[a_bonobo]

Depends on your definition of "suffering" -

if it's

>Physical suffering or discomfort caused by illness or injury

it has to be communicated to you, which in the case of animals is quite hard.

On the other hand, if you define "suffering" as

>an unpleasant situation causing signs of distress that is avoided by the sufferer,

then you can make better predictions, because "avoidance" or "distress" are easier to measure.