Swelling of cattle heel horn by urine

OBJECTIVES: To understand the likely mechanisms responsible for heel horn softening when cattle stand in their own effluent. To examine the effectiveness of some footbath chemicals in preventing heel horn softening. PROCEDURE: Shavings from the heels of cattle were used in a laboratory test to examine the swelling effects of cow urine, urea, sulphide and ammonia. Formalin, glutaraldehyde, glyoxal, zinc sulphate, copper sulphate, alum, tannic acid and a compound containing nitrocellulose plus nylon, were compared for their ability to prevent swelling in heel shavings induced by urea plus 2-mercaptoethanol. RESULTS: Cow urine caused heel horn to swell. Urea caused swelling at concentrations normally found in cow urine. Sulphide caused swelling at concentrations normally found in cow slurry. Low concentrations of ammonia solution also resulted in swelling. Formalin and glutaraldehyde prevented swelling induced by high concentrations of urea plus 2-mercaptoethanol. Copper sulphate had a moderate anti-swelling effect. Zinc sulphate, alum, tannic acid, and nitrocellulose plus nylon were relatively ineffective in preventing swelling. CONCLUSIONS: Cow urine can cause degradation of heel horn in cattle feet. The chemical agents that cause this could be urea, sulphide anions and ammonia. Degradation by urine can be prevented by pretreating heel horn with formalin. Glutaraldehyde may be an effective noncarcinogenic alternative to formalin.