During my communication sessions, one of the questions I am asked to find out is if it is their beloved companions' time to pass or if they are sick. I do not believe that animals know the exact time of their death any more than humans do. While I do believe that animals are more in tune with their bodies and nature, I do not think they are all-knowing.
In my experience, an animal knows when they don't feel well, and they may have an idea that their time is near. They sense or know that nothing further will help them, but they can go on living for weeks or months. What is important to them, is how that time will be spent. Similar to humans, they want to live life joyfully and feel good and have good experiences. Quality of life is most important.
Humans excel in science and biology and are able to label diseases and come up with treatment plans. Animals don't know this stuff. They just know they feel unwell. Animals cannot tell me that they have cancer, diabetes, or a neurological disorder. They can, however, describe to me what they feel inside their body. One beautiful boy told me that it felt as if he had a ball in his stomach and was very certain that he had not swallowed anything other than food. He did, in fact, have a tumor. Beyond knowing this, he could not tell us anything about it nor did he know if he was going to be cured, or anything else medical. In fact, he asked me how he could get rid of it!
I have had some beautiful souls tell me that they were ready to cross over and rid themselves of these earthly bodies. They did not, however, know the exact moment. Often times they hang on and are hopeful that something will change. Like humans, even if we are "ok" with crossing over, there is still that little part of us that doesn't want to leave our family and friends. Animals are no different.
Little Bear, my fur baby who passed, relayed to me his moments of hesitation. Moments when he started to give in to crossing over and then suddenly decided not to because he wanted to stay with us. This does not mean that animals control when they will leave. It does, however, show that willpower can play a huge part in healing and recovery. We see this same burst of energy in humans. We describe healing as a battle or "fighting for your life". The will or desire to live plays a huge part in recovery. Sometimes, it works and sometimes the body simply fails. This is the same for animals and humans alike.
Since no being really knows when our time on earth will end, make the most of each day. Spend time with family and friends in meaningful ways. Return calls, visit someone, and play with your animal companions regularly. Don't put off time spent with loved ones because you never know if that will become a missed opportunity. Love. Laugh, and be kind to all kinds.