Significance

• It is important for owners to understand normal changes and changes that require special attention.
  
  

Normal Changes

• Female dogs typically come into their first heat cycle between 8 and 16 months. This can cause your dog to either become more withdrawn or more aggressive. High energy dogs usually start to tone down at about 12 months, so a suddenly calmer dog is also normal.
  
  

Changes that need Attention

• If you notice that your dog is being more destructive than usual, then physical pain might be the cause of this personality change.
  
  

How to Know

• The only way to know for sure if your dog's new behavior is the result of normal development or something more serious is by taking your dog to a veterinarian.
  
  

Fun Fact

• At the age of one year, a dog is as physically mature as a 15-year-old person.