This isn't the first time this subject has been addressed, but I thought it was an interesting question to explore from the animals' perspective. As an animal communicator, I am blessed to get the "inside scoop". It is not very scientific and I did not do hours of research. I did, however, ask several animals to explain how they "know" it is dinner time, or how they know when it is time to go out, etc. So, here we go! Can animals tell time? How do they tell time?
The first thing is obvious, they do not read a clock (hand or digital). What animals use is their senses. Animals are very in tune with all of their senses, and have a really good gauge on how long things take. While we (humans) talk about this in terms of minutes and hours, such as "it takes 5 minutes to walk to the store", animals use their environment, their senses, and a sense of knowing. Before you think this is weird or made-up, think about your human friends. Some humans never wear a watch or look at the time and yet they keep a pretty good schedule. Others, whether they use a clock or not, are always late. Those people have a really bad "sense of time". They are also the individuals who never quote accurately how long it takes for anything. They may say "I'll be there in 20 minutes", and honestly believe that. Yet, when you look at google maps the trip is 30 minutes and that does not take into account time to get ready. These are our loved ones who are always late!
Then, there are those people who never use a clock, or seldom use one. I am one of these people. Some time ago, I trained myself to not use a clock and gauge time by how things feel. I know it sounds odd, and I honestly cannot explain it. It has something to do with senses; how long does an activity take me to complete, and what does that feel like to my body? I'm generally consistent in being within 5 mins one way or the other, but mostly on time. I listen to my body. I observe subtle changes in air, temperature, sounds, and anything else that changes. The body, when healthy, works like a well-oiled machine. We get up at the same time, we get hungry at the same time, we have to use the bathroom at the same time. Of course, this is as I said for a healthy body. Deviations in diet, illnesses, alcohol, and other negative habits will through off that cycle.
Animals function in the same way, but they have the added advantage of having heightened senses. They learn how it feels when you say certain things and how long till you return. If I say "I'm going to work", my dog sighs, and goes inside. She doesn't try to follow me. She knows that work means a long day. Some people say that animals can't tell the difference between 5 minutes and 8 hours, using the animals' excitement to see you as proof of this absurd statement. That is completely wrong. The most beautiful trait (or one of them) of our companions is living in the moment. Another beautiful trait is loving us unconditionally and showing us that love.
Animals tell the time in the ways of nature. The sunrise, sunset, mid-day heat, the smell of cold air bringing a new season, the smell of snow, the smell of springtime; they listen to the sounds of the other animals, such as night crawlers and birds that start the morning with a song. They also listen to their bodies. Bodily functions work pretty consistently in a healthy body. The one part of telling time without a clock that is so hard for me to put into words is simply having a "sense" or a "knowing" of how much time has passed. I believe we can all tap into this sense if we really tune in to our bodies and our surroundings. Become more aware of each action and also be more present.
Do not underestimate your companions' sense of time. When they greet you enthusiastically after only 10 minutes, consider yourself blessed to be so loved and missed by another being on this big planet.