Hi Imagosmith,
Welcome to SaleHoo! These suppliers have pet blankets but the items do not seem to be water proof -
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In line with your request, I searched outside of SaleHoo and found
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The website has been online since 2007 and they can customize their waterproof blankets with your logo or colors -
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Please be advised to use a safe payment method such as credit cards.
Hope this helps. :)