Honestly you have no idea if animals can suffer by extending into the future. You have no idea if they can share it with others. Simply because we can't speak to them.
Observationally we can see animals expressing fear and avoidance when approaching a stimuli that caused them pain before. You can also see animals teach other animals to avoid painful stimuli.
To me that indicates a level of suffering that extends beyond the present.
Likewise cruel experiments like the "swim test" (where a mouse is forced to swim in a tube of water until it is exhausted or gives up) shows that if you give a mouse hope that it will be rescued, it will swim for much longer than if it had no hope. This again shows future imagining is a part of at least some animals' consciousness.
In my view, if you do not know for certain if an animal suffers, it is ethical to err on the side of assuming that it does. Because if you are wrong, no harm has occurred. But the inverse is not true.
Another point is that if you claim animals only feel pain in the present moment, does it mean you shouldn't give anaesthetic to babies? Even if they don't remember the pain when they're grown up, so what? It was still excruciating in the moment.
The fact you think animals are not conscious is a massive red flag too. Animals are clearly shown to make decisions based on their environments and situations. The "automata" theory of animals is based on Cartesian arguments that have been debunked for years. Why would you assume that an animal's actions are due to "automatic responses" but humans' are not? Why would you assume that humans are magically special in having consciousness and the ability to suffer and all other animals are not?
Just because human perception of suffering is in some ways special does not mean all other ways of suffering are meaningless and thus we should do whatever we want to the natural world.
If you use a gradualist approach does this mean it's ok to torture babies? Children? What about people with dementia? Or does that not apply because "humans are special regardless of their level of consciousness"?
