These may include may types of behaviour. The pet is usually somewhat sluggish and apathetic. It fails to exert enthusiasm about the daily walk or a new ball or whatever that normally makes is jump on cloud nine. This is usually what we notice first. The second thing to check is how well-hydrated our dog is, and whether it urinates normally. If something about this makes us suspicious, don't hesitate to call the vet immediately. Many serious and lethal diseases have no other symptoms and if you fail to notice the above, you may have to say goodbye to your pet sooner than you thought you would have to. Eating habits, too, change during an illness. The animal may suddenly start to devour huge amounts of food and beg for more or, on the contrary, start skipping meals. It is also unnatural for dogs to vomit, sneeze, gag and cough repeatedly. If any of the eating anomalies last longer than two days, call a doctor.
Drooling, tooth and gum problems also indicate health problems. Take a look into your pet's eyes; cloudy or red eyes mean trouble, just as fever and rough and dull coat do.
It is easier, of course, to notice the symptoms of more serious illnesses, most popular of which include: dehydration, inability to urinate, fainting, collapsing, or inability to use its hind legs. These symptoms should alarm you and vet should be called immediately.
However healthy you think your pet is, do not let yourself be blinded by complacency. You can never tell what particular symptoms mean and sometimes it is a matter of minutes if your animal makes it through to the next day.