acute-phase protein. To assess the relevance of haptoglobin in fatty liver, cattle were classified in 3 groups (healthy control, haptoglobin-positive, and haptoglobin-negative); liver triglyceride content and several serum biochemical variables were evaluated for the 3 groups. Compared with the control and haptoglobin-negative cattle, haptoglobin-positive cattle had significantly (P less than 0.01) higher liver triglyceride content, serum bilirubin concentration, and aspartate transaminase activity. Serum haptoglobin concentration was high in slaughter cattle (27 of 40 cattle tested), particularly in cows (20/28).     

Reference values of blood parameters in beef cattle of different ages and stages of lactation.

Reference (normal) values for 12 blood serum components were determined for 48 Shorthorn cows (2-10 years old) and their 48 calves, 357 crossbred cows (12-14 years old), 36 feedlot bulls and 36 feedlot steers. In addition, hemoglobin, hematocrit, triiodothyronine, thyroxine and cortisol levels were determined for the crossbred cows, and feedlot bulls and steers. Reference values were tabulated according to sex, age and stage of lactation. Serum concentrations of urea, total protein and bilirubin, and serum activity of aspartate aminotransferase and lactate dehydrogenase increased with age (P less than 0.05), while calcium, phosphorus and alkaline phosphatase decreased with age (P less than 0.05) from birth to the age of ten years. The Shorthorn cows had the highest levels of glucose at parturition (P less than 0.05) with decreasing levels during lactation. Creatinine concentration decreased during lactation and increased during postweaning. Both lactate dehydrogenase and aspartate aminotransferase levels increased (P less than 0.05) during lactation. Urea and uric acid were present at higher concentrations in lactating than nonlactating cows (P less than 0.05). The values reported, based on a wide age range and large number of cattle, could serve as clinical guides and a basis for further research.     

Relationship of hepatic lipidosis to health and performance in dairy cattle

In a field study of 80 cows in 9 dairy herds, serial liver biopsies were performed over the peripartum period to determine degree of hepatic lipidosis. Cattle were separated into categories of mild, moderate, and severe hepatic lipidosis on the basis of maximal amounts of hepatic triglyceride that accumulated during this period. Number of cattle with mild, moderate, and severe hepatic lipidosis were 52, 16, and 12, respectively. Cattle with severe hepatic lipidosis had greater concentrations of hepatic triglyceride before calving and after parturition, and greater serum nonesterified fatty acid concentrations and body condition loss after parturition than cattle with mild hepatic lipidosis. Rate of disease and culling and death rate because of disease were greater in cattle with severe hepatic lipidosis. Cattle with severe hepatic lipidosis had reproductive performance equal to clinically normal cattle; however, cattle with moderate hepatic lipidosis had increased days to conception, possibly related to greater milk production.     

Effect on liver function of acetonaemia and the fat cow syndrome in cattle

The effect of fatty infiltration on liver function was studied in 29 dairy cows aged 6 +/- 0.4 (SEM) years with primary acetonaemia, secondary acetonaemia or the fat cow syndrome. The average interval from calving at diagnosis was 16.4 +/- 2.0 days and the animals had been anorexic for a mean of 5.6 +/- 0.8 days. Fatty infiltration of the liver occurred well before calving and was associated with severe clinical illness and intercurrent infections. The percentage of fatty infiltration in the liver (mean 53.1 +/- 2.8 per cent) was significantly correlated with both the degree of clinical illness (P less than 0.001) and the period of anorexia (P less than 0.05). Alterations in uptake, conjugation and excretion at the hepatocyte level were determined by measuring bromsulphthalein clearance, and plasma total bilirubin and total bile acid concentrations. Values for all three were positively correlated with the extent of fatty infiltration. Plasma albumin, urea and glucose concentrations were reliable indicators of the liver's synthetic function and together with plasma aspartate aminotransferase, iditol and glutamate dehydrogenase were correlated with the degree of hepatic lipidosis.     

Clinicopathologic evaluation of hepatic lipidosis in periparturient dairy cattle

BACKGROUND: Fatty change of the liver (FCL) is very common in dairy cattle periparturiently. Many laboratory methods have been implicated in order to assist the diagnosis. HYPOTHESIS: To investigate whether FCL in dairy cattle could be evaluated by assessment of ornithine carbamoyl transferase (OCT) by means of an assay modified for bovine serum, other enzyme activity, serum bile acids (SBA) concentration, or other biochemical constituents. ANIMALS: A total of 187 dairy cattle were included: 106 were suspected to have liver dysfunction and were examined after referral by veterinarians; 70 were clinically healthy with mild FCL; and 11 were clinically healthy without FCL. METHODS: Blood and liver biopsy samples were obtained after clinical examination. Histologic examination by light microscopy and classification of samples according to the severity of FCL was done, and total lipid and triglyceride concentration was measured. In serum, OCT, aspartate aminotransferase (AST), alanine aminotransferase (ALT), sorbitol dehydrogenase (SDH), glutamate dehydrogenase (GDH), alkaline phosphatase (ALP), and gamma-glutamyltransferase (gamma-GT) activity as well as SBA, glucose, ketones, total bilirubin (tBIL), and nonesterified fatty acids (NEFA) concentration were measured. RESULTS: OCT and AST activity and tBIL concentration correlate well with the degree of FCL. SBA concentration does not contribute well to FCL diagnosis. The majority of FCL cases appeared within the first 21 days-in-milk (DIM). The majority of moderate-to-severe and severe FCL cases arose in the first 7 DIM. CONCLUSIONS AND CLINICAL IMPORTANCE: Except for OCT, AST, and tBIL, none of the biochemical tests used, including SBA, had sufficient discriminatory power to differentiate reliably between mild and severe FCL because of poor sensitivity. A weak correlation between clinical signs and the extent of FCL was evident.     

Evaluation of total plasma bile acid concentrations for the diagnosis of hepatobiliary disease in horses

Plasma bile acid concentrations were measured in normal horses. There was no diurnal variation in values, and age and sex had no effect. There was no significant difference between serum and plasma bile acid concentrations in clinically normal horses. Plasma bile acids were stable on storage for one month at -20 degrees C. The total plasma bile acid concentrations together with total and direct bilirubin concentrations and plasma activities of aspartate aminotransferase, glutamate and iditol dehydrogenase were evaluated in horses with various types of hepatobiliary disease (hepatic necrosis, lipidosis, neoplasia and cirrhosis), gastrointestinal disease, cardiovascular, orthopaedic and various other conditions not affecting the liver. Total plasma bile acids together with plasma glutamate and iditol dehydrogenase activities were the best indicators of liver disease. Total plasma bile acid concentrations were the most sensitive indicator of a wide variety of hepatic diseases but alone were unhelpful in differential diagnosis and were of more value when combined with the other tests of hepatic disease.     

Serum free amino acid concentration in hepatic lipidosis of dairy cows in the periparturient period

Blood samples were taken from eight multiparous cows at a dairy farm on eight occasions between the prepartum period and peak lactation to study the serum concentrations of amino acids and biochemical constituents. The cows were classified as having either severe hepatic lipidosis (HL) or non-hepatic lipidosis (non-HL) according to their clinical condition after calving and changes in serum biochemical parameters. The serum concentrations of beta-hydroxybutyric acid were higher in the HL group than in the non-HL group (ANOVA: p<0.01). The serum concentrations of methionine (Met), phenylalanine, and arginine were significantly different between the two groups (ANOVA: p<0.05). In particular, the Met levels were significantly low for 14 days after calving in the HL group (p<0.05), although Met levels in the HL group tended to be lower than the values in the non-HL group until 30 days after calving, starting 14 days before calving. The results suggest that an insufficiency of Met during the periparturient period is related to the development of hepatic lipidosis.     

Relationship between plasma vitamin C and serum diagnostic biochemical markers in lactating cows

We investigated the relationship between plasma vitamin C concentration and serum levels of some diagnostic biochemical markers in 118 lactating Holstein cows. Blood sample was collected once from each cow and we measured the plasma vitamin C concentration and the serum levels of glucose, beta-hydroxybutyrate, free fatty acids, triacylglycerol, total cholesterol, albumin, total bilirubin, alkaline phosphatase, aspartate aminotransferase and gamma-glutamyltransferase. The regression of plasma vitamin C with each serum diagnostic biochemical marker indicated that the vitamin C concentration significantly decreased as glucose, alkaline phosphatase or aspartate aminotransferase level increased and as total cholesterol or albumin concentration decreased. Furthermore, the plasma vitamin C concentration was significantly lower in the cows showing that each of these marker levels was out of its reference interval than in the cows showing that the marker level was within its reference interval. The significant correlations were observed among total cholesterol, albumin, alkaline phosphatase and aspartate aminotransferase levels, to which the glucose concentration was not related. These results showed that the plasma vitamin C concentration was low in the cows that had concurrently low levels of total cholesterol and albumin, and high levels of alkaline phosphatase and aspartate aminotransferase. Therefore, a hepatic malfunction possibly decreases plasma vitamin C concentration through suppressing vitamin C production. On the other hand, the high level of glucose possibly decreases plasma vitamin C concentration through suppressing vitamin C recycling.     

Pathology of the mononuclear cell leukemia of Fischer rats. III. Clinical chemistry

Serum biochemical analyses were done on F344 rats in the early and late stages of mononuclear cell leukemia. There were marked increases in serum bilirubin, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase and alkaline phosphatase. Increases in these parameters generally were more severe in the late stages of leukemia. Both direct and indirect-reacting bilirubin were increased with the unconjugated form predominating early and the conjugated form predominating late in the course of the disease. Lactate dehydrogenase isoenzyme determination correlated with histological examination indicated that liver damage was responsible for the observed changes. Urinalysis revealed marked hemoglobinuria, bilirubinuria and increased urine urobilinogen. Serum protein electrophoresis revealed marked reductions in the alpha globulin fractions.     

Alterations in Coagulation Profiles and Biochemical and Haematological Parameters in Cattle with Traumatic Reticuloperitonitis

This study was designed to investigate alterations in coagulation, and in biochemical and haematological parameters in cattle with traumatic reticuloperitonitis (TRP). In the study, 28 dairy cattle with TRP and 10 clinically healthy cattle (control) of different ages and breeds were used. Cattle with TRP had prolonged prothrombin time (PT), thrombin time (TT) and activated partial thromboplastin time (APTT). Erythrocytopenia, thrombocytopenia and hyperfibrinogenaemia were detected in animals with TRP. Furthermore, the serum concentrations of total protein, globulin and total bilirubin, and the activities of alkaline phosphatase (ALP) and aspartate aminotransferase (AST) were also high in cattle with TRP compared to those of the control group. The serum concentrations of calcium were significantly low in the TRP group. The results of this study, therefore, indicate that TRP causes significant coagulation abnormalities and biochemical and haematological alterations in dairy cattle.     

Clinicopathologic study of horses surviving pyrrolizidine alkaloid (Senecio vulgaris) toxicosis

Twenty horses of various ages had inadvertently ingested alfalfa hay contaminated with Senecio vulgaris. Among them, 4 died of liver disease. Blood was collected from affected horses at monthly intervals for 7 months and at the 9th and 14th months. The following serum enzymes and chemical items were assayed: aspartate aminotransferase, lactate dehydrogenase, alkaline phosphatase, gamma-glutamyl transferase, sorbitol dehydrogenase, total bilirubin, BUN, glucose, cholesterol, inorganic phosphate, calcium, total protein, and albumin. Amino acid profiles, conjugated bile acids, sulfobromophthalein clearance times, and liver histopathologic changes via serial biopsies were also monitored. Liver histopathologic changes revealed lesions progressively increasing in severity. Aspartate aminotransferase and plasma amino acid ratios indicated chronic liver degeneration (0.05 level of significance). gamma-Glutamyl transferase and lactate dehydrogenase as well as BUN values fluctuated, but returned to within reference values. Horses appeared clinically normal 14 months after intoxication, but were unable to tolerate stress of exercise.     

Diurnal and seasonal variations of serum enzyme activity in cattle and sheep

In order to test the variation of enzyme activity in serum of cattle and sheep during the day, blood samples were taken at three hrs. interval from 6 a.m. to 9 p.m. The following enzymes were assayed: Aspartate aminotransferase (AspAT = GOT), alanine aminotransferase (AlAT = GPT), total lactate dehydrogenase (LDH), and a-hydroxybutyrate dehydrogenase (HBD). The variation between animals contributed by far to the greatest part of the total variation in clinical healthy animals. The time-of-day-dependant variation was less than 3 %, except for alanine aminotransferase.During the first two weeks of spring pasture serum aspartate and alanine aminotransferase levels were significantly raised in both cows and ewes, compared with serum levels of the same animals on indoor feeding. No such increase occurred in total lactate dehydrogenase.     

Changes in the profile of liver enzymes in newborn calves induced by experimental,subclinical acidosis in pregnant cows and osmotic diarrhoea

Experimental, subclinical acidosis was induced by oral administration of sacharose during the last 2 months of pregnancy in 15 cows. Seven cows and their newborn calves were used as a control group. The liver enzyme activities in the serum and the blood acid-base status were determined in the 15 calves from the cows in the experimental group. Mannitol was administered orally to 8 calves from the experimental group to induce osmotic diarrhoea. It was concluded that subclinical acidosis in pregnant cows alters the biochemical liver profile of their newborn calves, affecting the aspartate aminotransferase, alanine transaminase, beta glucuronidase, glutamate dehydrogenase and bilirubin activities in the serum, which are associated with oedematous changes to the hepatocytes. Diarrhoea was accompanied by an increase in the alkaline phosphatase and gammaglutamyl transferase activities and a decrease in the total protein concentration in the serum. These changes were apparently related to the numerous necrotic foci in the liver and the proliferation of the Kuppfer cells. It would appear from these results that the liver damage in the newborn calves was associated with the subclinical, metabolic acidosis in their dams and that osmotic diarrhoea occurring in the neonatal period additionally impaired the liver function.Abbreviations ALP alkaline phosphatase - ALT alanine transaminase - AST aspartate aminotransferase - GR betaglucuronidase - bw body weight - ELISA enzyme-linked immunosorbent assay - GD glutamate dehydrogenase - GGT gammaglutamyl transferase - IU international unit     

Liver biochemical and histopathological findings in dogs with experimentally induced exocrine pancreatic insufficiency

Routine liver biochemical parameters were evaluated in 8 dogs with exocrine pancreatic insufficiency (EPI) induced by surgical ligation of the pancreatic duct and the pancreatic branch of the pancreaticoduodenal artery and confirmed with the trypsin-like immunoreactivity test. Eight additional dogs were used as healthy controls. Data collection began at the 4th week postoperatively and continued weekly to the 21st week. In the dogs with EPI, the serum activity of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase were consistently elevated. The serum total and conjugated bilirubin concentrations remained within normal limits throughout the experimental period. Histopathological study revealed hepatic lipidosis in the dogs with EPI. Therefore, since this condition seems to be an additional consequence of EPI in dogs, laboratory evaluation of dogs with EPI must include assessment of liver function, to determine if additional or different therapeutic measures are indicated.     

Variations in parameters of liver function and plasma progesterone related to underfeeding and ketosis in a dairy herd

Twenty-eight Norwegian Red Cattle dairy cows were fed silage ad libitum and restricted amounts of concentrates. Blood samples were collected before morning feeding, once or twice weekly, from 2 weeks before to 12 weeks after calving. Parameters of liver function, carbohydrate status and fertility were recorded in order to assess their interrelationships. Eight cows were treated for clinical ketosis. Four of these had to be treated 2 or 3 times. Aspartate aminotransferase and bilirubin showed the highest within-animal coefficients of correlation with acetoacetate. Analysis of variance revealed a significant effect of carbohydrate status (indicated by plasma acetoacetate levels) on the levels of aspartate aminotransferase, glutamate dehydrogenase and sorbitol dehydrogenase, though only a small part of the total variation was explained by this factor. The estimated volume density of liver fat in the 4th week of lactation averaged 6.0 +/- 6.4% (+/- SD) ranging from 0.1-25.1%. Liver fat content at this stage of lactation was not significantly correlated with other indicators of liver function or carbohydrate status. Cows treated for clinical ketosis had significantly lower plasma progesterone values at the time of first ketosis treatment than untreated multiparous cows. The frequency of high progesterone values (greater than 3 ng/ml) being significantly lower in treated than in untreated cows during the period from 3-5 weeks post partum, though not at later stages. In conclusion, the results revealed a significant relationship between carbohydrate status and liver function, and also between clinical ketosis and luteal function.     

Ultrasonography as a diagnostic and prognostic approach in cattle and buffaloes with fatty infiltration of the liver

The aim of the present study was to determine whether ultrasonographic evaluation of the hepatic parenchyma could be used as a diagnostic and prognostic approach in cows and buffaloes with hepatic lipidosis. For this purpose, cows (n=16) and buffaloes (n=10) with fatty infiltration of the liver were examined by ultrasonography. Treated cows and buffaloes were monitored for hepatic changes ultrasonographically, biochemically and histologically. Clinical findings were non-specific and included anorexia, recumbency, muzzle necrosis, and icteric mucosal membranes. Laboratory data revealed neutrophilia, hyper gamma-globulinemia, elevated activities of aspartate aminotransferase, gamma-glutamyl transpeptidase, creatine kinase and lactate dehydrogenase, and high concentrations of insulin, total bilirubin, non-esterified fatty acids and beta-hydroxyl butyric acid. Laboratory results 7, and 21 days after treatment showed progressive improvement in the chemistry profile. On admission, ultrasonographic examination of the hepatic parenchyma in cows and buffaloes revealed either increased or decreased hepatic echogenicity; histologic examination revealed marked fatty infiltration of the hepatocytes. One week after treatment, the hepatic parenchyma was visualized easily, liver boundaries were clearly imaged, and histologic examination of hepatic specimen showed a moderate degree of fatty infiltration. Three weeks after treatment, the hepatic parenchyma was almost similar to normal, the hepatic and portal blood vessels could be easily imaged, and the histologic picture had greatly improved where the liver resembled the normal organ. Six cows and seven buffaloes made a full recovery while the remaining ten cows and three buffaloes were slaughtered and thoroughly examined postmortem. Ultrasonography showed a good correlation with histologic and laboratory findings.     

Serum Bile Acid Concentrations in Dairy Cattle With Hepatic Lipidosis

This study was designed to evaluate serum bile acid measurements as indicatory, of liver function and/or hepatic fat infiltration in dairy cattle. Serum bile acid concentrations were measured in healthy dairy cattle at different stages of lactation after fasting or feeding. Bile acid concentrations were compared with liver fat content and sulfobromophthalein (BSP) half-life (T 1/2). Serum bile acid concentrations were higher in cows in early lactation and with higher daily milk production. Compared with prefasting values, bile acid concentrations were decreased at 8,14, and 24 hours of fasting. Blood samples from fed cows at 1 - to 2-hour intervals had wide and inconsistent variations in bile acid concentration. Because serum bile acids correlated well with BSP T 1/2, it is suggested that both measurements evaluate a similar aspect of liver function. Neither bile acids nor BSP T I correlated with differences in liver fat content among cows. Because of large variability in serum bile acid concentrations in fed cows and the lack of correlation of measured values with liver fat content, bile acid determinations do not appear useful for showing changes in hepatic function in fed cows with subclinical hepatic lipidosis nor serve as a screening test for this condition.     

Clinical and pathologic features of acute bovine liver disease in Australia

Acute bovine liver disease (ABLD) is a sporadic hepatic disease affecting cattle in southern Australia, characterized histologically by striking periportal hepatocellular necrosis. The cause of ABLD is unknown; however, the seasonality and acute presentation of outbreaks suggest mycotoxin involvement. We describe here the clinical and pathologic findings of ABLD in 45 naturally affected cattle from 13 outbreaks occurring from 2010 to 2019 in Victoria, Australia. Outbreaks occurred in herds located along the southern coastal plain of Victoria and were observed most frequently in lactating dairy cattle. Clinical signs commonly included a combination of mild photosensitization, progressive neurologic signs, and hypogalactia, which preceded death by ≤ 48 h. All affected animals had marked elevations in activities of glutamate dehydrogenase, aspartate aminotransferase, and gamma-glutamyl transferase. At autopsy, the most common lesions were serosal petechiae and/or gastrointestinal hemorrhage, and hepatomegaly with a pronounced hepatic reticular pattern. The principal histologic lesion was widespread—severe periportal hepatocellular coagulative necrosis and erythrocyte pooling—which often extended to massive necrosis. Lesions in other organs were uncommon. Our study of ABLD suggests involvement of a potent hepatotoxin that is either directly cytopathic or requires bioactivation by periportal-specific enzymes.