Some states don't accept other state's rabies certificates. If the test is negative, preventative must be started within 10 days. Only Greyhound Friends for Life currently test for these diseases , though I've been told that many Southern California rescue groups are starting. GFFL offers testing a couple of time a year. ABAP back issue has more info on Ehrlichoisis and Babesiosis , two relatively unknown tick-borne diseases.
Most groups worm for hook, whip, and tape.
You need to know ahead of time what to expect of your new dog. Find out how they test. Most groups wash the dogs in good flea shampoo and trim nails. Some groups clean ears and express anal glands, too. This was the most important consideration for us.