Lamb producers are currently limited in their ability to make informed on-farm management changes with respect to disease and defects identified at processing. This is due to the limited accuracy and detail of information included in disease and defect feedback supplied by processors. Increasing transparency of the feedback can allow producers to make more informed on-farm decisions, and, subsequently, improve productivity and animal welfare. Aims: Using arthritis as a case study, the aim was to develop a scoring system that estimates hot standard carcass weight (HSCW) losses due to trimming at processing, so as to improve feedback to lamb producers. Methods: An observational cross-sectional study was conducted at a southern New South Wales commercial processing facility, over 6 months and in five week-long blocks, from 21 February 2019 to 5 July 2019. Carcass trim components removed due to the presence of arthritis (shank or leg) were recorded for 217 of the 42 164 lamb carcasses processed. Utilising average lot HSCWs, the total proportion of HSCW lost due to arthritis trimming (TPL) was calculated for each arthritic carcass. Linear regression analysis, with a logit-transform of TPL, was fitted to the data. Key results: Processing lot and trim-component category were found to be significant (P << 0.001) explanatory variables for variation in TPL. Trim-component categories that were not significantly (P > 0.05) different were combined, with final categories being assigned arthritis trim scores as follows: 1, any forequarter shank; 2, any hindquarter shank; 3, any forequarter leg; and 4, any hindquarter leg. At an over-the-hooks carcass price of AU$7.83/kg and an average HSCW of 23.13 kg, these scores were used to estimate producer revenue losses per carcass (range AU$2.95-AU$18.08). Conclusions: The accuracy and detail of information provided as feedback to lamb producers can be improved. For arthritis, this can be achieved using a trim-scoring system. Implications: Altering feedback to include HSCW losses for processed lots in both kilograms and dollars against the associated disease or defect will better equip producers to make cost-effective on-farm management changes and reduce the impact on the lamb supply chain.