Why Do Older Pets' Behaviour Change, and What Can You Do?

June 26 2026, 8 min reading time

Why Do Older Pets' Behaviour Change?

As pets age, changes in their behaviour are common. If you've noticed your senior dog or cat becoming clingier, withdrawn, anxious, confused or irritable, there is often an underlying reason.

One of the most common causes is age-related cognitive decline, but pain, dental disease, sensory loss and changes in routine can also affect your pet's behaviour. Understanding these changes can help you provide the support and care your pet needs during their golden years.

Older pets may experience behaviour changes due to cognitive decline, arthritis and joint pain, dental disease, hearing or vision loss, anxiety caused by routine changes, or underlying medical conditions. If your senior pet's behaviour changes suddenly or significantly, consult your veterinarian to identify the cause and discuss treatment options.

Cognitive Decline in Senior Pets

Just as some people experience dementia as they age, older pets can develop a condition known as Cognitive Dysfunction Syndrome (CDS). This age-related decline in brain function can lead to noticeable behavioural changes.

Signs of Cognitive Dysfunction Syndrome

Disorientation: Getting lost or appearing confused in familiar surroundings.
Changes in interactions: Becoming unusually clingy, withdrawn or less interested in family members.
Sleep-wake cycle changes: Waking during the night, vocalising excessively and sleeping more during the day.
House soiling: Forgetting litter box habits or toileting indoors.
Reduced activity levels: Less interest in play, walks and daily activities.

How to Help a Pet with Cognitive Decline

Feed a senior diet rich in Omega-3 and Omega-6 fatty acids, including DHA, to support brain health.
Consider supplements designed to support cognitive function.
Avoid scolding your pet for accidents indoors.
Continue providing training, puzzles and enrichment activities to keep their mind active.
Speak with your veterinarian about anxiety management or medications that may help.

Arthritis and Joint Pain

Pain from arthritis or other joint conditions can significantly affect your pet's behaviour. An older pet experiencing discomfort may become less active, reluctant to move, or react negatively when touched.

Signs Your Pet May Be Experiencing Joint Pain

Reluctance to jump or climb stairs
Stiffness after resting
Reduced activity levels
Irritability when handled
Difficulty getting comfortable

How to Help a Pet with Arthritis

Choose senior diets or supplements containing glucosamine and chondroitin.
Encourage gentle, regular exercise to maintain mobility.
Consider ramps as an alternative to stairs.
Provide warm, supportive bedding.
Use coats or jumpers during colder weather if appropriate.
Gentle massage and grooming may help improve circulation.
Talk to your veterinarian about pain management options.

Dental Disease

Dental disease is one of the most common health issues affecting older pets. Painful gums and teeth can make eating uncomfortable and may cause irritability, aggression or changes in appetite.

Signs of Dental Disease

Bad breath
Difficulty eating
Dropping food
Reduced appetite
Facial sensitivity

How to Support Your Pet's Dental Health

Provide dental chews or treats recommended by your veterinarian.
Brush your pet's teeth regularly.
Schedule routine dental checks.
Discuss professional dental cleaning with your veterinarian.

Hearing and Vision Loss

As pets age, their hearing and eyesight may decline. This can make them easier to startle and may lead to unexpected reactions when approached.

How to Help a Pet with Sensory Loss

Encourage family members and visitors to approach slowly.
Speak gently before touching your pet.
Avoid surprising them while they are sleeping.
Keep furniture and household layouts consistent where possible.

Changes in Routine

Senior pets often cope less effectively with change. Moving house, welcoming a new pet, changes in family structure or alterations to daily routines can cause stress and anxiety.

How to Help a Senior Pet Adjust

Maintain consistent feeding, exercise and sleeping schedules.
Provide a quiet, safe space for your pet to retreat to.
Consider calming supplements or pheromone diffusers.
Consult your veterinarian if anxiety becomes severe.

Underlying Medical Conditions

Behavioural changes can sometimes be the first sign of an undiagnosed medical issue. Conditions affecting the thyroid, kidneys, liver, heart or nervous system can alter your pet's behaviour.

If your pet suddenly develops behavioural changes, schedule a veterinary examination to identify any underlying health concerns.

When Should You Be Concerned About Behaviour Changes in an Older Pet?

While some behavioural changes are a normal part of ageing, sudden or significant changes should never be ignored. If your pet becomes unusually aggressive, confused, anxious, withdrawn or develops changes in appetite, sleep patterns or toileting habits, seek veterinary advice promptly.

Supporting Your Pet Through Their Golden Years

Sometimes behavioural changes seem to appear without warning. By considering your pet's age and looking for potential causes such as cognitive decline, pain, sensory loss or illness, you can better understand what they are experiencing.

With patience, empathy and appropriate veterinary care, many senior pets can continue to enjoy a happy, comfortable and fulfilling life throughout their golden years.

Frequently Asked Questions

Why is my senior pet suddenly anxious?

Senior dogs can become anxious due to age-related cognitive decline, hearing or vision loss, pain from arthritis, or changes in routine and environment. Older pets are often less resilient to change and may feel unsettled by moving house, new people or pets, or altered daily schedules. If your dog's anxiety appears suddenly or becomes severe, consult your veterinarian to rule out underlying medical issues and discuss treatment options.

Can dementia cause behaviour changes in pets?

Yes. Pets can develop Cognitive Dysfunction Syndrome (CDS), an age-related condition similar to dementia in humans. CDS can cause disorientation, changes in sleep patterns, house soiling, reduced activity, and altered interactions with family members. Senior diets rich in Omega-3 and Omega-6 fatty acids, mental enrichment, and veterinary guidance can help support affected pets.

Why is my older cat becoming aggressive?

Aggression in older cats is often linked to pain, dental disease, sensory loss, or cognitive decline. A cat that cannot see or hear well may startle easily, while arthritis or dental pain can make handling uncomfortable. Avoid surprising your cat, approach them gently, and schedule a veterinary check-up to rule out pain or illness.

How can I help a pet with cognitive decline?

You can help by feeding a senior diet that supports brain health, providing regular mental stimulation through games and training, keeping routines consistent, and avoiding punishment for accidents indoors. Some pets also benefit from supplements or medications recommended by a veterinarian to help manage anxiety and cognitive symptoms.

When should I see a vet about behaviour changes?

See your veterinarian if your pet’s behaviour changes suddenly, becomes severe, or is accompanied by symptoms such as pain, loss of appetite, weight loss, increased thirst, confusion, aggression, or house soiling. Behavioural changes can sometimes be the first sign of an underlying medical condition that requires treatment.