We may not be veterinarians, and many things escape our understanding and we may not even realize that the dog may be wrong, because they cannot talk to us, but if we know our pet we will surely notice changes in case it is ill. And it is very important to notice these small changes because they can tell us that there is something wrong.
It is not always a dangerous disease, but the truth is that it does not hurt to worry as soon as we see that something change on our dog. Taking him to the vet for a general check-up or to rule out diseases is always the best solution in these cases, since they are the professionals who can advise us the best.
One of the things that best tell us that our dog may be sick is the loss of appetite. One day they may feel unwell for having eaten something they shouldn't have, but if this repeats we will have to go to the vet, since apathy at mealtime can indicate that something is wrong and there are many diseases that lead to loss of appetite in the dog. This is especially significant if you are a dog that eats well.
La lack of energy it can be another sure sign that the dog is unwell. When they get older they are calmer and spend more time sleeping, but this is progressive, it does not happen overnight. If we suddenly find that our pet is very dull, does not want to play and has little energy, spending the day apathetic and doing nothing, it may be that he is feeling bad about something.
There are also other symptoms, such as they lick an area a lot, which may indicate that they feel pain in it. And if they drink a lot of water it may have to do with a urine infection or diabetes. Of course there are many possibilities, but before these behaviors it is better to take them to the vet.