Dog Aging Chart: Calculating your Pet’s Age in Dog Years, Life Expectancy & Age-Related Problems in Dogs

If your dog was a human, how old would he or she be? Like all curious pet parents, we’re sure you’ve also wondered what’s your pet’s age in dog years. Probably that’s why you’re here reading. People have been trying to find a good way to convert dog years to human years since the 1200s. One of the earliest examples of this is an inscription at Westminster Abbey that dates back to the year 1268 and calculates that one human year is equivalent to nine dog years.
 
However, recent studies have shown that your pet’s human-equivalent age is not a simple linear equation. We know that dogs age at different rates than humans. Larger breeds tend to age faster and hence have a smaller lifespan than smaller breeds. Compared to humans, dogs age more quickly at the beginning of their lives and slower toward the end. Therefore, calculating your dog’s age relative to yours is a bit tricky, but luckily it’s possible.

Aging in Dogs

Why is it important to know your dog’s age?

Knowing your pet’s age helps you provide for them appropriately. A puppy needs different care than an adult or senior dog. Their training, exercise, veterinary, dietary and even grooming requirements change with their age.
 
Growing puppies have different training & dietary needs than a senior dog. You also need to keep a closer tab on their vaccination schedules while they’re young. As dogs mature, their training and vaccination needs may settle. Of course, their diet will need to change to suit their adult life stage and lifestyle. Their exercise and grooming needs too, may change with age.
 

 
As our pets get older, they need extra care and attention. Aging is not a disease, though senior dogs may develop age-related problems. While it’s easy to spot the outward signs of aging such as greying hair and a slower pace, the changes in pet’s internal organs are far less evident. But their bodies are constantly changing, and their care should support those changes.
 
An older dog is more likely to develop diseases such as diabetes, heart, kidney and liver diseases, arthritis or even cancer. But good care allows them to live happy, healthy and active lives in their senior years. A healthy and balanced diet lowers the risk of developing such life-threatening diseases. Regular veterinary examinations can detect problems in older pets before they turn life-threatening. Tracking your dog’s age helps you plan for appropriate care, prepare for age-related problems and thereby, improve life expectancy and the quality of life.
 

Aging Profiles & Longevity in Dogs

Do all dogs age the same?

The life of a dog is broadly divided into three main stages: Puppyhood, Adult, and Senior (Geriatric). A dog is considered a Puppy during his early growth period. This is when he grows from a tiny lump of fur to full adult size. This is characterized by rapid changes in size and weight. Bones & teeth grow quickly, and the puppy is extremely active and agile. This life stage is equivalent to the first 15-18 years of human life.
 
The dog is considered an Adult as soon as sexual characteristics start appearing, for example, the onset of heat cycles in a female puppy. The dog undergoes many personality and behavioral changes, attaining full emotional maturity over the period of this life stage. This is equivalent to age 20 – 40 years in humans.
 
The Geriatric stage in dogs is marked by a general decrease in activity levels, tendency to sleep more, and fading enthusiasm in walks or other physical activities. In some pets, it’s also the onset of age-related problems that are less common in younger ages. The dogs become less mobile and may develop joint problems such as arthritis, or teeth and gum issues. They also start losing vision, and other senses. This is similar to humans aged beyond 40-50 years of age.
 
Aging profiles in dogs vary across different breeds & adult sizes. In general, larger dogs grow slower in the puppy stage and age faster in the geriatric stage. They also have a shorter lifespan compared to smaller dogs. However, exceptions may be noted depending on breeds and living conditions.
 

Dog Years VS Human Years

The terms “dog years” and “human years” are frequently used when describing the age of a dog. However, there are two diametrically opposite, almost conflicting nomenclature systems in which these terms are defined. Both systems are correct and widely used.

1. The first system uses “human year” to represent a 365-day long calendar year. “Dog year” is the equivalent time of the dog’s lifetime, as a calendar year would be for a human. For example, a 5-year-old dog would be 5 human years or about 36 dog years old.
2. The second system uses “dog year” to represent a calendar year in a dog’s life. “Human year” is the equivalent age of a human being. In this system, a 5-year-old dog is considered to be 5 dog years or about 36 human years old. This is the exact opposite of the first system, and the nomenclature we’ll use throughout this article.

Calculating Your Dog’s Age in Human Equivalent

For years, people have been quoting the Seven-Year Rule – that 1 dog year is equivalent to 7 human years. However, this rule does not take into account the breed or size of the dogs. The origin of the seven-year rule (read: myth) is unknown. It’s believed that the formula was devised on the assumption that people lived to about 70, and dogs to about 10 years of age, approximately. Similarly, several other formulas have been suggested, but none scientifically proven correct or consistent enough.
 
The American Veterinary Medical Association suggests the following as the most acceptable guideline to calculate your dog’s age equivalent to human years.

1. The first year of the puppy’s life is equivalent to 15 human years.
2. The second dog year equals about 9 human years.
3. Thereafter, each dog year converts to about 4 human years until the dog reaches their geriatric stage.
4. Larger dogs age faster than smaller dogs in their geriatric stage – each dog year in this stage is equivalent to 6 human years for larger breeds, 4 human years for smaller dogs.

There are several factors to consider while estimating the age of dogs and not all of them can be documented precisely. The National Center for Health Statistics doesn’t keep records for dogs. Instead, there are three main sources for data on the longevity of dogs: pet-insurance companies, breed-club surveys, and veterinary hospitals.
 
The longevity studies include studying the lifespans and medical histories of several hundreds of dogs from various size classification, breeds and age groups. The results are compiled and generalized for public use. It is important to understand that these numbers are merely indicative, and do not represent the exact physical and mental state of your furry baby.
 

Estimating Age when Birth Details are Unknown

If you’ve adopted a rescued dog, his exact birth details and history may not be known. This may make it even more complicated to calculate the dog’s age. However, a fair estimate of a puppy’s age can be made by looking at the physical characteristic of the dog – especially the teeth.
 
When a puppy is born, he’s toothless, and his eyes and ears are closed. They open their eyes in about 2 weeks, the ears take about 3 weeks to open. This is also when the first teeth start appearing. The puppy will have a full set of 28 baby teeth by 6 – 8 weeks of age.
 
At about 2 months of age, the temporary teeth will start falling as the adult teeth push them out. By the age of 7 – 8 months, all temporary milk teeth will be replaced with a full set of 42 clean white permanent adult dog teeth.
 
As the dog turns adult, the teeth will become a little dull and yellowing may be noticed in the rear teeth by the age of 1 – 2 years. This is a good time to start a brushing routine with your dog. At age 3 – 5 years, some tartar buildup and wearing are noticed. By 5 – 10 dog years, signs of tooth wear and dental diseases get more prominent.
 
With geriatric dogs, heavy tartar buildup may be noticed by the age of 12 – 15 dog years. Some teeth may be missing or loose. Cloudy eyes, grey hair around the muzzle, eyes, and face, loosening skin and stiff legs are other signs of aging dogs.
 

 

Effects of Aging in Dogs

Dogs and humans age similar in the way their bodies change. Senior dogs are often less active and playful. They love sleeping and avoid running, jumping or other physical exercises. They become more sensitive to changing weather conditions and may develop digestive or skin issues more frequently. They’re prone to a number of diseases and may lose interest in play or daily activities.
 
Some age-related effects observed in aging dogs are:

• Loss of vision and/or hearing
• Loss of teeth and periodontal diseases
• Decreased activity, lower energy levels (partly due to reduced lung efficiency)
• Frequent gastric & stomach upset, and decreased digestive tolerance
• Weight gain & obesity
• Weakened immunity, increasing infections
• Diabetes
• Weakness in muscles & bones
• Drying, darkening and brittle skin, loss or greying of hair
• Thicker and more brittle nails
• Arthritis, hip dysplasia, and other joint problems
• Urinary issues or toilet-accidents (incontinence in both genders and prostatitis in male dogs)
• Cardiac & respiratory issues due to reduced heart and lung efficiency
• Cysts and tumors
• Unusual aggression or irritability
• Dementia or confused/disoriented behavior

Factors Affecting Life Expectancy

The average life expectancy of a randomly-bred dog (also known as mongrel or mutt) is 13.2 dog years. However, it varies greatly across breeds and dogs living in different conditions. As we’ve seen in the table above, larger dogs have a shorter lifespan than smaller dogs. Many attempts have been made to study this relation between breeds/size and longevity, but no conclusive results have been found.
 
The Dog Aging Project is studying the aging process in dawgies, using geroscience research to “delay aging and promote healthy longevity.” Some of the factors that impact life expectancy in pet dogs are:
 

1. Diet – Your dog’s food greatly impacts his life and longevity. Pets that feed on a balanced and complete diet generally live longer and are healthier than those that are fed a packaged commercial, or otherwise unbalanced diet. Read more about how food can change your dog.
2. Spaying and Neutering – Whether your dog is sterilized or intact, and the procedure used to sterilize your pet may impact their life expectancy. While some studies have shown that spaying and neutering may reduce the risk of early deaths in dogs, some other studies show different, rather contradictory results. Thus, careful deliberation is needed before you decide to get your pet spayed or neutered.
3. Exercise – A tired dog is a healthy dog. Your pet is likely to stay healthier when his body and senses are constantly exercised. The exercise your dog receives must be appropriate to suit his life stage. A puppy needs more physical exertion while a senior dog must be engaged in more mental exercises to keep them healthy and happy.

One of the most important aspects of good pet parenting is to understand your dog’s needs. It starts by planning and providing age-appropriate care to your darling. Watching a puppy grow into a beautiful old dog is perhaps the most beautiful experience ever. Participating and positively contributing to the process is the next best.