Sentience is not a binary thing, it's a continuum.

Humans alone, so far as we know, go so far as to understand the story arc of their own lives, and their mortal fate. As such, we bear a unique burden, which we struggle to integrate and transcend.

Our dogs are sentient and self-aware at a lesser amplitude, but I don't think either of them contemplate their mortality, because they don't understand it.

There are differences even between the two. One is a typical terrier, dumb as a post in many ways, and tenacious (or "dogged" if you will!) to a point of laser focus that blinds her to nuance. The other, a mix, is far more broadly intelligent and even has some low-level existential angst, the product of his pre-rescue puppyhood in which he was confined to a cage for long periods, taken from his mother too soon, and developed an escape mentality that turned him into a "run and hump" neighborhood nuisance. We actually give him Prozac and Vallium or he would whine anxiously all day. He requires a certain daily routine or he panics. He's the epitome of that dog meme where the dog wonders, "what if I never figure out who's a good boy??" But ... he will never invent a god for himself and certainly not an afterlife. He's totally in the moment.

This view allows me to understand and value the legitimacy of our dog's emotional life and physical pain no less than I value ours -- and yet to make a useful distinction between the depth of his experience and ours.

So yes animals are sentient, the higher animals have nearly the same emotional range, but not as self-aware. Lower life forms have less range but to the extent they can relate to humans in a dependent relationship should still be treated with kindness and empathy, their pain taken seriously, their right to exist affirmed. They are not automatons.

Of course they are..apparently even plants are. Everything in the universe is made out of the same energy.

"Trees of the same species are communal, and often form alliances with trees of other species. Forest trees have evolved to live in cooperative, interdependent relationships, maintained by communication and a collective intelligence similar to an insect colony.

All the trees here, and in every forest that is not too damaged, are connected to each other through underground fungal networks.
Trees share water and nutrients through the networks, and also use them to communicate. They send distress signals about drought and disease, for example, or insect attacks, and other trees alter their behavior when they receive these messages.”

Read more: [smithsonianmag.com]

"What do you think makes something sentient?"

This is the first, and most important question to explore. Please provide a definition of sentience and perhaps we might actually have a meaningful discussion. Without a clear definition of this 'loaded' term, however, what we offer in response likely leads to a waste of our time.

We do them and us disservice by subjecting them to judgement from our own frame of reference. The real question is, Why are humans so dumb?

I believe that sentience, like any evolved quality, has a range that varies among animals, from "does not possess the trait" to "has the highest degree of that trait".

some aren't, some are, and the amount to which they are varies based on biological traits they have evolved.

the awareness of self and the ability to understand that things are distinct from experience. this includes such things as empathy, theory of mind, intentional deception, abstraction in problem solving.

basically, having a model in the mind that represents the world around you, as opposed to reacting to each stimulus by rote or instinct, and projecting behavior from the expectations of that model, and also being able to experience "qualia" instead of just "stimulus", are linked to sentience.

depends what you mean by emotion

Yes. They have senses and are able to process information from those senses and act accordingly.

Now, if you asked if they're sapient, I'd have to say 'probably not.'

...as I watch my cat go in and out of the same cupboard. Repeatedly. Because he clearly forgot what he saw in there the first three times.