I would discuss with the seller about being able to post-date the check for your security. Put the date for, say...two weeks from now, or some length of time that would be appropriate for you to receive your animal. If the animal isn't shipped to you by the time it should be (which should be a few days BEFORE he would be able to cash the check), or it's in bad condition, then you have time to put a stop order on the check before he would be able to cash it.