Ageing

What is ageing?

An accumulation of physical changes over time that render organisms more susceptible to disease and death.

A progressive loss of physiological integrity, leading to impaired function.

What are some of the most easy to see signs of ageing?

Patches of grey hair

Less energetic or mobile

Less responsive

Overweight, incontinent, stinky

Why do old dogs shed hair and become grey?

Hair follicles become atrophied meaning they cannot support hair. Less melanocytes.

What is sarcopenia?

Weight/muscle loss due to old age.

Reduction in muscle fibres.

Affects ‘normal’ activity

What happens to the skin with ageing?

It becomes dry and flaky.

Sebaceous glands are less active.

Why do old dogs smell?

Reduced immune function

Recurrent secondary skin infections.

What happens to the immune system due to ageing?

Reduced level of immune cells, ones that are left are less capable

Impaired ability to fight infection and target cancer cells

What are the types of vision loss old dogs may experience?

Cataracts, lens becomes cloudy

Iris atrophy, becomes more sensitive to light

Retinal degradation

Why do old dogs experience hearing loss?

Degeneration of nerve cells

Loose high frequencies first.

What happens to old dogs vocally?

Muffled/weak bark

Degeneration of nerve cells in the larynx

Why do old dogs experience incontinence?

Weaker anal and urinary sphincters

Changes in hormone levels can also affect urinary sphincters

What are the cognitive effects of ageing?

Changes in behaviour

Secondary to age-related degeneration of the brain

There is the canine cognitive dysfunction rating (CCDR)

What happens to kidneys during ageing?

Chronic renal failure:

Destruction of nephrons

Can be no clinical signs until 70% of kidney function is destroyed

What things cause cardiac failure due to ageing?

Dilated cardiomyopathy

Valvular disease

Arterial hypertension

How does ageing affect diabetes risk?

Increased risk of diabetes mellitus

Insufficient insulin production

More common in overweight animals

What is genomic instability (hallmarks of ageing)?

DNA is continually being damaged, mutated and altered

The longer an organism is alive, the greater the chances that a DNA change could lead to disease

What is proteostasis (hallmarks of ageing)?

Impaired protein homeostasis

Proteostasis involves mechanisms for the stabilisation of correctly folded proteins and the degradation of incorrect or unneeded proteins by the proteasome or the lysosome.

What is cellular senescence (hallmarks of ageing)?

Stable arrest of the cycle coupled to stereotyped phenotypic changes.

The accumulation of senescent cells in ages tissues can affect function and cause inflammation.

What is stem cell exhaustion (hallmarks of ageing)?

Decline in the regenerative potential of tissues

One of the ultimate culprits of tissue and organismal ageing

Recent promising studies suggest that stem cell rejuvenation may reverse the ageing phenotype at the organisms level.

What is altered intracellular communication (hallmarks of ageing)?

Alterations in communications between cells and tissues can have widespread effects.

Pro-inflammatory status (inflammaging) impacts many organ systems

Parallel dysfunction in the immune system can aggravate the ageing status.