You will know if your pet itches its self alot all over its self. Also some times depending on how bad it is you can actually see the fleas jumping all over it. Lastyly you can look on the fur and...
Usually if you part the hair and look at the skin near the eyes, on the tummy, under their legs in the "underarm" area, or on the back end, you can see them as tiny dark brown or blackish moving...
This is a pretty obvious one. Your animal would be scratching and biting themselves where they are being bitten. You will most likely be bitten many times yourself by the fleas and they are visible....
When you own a dog you should keep the rabies shots up. I do believe that in the U.S. this shot is given every year whereas in Canada one shot lasts three years.
If your dog isn't left to roam and...