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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.
[Antithrombin III determination in horses. Reference values and acquired antithrombin III deficiency]. Antithrombin III (AT III) determinations were done in healthy and sick horses using the chromogenic substrate Chromozym TH. Reference values for adult horses at 25 degrees C were 18-25 IU AT III per ml plasma and 84-118% AT III activity of normal horse plasma, respectively. Precision and accuracy were good (intra assay coefficient of variation less than 2%, accuracy 10%). Surgical operations on healthy horses led to a biphasic decrease in AT III activity touching the lower border of the reference values on the second postoperative day. Other reasons for acquired AT III deficiencies included di...
Antipyrine and lidocaine are cleared faster in horses than in humans: acetaminophen may be handled similarly. The following studies were designed to evaluate plasma elimination kinetics of intravenously administered antipyrine, acetaminophen and lidocaine among 9 healthy adult horses and 9 healthy drug-free humans (3 each per drug group), in order to compare potential species differences in drug-metabolizing ability. Acetaminophen is largely biotransformed in humans by hepatic glucuronide and sulfate conjugation, whereas both antipyrine and lidocaine are oxidized by hepatic microsomal mixed-function oxidases. Thus, plasma clearances of these drugs are thought to reflect differences in hepatic oxidativ...
Lipids in the laminated layer of liver, lung and daughter hydatid cysts of equine Echinococcus granulosus (Cestoda). Lipids extracted from the laminated layers of horse liver and lung hydatids, including a daughter liver cyst, were analysed using TLC. No differences in lipid composition was detected in 11 liver cysts, whether from the same or different livers, and di- and triacylglycerols, cholesterol, wax and steryl esters, oleic acid, sphingomyelin, phosphatidyl choline, phosphatidyl inositol and ceramide hexosides were detected. The daughter cyst differed from its "parent" cyst in lacking diacylglycerols and wax and steryl esters. The lung cyst differed from the liver cysts in that cholesterol, wax and st...
Antithrombin III (ATIII) activity in plasmas from normal and diseased horses, and in normal canine, bovine and human plasmas. Plasma Antithrombin III (ATIII) activity was quantitated in 24 clinically normal Standardbred/Thoroughbred horses using a clotting time technique. ATIII activity ranged from 80 to 106% of the pooled reference standard plasma, with a mean of 94%. Horses presenting with impaction or spasmotic colic (n=17) had normal plasma ATIII activity, while 15 horses presenting with acute diarrhea/colitis had significantly lower plasma ATIII activity with a mean of only 74% of the reference plasma. Seven horses presenting with liver disease had significantly higher plasma ATIII activity with a range of 127 t...
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...
The trans-cis isomerization of trans-4′-(2-hydroxy-3,5-dibromo-benzylamino)cyclohexanol in vivo and in vitro in different species. Isomerization of trans-4'-(2-hydroxy-3,5-dibromo-benzylamino)cyclohexanol (HDBC) in vivo has been investigated in horse, cow, dog, rat and man. Following oral administration of 4'-trans-HDBC to the horse, a very efficient first-pass trans-cis isomerization was observed. In the urine of the horse and cow, 40% and 29% respectively of the conjugated alcohols consisted of the 4'-cis isomer. Isomerization in rat and dog took place only to a small extent, and in man no 4'-cis isomer was detected. Oxidation of HDBC to the corresponding ketone, at pH 9.0, was highest with horse- and rat-liver 10 000 g...
Characterization of amyloid protein AA and its serum precursor SAA in the horse. Amyloid was extracted from the liver of a horse that had developed amyloidosis after being used for several years for the production of antibodies to bacterial antigens. The amyloid fibrils were shown to be of the AA type. Two AA proteins with molecular weights of 9000 and 11,000 and with identical partial N-terminal amino acid sequences were identified. Marked structural homology with AA from other species including man was seen, although clear species-related antigenic specificity was observed. SAA isolated from an acute phase (septic abortion) horse serum was identical to AA with respect to...
Chronic granulomatous bowel disease in three sibling horses. Chronic granulomatous bowel disease was diagnosed in 3 sibling Standardbred horses. Clinical signs included weight loss, loose feces, and decreased appetite in the terminal stage of the disease. Abnormal laboratory findings included hypoproteinemia and low xylose absorption. Necropsy revealed granulomatous inflammation of the intestines, mesenteric lymph nodes, and liver. Eosinophilic infiltration of the granulomatous lesions was a prominent finding in one horse. A causative agent was not detected by special histochemical staining or bacteriologic culturing.
Copper, zinc and manganese concentrations in equine liver, kidney and plasma. Five groups of horses were fed different diets of known trace mineral concentration for a minimum of six months. Copper (Cu), zinc (Zn) and manganese (Mn) concentrations were measured in livers of 125 yearling horses and kidneys of 81 yearling horses as an assessment of trace mineral status. Plasma Cu and Zn determinations were made for all horses.Mean hepatic Cu concentrations of horses fed diets containing 6.9 to 15.2 mg Cu/kg dry matter (DM) feed were 0.27 to 0.33 mumol/g DM tissue. Plasma Cu concentrations ranged between 22.8 to 28.3 mumol/L. There was no simple mathematical relationship b...
Corynebacterium equi Infections in Horses, 1958-1984: A Review of 131 Cases. Of 131 cases of Corynebacterium equi infection in horses submitted for necropsy to the Ontario Veterinary College or Veterinary Laboratory Services, OMAF, Guelph, Ontario from 1958 to 1984, 115 were diagnosed as suppurative pneumonia, and of these 55 had associated ulcerative enterocolitis. Only five animals had intestinal involvement without pulmonary lesions. The remaining 11 cases included arthritis/cellulitis, skin abscesses and submandibular lymphadenitis. While the lung, intestine and associated lymph nodes yielded C. equi most frequently, in 21% of cases C. equi was also cultured from p...
Diseases of the abdomen. Because the abdomen of the adult horse is too thick to obtain good-quality radiographs, diagnostic ultrasound is a particularly valuable imaging modality in the diagnosis of abdominal disease. The size, shape, position, and texture of the liver, spleen, kidneys, urinary bladder, gravid uterus, and gut wall can be determined by scanning the abdominal surface. The presence or absence of abdominal fluid can be determined efficiently. Gut motility as well as ileus secondary to peritonitis or obstruction can be assessed. Suspected adhesions of the bowel can often be documented, and primary or secon...
Diseases of the liver. The ability to image the liver in horses can add valuable diagnostic information or aid in guided biopsy procedures. Anytime the size, shape, position, and texture of the liver can be determined, additional information about the horse's condition is gained. Conditions such as cholelithiasis, neoplasia, fibrosis can be detected ultrasonographically.
Ultrasound-guided renal and hepatic biopsy techniques. Diagnostic ultrasound is an easy, accurate method of locating both kidneys and liver in the horse. Good contact between the transducer and body wall is essential for clear, precise images. The greatest limitation to ultrasonic organ localization and biopsy guidance is the inability of ultrasound to transmit through gas-filled structures and bone. These structures act as barriers to sound-beam penetration and prevent visualization of soft-tissue structures deep to them. Organ parenchyma can be evaluated with ultrasonography. Focal and/or diffuse lesions can alter the normal parenchymal pattern ...
[Development of autoimmune reactions in horses serving to produce antitetanus serum]. The hyperimmunization of horses with large doses of tetanus toxoid is accompanied by an increase in the levels of both specific antitoxic antibodies and autoantibodies to the tissue antigens of the liver, the spleen, the heart. The reverse relationship between the level of autoantibodies and the titer of antitoxin has been established. The authors suggest that the synthesis of autoantibodies is stimulated by the presence of antigen-antibody immune complexes in the circulating blood, as well as by the action of exo- and endopolyclonal stimulators.
Vitamin E requirements of adult Standardbred horses evaluated by tissue depletion and repletion. Vitamin E requirements of adult Standardbred horses were evaluated by tissue depletion and repletion. All the horses used in the study were given the same basal feed low in vitamin E during the eight months of the experiment. After an initial depletion period of two-and-a-half months the horses were divided into groups according to the amounts of DL alpha-tocopheryl acetate given (0 mg, control; 200, 600, 1800 and 5400 mg, respectively) as a daily oral supplement. The supplement study was followed by a second depletion period. Total vitamin E content and individual natural tocopherol isomers a...
Strongylus equinus: development and pathological effects in the equine host. The development and pathological effects of Strongylus equinus were studied in 17 pony foals and one horse foal raised in isolation and examined at necropsy from seven days to 40 wk postinfection (PI). Following inoculation of 15000 +/- 6% or 16000 +/- 6% infective larvae by stomach tube foals were monitored for clinical signs and selected blood changes. Larvae penetrated the wall of the ileum, cecum and colon. The molt to the fourth stage occurred mostly in the wall of the ventral colon before 2 wk PI and larvae attained the liver mainly via the peritoneal cavity as early as eight days PI and...
Haemolytic crisis associated with ragwort poisoning and rail chewing in two thoroughbred fillies. Events leading to the deaths of two fillies at pasture are described. Pasture hay containing the flowering stages of Senecio jacobea (ragwort) had been fed three to four months earlier. Paddocks were subdivided with posts and rails treated with copper chrome arsenate. Six horses on the property chewed rails spasmodically. Both fillies presented with haemoglobinurea. Values in liver of 83 mg Cu kg and kidney 35 mg Cu kg wet weight and serum 1.4 mg Cu/l together with histophathology of seneciosis support a sequence of ragwort poisoning followed by copper accumulation in liver and kidney terminat...
Choledocholithotripsy in a mare. Obstructive choledocholithiasis in a 12-year-old mare was corrected surgically by choledocholithotripsy. The mare had a history of chronic weight loss, intermittent fever, partial anorexia, jaundice, recurrent abdominal pain, and an abdominal mass palpable per rectum. Values for alkaline phosphatase, bilirubin, gamma-glutamyl transferase, sorbitol dehydrogenase, and bromsulpthalein half-life were increased and bilirubinuria was evident before surgery. Two liver biopsies revealed periportal and portal fibrosis, bile duct proliferation, cholestasis, and variable amounts of hepatocellular necrosi...
Suspected Tyzzer’s disease in two foals. Tyzzer's disease was diagnosed histologically in two foals, a 4-week-old Thoroughbred cross and a 6-week-old Arabian foal. Clinically both foals were in good health prior to a short illness lasting only a few hours. The liver lesions in both foals were characterized microscopically by multiple foci of necrosis. Variable numbers of elongated slender intracytoplasmic bacilli resembling Bacillus piliformis were demonstrated within hepatocytes bordering the necrotic foci.
[Extrahepatic cholestasis due to pancreas fibrosis in a trotter]. A trotter stallion showing symptoms of emaciation was suspected of disease of the liver associated with cholestasis in view of clinical symptoms (poor appetite, sluggishness, jaundice and oedema) and the results of examination of the blood (increased concentrations of gamma-glutamyl, transpeptidase, sorbitol dehydrogenase, alkaline phosphatase, aspartate aminotransferase and markedly increased conjugated bilirubin). A specimen removed at biopsy of the liver revealed the presence of portal fibrosis and severe cholestasis. At autopsy, it was found that very extensive fibrosis of the pancreas (pr...
Microquantitative determination of the distribution patterns of alcohol dehydrogenase activity in the liver of rat, guinea-pig and horse. Microquantitative measurements of ADH-activity were carried out on the livers of male and female rats, guinea-pigs and horses (two geldings and a mare). Lyophilized cryostat sections of liver parenchyma were microdissected the whole way along the sinusoidal length from the terminal afferent vessels to the terminal efferent venule. ADH activity in samples of about 50-150 ng was measured in a microbiochemical assay using the oil-well technique without enzymatic cycling, by direct luminometric determination of NADH. On the basis of the single measurements, mean values of total hepatic ADH activit...
Cynoglossum officinale (hound’s-tongue)–a cause of pyrrolizidine alkaloid poisoning in horses. The death of 10 horses was attributed to feeding dried grass hay containing hound's-tongue, Cynoglossum officinale. Affected horses developed weight loss, icterus, photosensitization, and hepatic encephalopathy. Histologic examination of the liver of 3 of the horses revealed megalocytosis, biliary hyperplasia, and fibrosis characteristic of pyrrolizidine alkaloid poisoning. Hound's-tongue was found to contain large quantities (0.6% to 2.1%, dry matter basis) of toxic pyrrolizidine alkaloids, which, when fed to a pony for 20 days, caused liver fibrosis and biliary hyperplasia.
Equine hydatidosis: a new record for New Zealand. Cysts found in the liver of a horse which had never been out of New Zealand were used to infect two dogs which were slaughtered 35 days after infection. Large numbers of Echinococcus granulosus were recovered. These cestodes were compared with mature dog-sheep cestodes, using light and scanning electron microscopy and identified as the dog-horse strain of E.granulosus.
Drug disposition in the neonatal animal, with particular reference to the foal. Differences between neonatal and adult animals in their response to drugs can usually be attributed to altered disposition (ie, distribution, metabolism and excretion) processes during the neonatal period. These alterations affect the plasma concentrations as well as the concentrations of drug attained at the receptor site. Some characteristics of the neonatal period include greater absorption from the gastrointestinal tract, lower extent of plasma protein binding, increased apparent volume of distribution of drugs that distribute in extracellular fluid or total body water, increased permeabil...
Pyloric stenosis in a yearling with an incidental finding of Capillaria hepatica in the liver. PYLORIC stenosis occurs commonly in man and the dog but only rarely in the horse and cat. Two reports of pyloric stenosis in the horse have been published, both of these occurring in foals of less than two months of age (Barth, Barber and Mackenzie 1980; Crowhurst, Simpson, McEnery and Greenwood 1975). Surgery on the pylorus performed under general anaesthesia was successful in both cases. This report describes a case of pyloric stenosis in a Thoroughbred yearling.
