How can I tell my dog’s age?

Article by Dr Ivana Crnec

Dr Ivana Crnec is a licensed doctor of veterinary medicine, a passionate writer, and a devoted pet parent.

One aspect of having a rescue dog is not knowing quite what your canine friend got up to before you met. For example, how old is your dog? Unlike with a pedigree, rescue dogs don’t come with a birth certificate.

While you won’t be able to pin it down to the exact date, there are ways that you can take an informed guess as to when your dog was born. As a vet, here are some of the techniques that I use.

Dental examination

With a puppy, determining the animal’s age is relatively simple. Here are some basic facts you need to know before making an educated guess on your pet’s age:

  • Milk teeth start piercing the gums at one month old
  • Milk teeth start falling at around three to four months
  • Permanent teeth start coming out at five months
  • All permanent teeth are in place at approximately seven to eight months. 

In older dogs, you’ll probably need a more experienced eye to spot the clues. In fact, it’s likely that you’ll need to speak to your vet whose training will help them make an estimate based on:

  • Presence of ridges and unevenness of the front (incisor) teeth
  • Level of erosion on the surface of the canine teeth
  • Amount of tartar build-up
  • Amount of staining
  • Number of missing teeth. 

Such dental examinations used to be the gold standard of gauging a dog’s age. Today, though, their usefulness is less certain because so many different variables can influence dental wear, such as::

  • Congenital problems: A dog with misaligned teeth will develop uneven wear early in life, sometimes even before puberty
  • Diet: A dog eating soft food will experience less wear on their teeth than a dog that eats harder foods, such as kibble, and a dog that regularly gnaws on bones will have significant wear level even at an early age
  • Overall oral health and hygiene: A dog that has its teeth regularly brushed (daily) and scaled (once or twice a year at the vet’s surgery) will have healthier teeth than a dog of the same age that hasn’t had such dental care
  • Chewing tendencies: A dog with behavioural issues that manifest themselves through excessive and destructive chewing will experience dental wearing much earlier than a dog without chewing habits
  • Dental trauma: Fractured teeth, tooth loss, and dental diseases can all cause premature and uneven teeth wearing. 

Considering all the above, it is safe to assume that this method is not 100% reliable. Studies suggest that dental age estimates tend to be more accurate in puppies and adult dogs younger than four years of age. 

Eye examination

This must be carried out by an experienced vet. To conduct the examination and estimate the dog’s age, the vet will place it in a darkened room and shine a penlight into their eyes.

When light touches the eye’s surface, it creates two types of reflections: nuclear and capsular. The vet will estimate the dog’s age based on the presence and features of those reflections.

Studies suggest that this method is more accurate in dogs older than four years of age.

Dog DNA tests

Dog DNA tests are a hot topic right now. They can be used to gain a plethora of useful information that is easy to use and readily available. There are several DNA tests on the market that promise specifically to determine your dog’s age. However, unlike a quick trip to the vet’s, these dog DNA tests can be pricey.

There’s another potential drawback, too. Genetic or biological age is not the same thing as the dog’s chronological age. The biological age is based on the dog’s current health status and predicts the dog’s lifespan. Knowing the biological age can be more important medically that knowing how many years your dog has been on the Earth but it might not help you mark in the diary exactly when to buy the doggy birthday cake.

Other methods

As dogs age, certain body functions deteriorate and individual traits change. For example, hearing and vision deteriorate, muscle tone decreases, and coat hairs turn white.

These changes can help to determine that a dog is old but not how old. What is more, these changes are not always age-related. Many health problems and conditions can trigger their onset. For example, an untreated middle ear infection can impair the dog’s hearing sense while stress may cause premature hair pigment loss.

Does it matter how old my dog is?

Having said all that, you might wonder “Is it really that important to know your dog’s exact age?” After all, we adore our canine companions, regardless of their age.

Yes, it is important. Dogs at different stages of their lives have different nutrition, exercise, and veterinary care requirements. Being a responsible dog parent means fulfilling those requirements as fully as possible, which involves knowing the dog’s age or at least a rough estimate of it.

So, in that case, which method of measuring your dog’s age is best? There is, unfortunately, no perfect answer. However, as a general rule, if you suspect your pooch is younger than four years old, then a dental examination by your vet will give you the best answer. Older than four and your vet will most likely recommend an eye inspection.

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