In the US alone, there are about 90 million dogs and near one third are senior dogs. That means 30 million is the staggering number of senior dogs living in the USA. Aging is a time when dogs suffer from many health issues. There is a big chance your dog is in that group or will be soon. For that reason, we tried to compile the answers to many questions regarding senior dog health.
In this article we will address :
- What is aging, the process senior dogs go through?
- When senior dogs become senior dogs?
- How old is a dog in human years?
- Do dogs of some breeds live longer?
- What will happen to a senior dog?
- What senior dogs do when under stress (and why are they stressed?)
- What do senior dogs need (exercise; small routine changes; house soiling)?
- What food should senior dogs eat?
- What to do when nothing else works (drugs prescribed by Vets for senior dogs)?
What is aging in the first place?
Aging is an irreversible process occurring in pets during the last quarter of their lifespan. What basically marks this period is a gradual loss in cognitive (mental) and physical activity. Aging occurs for several reasons. One is the gradual accumulation of mutations in the cells that compose the body as time goes by. A mutation is an irreversible change in the normal DNA sequence. DNA is the footprint for the production of proteins needed for bodily functions. If there is too much DNA damage in many cells the normal functioning of the body will be altered, sometimes so badly altered that cancer and degenerative disease can arise. Actually, cancer is one of the main life-threatening diseases in old dogs (almost half of the senior dogs will die of cancer).
Scarry enough already.

Another cause of aging is the abundance of free radicals as the body tears off. Free radicals are chemicals produced in the body or through chemical transformations of the food. These chemicals are very reactive which means they will chemically react with normal molecules in the body, impairing the function of many organs. It is a vicious cycle because as the body ages more free radicals are produced (and the buffering mechanisms for free radicals become tired) and as more free radicals are produced, the faster animals will age. Inappropriate (or excess) food will produce lots of free radicals. To make things worse, free radicals can damage DNA as well (more DNA damage, more mutations), worsening the vicious cycle. Keep reading if you want to know at what age a dog is considered senior, what to expect and what can we do to improve their life quality.

When dogs turn senior dogs?
You may wonder what age a dog is considered to be a senior. Dogs are said to be old or senior as a rule of thump at 7 years of age but there are breed size differences. Larger breeds become old earlier (at 6 years and 7 months of age) and smaller dogs later (as we said before, from 7 years of age on). In summary: a 7-year-old dog can be considered senior.
Human years to dog years
How old is a dog in human years? People usually make an equivalence of 7 human years to 1 year in a dog’s life (this is the result of dividing human 70 years lifespan by the approximate 10 years lifespan of a dog. This estimate would be true if this linear mathematical function would correspond with biological reality which happens not to be the case). We will explain this: Dogs’ early development after birth (childhood) is very fast compared to humans to later level up. Reproduction in dogs is possible when they are around 6 months of age. Humans can reproduce when they are between 10 and 12 years old (average). So, you see? A one-year-old dog cannot be equivalent to a 7 years old girl or boy. We know this intuitively already for some time but only recently we are close to knowing the most exact equivalence of <human years to dog years thanks to scientific work based on DNA studies>.
According to this new more exact estimation, a 1-year old dog is equivalent to a 31-year-old human, and a 2-year-old dog is similar to a 42-year-old human
Here is a calculator to estimate how many years your dog is in human years:
If you would like to take a look at the whole picture, here is a table to estimate how many years your dog is in human years:

Therefore a 2 years old dog does not have the energy of a 14 years old boy. Or maybe we expect our 5 years old dog to be playful but forget he or she is the equivalent of a 57 years old man or woman. This is important to keep in mind when thinking about the quality of life of our pets as they become older.
What is the average age when a dog dies?
Although we hate the idea of our pets dying it is important to know what is the normal age when this happens.
General lifespan in dogs is 7 to 12 years.
In this infographic, you will be able to see the different causes of dog death in numbers:

Dog breeds and longevity
There are some interesting facts about breeds and longevity*:
- In general longer lived breeds are small, toy breeds
- Breeds with longest lifespans are <mongrels>, Jackrussels, miniature poodles, and whippets.
- Lifespan average of dogs: 12 years and 8 months
- Near 1 in 10 dogs live longer than 15 years
- Maximum observed lifespan in dogs: 22 years
- 64% of dogs die of disease as opposed to natural causes
*Information gathered from the scientific article based in UK dog populations: Michell AR. 2015. Longevity of British breeds of dog and its relationships with sex, size, cardiovascular variables and disease. The Veterinary Record
In this infographic, we will show you the 10 longest-lived dog breeds*:

In this infographic, we will show you the 5 shortest-lived dog breeds*:

*Information gathered from the scientific article based in UK dog populations: Michell AR. 2015. Longevity of British breeds of dog and its relationships with sex, size, cardiovascular variables and disease. The Veterinary Record
We cannot control when our pets die but we can take actions for them to live longer while offering them the best possible quality of life. The senior years of our dogs should be the best ever.

What to expect from a senior dog? (Signs of a dog at old age)
Senior dogs are less healthy than younger animals. Several diseases are common among the old dog population. Senior dogs suffer more of the following ailments: <Cancer>, Heart disease, Kidney/urinary disease, Liver disease, Diabetes, Arthritis, <Brain function> decrease, Muscle weakness, and Dental decay.

Medical problems can produce behavior problems in dogs, particularly if two ore more diseases appear simultaneously. For example, if a dog has arthritis and periodontal disease he will probably have joint ache and a sore mouth. This generalized pain will make this dog more prone to show aggressive behavior (wouldn’t we if we were in such discomfort). In another example, a dog with liver disease and diabetes and arthritis won’t probably have the energy nor they will move (his pancreas and liver are not doing their function on this respect and joints will likely be stiffened and painful). This dog will be inactive. There is less chance of behavior changes in old dogs if only one medical condition is present (which is not usually the case).
Several diseases in senior dogs create <stress> which brings more problems.
Even when diseases does not appear in senior dogs, the normal tear and wear will gradually produce Muscle degeneration, Organs degeneration, Low energy reserves, Low adaptation capacity. As a result of this gradual loss of function in the body, pets will show behavioral changes such as lower activity levels, lethargy (sleepiness), and lower appetite. People will notice they do not want to play as in the past, they sleep more and sometimes leave their food untouched.

Behavioral Responses to stressful situations
Pets’ life (just like ours’) is full of stressful situations. Stress is any condition (internal or external) that unbalances our internal equilibrium. When things get out of balance, we feel an unpleasant psychological sensation and we normally call it stress. Small internal or external changes are easily adjusted so that we quickly recover our wellbeing. This adaptation to changes occurs thanks to the work of the nervous system (autonomic nervous system) and the endocrine (stress hormones).
Those two systems are activated when we need to cope with challenging or fearful situations (aka, stress). Every time a dog is relocated, a new family member arrives or one of the owners travels for a long time, pets get stressed. Younger dogs (with brand new nervous and endocrine systems) are much better suited to cope with these situations. Old dogs, who have such organic systems tear down have a hard time dealing with those situations (they produce lower amounts of stress hormones and the nervous central system works less efficiently). Common stress-driven problems in older dogs are anxiety and aggressive behavior.
How to notice senior dogs stress?
We can notice senior dog behavior changes when they are under stress.
Some signs related to senior dog behavior that you can notice (indicating they are under stress) are:
- Changes in routine/activity
- Changes in sleeping patterns
- Altered social interactions
- Reduced water and/or food consumption
- Increase in fear associated huddling and shivering

What do senior dogs need?
Here we will go in depth about how to cope with an old dog needs and problems.
Senior age is not a nice time for many dogs. In general, our pats need the best quality of life that we can provide them. If there is one word that can summarize what we should do for our senior pets this is <enrichment>
In general, enrichment is any measure we take to provide our pets with stimuli that promote optimal psychological (mind) and physiological (physical) well-being.
There are several aspects to consider to make an old dog comfortable and healthy as far as possible.
What we want to achieve with our senior dogs is 1) to stimulate their mental activity and 2) routine daily exercise
This can be done through:
- Gentle exercise / play
- Introduction of new exciting toys
- No uncertainty
Remember that uncertainty is when dogs (animals in general) do not know what to expect. This is one of the bigger stressors in pets, but worse in senior dogs. Old pets just don’t tolerate changes in their routines. Changes should be handled in such a way that senior dogs get time to get used to the new situation. So, changes should be gradual and when this is not possible, we have to be patient and go on with some other suggestions below. This way we can avoid or diminish most senior dog behavior problems.
Inactivity / exercise
For dogs, games involving exploration, hide and seek, exploration, object retrieval, find hidden food, find thrown food (see video below) can be very rewarding. Remember to be gentle when putting these games in practice.

The enrichment approaches mentioned above considerably increase a positive social interactivity of senior dogs.
Small routine changes
Although we mentioned that routine changes are not very welcomed by senior pets and changes should be done gradually there are stimulating games in which we alter the normal everyday activities in small “doses”. For instance, we can take our dog for a small walk to a totally different place (with quite new different <smells>). Or <play the games described above> at unusual times. This little (non-excessive) changes can be very gratifying for our pets.
House soiling
House soiling can be reduced by:
- More frequent walks or garden outings
- Set an indoor toilet area
- Free access to outdoors (Interior dog doors can be installed)
Night insomnia
Let’s remember that the sleep-wake cycle is altered in senior pets. That means our senior dogs can be totally awake at night, and even worse vocalizing (aka. barking or howling). Senior dog anxiety at night can be reduced by trying these tips:
- Access to light (even artificial) during the day (this gives a better cue to the brain about the <correct light-darkness information>: light = day = awake; dark = night = sleep)
- Reduce access to artificial light at night (use blinds or other mean to make your pet sleeping area dark)
- Get your pet tired during the day <plenty of enrichment play time>
Nutrition for senior dogs
Besides enrichment, nutrition is the second key element that can make a real difference in the wellbeing of senior dogs. Older pets have different nutritional requirements than younger ones. Let’s remember that senior dogs can have their bodily functions overwhelmed by the excessive production and defective dealing with free radicals, those nasty disease-producing chemicals in the body.
Senior dogs require quality food and are benefited by nutraceticals
Nutraceuticals are medicinally or nutritionally functional foods (also called medical foods, designer foods, phytochemicals, functional foods and nutritional supplements)
More <detailed nutritional strategy for senior dogs> can be found in Biopetnology.com
Veterinary drugs for senior dogs (and cats)
Sometimes drugs are necessary for the old/senior condition in dogs and cats. This is particularly true for the very debilitating, Alzheimer-like, Cognitive Dysfunction Syndrome in dogs and cats
Current medical knowledge states that this condition cannot be cured but delayed and improved with proper enrichment and nutritional strategies. Medication can also play a positive role in the quality of life of senior dogs and cats.
There are specific drugs that can be prescribed by your veterinarian. These are some of them:
Selegiline. This is licensed for dogs but also prescribed off-label for senior cats. It improves mental problems in senior dogs and cats because it protects the brain against free radical damage.
Propentofilline. This drug can improve the condition of depressed or inactive dogs and cats (although more research about the action of this drug is needed). It works by bringing extra blood flow to the brain and muscles. When muscles receive more blood (thus more nutrients including oxygen) dogs and cats will have more energy available to get into action.
Nicergoline. Helps with behavior problems in dogs and cats by increasing brain blood flow and improving neuron performance.
Adrafinil. Keep senior dogs awake during the day (<dogs and cats sleep cycle is very peculiar>) improving sleep quality during the night.
Ask your veterinarian about the possibility of using these drugs to improve your senior dog or cat’s quality of life in case the problems are too severe and other approaches are not satisfactory.
Summary
Senior dogs suffer from several diseases and show behavior problems (often simultaneously). Most of these conditions can be addressed with more attention and a loving attitude towards our pets but especially providing a safe physical environment, moderate engaging exercise, and proper nutrition. Let’s remember that we will also be old someday.
Let us know if you have a senior dog and what problems have you encountered (you may post your questions as well).
You will probably enjoy our article on <dog comfort at home> (and what this has to do with dog health).