Handy Hint 2 - Keeping the Shoes Tightly in Place during wet weather by Dr John Kohnke

The shoes often work loose and are more easily cast on horses which are turned out onto dew soaked and rainy wet pastures after daily training.
Wet weather can soften the hoof wall around the pressure area under the clinches,
allowing the nail clinch to pull downwards to loosen the shoe.
Once sand becomes wedged under the shoe, it can continue to pack in and separate the shoe from the hoof wall, increasing the risk of loosening the shoe.
One way to reduce this risk is to thoroughly wipe around the clinches on each hoof with methylated spirits to repel moisture and clean away oils and soil, then apply a dollop of silastic window sealant, spreading it over the clinches to seal out the moisture.
Stand the horse to feed for a few minutes while the sealant hardens before turning the horse out into wet pasture. It also helps to keep the shoes tight on horses which are washed to hose off sweat each day, or swum as part of training or to assist cooling out after exercise.
You can use silastic in the same way to seal over any cracks in the hoof wall or broken away hoof edges.

Article courtesy of Dr John Kohnke BVSc RDA - Talking Horses newsletter