Brain Aging Causes Personality Changes in Old Dogs

Adrienne is a certified dog trainer, behavior consultant, former veterinarian assistant, and author of "Brain Training for Dogs."

What Happens in Old Dogs to Trigger Behavior Changes?

As your dog ages, several changes occur in his brain which may affect the way he acts and interacts with you. As much as this may sound like bad news, consider the good news: Dogs are living longer lives due to better veterinary care. This is also why we are seeing many more conditions related to old age, such as cancer, organ failure, painful arthritis, and yes, behavior changes due to old age.

But what happens exactly to the dog's brain to cause these cognitive changes? Do dogs develop the canine version of Alzheimer's disease? To better understand this, we must look at the dog's brain more closely.

Free Radicals and the Process of Oxidation

Aging in dogs is not a disease, it's a process. The brains of aging dogs undergo several changes at a molecular and cellular level. A main cause of aging is unstable oxygen molecules better known as free radicals, which damage the cells and cause loss of brain function under the form of behavioral changes.

While several free radicals are present in the dog's environment, a great quantity are simply produced by the dog's own body. It's a known fact that the mitochondria of a young dog produce more energy and less free radicals; whereas, the mitochondria of older dogs produce less energy but increased numbers of free radicals.

Why are dog brains so vulnerable to free radicals?

According to Hill's Vet, the brain is a target of free radicals because it has a high lipid content and has limited antioxidant defensive mechanisms ad limited repair capabilities. Last but not least, the nervous system tissue is particularly vulnerable to attack by free radicals.

While this process of oxidative damage to a dog's brain cannot be stopped, it can be slowed down by antioxidants, vitamins and minerals and several other methods.

What Behavior Changes Should You Expect in an Older Dog?

Several behavior changes may be seen in older dogs. Some of these changes tend to appear gradually over time, rather than all at once. If your dog shows behavior changes, see your vet, as they may indicate some medical problem or cognitive issues. Following are some common changes you may notice in your aging dog.

Different Sleeping Patterns

Why do old dogs sleep a lot more? This is a normal part of the aging process, so it's quite natural for your senior dog to sleep a lot more compared to when he was younger. Interestingly, puppies and older dogs tend to dream more compared to adults, so you'll likely see your older dog acting out his dreams in REM stage quite often. The old adage "let sleeping dogs lie" is true and you should avoid abruptly waking up your old pal to prevent him from getting startled.

Why does my old dog wake up in the middle of the night? Along with sleeping more, you may notice different sleep-wake cycles. Your older dog may sleep more during the day and then have difficulty sleeping at night. This can be a sign of canine cognitive dysfunction, the canine version of Alzheimer's disease, but can also be a sign of discomfort or pain. Or it could be dog wakes up because has a need to go potty, which brings us to the next behavior change.

Accidents Around the House

Why do older dogs have accidents around the house? Something you'll likely notice is accidents around the house in previously well house-trained dogs, why is this happening? Elderly dogs can be prone to several medical conditions that can increase their urination or defecation frequency or can cause them to have less control over their bodily functions, explains veterinarian Theresa DePorter.

Cognitive dysfunction may be a cause, but so can urinary tract infections, kidney disease, hormonal changes, gastrointestinal problems and neurological issues.

Mobility issues may also cause a dog to be reluctant to move about to go potty or reluctant to go to the door to inform you about the urge. Accidents around the house when the owner is away may be a sign of separation anxiety in older dogs.

Onset of Separation Anxiety

Why is my old dog so clingy? Many owners of senior dogs notice their dogs getting more clingy, some up to the point of developing separation anxiety, something they have never suffered earlier in their lives. This can stem from the fact that older dogs may have trouble coping with changes in their routines and the fact that they may be subject to age-related vision or hearing loss which makes them feel vulnerable and anxious. They may, therefore, rely more and more on their owners and feel vulnerable when they are left alone.

Prone to Get Easily Irritated

Why is my old dog getting aggressive? If you thought grumpiness only affects old men, think again—old dogs tend to get grumpy too. If you notice the onset of aggression in your dog, consider that it can often be a sign of a medical problem. Old dogs are prone to painful conditions such as arthritis and painful dental disease. On top of that, vision or hearing loss may make them more likely to startle from unexpected touches or noises.

Also, consider that a dog who has painful joints and mobility issues is more likely to react by growling, snarling, snapping or even biting to get out of an unpleasant situation rather than removing himself by getting up and leaving as he may have done in the past before getting old. This means old dogs require close supervision so they are not pestered by a child or other pets in the household.

This may not be the ideal time to get a new puppy, especially if your older dog is more irritable and less mobile. Sometimes younger dogs may get into squabbles with older dogs, and this is often believed to be attributed to the younger dog trying to rise in rank, when, chances are, the conflict arises simply because older dogs may fail to offer appropriate social signals due to physical impairment, explains veterinary behaviorist Lisa Radosta.

Phobia of Noises

Why is my old dog more reactive to noises? Some older dogs may become noise sensitive as they age. This may sound strange if you think that many older dogs start losing their ability to hear as they age so you would assume that noises would bother them less. Dogs may become more noise sensitive because they feel more vulnerable since they are more reluctant to get up and check the noise source or it could be they may not be able to remove themselves from the source of the noise.

Some dogs may also become more reactive to noises because they cannot determine its source as before or they may be unable to cope with stress as before. Vocalizations under the form of barking or whining as a result of noises may, therefore, increase with aging.

Appearing Confused and Forgetting

Why is my old dog acting oddly? Canine cognitive dysfunction, just as Alzheimer's disease, takes place when there is a decline in a dog's cognitive ability. Affected dogs may appear confused, forget commands and sometimes may even not recognize friends or their owners. Affected dogs may forget where to potty or which door to ask out. They may pace at night, stare at things or get stuck in corners. Some dogs may engage in obsessive behaviors or develop anxious behaviors.

As much as all these behavior changes may sound like bad news, the good news is that there are many things you can do to make the life of your senior dog better. In the next paragraphs, we will see how.

Dogs are not our whole life, but they make our lives whole.

— Roger Caras

Tip for Coping With Senior Dog Behavior Changes

As seen, senior dogs go through several behavior changes. When caught early, the first signs of canine cognitive dysfunction can be managed fairly well with the aid of your veterinarian. There are many steps you can take to help your senior dog cope better with the aging process. Following are ways to help your senior dog.

  • See your vet. As we have seen, many times what appears to be a behavior problem may actually turn out being a medical issue. Once your dog's medical problems are addressed, you may see a change in behavior for the best. Senior dogs benefit from twice-a-year wellness exams so issues can be caught early.
  • Manage painful conditions through acupuncture, massage, herbs, chiropractic care, physical therapy or drugs as prescribed by your vet.
  • If your dog checks out well in the health department but likely has some level of cognitive dysfunction, consider that the drug L-Deprenyl. Also known as Anapryl or selegiline hydrochloride, it can be beneficial.
  • Some nutraceuticals can be given under the guidance of your vet. Novifit® by Virbac has shown to alleviate cognitive dysfunction signs in a double-blinded, placebo-controlled study. ProNeurozone® by Animal Health Options combines antioxidants and vitamins to slow down the progression of cognitive dysfunction, while Senilife® by Ceva has shown effectiveness within 7 days, explains veterinary behaviorist Lisa Radosta.
  • Keep your dog lean, as there is less weight putting pressure on the joints.
  • Feed a good senior-dog diet. Antioxidants such as vitamin E protect the cell membranes from the damaging effects of oxidation, and thus, can help improve cognitive abilities in senior dogs. Vitamin C also plays a strong role in preventing oxidative damage. Omega 3 fatty acids promote the health of cell membranes and are beneficial thanks to their anti-inflammatory properties. Acetyl L-Carnitine and Alpha-lipoic acid are also healthy supplements that Dr. Wynn, a nutritionist at Georgia Veterinary Specialists in Sandy Springs, Georgia, suggests for dogs with cognitive dysfunction in addition to antioxidants.
  • Dr. Gary Landsberg, a veterinary behaviorist notes that a high intake of fruits and vegetables have antioxidant and anti-inflammatory properties which may help fight cognitive dysfunction. Not to mention, the extra beneficial flavonoids and carotenoids.
  • Keep on training and exercising your dog. Moderate exercise under the form of walks keeps blood flowing to the joints. Ask your vet about an appropriate regimen. Also, keeping the dog exercised and mentally stimulated through training and puzzles may keep the mind busy and can reduce the instances of pacing in the night.
  • Provide environmental enrichment. Exercise, rotating toys on a weekly basis, food puzzles, foraging. "With more blood flow to a particular organ, you’ll see more nerves firing and more synaptic involvement, and you should definitely increase cognitive ability at that point, too," explains Jonna Kanable, a Certified Canine Rehab Practitioner (CCRP) working for Atlanta Animal Rehab and Fitness in Roswell, Georgia.
  • A predictable routine is reassuring to senior dogs, so best to minimize the chances for abrupt changes which may cause stress.

© 2015 Adrienne Farricelli

Adrienne Farricelli (author) on August 30, 2015:

Sounds like they were great pals. Good thing old dog Buck found an effective, yet gentle way to tell he had had enough and that Barney was getting the message.

Lawrence Hebb from Hamilton, New Zealand on August 21, 2015:

Reading this reminded me of when Barney was a pup. Our minister would call round at times with his Dog 'Buck' an old Labrador, we'd put them both in our yard and 'Buck' would literally shedd years as he played with Barney.

Once he'd had enough Buck would lie down and wait for Barney to come close, then up would go the paw and with a mighty thump it would come down pinning Barney who wouldn't even yelp, he'd just lick Buck as if to say "Okay old timer, I get the message" Buck passed away six years ago but for two years every time we passed Buck's house Barney would look for him!

Really enjoyed this hub


Kevin Goodwin on August 14, 2015:

Changes in your dogs personality can occur as early as 7 years old, there is now dog food specifically for this issue.

My old dog is acting strange: what to do

If you notice a change in your old dog’s behavioral pattern, such as an increase in aggressiveness, destructive behaviors or the obsessive repetition of certain actions: consult your vet. A professional can verify the health status of your dog and perform the necessary tests needed to determine if any health problem may be causing the behavioral problems.

If an organic cause has been ruled out, we advise consulting a canine educator or ethologist. They will be able to help you correct inappropriate behavior with a set of developed guidelines.

In addition, it is essential that your older dog is surrounded by a positive environment and receives constant proper care both to prevent and treat behavioral problems.

Brain Aging in Dogs: Symptoms & Treatment

What is brain aging in dogs?

Just like the rest of the body, the brain is affected by the aging process. Damage to the brain’s cells can lead to changes in your dog’s behavior and alertness.

It's important to remember that aging is a natural part of your dog's life. Half of all dogs 8 years and older will show some signs of brain aging, and as your dog ages, he may begin to act differently. Thanks to advances in medicine and pet nutrition, the right dog food and veterinary advice can help limit the effects of brain aging and maintain your dog’s activity level.

What causes my dog’s brain to age?

Aging takes a toll on a dog's entire body, including his brain. In recent years, scientists have made great strides in understanding the aging process. Today, many experts agree that aging is primarily caused by unstable oxygen molecules called free radicals. As the brain ages, free radicals cause damage to the cells. Although some free radicals may be caused by the effects of environmental conditions, the majority are produced by the body’s own metabolism.

The aging process attacks all body systems and organs in a dog, including the brain. The result is a loss of brain function, and often, the appearance of behavioral changes that were not present in a dog’s younger years.

Why is the brain susceptible?

  • High lipid content, a prime target for free radicals
  • High demand for oxygen
  • Limited antioxidant defense and repair capabilities
  • Nervous System tissue is especially vulnerable to attack by free radicals.

Healthy Older Brain

Older Brain with Damage
MRI scans show loss of brain tissue in affected dogs.
Note: MRI scans are not harmful to dogs.

Older, compromised mitochondria produce less energy and more highly toxic free radicals

  • Mitochondria are a source of energy production within cells, but also produce highly toxic free radicals as a by-product
  • As the brain ages, mitochondria produce an ever-increasing number of free radicals
  • Damage caused by free radicals leads to reduced brain function and possible behavioral changes

Little can be done to stop free radicals from being produced. Antioxidants, vitamins and minerals have been found to counteract the damage caused by free radicals and may help maintain normal behavior for a long and healthy life.

Is my dog showing signs of brain aging?

Changes in brain function occur very slowly. The first thing you’ll notice may be small differences in behavior, such as increased sleeping, lack of energy or irritability. You may not notice these changes until they start to interfere with your dog’s everyday life. The following signs are commonly used by veterinarians in the diagnosis of brain aging.

  • House-soiling accidents
  • No longer "asks" to go outside
  • Doesn't greet family members
  • Does not want attention/petting
  • Does not recognize familiar people or places
  • Does not respond to verbal cues
  • Sleeps more during the day or less at night
  • Appears lost or confused in the house or yard
  • Wanders or paces
  • Stares into space or at walls

If any of these signs are affecting your dog, discuss them with your veterinarian.

Treatment: The importance of nutrition

To keep your dog acting young and healthy, proper nutrition is important. As your dog ages, continue to feed him foods rich in antioxidants and essential nutrients to keep him active and alert. Older dogs can continue to have a high quality of life and the food your dog eats plays an important role in his overall health and well-being. Balanced nutrition is an essential part of an active, healthy lifestyle. For accurate diagnosis and treatment options, always consult your veterinarian and ask them to recommend the best food for your dog’s brain health.

Why Do Dogs Suddenly Become Aggressive?

Dog aggression toward people may involve a variety of behaviors such as barking, lunging, snarling, growling, snapping, nipping, and biting. Dogs can also have "leash aggression," which occurs when they're on walks and may include lunging, pulling, and barking, mostly at other dogs.

It's not normal when a happy, loving dog suddenly exhibits aggressive behavior for no obvious reason. If you take a closer look, always enlisting the help of your vet, you may be able to figure out the cause of your dog's behavior change.

  • Fear can elicit sudden behavioral and temperament changes such as aggression. If the aggression is temporary, it might be that your dog is simply reacting to a perceived threat. However, it's still important to figure out why your dog reacted as it did if it hasn't done so in the past. You don't want to be caught off guard or put your dog in a situation that could lead to another bout of aggression.
  • Many common health problems can also affect your dog's personality, and some can be serious. This is especially common as your dog becomes a senior and begins to develop age-related diseases. In some cases, sudden aggression in an older dog may be related to canine cognitive dysfunction or dementia.
  • If your dog's aggression is accompanied by other symptoms, like hair loss, weight gain, or lethargy, it could be a sign of hypothyroidism. If accompanied by convulsions or rapid mood changes, it could be from seizures. Brain damage to specific areas of the brain from tumors, thyroid issues, and trauma can also result in aggression problems.
  • An ear infection could be the culprit if your dog suddenly becomes aggressive in the presence of loud noises.
  • If eating makes your dog grumpy, a dental issue may be the cause.
  • An injury could be the source of your dog's sudden aggression if it seems to be in pain. To explore this possibility, start with a cursory physical exam. Look for swelling, cuts, torn paw pads, insect stings, or tender spots. Anything that looks out of the ordinary could be hurting your dog and causing aggression.
  • Check the inside of your dog's mouth if you feel safe doing so to see if a foreign object may be causing the aggression. It might be a daunting prospect if the dog is feeling snappy, but the problem could be something as simple as a piece of food, toy, or stick caught in your dog's teeth. If your dog threatens you in any way, though, leave the oral exam up to your veterinarian.
  • Take note of any and all other symptoms, such as vomiting, diarrhea, loss of appetite, and lethargy, and write this information down so you can share it with your veterinarian.

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