The use of non-steroidal anti-inflammatory drugs (NSAIDs) can be associated with severe adverse effects. The aim of this experimental study was to investigate the effect of piroxicam and ketoprofen, two NSAIDs with different excretion pathways, on the gastric mucosa, kidney, liver, and hematopoietic system of dogs. Fifteen mixedbreed healthy dogs of both sexes aged between 1 to 8 years were randomly divided in three groups and treated with piroxicam (0.15 mg/kg intramuscularly (IM)), ketoprofen (1 mg/kg IM) or placebo daily for 21 days. Although not statistically significant (p>0.05), the dogs receiving ketoprofen showed fewer and less severe lesions than the dogs in the piroxicam group. None of the dogs showed any clinical signs related to the gastric lesions. Serum biochemical and complete blood count parameters did not change significantly after NSAlD administration (p>0.05). However, by day 14, a decreased number of platelets and prolonged bleeding time were detected in treatment groups compared with the control group (p<0.05). The clinical significance of this prolongation is unclear. This study suggests that ketoprofen and piroxicam produce mild lesions when administered to healthy dogs for 21 days, and there is no difference between the two groups in the number and severity of lesions. There may be an indication that longer duration of drug administration may result in a greater number of gastric lesions. However, after long-term NSAID exposure (21 days in our study), gastric tolerance to the damage caused by NSAIDs will be developed.

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