Development and application of a scoring system for prognostic evaluation of equine liver biopsies

Pharmacokinetics, clinical efficacy and safety of acetaminophen (paracetamol) in adult horses with naturally occurring chronic lameness

BACKGROUND

Acetaminophen is used clinically in horses with musculoskeletal pain; however, no studies have been performed in horses with chronic lameness.

OBJECTIVES

To determine the pharmacokinetics, safety and efficacy of chronic dosing of acetaminophen in horses with naturally occurring chronic lameness.

STUDY DESIGN

Longitudinal.

METHODS

Twelve adult horses with chronic lameness were treated with acetaminophen (30 mg/kg PO) every 12 h for 21 days. Plasma concentrations of acetaminophen were analysed on days 7 and 21 via LC-MS/MS and noncompartmental pharmacokinetic analysis. Lameness was evaluated by body-mounted inertial sensor (BMIS) and 10-point subjective lameness score on day 21 and compared to untreated baseline evaluation on day 35. Clinicopathological analysis (n = 12), hepatic biopsy (n = 6) and gastroscopy (n = 6) were evaluated on days -1 and 22.

RESULTS

Maximum plasma acetaminophen concentration (Cmax ) was 20.83 ± 10.25 μg/mL at time (Tmax ) 0.40 ± 0.22 h on day 7. The Cmax on day 21 was 17.33 ± 6.91 μg/mL with a Tmax of 0.67 ± 0.26 h. Subjective lameness scores significantly improved at 2 and 4 h post-treatment; Significant percent improvement was detected in PDmax for horses with hindlimb lameness at 1, 2 and 8 h post-treatment. There were no significant differences in gastroscopy or hepatic biopsy scores between days -1 and 22.

MAIN LIMITATIONS

Small sample size, multi-limb lameness of varying severity and aetiology, lack of intermediary lameness evaluation.

CONCLUSIONS

In horses with naturally occurring chronic lameness, acetaminophen at 30 mg/kg produced a transient improvement in subjective lameness and BMIS evaluation. Acetaminophen may not be effective as a monotherapy. Acetaminophen was safe following 21 days of 30 mg/kg PO every 12 h, with no evidence of clinically significant changes in clinicopathological analysis, hepatic biopsy or gastric ulceration scores.

Investigation of Serum Markers of Hepatic Fibrosis in Equids

Liver disease is common in equine practice, and treatment and prognosis are dependent on histopathologic examination of biopsies. Liver biopsy is invasive and expensive which restricts its use. Serum markers are used to predict hepatic fibrosis in humans. This study aimed to investigate the enhanced liver fibrosis (ELF) test, based on serum Hyaluronic Acid (HA), procollagen III N-terminal peptide (PIIINP), and tissue inhibitor of metalloproteinase 1 (TIMP-1) to detect hepatic fibrosis in equids. Four groups were included; two with increased serum concentrations of liver-derived enzymes and a liver biopsy (group H; 10 horses and ponies and group D; 10 donkeys) and two without any evidence of liver disease (group HC; 10 horses and ponies and group DC; 10 donkeys). All samples were analyzed for concentrations of HA, PIINP, and TIMP-1. Given the failure to detect TIMP-1 in most subjects, a novel eELF (equid ELF) score was calculated, based on HA and PIIINP. HA and PIIINP concentrations and the eELF score, were compared with determined hepatic fibrosis. HA, PIIINP, and eELF were significantly greater in horses and ponies with a histopathologic fibrosis score ≥ 2 compared with those < 2. A similar observation was found with donkeys for HA and eELF. A significant correlation was found between fibrosis score and HA, PIIINP, and eELF for horses and ponies, and between fibrosis score and HA and eELF in donkeys. Serum HA and the eELF score might be useful serum markers to predict and monitor hepatic fibrosis in horses, ponies, and donkeys.

Bile Acids, Direct Bilirubin and Gamma-glutamyltransferase as Prognostic Indicators for Horses with Liver Disease in the Eastern United States: 82 Cases (1997-2019)

Serum biochemistry results and presence of fibrosis on liver biopsies are frequently used as prognostic indicators in horses with liver dysfunction. The objective of this retrospective multicenter study was to determine if the magnitude of abnormal liver specific biochemical tests such as bile acids (BA), direct bilirubin and gamma-glutamyltransferase (GGT), or the presence of fibrosis reported on liver biopsies was associated with prognosis in horses with liver dysfunction. Eighty-two horses older than one year, examined at four referral hospitals in the eastern United States, with BA values greater than 30 µmol/L and having 6-months or more follow-up were included in the study. The association of the maximal BA, GGT and direct bilirubin values of each horse with survival was determined by logistic regression analysis. The presence or absence of fibrosis (non-quantitated) on a liver biopsy was compared between survivors and non-survivors by chi square test. The degree of increase in BA concentration and GGT activity was not related to outcome (OR 0.9999, 95% CI 0.9923 - 1.007, P = 0.97, and OR 1.0, 95% CI 0.9997 - 1.001, P = 0.31 respectively). Direct bilirubin concentration was positively associated with non-survival (OR 1.95, 95% CI 1.34-3.19, P = 0.0023). The presence of fibrosis was not associated with outcome (P = 0.37). These findings suggest that the magnitude of GGT and BA values or the mere presence of fibrosis on liver histopathology should not be used as prognostic indicators. In this study, direct bilirubin values were a better predictor of outcome.

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.

Pre-analytical stability of sorbitol dehydrogenase in equine heparinized plasma

Sorbitol dehydrogenase (SDH) activity is one of the most sensitive and specific markers for hepatocellular injury in horses, but its reported lability makes it impractical for use in many clinical settings. To date, stability of SDH in equine samples has only been evaluated in a limited number of studies in serum samples of horses with activities within reference intervals. The objective of the study was to determine pre-analytical stability of equine SDH activity in heparinized plasma stored at different temperatures for up to 72 h. Twenty client-owned horses admitted to a veterinary teaching hospital for any reason were included in the study. Blood samples collected in lithium-heparin tubes were immediately centrifuged and SDH activity was analyzed within 1 h of collection (T0). Aliquots of plasma were stored at room temperature, 4 °C and -20 °C and SDH activity was re-analyzed after 4 h (T4), 24 h (T24) and 72 h (T72). A significant difference from values measured at T0 was found for samples stored at room temperature (P = 0.022) and -20 °C (P < 0.001), but not at 4 °C. The activity of SDH was within ±20% of that measured at T0 for all samples under all temperature conditions stored for 4 h, and for all samples stored at 4 °C for 24 h. Bland-Altman plots revealed narrow limits of agreement at T4 for all storage temperatures and at T24 for samples stored at 4 °C. The mean absolute percentage error and 95th percentile of the absolute percentage error were lower for samples stored at 4 °C than those stored at room temperature or -20 °C. The activity of SDH has adequate stability for 4 h regardless of storage temperature and 24 h if stored at 4 °C across a wide range of values. Knowledge of the pre-analytical stability of SDH may permit its broader use in assessing hepatic disorders in horses.

Gastrointestinal Disorders of Donkeys and Mules

A review of common gastrointestinal disorders of donkeys and mules is presented. Clinically relevant aspects of donkey behavior, anatomy, and physiology are highlighted. Diagnosis, management, and treatment of conditions affecting the gastrointestinal tract from stomach to rectum, including liver and pancreas, are discussed.

Pharmacokinetics and safety of repeated oral dosing of acetaminophen in adult horses

BACKGROUND

There are no published studies on the pharmacokinetics of acetaminophen at the dosage used clinically (20 mg/kg), nor has the safety of multiple doses in horses been investigated.

OBJECTIVE

Define the pharmacokinetic parameters of oral acetaminophen at 20 mg/kg in adult horses as a single dose, and twice daily for 14 days to assess the safety of multiple dosing.

STUDY DESIGN

Pharmacokinetic study, multiple dose safety study.

METHODS

Eight healthy Thoroughbred geldings were given acetaminophen (20 mg/kg; 500 mg tablets) orally as a single dose followed by doses every 12 h for 14 days. Serial blood samples were collected for determination of plasma acetaminophen concentrations using high performance liquid chromatography with ultraviolet detection. Serum biochemical analysis, gastroscopy and liver biopsy were examined during the safety study.

RESULTS

Following a single dose, mean maximum concentration (C_max ) was 16.61 μg/mL at 1.35 h (T_max ), and drug concentration was below the lower limit of detection in most horses by 24 h. Elimination half-life (T_1/2 ) was 2.78 h. No significant accumulation was noted following multiple doses. Average C_max of acetaminophen following multiple oral dosing was 15.85 μg/mL, with a T_max of 0.99 h and T_1/2 of 4 h. Serum activities of sorbitol dehydrogenase were significantly decreased and total bilirubin concentrations were significantly increased following the last dose. No statistically significant changes were noted in gastroscopy scores.

MAIN LIMITATIONS

Only one dose level (20 mg/kg) was studied, sample size was small and only a single breed and sex was used, with no pretreatment liver biopsies.

CONCLUSION

This study described the pharmacokinetics of acetaminophen following single and multiple 20 mg/kg oral doses in adult horses and demonstrated the safety of acetaminophen with multiple oral dosing over 14 days. The summary is available in Portuguese - see Supporting information.

Metallothionein Expression in Horses With Chronic Liver Disease and Its Correlation With Ki-67 Immunoreactivity

Chronic liver disease is an important cause of illness in horses, and treatment is mainly supportive. Research into new treatment modalities for humans has shown promising data regarding metallothionein (MT), which has been shown to possess regenerative, antifibrotic, and anti-inflammatory properties. This study aimed to examine the relationship between hepatic MT expression and the histopathologic markers of hepatic inflammation, fibrosis and bile duct proliferation, as well as cellular regeneration in 77 selected cases of chronic liver disease in horses. We hypothesized that higher MT expression would be associated with increased heptocellular proliferation and decreased fibrosis, inflammation, and bile duct proliferation. Hepatocellular MT expression was evaluated with immunohistochemistry. Additionally, cellular regeneration was evaluated with immunohistochemistry for Ki-67, a protein expressed during all active stages of the cell cycle. The severity of inflammation and fibrosis was scored, and bile duct proliferation was assessed by counting bile duct profiles. MT expression was observed in 73 of 77 (94.8%) cases of chronically diseased livers. Ki-67 expression was seen in resident Kupffer cells ( n = 42, 54.6%), lymphocytes ( n = 39, 50.7%), bile duct epithelium ( n = 10, 13.0%), and hepatocytes ( n = 8, 10.4%). MT expression was significantly associated with Ki-67 staining in bile duct epithelium and Kupffer cells. Additionally, median MT expression was higher in cases containing lymphocytic infiltrates as compared with cases with no lymphocytic infiltrate ( P < .05). These findings are the first known report of MT expression within chronic equine hepatic disease.

Serum bile acid concentrations, histopathological features, and short-, and long-term survival in horses with hepatic disease

BACKGROUND

Serum bile acid concentrations (SBA) and a histopathological biopsy score [Equine Vet J 35 (2003) 534] are used prognostically in equine hepatic disease.

HYPOTHESIS

Histopathologic features and scores, but not SBA, differ between survivors and nonsurvivors and correlate with histopathologic evidence of hepatic inflammation and fibrosis.

ANIMALS

Retrospective study. Records (1999-2011) of horses with hepatic disease diagnosed by biopsy and with concurrent measurements of SBA.

METHODS

Retrospective cohort study. Biopsies were examined for inflammatory cell infiltration including type and distribution, fibrosis, irreversible cytopathology affecting hepatocytes, hemosiderin, or other pigment deposition and bile duct proliferation. SBA, histopathological findings and a histological score [Equine Vet J 35 (2003) 534] were compared between short- (survival to discharge) and long-term (>6 months) survivors and correlations between SBA and histopathological findings investigated.

RESULTS

Of 81 cases 90% survived short-term and 83% long-term. Short-term and long-term nonsurvival were associated with SBA (P = .009; P = .006), overall (P = .001; P = .002) and parenchymal (short-term only; P = .01) inflammation, portal and bridging fibrosis (all P < .001), apoptosis or single cell necrosis (P < .001; P = .008), hemosiderin deposition in hepatocytes (P = .011; P = .028), biliary (both P < .001), vascular (P = .003; P = .045) and endothelial (P < .001; P = .02) hyperplasia, nucleic changes (P = .004; P < .001) and the histopathological score (both P < .001). SBA were significantly and positively correlated with overall (P = .001), parenchymal (P < .001) and portal (P = .004) inflammation and portal (P = .036) and bridging (P = .002) fibrosis.

CONCLUSIONS AND CLINICAL IMPORTANCE

SBA, histopathological findings and scores differ between survivors and nonsurvivors. SBA concentrations are associated with inflammation and fibrosis suggesting interference with hepatic function. A histopathological score >2 and, less so, SBA >20 μmol/L are specific but not sensitive indicators of nonsurvival.

Blood parameters in female Zandi lambs as affected by liver biopsy methodology

The aim of the present study was to investigate the normal blood parameters of Iranian fat-tailed sheep (Zandi) and their changes due to rapid liver biopsy technique with a tru-cut biopsy needle. In ten ewe lambs, blood samples were collected from jugular vein and biopsy needle was inserted through the dorsal one third of the 11th intercostal space, on the right hand side of the lambs and liver specimen was collected. Physical examinations were performed on alternate days during the experiment. Blood collection was done on both before (day 1) and after (day 17) the biopsy. All animals were slaughtered at day 17. Values were compared using paired t test. While biopsy did not make any significant changes in mean values of body temperature, heart rate, respiratory rate, PCV, WBC, neutrophil, lymphocyte, eosinophil, monocyte, total serum protein, AST, ALT, and serum calcium (p > 0.05), it made a significant difference on the values of ALP (p < 0.001), serum inorganic phosphate (p = 0.035), and magnesium (p = 0.013). Necropsy examination revealed the points of hitting the biopsy needles on the diaphragmatic surface of the livers, surrounded by a zone of intense hyperemia. Peritoneal adhesions accompanying with typical strands of fibrous connective tissue between diaphragmatic surface of the liver and adjacent abdominal wall were found in two cases.

An evaluation of diagnostic data in comparison to the results of liver biopsies in mature horses

REASONS FOR PERFORMING STUDY

The diagnostic value of several investigative procedures commonly used during the evaluation of suspected equine hepatopathy cases has not been specifically quantified in previous studies.

HYPOTHESIS

No noninvasive procedures would clearly discriminate between horses with and without significant liver disease.

METHODS

Histopathology of biopsy samples was used as the 'gold standard' technique for definitive diagnosis of the presence or absence of significant liver disease. Clinical, ultrasonographic and clinicopathological data obtained during the investigation of 82 suspected cases of hepatopathy in mature horses were compared with the results of subsequent biopsy in order to quantify the diagnostic value of each test.

RESULTS

Of the 82 cases, 61 were confirmed to have significant liver disease and 21 were not. Only serum concentrations of gamma-glutamyltransferase (gammaGT), globulins and alkaline phosphatase (AP) were found to be significantly different between the 2 groups of horses. Clinical and ultrasonographic abnormalities were found, when present, to be good indicators of the presence of liver disease. Certain single serum biochemical tests and combinations thereof were found to have high values for sensitivity (SN), specificity (SP), positive predictive value (PPV) and/or negative predictive value (NPV), but none showed high values for all 4 parameters leading to important limitations in their practical diagnostic application. Of all serum biochemical tests studied, the PPVs of only gammaGT and globulins could be clearly improved by considering especially high positive results.

CONCLUSIONS

The single positive test results of greatest diagnostic value were presence of hepatic encephalopathy (HE), increased gammaGT, hyperglobulinaemia, hypoalbuminaemia, increased AP, increased total bile acids (TBA) and increased total bilirubin (TBil). Increased aspartate aminotransferase (AST) and increased glutamate dehydrogenase (GLDH) were also of good diagnostic value, but only when used in combination with the above tests. However, no single, combination or sequential test was able to discriminate fully between horses with and without biopsy-confirmed liver disease and reliance on the use of noninvasive tests for the prediction of the presence or absence of significant liver disease may lead to frequent diagnostic errors. Although certain positive results did reliably predict the presence of liver disease, negative test results were invariably poor predictors of the absence of liver disease.

POTENTIAL RELEVANCE

Application of the findings in this study may not be directly applicable to other case populations. However, the results may help clinicians with their selection and interpretation of appropriate test results in cases of suspected liver disease.

Retrospective analysis of historical, clinical, ultrasonographic, serum biochemical and haematological data in prognostic evaluation of equine liver disease

REASONS FOR PERFORMING STUDY

Results of noninvasive tests of liver disease do not always correlate with the degree of hepatic disease nor outcome of the case.

OBJECTIVE

To investigate the prognostic value of data collected using noninvasive tests during the investigation of cases of suspected liver disease in mature horses.

HYPOTHESIS

Much of the data gathered during the investigation of suspected hepatopathy cases offers little prognostic guidance and interpretation of such data can be misleading.

METHODS

The results from a range of common and noninvasive diagnostic techniques applied in 116 mature horses with suspected liver disease, were assessed for their ability to predict survival within a 6 month period.

RESULTS

A significantly poorer prognosis was found in association with clinical signs suggestive of liver disease, presence of hepatic encephalopathy, ultrasonographic abnormalities, increased serum globulins, increased total bile acids (TBA), increased alkaline phosphatase (AP), increased gamma-glutamyl transferase (gammaGT), erythrocytosis, leucocytosis, low serum albumin and low serum urea. Additional significant novel findings of interest included an association between increased plasma fibrinogen and low serum creatinine concentrations with nonsurvival in cases of liver disease, an association between raised serum concentrations of AP and gammaGT with biliary hyperplasia and also an association between hepatic fibrosis, haemosiderosis and biliary hyperplasia with ultrasonographically detected hepatic abnormalities.

CONCLUSIONS

The most useful noninvasive prognostic test in cases of suspected liver disease in mature horses is the severity of clinical signs. Other data may be of some limited prognostic value.

POTENTIAL RELEVANCE

Application of the findings in this study may not be directly applicable to other case populations. However, the findings should at least be considered when prognosis is based on similar criteria.