ABN stands for Advanced Beneficiary Notification. An ABN must be signed prior to providing a Medicare service or test to document that the patient is willing to assume responsibility for payment of services that Medicare may not cover when subject to either National or Local Coverage Determinations (NCD) or (LCD).
Chinchillas are crepuscular (most active around dawn and dusk) rodents, slightly larger and more robust than ground squirrels. They are native to the Andes mountains in South America and live in colonies called  herds  at high elevations up to 4,270 m (14,000 ft).
Rabbits and guinea pigs are obligate herbivores. Although chinchillas do occasionally eat insects in the wild, their main diet is herbivorous. Small herbivore nutrition should, one supposes, take as its starting point the grasses and wild plants that these animals would eat in the wild.