My Old Dog Is Acting Strange? Here’s Why!

Just like people, when dog’s age, their metabolisms slow down, and the bodily functions are simply not as efficient as they used to be. The coat hair loses its pigment and natural luster and turns grey. The joints stiffen, lose their lubrication, and can achieve smaller motion ranges. The muscles lose their strength, contractibility, and tone. The senses decline causing impairments in sight, hearing, and taste. The nervous system becomes less sharp, and the dog responds to stimuli more slowly and less intensely.

So, if you were puzzled by the question, why is my old dog acting strange, the answer is because of the above-listed changes. In simple words, the age-related changes that generally occur in dogs affect both their physical and behavioral state. For that reason, it is not uncommon for older dogs to behave differently than usual or even strange.

This article will explain the dog’s aging process, the expected changes, and the likely behaviors to follow those changes.


In its original habitat, the dog’s ancestor’s lifespan was limited by food resources, shelter availability, defense abilities, and illness/injury resistance. Considering the complexity of these factors, it is only logical that the dog’s ancestor would have a shorter lifespan.

By domesticating the dog, we influenced and prolonged its lifespan. Our modern dogs live long enough to become real seniors and experience all the changes old age brings.

Old age is not a disease per se. However, it is linked with several diseases that occur as a result of the body’s decreased efficiency.

As weird as it may sound, an aging dog will express those age-related changes and conditions not only through physical limitations but also – behavioral changes.

Disinterest in social relationships, sleep pattern alterations, wall-staring, pacing, sitting in corners, increased anxiety and irritability, frequent and unexpected mood swings – these are just a small fraction of the strange behaviors old dogs manifest.

It is an interesting and unexplained curiosity that spayed females become more aggressive and irritable with age, while neutered males become calmer and more even-tempered.


Reasons why old dogs act strange

There are several reasons to why old dogs act strange, and these are the most important.

The Cognitive Dysfunction Syndrome (CDS)

Cognitive Dysfunction Syndrome (CDS) is the canine alternative of Alzheimer’s disease in humans. CDS is the number one reasons why old dogs act strange. Recognized as a true medical disorder, CDS involves an array of different behaviors.  

Cognition is the ability to conduct mental processes that allow memory, perception, learning, decisions, and awareness. In simple words, cognition enables the dog to receive information, analyze them and act in accordance. An older dog with CDS is incapable of doing the described chain of actions.  

The symptoms of CDS are classified in four different categories. To remember them more easily scientists came up with an acronym – DISH. The acronym stands for:

  • Disorientation 
  • Interactions
  • Sleep
  • House training. 

Disorientation means that old dogs need more time to remember and figure out the “where, when, what and who” in their lives. 

Interaction refers to the old dogs’ reluctance to be as sociable and friendly as they once used to. Older dogs thrive on peace and comfort. Socializing and making new friends is not their turf anymore. 

Sleep indicates the changes in old dogs’ sleeping patterns. Namely old dogs are more likely to sleep through the day and then restlessly pace and night. 

House training describes the old dogs’ proneness to accidents around the house. As dogs age their muscles loosen and they become less able to hold it. This physical limitation combined with the disorientation lead to frequent house soiling. 

The specific clinical signs associated with CDS include:

  • Excessive vocalizing, including barking, whining, crying, grunting 
  • Increased irritability and anxiousness
  • Onset of new fears and phobias
  • Clingy behavior toward the owner
  • Unusual destructiveness 

Finally, it is worth noting that older dogs are the ultimate creatures of habit. Certain habits, like going to bed time, feeding time, walking time, are deeply ingrained in their sub-consciousness. These habits are the only constant in their ever-changing world. 

The diminished senses 

Assume the following situation – you had impeccable sight and hearing abilities, and now all of a sudden, you cannot rely on them as much. You would be confused, right? Well, the same principle applies to dogs. 

As dogs age, the impulses that travel through the nervous system carrying messages slow down, and the senses diminish. Although all senses deteriorate, sight and hearing are affected the most. 

Sight – certain dog breeds are at higher risk of developing eye problems that can trigger an earlier onset of vision impairments. However, once old enough (+9 years), all dogs develop lenticular sclerosis. Lenticular sclerosis is an age-triggered issue in which the connective tissue inside the lens changes and causes vision deficits and nearsightedness. 

Hearing – in older dogs, total deafness can occur in as little as six months. Sometimes, the deafness onset is so sudden, and dog parents assume it is selective hearing – a dog’s decision that it does not always need to obey commands and do what it is told.

The aching joints

Painful joints are an unavoidable part of aging. All dogs are prone to joint issues. In some dogs, the joint issues may start earlier than in others, and sometimes the pain can be concentrated in certain joints while other times it affects all of them. Regardless, all senior dogs have joint issues, and joint issues are painful.

The pain associated with joint issues is low-grade but constantly present. Because of that, most old dogs learn how to ignore it and act like they are totally fine. However, when the pain threshold is passed, it is not uncommon for senior dogs with joint-related pain to start acting strange.

Pain is a powerful trigger, and a dog in pain must not be held accountable for its actions and strange behaviors.


old dog in pain

Old age is not classified as a disease on its own. However, it is associated with certain conditions. Some of those conditions can be quite painful. Since pain is manageable and preventable it is of paramount importance to be able to recognize pain in old dogs.

The most common signs that an old dog is in pain are:

  • Increased fatigue
  • Reluctance to walk on slippery surfaces
  • Reluctance to jump on and of beds
  • Reluctance to climb up and downstairs
  • Reluctance to squat while defecating
  • Reluctance to be touched or picked up
  • Difficulty lifting the head to take a treat
  • Difficulty getting up from a lying position
  • Limping, lameness, and weight shifting
  • Eating and drinking from a lying or sitting position
  • Restlessness or pacing at night
  • Avoiding once pleasing activities (playing, walking, bathing, grooming).

Recognizing the above-listed signs is not a straightforward process because as mentioned, most dogs will try to mask them. Plus, not all dogs will exhibit all of the signs. Some dogs can show a sign or two and on infrequent occasions.

Therefore, if in doubt, it is best advised to consult with your trusted vet. The vet will determine whether your senior dog is in pain and prescribe adequate pain management.


With proper care and some adjustments, senior dogs can have high-quality lives. However, when the age-related changes and conditions become unmanageable and start affecting the quality of life, it is time to consider end-of-life options.

It goes without saying that this is the hardest decision in the dog parenting experience. For a senior dog that is suffering, euthanasia is the best option. As painful as it sounds there comes a point when holding on is more painful and damaging for the dog than letting go.  


1. Why do old dogs act weird?

From senility and pain-causing ailments to irritability and anxiety, old dogs go through various age-related processes and changes that cause alterations in both their physical health and behavior.

2. How do I know if my senior dog is in pain?

Dogs usually try to be brave and hide their pain – this is part of their survival instincts. However, once the pain is too big to cover, senior dogs manifest it by decreased appetite and water intake, lying while sipping water, avoiding physical activity, reluctance to stand up and greet you and disinterest in interactive games and playing.

3. Is seven years old for a dog?

The exact answer depends on the breed. However, the rule of thumb is that dogs enter their senior years after the age of seven years. All age-related changes are likely to occur past this point.

4. What should I do if my senior dog is acting weird?

If your senior dog is acting weird it is best advised to schedule an appointment and consult with your trusted vet. Even if the weird behavior is triggered by age-related changes you expected, the vet’s pint of view is vital, as she/he could give you tips on how to manage the situation or even use medication that could improve the quality of life.


Just like senior people, old dogs go through several age-related changes. Some of those changes can be slowed down, others because of their predictability, can be prevented or at least managed.

The relationship between you and your trusted vet is essential throughout your dog’s entire life. However, it is vital once your dog enters its senior years. Proper care and regular checkups are the basis of ensuring your old dog’s quality of life is on a satisfactory level.

Today, the frequency and array of geriatric conditions in dogs are significantly more extensive than in the past. This is because the advancement in the field of veterinary medicine prolonged the dog’s lifespan. As a responsible dog parent, it is your responsibility to make everything within your power so that your dog can reach its entire potential lifespan.


  • Brad

    Hi I'm Brad, the founder of Having been a vet of 6 years I work alongside our team to provide valuable insight into your dog's health. I have a frenchie myself named Senzu who is my pride and joy!