The effect of environmental insult on permeability barrier of the claw horn of cattle
Mgasa, M.N|Kempson, S.A / 2000

When cattle are housed or are in enclosures the claw horn is exposed to various environmental insults that are thought to predispose to lesions which may have some detrimental effects on claw horn function. The effects of pyroleum pini (Stockholm tar) 15% and 25% soap solutions and water on the permeability barrier function of the bovine claw was studied using tracer techniques and studied by both light and electron microscope. Horse radish peroxidose and 3% Lanthanum nitrate were used as tracers for light microscopy and electron microscopy (TEM) respectively. Blocks of clinically normal claw horn were immersed in the test solutions. The blocks were left for 48 hours, 4 days and 2 weeks in each test solution. Regions observed were the wall, the white line and sole in the distal toe of the claw and the palmar plantar surface of the heel. All the claws used in the experiments were clinically normal. The effect on the permeability barrier of all treatments (pyroleum pini soap solution and water) increased with time, with the maximum effect being seen at two weeks. Changes in the permeability barrier with treatment were greatest in the heel and least in the wall. Areas of damage or microcracks in the wall allowed greater penetration of tracer than non-damaged wall horn. Water particularly affected the laminar horn leaflets of the white line, reducing the permeability barrier and allowing greater penetration of the tracer. Observations in the TEM showed a significant effect on the intercellular lipids following treatment in a 25% soap solution. The cell membranes were also altered to allow the lanthanum nitrate to enter the corneocytes. In conclusion, pyroleum pini caused minimal damage to the permeability barrier of the horn, soap solutions should be used with caution and it is inadvisable to leave cattle standing in water for long periods of time.