10. Lethargy
Every dog has a unique personality and dog owners get to know their pet’s routine very well, so it’s usually easy to tell when something isn’t quite right. Just like us, dogs will get a bit tired out once in a while, especially if they have been doing a lot of running around or otherwise exerting themselves. You can usually tell when your dog is a bit tuckered out from more than the usual amount of exercise, but if you notice that he or she seems worn out and acting lethargic for no obvious reason, it is a good idea to give the vet a call to be sure it’s nothing serious.