WARNING SIGNS IN SENIOR DOGS AND CATS: WHAT EVERY PET OWNER SHOULD KNOW

Aging is not a disease, but a natural process that brings a series of changes to the body.
In both dogs and cats, advanced age is associated with an increased likelihood of suffering from chronic diseases that, even when not obvious, leave subtle traces in daily behavior.
Recognizing these signs early can make the difference between a life of discomfort and one in which our companions enjoy comfort, care, and quality of life.

A dog that growls when touched, or a cat that suddenly isolates itself, is not simply “in a bad mood.” Very often, these behavioral changes are the earliest warning signs of an underlying physical illness.
An animal’s behavior is closely linked to its physical health status. Changes in character, social interaction, or daily habits may indicate chronic pain, hormonal imbalances, neurological disorders, or even silent organic diseases.

In senior pets, these signs are often misinterpreted as “normal aging,” when in fact they are valuable clues that something is wrong internally.
Ignoring them may delay important diagnoses.

• Systemic diseases as a cause of behavioral problems in cats: study linking arthritis, kidney disease, and endocrine disorders to behavioral changes.
https://www.mdpi.com/2813-9372/2/2/21
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• A Review of Medical Conditions and Behavioral Problems in Dogs and Cats:
comprehensive review connecting various systemic diseases (endocrine, neurological, pain-related, etc.) with behavioral alterations in dogs and cats.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6941081/

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Chronic Pain – The Silent Enemy

Animals don’t express pain the same way humans do. They rarely cry out, but their body language and behavior say a lot.
A dog that struggles to get up in the morning, a cat that avoids its favorite resting spot, or a pet that no longer enjoys being touched—all of these behaviors may signal pain.
You might also notice stiffness after rest, refusal to play, mood swings, or changes in sleep patterns.

Did you know?

A sudden change in a cat’s litter box habits—such as avoiding it or urinating next to it—is not always stress or defiance: it may indicate joint pain, a urinary infection, or even cognitive dysfunction.
Cats, being both hunters and prey animals, have a strong instinct to hide weakness.
A cat with arthritis rarely limps—it simply stops jumping or prefers lower resting spots.
Cats with chronic dental pain groom themselves less, hide more, and avoid facial contact.
It’s not “bad temperament”—it’s discomfort.

Behind these behaviors lie many age-related diseases.
Osteoarthritis and degenerative joint disease (see article ES – 010 – Geriatría – II.B.1 – Artrosis, signos y diagnóstico en mascotas mayores) are among the most common, especially in large dogs, though cats are frequently affected as well.
Chronic dental diseases such as periodontitis or FORL lesions cause constant, silent pain that often goes unnoticed.
We must also mention chronic digestive disorders (e.g., pancreatitis or inflammatory bowel disease), which create constant discomfort, as well as tumors or neoplasms, which may cause local or generalized pain.

The key point: chronic pain should never be considered a “normal” sign of aging.
There are treatments, supplements, and therapies that can control it and greatly improve the animal’s quality of life.

Pain evaluation should be a core part of every veterinary visit, especially for senior pets.
Tools such as specific pain scales for dogs and cats help identify “silent” cases.
Often, initiating analgesic therapy or joint supplementation allows pets to return to their normal behavior within just a few days.

• Behavioral assessment in chronic pain in dogs: explains how persistent pain can trigger behavioral changes before physical symptoms appear.
https://www.frontiersin.org/articles/10.3389/fvets.2024.1374858/full
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• Behavioral analysis as a diagnostic tool in chronic pain: Frontiers in Veterinary Science study linking persistent pain to subtle behavioral alterations in senior pets.
https://www.frontiersin.org/articles/10.3389/fvets.2024.1374858/full
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AAHA Pain Management Guidelines for Dogs and Cats: official document outlining updated protocols for chronic pain and its behavioral effects.
https://www.aaha.org/globalassets/02-guidelines/2022-pain-management/resources/2022-aaha-pain-management-guidelines-for-dog-and-cats_updated_060622.pdf

Thyroid Disorders – When the Gland Rules

These hormonal imbalances often go unnoticed unless specific blood tests are performed.
The good news: once detected, they can be easily treated with hormone therapy and a suitable diet.

Hypothyroidism in Dogs

Hypothyroidism is one of the most common endocrine diseases in older dogs.
It results from an insufficient production of thyroid hormones, which slows down the metabolism.

Owners usually notice that their dog seems more tired than usual, less willing to move, and gains weight even though food intake hasn’t increased.
The coat loses its shine, hair loss appears (sometimes symmetrically), the skin becomes dry and flaky, and recurrent skin infections are common.
Another telltale sign is sensitivity to cold—affected dogs constantly seek warm spots.

The positive side: when diagnosed early and properly treated, the symptoms can be reversed, and the dog regains vitality and energy.

• Behavioral manifestations of canine hypothyroidism: scientific review examining changes in mood, apathy, and aggression in hypothyroid dogs.
https://www.mdpi.com/2076-2615/9/12/1133

Hyperthyroidism in Cats

In cats, the most frequent thyroid condition is the opposite: hyperthyroidism, an overproduction of thyroid hormones that accelerates metabolism.

Owners are often surprised, as their cats appear overactive, nervous, or even hyperactive.
They eat ravenously or anxiously but continue to lose weight.
Vomiting or alternating diarrhea may occur, and the coat becomes unkempt, dull, and rough.

Some cats meow more frequently, especially at night, which can disturb the household.
Although it may seem like the cat has “become young again,” this is in fact a disease that heavily strains the body and, if left untreated, can damage the heart, kidneys, and liver.

Heart Failure – Tired Hearts

The heart also ages, and over time its pumping capacity may weaken.
In older dogs—particularly in predisposed breeds—heart failure is a frequent diagnosis.

Night-time coughing is one of the most characteristic signs in dogs with heart disease.
Cats, however, rarely cough; instead, they show panting, weakness, and reduced stamina.

Owners often notice that their pet tires more quickly, pants excessively after walks, or develops a persistent cough, worse at night.
In advanced stages, abdominal distension (ascites) or brief fainting episodes (cardiac syncope) may occur.

Although heart failure cannot be cured, modern treatments allow for excellent symptom control and significantly improve both quality and length of life.

Chronic Kidney Disease – When the Kidneys Weaken

Among geriatric diseases, chronic kidney disease (CKD) holds a central place, especially in cats.
Over time, the kidneys lose their ability to filter toxins from the blood, leading to noticeable everyday symptoms.

In cats, it is the most common cause of veterinary visits in advanced age.
The earliest signs are usually increased drinking (polydipsia) and more frequent urination (polyuria); an ammonia-like breath odor can also be a clue.

Affected animals lose weight, eat less, and vomit more often.
Their coat becomes dull and dry, and cats groom themselves less.

Early detection is essential: with specialized diets, medication, and regular monitoring, disease progression can be slowed and wellbeing greatly improved.

Cognitive Dysfunction and Senility

Finally, we must not forget the brain.
Just like humans, senior dogs and cats may suffer from a progressive decline in cognitive function.

This condition, known as Cognitive Dysfunction Syndrome (CDS) (see article ES – 016 – Geriatría – III.B.1 – Síndrome de Disfunción Cognitiva, Síntomas en mascotas mayores), is a form of animal dementia, sometimes referred to—incorrectly—as “dog or cat Alzheimer’s.”

The animal gradually loses its routines and habits.
Owners often observe that it gets lost around the house, stares blankly at walls, or seems disoriented in familiar places.
It may confuse day and night, becoming restless at night and sleeping more during the day.
It can also forget learned commands or become housesoiling again.

Up to 60% of dogs over 11 years old show signs of cognitive dysfunction.
Cats can also develop senile dementia, though it is diagnosed less frequently.

Beyond the cognitive syndrome itself, senility may involve neurological problems such as tremors, seizures, vision loss, or progressive deafness.
There is no complete cure, but supplements, medication, and environmental enrichment can slow progression and preserve quality of life.

A Complete Examination – A Small Step that Makes a Big Difference

Behind every behavioral change, there may be an underlying physical cause.
That’s why every geriatric check-up should include not only a thorough physical examination but also a behavioral assessment:
Is the pet eating differently? Has its sleep pattern changed? Does it play less or isolate itself?

These seemingly small details provide the veterinarian with valuable clues that may indicate a systemic disease.
A simple blood test or hormone panel can be enough to identify the cause of a behavioral change and enable targeted treatment.

A classic example:
A dog suddenly becomes “irritable” or reacts aggressively when touched—very often, the real reason is pain.
Or a cat labeled as “grumpy” for not using the litter box may in fact suffer from arthritis and can no longer climb into it comfortably.

Any sudden behavioral change lasting more than two weeks should be considered a warning sign.
It’s not “mood” or “personality,” but the body’s way of saying something is wrong.

Your veterinarian recommends:

• Keep a small behavior journal to detect changes early.
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• Combine clinical and behavioral observations at every check-up.
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• For older pets, it’s best to schedule a geriatric examination twice a year—many conditions can be caught early this way.

Conclusion – Body and Behavior Are Inseparable

Behavioral changes are no coincidence—they are a reflection of the animal’s internal state.
By learning to read these signs, we not only improve their quality of life but also strengthen the bond that connects us to them.
A dog or cat that feels understood suffers less—and that is ultimately the goal of geriatric medicine:
comfort and wellbeing at every stage of life.