Animals have the power of perception by the senses and can feel, perceive, and experience subjectively. That's sentience, so those people are wrong.
Most animals aren't sapient though, which is probably what gets people confused. Even then, some animals might be intelligent enough to prove sapient, such as apes, dolphins, elephants, etc.
RE: TIL livestock are often left on transport trucks for days sometimes without being unloaded for rest, food, or water.