Potentially yes, Monique. Fabric softener products can contain detergents known as cationics that have the potential to produce significant gastrointestinal irritation, particularly when the sheets haven’t yet been used. These effects include drooling, appetite loss, oral burns and, in some cases, possibly even ulceration of the gastrointestinal tract.
While dogs and other animals can also be affected, cats are especially sensitive to cationics. As such, we would advise not to let your feline friend play with fabric softener sheets—whether fresh or used.