It is considered derogatory to say someone is living like an animal. It is not advised to live like an animal by either the materialistic fellows or the spiritual ambassadors.
Materialistic or worldly fellows feel that an animal is not achieving any goal. Just fulfilling physical needs is not enough. They argue for higher echelon of needs like self-esteem and self actualization.
why would you need any sense of achievement if you have SATISFACTION. if you examine it closely, you will find satisfaction to be bigger than that. Animals are satisfied creatures by nature. They try to fulfill their basic needs. They don't worry about the future. They just keep on doing what they are genetically programmed (upto the level of their intelligence) to do.
Animals dont create karma. they burn off all the karma they have accumulated in past lives. They dont create karma because they dont desire. They work on fulfilling their needs and work on it without any other expectation. It is a little fine here. Desire is different from need. Need is natural, desire is un-natural. if we look a little deep, we can identify anything we seek as need or desire.
But despite all, saints dont recommend you to live like an animal. They ask you to rise a level above, above living without desire, above burning-karma mode. They ask you to explore the possibility of achieving the supreme state which is possible only in human form. The state which liberates you from the cycle of karma forever.