No, you have no grounds to demand a refund of your purchase of the animal. You should have inspected the animal more closely when you bought it. However, if you incurred veterinarian charges for removing the ticks and perhaps medication for the animal and you can prove it had the ticks on it when you bought it, you have a basis for seeking the reimbursement of these costs.If you do, you should write a letter to the person from whom you bought the animal from with copies of the invoices, canceled checks and receipts showing the payments made and ask for reimbursement of such. Hopefully the former owner will reimburse you the moneys you did not expect to incur.Good luck.