What is Normal Hair Loss for Pets?

SOME DOGS TEND TO LOSE THEIR HAIR AS THEY AGE, BUT WHEN IS IT NORMAL?  NORMAL HAIR LOSS IS USUALLY EVENLY DISTRIBUTED AND GRADUAL OVER TIME.  HOWEVER, MOST HAIR LOSS IN DOGS TENDS TO COME IN PATCHES AND IS USUALLY THE RESULT OF A DOG THAT SCRATCHES OR GNAWS EXCESSIVELY.  THE CAUSE IS THE REAL CONCERN.  IT COULD BE DUE TO A FLEA BITE, OR MINOR WOUND, BUT IT COULD ALSO BE DUE TO AN INFECTION OR SERIOUS AILMENT.  IF THE HAIR LOSS IS PATCHY OR UNEXPLAINED, HYPOTHYROIDISM OR ANOTHER PATHOLOGY MAY BE REARING ITS HEAD.  IF YOU ARE UNSURE, A VETERINARIAN SHOULD EXAMINE YOUR DOG AS SOON AS POSSIBLE.