Some cats need advanced diagnostic procedures to establish a diagnosis. St. Louis Cat Clinic refers patients to the specialists at Associated Veterinary Services (AVS) for these procedures. AVS is where Dr. Freesh takes her pets when she needs help with a diagnosis. AVS takes time with patients and cat owners. The doctors and technicians are thorough and excellent. The specialist fees at AVS are reasonable and Care Credit is available as an option for payment. You will get an estimate before anything is done.