Serum biochemistry was available for a subset of the dogs that completed the study in order to monitor changes in urea, creatinine, ALT and AST over the 30-day treatment period although collection of blood samples was not a prerequisite for inclusion in the study. Thus, the aim was to collect population data about changes in these biochemical parameters over a 30-day treatment course with cimicoxib, rather than track changes in these variables over time in individual animals. The blood samples were not analysed in a standard manner, with a variety of different analysers being used to measure all biochemical parameters, although studies generally report good consistency between laboratories for the biochemical parameters measured in the present study, and between laboratory and bench top point of care analysers [34] . However knowing this limitation the biochemical data are presented as a distribution compared to a reference value to highlight if there was a change in the whole population distribution and to see if there was a trend towards an increase in “above the reference” group after treatment with cimicoxib independent of the analyser, and the biochemical data were not subject to statistical analyses. The cut off values for each of the parameters that defined a dog to be abnormal or normal are similar to reference values for normality used by many laboratories and were calculated following a synthesis of references values published in the literature. There was a numerical increase in the proportion of dogs with an abnormal serum urea concentration documented at D30 compared with D0, but this was not accompanied by a numerical increase in the proportion of dogs with elevated serum creatinine at D30 compared with D0. Serum urea concentration is influenced by hydration status of the dog and recent dietary protein intake [35] , therefore the contribution of cimicoxib administration to the changes in urea is unknown. Compared with changes in serum urea concentration, increased serum creatinine concentration is generally considered to be more specific for altered renal function [36] . The proportion of dogs with abnormal ALT and AST was not numerically different at the start and end of the treatment period, which is in accordance with data reported in other clinical studies monitoring changes in biochemical parameters related to liver damage following NSAID therapy over a similar time course [3] .

Gastro-intestinal side effects associated with NSAID administration are a significant cause for concern amongst veterinarians [37] , although the prevalence associated with administration of NSAIDs to dogs for OA is difficult to quantify in general practice. Only limited data were collected from owners to probe the occurrence of gastrointestinal side effects associated with cimicoxib administration, nonetheless the majority of owners agreed with the statement that their dog had no visible side effects during the treatment. This suggests that the gastrointestinal side effect profile of cimicoxib is similar to other currently licensed NSAIDs.

This survey demonstrated improvements in locomotion, mobility, pain scores and dog demeanor and body condition in dogs treated with cimicoxib for thirty days by both owners and veterinarians and provides evidence that these outcome measures, as measured by veterinarians continue to improve after 15 days of treatment up to the 30-day time point. However, these data must be interpreted with knowledge of limitations in the study design, which will have likely resulted in measurement bias for the different outcome variables. Data relating to the use of a new NSAID in the field environment are useful for veterinarians making decisions about which NSAID to administer to dogs that require pain management for OA.

The authors would like to thank Gary Coxon MRCVS for his technical expertise in the design of the study.