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.
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 E2 (PGE2) 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 × 103 cells/μL). 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 PGE2 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.