Evaluating the effects of USDA organic approved therapies on foot rot

Objective

Foot rot is an infectious disease that can cause severe lameness and permanent damage, if treated improperly. This disease is caused by a physical abrasion or tear in the interdigital skin that often leads to an infection in the subcutaneous tissue. Clinical foot rot can be characterized by symmetrical swelling, redness, and foul odor depending on severity. Early detection, removal of necrotic tissue, and antibiotic therapy have been an industry standard when treating foot rot on conventional dairy operations. Managing foot rot cases on USDA certified organic dairy operations requires the use of non-antibiotic therapies, and few evaluations of these products have been reported on. The lack of evidence-based treatment recommendations puts organic producers at risk of prolonged lameness and delayed healing for animals diagnosed with foot rot. The objective of this prospective randomized clinical trial was to evaluate the effectiveness of four topical non-antibiotic alternatives for the treatment of foot rot on U.S. organic dairies.

Materials and methods

Two hundred and forty lactating dairy cows were enrolled and randomized into four treatment groups between April of 2018 and December of 2020. Locomotion scores for each animal were recorded by a trained veterinarian prior to the animal’s treatment. At each evaluation, the animal was restrained in a hoof trimming chute, the lesion was cleaned and any necrotic tissue was removed. In addition, rectal temperature and physical assessments of generalized foot swelling and the presence of a skin fissure were recorded. Enrolled animals were randomized into one of four treatment groups: a) copper sulfate and water, b) seven percent iodine tincture, c) organic honey, or d) hydrogen peroxide. All treatments were applied along with a light bandage. Animals were scheduled for re-evaluation on D 7, 14, 28, 56, and 112. The randomized treatment was applied on D 0, 7, and 14. Statistical methods included mixed linear models for: a) absolute locomotion score at each observation day, and b) change in locomotion score from the previous observation. Full-factorial models of treatment * day effect were built. Meanwhile, survival analysis using Cox proportional hazards regression for time-to-recovery (defined as days to locomotion score=1 and no swelling of the foot, or else right-censoring on or before D112) also was deployed. Since this study was performed on a USDA certified organic operation, it was not possible to include a systemic antimicrobial treatment group, the gold standard of therapy in conventional operations. All animals were monitored for welfare issues associated with treatment failure and processes in place to manage such situations without compromising the welfare of the animal. [...]