Sisal is a natural fiber derived from the 'agave sisalana' cactus plant. It is important during cleaning to control the amount of moisture. It is NOT recommended that the natural fiber be steam cleaned, wet shampooed or any other method that involves water saturation. It is recommended that a dry cleaning process be used for overall cleaning.
If she wants just the blood stains cleaned you may have to use a mild detergant and a white cloths and clean by hand, dry immediately with a hairdryer or fan to avoid water staining, that is when it becomes your problem. If they already have water marks from her trying to clean it than note that on the invoice and have her sign it and tell her they may be permanent.