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Topic:Liver Function
Liver function in horses encompasses a range of physiological processes essential for maintaining homeostasis. The liver is responsible for various metabolic, detoxification, and synthetic activities, including the metabolism of carbohydrates, proteins, and fats, as well as the detoxification of endogenous and exogenous substances. It also synthesizes proteins such as albumin and clotting factors, and produces bile necessary for digestion. Liver function can be assessed through biochemical tests that measure enzyme activities and metabolite levels in the blood. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, assessment, and clinical implications of liver function in equine health.
Influence of fat content on physico-chemical and oxidative stability of foal liver pâté. The effect of fat content on physico-chemical properties and lipid and protein stability of foal liver pâté was studied. For this purpose, two batches (10 units per batch) of foal liver pâté with different pork back fat content [30% (30F) and 40% (40F)] were manufactured. 30F foal liver pâté was darker (lower L* value, P>0.05), redder (higher a*, P<0.001) and harder (higher hardness value; P<0.001) compared to those with 40F. Fat level was closely related to the calorific value of foal liver pâté, being more calorific in those with higher fat contents (352 kcal/100 g; P<0.0...
Acute encephalopathy with concurrent respiratory and metabolic disturbances in first known parenteral human administration of flunixin meglumine and acepromazine maleate. Flunexin is a nonsteroidal anti-inflammatory drug approved for veterinary use in horses and cattle. Acepromazine is a phenothiazine derivative used in horses, dogs, and cats. Human exposure to these substances is rare. Methods: We report a case of a human injection of two equine medications, flunixin and acepromazine, which resulted in altered mental status, respiratory alkalosis, gastrointestinal bleeding, and elevation of liver transaminases in a 43-year-old woman who worked as a horse trainer. The patient intentionally self-injected these medications and subsequently presented to the Emerge...
Indigofera spicata (creeping indigo) poisoning of three ponies. Three ponies continuously grazed a pasture containing an estimated 24% Indigofera spicata (wet weight basis) for 4-6 weeks in April and May 2004. They developed ataxia, paresis, depression, muscle fasciculations, dysphagia, ptyalism and halitosis. Two also developed corneal opacity. One pony recovered with supportive treatment, but the other two were euthanased and necropsied. Neuropathology was not present in either case, but both livers had periacinar and periportal lymphocytic infiltrations and hydropic degeneration of mid-zonal hepatocytes, with mild to moderate periacinar necrosis also ev...
Fructokinase, Fructans, Intestinal Permeability, and Metabolic Syndrome: An Equine Connection? Fructose is a simple sugar present in honey and fruit, but can also exist as a polymer (fructans) in pasture grasses. Mammals are unable to metabolize fructans, but certain gram positive bacteria contain fructanases and can convert fructans to fructose in the gut. Recent studies suggest that fructose generated from bacteria, or directly obtained from the diet, can induce both increased intestinal permeability and features of metabolic syndrome, especially the development of insulin resistance. The development of insulin resistance is driven in part by the metabolism of fructose by fructokinase...
Fumonisin B(1): a neurotoxic mycotoxin. Fumonisin B(1) (FB(1)) is a mycotoxin produced by Fusarium spp. moulds that contaminate crop, predominantly maize, all around the world. More than 15 types of fumonisins have been indentified so far, but FB(1) is the most abundant and toxicologically the most significant one. FB(1) has a wide range of toxic effects, depending on animal species. In horses FB(1) causes equine leukoencephalomalacia (ELEM), in pigs pulmonary oedema and in experimental rodents nephrotoxicity and hepatotoxicity. In humans exposure to FB(1) is linked with higher incidence of primary liver cancer and oesophageal cance...
Metabolic studies of formestane in horses. Formestane (4-hydroxyandrost-4-ene-3,17-dione) is an irreversible steroidal aromatase inhibitor with reported abuse in human sports. In 2011, our laboratory identified the presence of formestane in a horse urine sample from an overseas jurisdiction. This was the first reported case of formestane in a racehorse. The metabolism of formestane in humans has been reported previously; however, little is known about its metabolic fate in horses. This paper describes the in vitro and in vivo metabolic studies of formestane in horses, with the objective of identifying the target metabolite with the lon...
[The prevalence of liver trematodes in equines in different cities of Turkey]. This study was carried out between March 2004- April 2005 to determine the prevalance of liver trematode infections of equids in different cities of Turkey. Methods: A total of 117 equids (72 horses, 39 donkeys and 6 mules) in Ankara were examined for liver parasites after the slaugthering process. On the other hand, a total of 620 feces of horses in Bursa, Gemlik, Malatya, Eskişehir and Ankara provinces were detected for determining liver trematodes in live equines. The fecal samples of horses were examined for liver fluke infection by Benedect's sedimentation methods. Results: Of these 117 ...
Liver lobe torsion in six horses. 6 horses were determined to have torsion of a liver lobe at 4 referral institutions over a 21-year period. Results: Clinical findings were nonspecific but often included signs of marked inflammation. Two of the 6 horses were examined because of colic, and 2 were assessed because of peritonitis that failed to respond to treatment; the remaining 2 horses were examined because of nonspecific clinical signs that included inappetence, lethargy, and weight loss. The results of laboratory tests were widely variable, and values for liver enzyme activities were typically within reference limits or only...
Congenital ascites due to hepatoblastoma with extensive peritoneal implantation metastases in a premature equine fetus. A premature dead equine fetus with excessive fluctuating distension of the abdomen was delivered by extraction. Post-mortem examination revealed ascites and a solitary, irregular, bulging, multinodular, firm, yellow mass of 25 cm in diameter in the right liver lobe. Extensive peritoneal implantation metastases were present. The masses were composed of polygonal embryonal cells arranged in sheets and nests. Based on the immunohistochemical expression of Ki67, low molecular weight cytokeratin and alpha-1 fetoprotein, a diagnosis of hepatoblastoma with peritoneal implantation metastases was made....
Hepatoencephalopathy syndrome due to Cassia occidentalis (Leguminosae, Caesalpinioideae) seed ingestion in horses. Cassia occidentalis is a bush from the Leguminosae family, subfamily Caesalpinoideae, and is a toxic plant of veterinary interest due to the occasional contamination of animal rations. This report describes the clinical and histopathological findings of an outbreak of C. occidentalis poisoning in horses. Twenty mares were poisoned after consuming ground corn contaminated with 8% of C. occidentalis seeds. Of the 20 animals affected, 12 died: 8 mares were found dead, 2 died 6 h after the onset of clinical signs compatible with hepatic encephalopathy and the 2 other animals were subjected to euth...
Copper-associated hepatic cirrhosis in a Friesian horse. A 6-year-old Friesian stallion was examined because of signs of exercise intolerance, stiff gait and symmetrical hind weakness, and increased serum liver enzymes. On presentation, the horse showed muscle atrophy of the hindquarters. Neurological investigation showed no abnormalities. Laboratory findings revealed a prolonged prothrombin time and increased levels of alkaline phosphatase (AF), aspartate aminotransferase (ASAT), gamma-glutamyl-transferase (GGT), lactate dehydrogenase (LDH), and bile acids. Histological evaluation of the liver revealed severe cirrhosis and intracytoplasmic greyish ...
Peripheral primitive neuroectodermal tumor in a two-year-old paint horse. A 2-year-old gelding presented with a history of lethargy and anorexia. Physical examination revealed pleural and abdominal fluid, as well as several masses in the scrotum. The horse became acutely dyspneic despite 7 days of supportive care. Because of the poor prognosis, the owners elected euthanasia. Gross necropsy findings included multiple masses in the scrotum and inguinal canals and along the dorsal peritoneal cavity. The neoplasm infiltrated the kidneys, liver, spleen, mesenteric lymph nodes, mesentery, and abdominal surface of the diaphragm. Histologically, the neoplasm is composed of ...
Mycobacterium DNA detection in liver and skin of a horse with generalized sarcoidosis. Sarcoidosis is a rare equine skin disease characterized primarily by an exfoliative and granulomatous dermatitis but also presenting granulomatous inflammation of multiple systems. The current report presents the clinical and histopathological findings of sarcoidosis in a 16-year-old American Quarter Horse gelding with nested polymerase chain reaction Mycobacterium spp. DNA detection within hepatic and skin samples. Mycobacterium spp. may play a role in the pathogenesis of equine sarcoidosis as has been proposed for human sarcoidosis.
Supplementation of Ascorbic Acid in Weanling Horses Following Prolonged Transportation. Though horses synthesize ascorbic acid in their liver in amounts that meet their needs under normal circumstances, prolonged stress results in low plasma concentrations due to enhanced utilization and renal excretion and can reduce immune function. It was hypothesized that plasma ascorbic acid could be maintained in weanling horses by oral supplementation following prolonged transportation. Weanlings were supplemented with no ascorbic acid (Tx 0: n = 4), 5 grams ascorbic acid twice daily for 5 days (Tx 1: n = 4) or for 10 days (Tx 2: n = 4) following >50 hours of transportation. Supplementa...
Long term intensive exercise training leads to a higher plasma malate/lactate dehydrogenase (M/L) ratio and increased level of lipid mobilization in horses. Continuous high intensity training may induce alterations to enzyme activities related to glucose and lipid metabolism in horses. In our study, five Thoroughbred race horses (3 male and 2 female, avg age=5 yrs old) were compared against five riding horses (1 male, 1 female, 3 gelding, avg age=13 yrs old) in terms of energy metabolism, by examining plasma malate (MDH) and lactate (LDH) dehydrogenase activities and M/L ratio. MDH is involved in NADH and ATP generation, whereas LDH can convert NADH back into NAD(+) for ATP generation. An increase in plasma M/L ratio can reflect heightened energy ...
Differential gene expression of CYP3A isoforms in equine liver and intestines. Recently, seven CYP3A isoforms - CYP3A89, CYP3A93, CYP3A94, CYP3A95, CYP3A96, CYP3A97 and CYP129 - have been isolated from the horse genome. In this study, we have examined the hepatic and intestinal gene expression of these CYP3A isoforms using TaqMan probes. We have also studied the enzyme activity using luciferin-isopropyl acetal (LIPA) as a substrate. The results show a differential gene expression of the CYP3A isoforms in the liver and intestines in horses. In the liver, CYP3A89, CYP3A94, CYP3A96 and CYP3A97 were highly expressed, while in the intestine there were only two dominating isof...
Natural Heterobilharzia americana infection in horses in Texas. The schistosome Heterobilharzia americana infects dogs, raccoons, and other mammals in the southeastern United States. Migration of eggs into the liver results in parasitic granulomas with varying degrees of fibrosis and inflammation. Recently, hepatic parasitic granulomas in horses were shown to be caused by H. americana infection. In the present study, samples of liver from 11 of 12 horses with hepatic granulomas identified at necropsy (n = 11) or surgical biopsy (n = 1) were used for DNA extraction, polymerase chain reaction amplification and sequencing using primers specific for a portion ...
Lactate production and measurement in critically ill horses. Blood lactate concentration can be easily measured by practitioners using inexpensive point-of-care meters. Anaerobic tissue metabolism resulting from inadequate oxygen delivery (DO2) is the most important cause of an increase in blood lactate concentration in equine patients. However,hyperlactatemia also occurs under conditions of apparently adequate DO2, usually in association with sepsis and an intense inflammatory reaction. Numerous mechanisms have been proposed for aerobic hyperlactatemia, including increased Na+/K+-ATPase activity in response to inflammatory mediators; inhibition of pyru...
[Pyrrolizidine alkaloids and seneciosis in farm animals. Part 2: clinical signs, species-specific sensitivity, food residues, feed contamination, limit values]. At the forefront of pyrrolizidine alkaloid (PA) poisoning is the chronic ingestion of contaminated hay, which causes liver damage resulting in an ongoing fatal liver cirrhosis or in the veno-occlusive disease in liver or lung, respectively. The symptomatology of PA-poisoning is not identical for all animal species, and also includes central nervous symptoms. In affected horses significantly elevated levels of hepatogenic serum enzymes and an increase of the retention time for bromosulfophthalein indicates the fatal outcome of the intoxication. Chronic seneciosis of horses is incurable. Rabbits...
Inhibition of cytochrome P450 enzymes involved in ketamine metabolism by use of liver microsomes and specific cytochrome P450 enzymes from horses, dogs, and humans. To identify and characterize cytochrome P450 enzymes (CYPs) responsible for the metabolism of racemic ketamine in 3 mammalian species in vitro by use of chemical inhibitors and antibodies. Methods: Human, canine, and equine liver microsomes and human single CYP3A4 and CYP2C9 and their canine orthologs. Methods: Chemical inhibitors selective for human CYP enzymes and anti-CYP antibodies were incubated with racemic ketamine and liver microsomes or specific CYPs. Ketamine N-demethylation to norketamine was determined via enantioselective capillary electrophoresis. Results: The general CYP inhibit...
Development and validation of a method for Cd, Pb and As analysis in bovine, equine and poultry liver by inductively coupled plasma mass spectrometry. A method for the determination of As, Cd and Pb in bovine, equine and poultry liver by ICP-MS was developed and validated. Samples were digested in a microwave oven using a 10% HNO(3) solution. A set of experiments was made according to a central composite design (CCD) for optimisation of the plasma argon flow, nebuliser argon flow and radiofrequency power applied to the plasma. During the validation, Rh and Ru were evaluated as internal standards and, after validation, the best was Rh for Pb and Cd analysis, but for As better results were obtained without an internal standard. The method allo...
Heterobilharzia americana infection as a cause of hepatic parasitic granulomas in a horse. CASE DESCRIPTION-A 22-year-old American Paint Horse gelding from the Gulf Coast region of Texas was evaluated for regrowth of a perirectal squamous cell carcinoma that had been surgically removed 11 months previously. CLINICAL FINDINGS-A necrotic and ulcerated mass was present below the anus. The horse had paraphimosis and was having difficulty with urination. Histologic examination of the mass revealed that it was squamous cell carcinoma, and the horse was euthanized because of the unlikelihood that the mass could be adequately resected and its close proximity to the urethra. OUTCOME-At necro...
Crotalaria medicaginea associated with horse deaths in northern Australia: new pyrrolizidine alkaloids. Crotalaria medicaginea has been implicated in horse poisoning in grazing regions of central-west Queensland, which resulted in the deaths of more than 35 horses from hepatotoxicosis in 2010. Liver pathology was suggestive of pyrrolizidine alkaloidosis, and we report here the isolation of two previously uncharacterized pyrrolizidine alkaloids from C. medicaginea plant specimens collected from pastures where the horses died. The first alkaloid was shown by mass spectometric and NMR analyses to be 1β,2β-epoxy-7β-hydroxy-1α-methoxymethyl-8α-pyrrolizidine, which, like other alkaloids previousl...
Clenbuterol toxicosis in three Quarter Horse racehorses after administration of a compounded product. 3 Quarter Horse racehorses were examined for suspected clenbuterol overdose 12 to 24 hours after administration by mouth of a compounded clenbuterol product. Results: All horses developed sinus tachycardia, muscle tremors, hyperhidrosis, and colic. Abnormalities on serum biochemical analysis included hyperglycemia, azotemia, and high creatine kinase activity. The presence of clenbuterol in the serum of all 3 horses and in the product administered was confirmed and quantified by use of liquid chromatography-electrospray tandem mass spectrometry. Results: Propranolol (0.01 mg/kg [0.005 mg/lb], I...
Lipopolysaccharide infusion up-regulates hepcidin mRNA expression in equine liver. Hepcidin has been found to be the key regulator of iron metabolism that leads to hypoferremia during inflammation. Recent work has shown that equine hepcidin is predominantly expressed in the liver of horses. In this study, hepcidin gene expression was determined in the liver and bone marrow of six healthy horses after iv infusion of Escherichia coli O55:B5 LPS. The IL-6 gene expression was also determined in liver and bone marrow samples. Clinical and laboratory evaluations were measured at multiple time points between 0 and 240 h post-LPS infusion (PI). Liver and bone marrow biopsies were ...
In vitro metabolism of tiletamine, zolazepam and nonbenzodiazepine sedatives: Identification of target metabolites for equine doping control. Within horseracing, the detection of prohibited substance doping often requires urine analysis; hence, it is necessary to understand the metabolism of the drugs in question. Here, the previously unknown equine metabolism of eight sedatives is reported in order to provide information on target metabolites for use in doping control. Phase I metabolite information was provided by incubation with equine liver S9 fraction. In vitro techniques were chosen in order to reduce the ethical and financial issues surrounding the study of so many compounds, none of which are licensed for use in horses in th...
Clinical implications of high liver enzyme activities in hospitalized neonatal foals. To determine whether high liver enzyme activities were negatively associated with outcome in sick neonatal foals as compared with foals that did not have high liver enzyme activities. Methods: Retrospective case-control study. Methods: 147 foals < 30 days old with high γ-glutamyltransferase activity, high sorbitol dehydrogenase activity, or both (case foals) and 263 foals < 30 days old with γ-glutamyltransferase and sorbitol dehydrogenase activities within reference limits (control foals). Methods: Medical records were reviewed for information on signalment, physical examination findin...
Starry sky hepatic ultrasonographic pattern in horses. The starry sky hepatic pattern is an unusual ultrasonographic appearance of equine liver characterized by numerous small, hyperechoic foci, some of which cast an acoustic shadow, distributed randomly throughout the hepatic parenchyma. Our objectives were to describe the signalment, clinical signs, clinicopathological findings, primary disease process, and ultrasonographic findings of horses with this ultrasonographic pattern, as well as determine the associated gross and histologic changes. The starry sky pattern was identified in 18 adult horses of mixed gender and breed. The horses had vario...
Serum amyloid A is expressed in histologically normal tissues from horses and cattle. mRNA expression of the acute phase protein serum amyloid A (SAA) in histologically normal tissues derived from horses (n=13) and cattle (n=4) was investigated by quantitative reverse-transcriptase real-time polymerase-chain reaction. As expected, high constitutive SAA mRNA expression was demonstrated in hepatic tissue in both species. In horses, moderate (>1% of the hepatic expression) SAA mRNA expression was detected in the lung, mammary gland, pancreas, synovial membrane, thymus, thyroid gland and uterus. Other equine tissues and organs sampled included adipose tissue, adrenal gland, aort...
