The shirts we have are made from a very fine silk crepe that can cope with a 30 degree gentle cycle wash. 

For best results we recommend quick washing by hand in a mild warm soapy solution and line drying inside out.

I like to use Naf Leather care products . Naf offer a wide range of different products to keep leather soft, supple and serviceable. Naf products are available from most good saddlery stores 

There are lots of good videos about how to put on pressure halters and best use them. Simply go on line to find out lots of good information.