Defining Life Stages

Professional pet care recommendations require a fluid, evolving approach that changes as the pet moves through different life stages. On the one hand, it is helpful to understand the six basic life stages of dogs and cats. On the other hand, it is very difficult to say at which time a dog or cat moves from adult to senior to geriatric. There is also a very wide range to those categories depending on the breed. These ranges provide an approximate framework.
Life Stages Dogs Cats
Neonate birth to 6 weeks birth to 6 weeks
Pediatric 6 weeks to 6 months 6 weeks to 5 months
Adolescent 6 months to 2 years 5 months to 1 year
Adult 2 years to 7 years 2 years to 8 years
Senior (last 25% of expected lifespan) 7 to 10 years 8 years to 14 years
Geriatric (beyond expected lifespan) over 10 years 14 years+

Pets enter the geriatric stage based on breed, chronic illness and individual differences. For example, a miniature poodle may live to be more than 16 years old, but a St Bernard may live to be 10.

The age when your beloved dog becomes “geriatric” will depend on many factors. Signs that should alert you to the need for a veterinary evaluation include:

  • Sudden weight loss or gain
  • Significant increase in appetite
  • Diarrhea lasting over three days
  • Change in housebreaking
  • Inability to chew dry food
  • Sudden collapse or weakness
  • Persistent coughing or gagging
  • Lameness lasting more than five days
  • Noticeable decrease in vision
  • Open sores or scabs that persist for more than one week
  • Foul mouth odor or drooling that lasts for more than two days
  • Repeated vomiting
  • Difficulty in passing stool or urine
  • Excessive panting
  • Blood in stool or urine
  • A seizure (convulsion)
  • Breathing heavily or rapidly at rest
  • Lameness in more than one leg
  • Increasing size of the abdomen
  • Increasing inactivity or amount of time spent sleeping
  • Hair loss, especially if accompanied by scratching or if in specific areas
  • Sustained, significant increase in water consumption or urination


This list is from The American Animal Hospital Association.