Carprofen-induced oxidative stress in mitochondria of the colonic mucosa of the dog.

The purpose of the study was to compare the conductance and mannitol permeability of canine colonic mucosa in response to carprofen or 2,4-dinitrophenol (DNP) with or without tempol pretreatment. Ten colonic mucosa sections per dog were mounted in Ussing chambers. Treatments were done in duplicate. Mucosa was exposed to carprofen (200 µg/mL) or DNP (0.25 mM), both with and without tempol (1 mM) pretreatment. Conductance was calculated every 15 min for 240 min. Mannitol flux was calculated over 3 consecutive 60-minute periods. Histology or electron microscopy was done after exposure. Conductance over time, mannitol flux, frequency of histologic categories, and electron microscopic changes were analyzed for treatment effects. The mean ± standard deviation (SD) conductance over time for carprofen or DNP-treated colons was not significantly different from control regardless of tempol pretreatment. Period 3 mannitol fluxes for carprofen and DNP-treated colon were not significantly different, but were greater than control. Period 3 mannitol flux for tempol + carprofen was significantly less than tempol + DNP-treated colon. Sloughing of cells and erosions were seen in the mucosa of carprofen-treated colon. Mitochondrial damage was seen more often in carprofen-treated than DNP-treated or control colon. Tempol pretreatment resulted in more ruptured mitochondria in the carprofen-treated colon; however, other mitochondrial changes were not significantly affected by tempol pretreatment in either carprofen or DNP treated colon. Treatment with carprofen or DNP increased the mannitol flux, but pretreatment with tempol mitigated the carprofen effect. It is apparent that structural mitochondrial damage occurs in the canine colonic mucosa after carprofen and DNP exposure.

L'objectif de la présente étude était de comparer la conductance et la perméabilité au mannitol de la muqueuse du côlon de chien en réponse au carprofène ou au 2,4-dinitrophénol (DNP) avec ou sans prétraitement au tempol. Dix sections de muqueuse du côlon par chien furent montées dans des chambres d'Ussing. Les traitements furent effectués en duplicata. La muqueuse fut exposée à du carprofène (200 µg/mL) ou du DNP (0,25 mM), chacun avec ou sans prétraitement (1 mM) au tempol. La conductance fut calculée à des intervalles de 15 minutes pour 240 minutes. Le flux de mannitol fut calculé sur trois périodes consécutives de 60 minutes. Un examen histologique ou par microscopie électronique fut effectué après l'exposition. La conductance dans le temps, le flux de mannitol, la fréquence des catégories histologiques, et les changements en microscopie électronique furent analysés pour les effets de traitement. La moyenne ± l'écart-type de la conductance dans le temps des côlons traités avec du carprofène ou du DNP n'était pas significativement différente des côlons témoins indépendamment d'un prétraitement au tempol. Les flux de mannitol à la période 3 pour les côlons traités avec du carprofène ou du DNP n'étaient pas significativement différents l'un de l'autre, mais étaient plus élevés que pour les témoins. Le flux de mannitol pour la période 3 pour le traitement tempol + carprofène était significativement moindre que celui des côlons traités avec DNP + tempol. La perte de cellules et des érosions furent observées dans la muqueuse des côlons traités avec du carprofène. Des dommages aux mitochondries ont été vus plus souvent dans les côlons traités avec du carprofène que ceux traités avec du DNP ou les témoins. Le prétraitement au tempol a résulté en plus de mitochondries rupturées dans les côlons traités avec du carprofène; toutefois, les autres dommages mitochondriaux n'étaient pas significativement affectés par un prétraitement au tempol autant pour les côlons traités avec du carprofène que du DNP. Un traitement avec du carprofène ou du DNP augmenta le flux de mannitol, mais le prétraitement avec du tempol a réduit l'effet du carprofène. Il est évident que des dommages mitochondriaux structuraux se produisent dans la muqueuse du côlon de chien suite à une exposition à du carprofrène ou du DNP.(Traduit par Docteur Serge Messier).

Effects of clenbuterol administration on serum biochemical, histologic, and echocardiographic measurements of muscle injury in exercising horses.

OBJECTIVE: To determine the effects of clenbuterol, at a dosage of up to 3.2 µg/kg for 14 days, PO, on skeletal and cardiac muscle in healthy horses undergoing treadmill exercise. ANIMALS: 12 healthy horses from 3 to 10 years old. PROCEDURES: Horses were randomly assigned to a control group (n = 6) or clenbuterol group (6) and received either saline (0.9% NaCl) solution or clenbuterol, PO, every 12 hours for 14 days. Horses were subjected to submaximal treadmill exercise daily during treatment. Muscle biopsy specimens were collected before and after treatment for determination of apoptosis. Echocardiographic measurements, serum clenbuterol and cardiac troponin I concentrations, and serum activities of creatine kinase and aspartate aminotransferase were measured before, during, and after treatment. Jugular venous blood samples were collected every 3 days during treatment. Echocardiography was repeated every 7 days after beginning treatment. Response variables were compared between treatment groups and across time periods. RESULTS: No significant effect of clenbuterol or exercise on response variables was found between treatment and control groups at any time point or within groups over time. CONCLUSIONS AND CLINICAL RELEVANCE: Results did not reveal any adverse effects of treatment with an approved dose of clenbuterol on equine cardiac or skeletal muscle in the small number of horses tested.

Clenbuterol toxicosis in three Quarter Horse racehorses after administration of a compounded product.

CASE DESCRIPTION: 3 Quarter Horse racehorses were examined for suspected clenbuterol overdose 12 to 24 hours after administration by mouth of a compounded clenbuterol product. CLINICAL FINDINGS: 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. TREATMENT AND OUTCOME: Propranolol (0.01 mg/kg [0.005 mg/lb], IV) was administered to all 3 horses for antagonism of ß-adrenergic effects and caused a transient decrease in heart rate in all patients. All horses also received crystalloid fluids IV and other supportive treatment measures. Two horses were euthanatized (2 and 4 days after admission) because of complications. One horse recovered and was discharged 4 days after admission to the hospital. In the 2 nonsurviving horses, skeletal and cardiac muscle necrosis was evident at necropsy, and tissue clenbuterol concentrations were highest in the liver. CLINICAL RELEVANCE: Clenbuterol is a ß(2)-adrenergic receptor agonist licensed for veterinary use as a bronchodilator. At doses ≥ 10² µg/kg (4.5 µg/lb), in excess of those normally prescribed, ß-adrenergic stimulation by clenbuterol may cause sustained tachycardia, muscle tremors, hyperglycemia, and cardiac and skeletal muscle necrosis. Laminitis, acute renal failure, rhabdomyolysis, and cardiomyopathy were fatal complications associated with clenbuterol overdose in 2 horses in the present report. At the dose administered, propranolol was effective for short-term control of sinus tachycardia, but it did not alleviate all clinical signs in patients in the present report. These cases demonstrated the risks associated with the use of nonprescribed compounded medications for which the ingredients may be unknown.

In vitro effect of carprofen and meloxicam on the conductance and permeability to mannitol and the histologic appearance of the gastric mucosa of dogs.

OBJECTIVE: To evaluate the effects of carprofen and meloxicam on conductance and permeability to mannitol and on the histologic appearance of sections of canine gastric mucosa. SAMPLE: Gastric mucosa from 6 mature mixed-breed dogs. PROCEDURES: Sections of gastric mucosa were mounted in Ussing chambers, and carprofen (40 or 400µg/mL [CAR40 and CAR400, respectively]), meloxicam (8 or 80µg/mL [MEL8 and MEL80, respectively]), or no drug (controls) was added to the bathing solution. For all sections, conductance was calculated every 15 minutes for 240 minutes and flux of mannitol was calculated for 3 consecutive 1-hour periods; histologic examination was performed after the experiment. The area under the conductance-time curve for each chamber was calculated. Values of conductance × time, flux of mannitol, and the frequency distribution of histologic findings were analyzed for treatment effects. RESULTS: For CAR400- and MEL80-treated sections, conductance X time was significantly higher than that for control and MEL8-treated sections. The effect of CAR40 treatment was not different from that of any other treatment. Over the three 1-hour periods, mannitol flux increased significantly in MEL80-, CAR40-, and CAR400-treated sections but not in MEL8- treated or control sections. Major histologic changes including epithelial cell sloughing were limited to the CAR400-treated sections. CONCLUSIONS AND CLINICAL RELEVANCE: In the gastric mucosa of dogs, carprofen and meloxicam increased in vitro conductance and permeability to mannitol. At a concentration of 400 µg/mL, carprofen caused sloughing of epithelial cells. Carprofen and meloxicam appear to compromise gastric mucosal integrity and barrier function in dogs.

Pathophysiologic effects of phenylbutazone on the right dorsal colon in horses.

OBJECTIVE: To determine pathophysiologic effects of phenylbutazone on the equine right dorsal colon (RDC). ANIMALS: 12 healthy adult horses. PROCEDURES: A controlled crossover observational study was conducted. Clinical and serum variables, colonic inflammation (histologic grading), and measurement of myeloperoxidase (MPO) activity, malondialdehyde (MDA) and prostaglandin E(2) (PGE(2)) concentrations, ingesta volatile fatty acid (VFA) content, and arterial blood flow in the RDC were evaluated for a 21-day period in horses administered phenylbutazone (8.8 mg/kg, PO, q 24 h) or a control substance. RESULTS: Data from 8 horses were analyzed. Plasma albumin concentrations decreased significantly from days 10 to 21 during phenylbutazone treatment, compared with results during the same days for the control treatment. Phenylbutazone treatment caused neutropenia (< 3.0 x 10(3) cells/microL). No other clinical or hematologic abnormalities were detected for phenylbutazone or control treatments. Two horses developed colitis while receiving phenylbutazone. No significant differences were detected in the RDC between phenylbutazone and control treatments for MPO activity, MDA and PGE(2) concentrations, and histologic evidence of inflammation. Arterial blood flow in the RDC was significantly increased during phenylbutazone treatment, compared with values for the control treatment. Differences were identified in VFA production during phenylbutazone treatment, compared with the control treatment, with a decrease in acetic acid concentrations over time. CONCLUSIONS AND CLINICAL RELEVANCE: Prolonged phenylbutazone administration caused hypoalbuminemia, neutropenia, changes in RDC arterial blood flow, and changes in VFA production. Veterinarians should monitor serum albumin concentrations and neutrophil counts and be cautious when making dosing recommendations for phenylbutazone treatment of horses.

Effects of carprofen on the integrity and barrier function of canine colonic mucosa.

OBJECTIVE: To measure effects of carprofen on conductance and permeability to mannitol and histologic appearance in canine colonic mucosa. SAMPLE POPULATION: Colonic mucosa from 13 mature mixed-breed dogs. Procedures-Sections of mucosa from the transverse colon and proximal and distal portions of the descending colon were obtained immediately after dogs were euthanized. Sections were mounted in Ussing chambers. Carprofen (400 microg/mL) was added to the bathing solution for treated sections. Conductance was calculated at 15-minute intervals for 240 minutes. Flux of mannitol was calculated for three 1-hour periods. Histologic examination of sections was performed after experiments concluded. Conductance was graphed against time for each chamber, and area under each curve was calculated. Conductance X time, flux of mannitol, and frequency distribution of histologic findings were analyzed for an effect of region and carprofen. RESULTS: Carprofen significantly increased mean conductance X time, compared with values for control (untreated) sections for all regions of colon. Carprofen significantly increased mean flux of mannitol from period 1 to period 2 and from period 2 to period 3 for all regions of colon. Carprofen caused a significant proportion of sections to have severe sloughing of cells and erosions involving >or= 10% of the epithelium, compared with control sections. CONCLUSIONS AND CLINICAL RELEVANCE: Carprofen increased in vitro conductance and permeability to mannitol in canine colonic mucosa. Carprofen resulted in sloughing of cells and erosion of the colonic mucosa. These findings suggested that carprofen can compromise the integrity and barrier function of the colonic mucosa of dogs.

Flood injury in horses.

There is no way to prepare for every situation that arises in a disaster. By working closely with other producers and agricultural leaders, however, horse owners can lessen the impact of a disaster on their operation. Preparation and detailed planning are the most important aspects of flood-related injury prevention. Encouraging animal owners and caretakers to have an evacuation plan and dispersing knowledge about local and regional disaster authorities are critical for a successful disaster response. Educational programs on future disaster response empower communities to care for their people and animals responsibly.

Investigation of the effect of black walnut extract on in vitro ion transport and structure of equine colonic mucosa.

OBJECTIVE: To examine the secretory response (in the presence and absence of prostaglandin inhibition) in vitro and structural alterations of colonic mucosa in horses after intragastric administration of black walnut extract (BWE). ANIMALS: 14 adult horses. PROCEDURE: Seven horses were administered BWE intragastrically and monitored for 11 hours. Tissue samples were obtained from the right ventral, left ventral, and right dorsal colons (RVC, LVC, and RDC, respectively) of the 7 BWE-treated and 7 control horses. Tissue samples were examined via light microscopy, and the extent of hemorrhage, edema, and granulocytic cellular infiltration (neutrophils and eosinophils) was graded. Colonic mucosal segments were incubated with or without flunixin meglumine (FLM) for 240 minutes; spontaneous electrical potential difference and short-circuit current (Isc) were recorded and used to calculate mucosal resistance. RESULTS: Colonic tissues from BWE-treated horses (with or without FLM exposure) had an overall greater Isc during the 240-minute incubation period, compared with tissues from control horses. The resistance pattern in RVC, LVC, and RDC samples (with or without FLM exposure) from BWE-treated horses was decreased overall, compared with control tissues (with or without FLM exposure). Histologically, colonic mucosal tissues from BWE-treated horses had more severe inflammation (involving primarily eosinophils), edema, and hemorrhage, compared with tissue from control horses. CONCLUSIONS AND CLINICAL RELEVANCE: In horses, BWE administration appears to cause an inflammatory response in colonic mucosal epithelium that results in mucosal barrier compromise as indicated by decreased mucosal resistance with presumed concomitant electrogenic chloride secretory response, which is not associated with prostaglandin mediation.

Prostaglandin E2 and reactive oxygen metabolite damage in the cecum in a pony model of acute colitis.

The objective of this project was to determine early tissue biochemical events associated with increased colonic secretion during the acute stage of castor-oil-induced colitis by measuring cecal mucosal and submucosal malondialdehyde (MDA) and prostaglandin E2 (PGE2), levels in ponies. Intestinal tissue (inflamed or healthy) samples were obtained from 4 age- and sex-matched Shetland ponies. Biochemical methods were used to determine MDA and PGE2 levels in intestinal tissue samples from inflamed and healthy equine intestine. Inflamed tissue MDA and PGE2 levels increased with time after castor oil challenge and correlated with granulocyte infiltration, as determined by myeloperoxidase levels in a companion study. Elevated intestinal tissue MDA levels suggest that lipid peroxidation could be attributed to reactive oxygen metabolites (ROM) released from stimulated, recruited, and resident granulocytes. Tissue levels of MDA and PGE2 suggest a role for granulocyte-derived mediators of intestinal inflammation in the massive secretory response in cases of acute equine colitis. Tissue MDA and PGE2 levels may be useful laboratory tools to quantify and characterize intestinal secretory inflammatory responses in acute inflammatory conditions in the equine colon.