Physical and Mental Changes in The Senior Years

As dogs reach old age, they start to slow down, they lose the endurance they used to have and find it more difficult to get around.  There are various mental and physical changes that can take place as the tissues and organs deteriorate with advancing years.

Integumentary system

Hair & Skin

One of the first signs of a dog ageing is the hair on the muzzle and around the eyes starting to go grey.  Over time, this will spread to the back, legs and tail.  The coat may become thinner and duller.  Older dogs may need to be groomed more frequently, with special attention given to the anal area.

The skin of the older dog may become thinner, leading to them being more likely to get injured, and dry skin can be a problem for older dogs.  Some older dogs also develop multiple tumours on the skin, and cancerous tumours of the skin can also occur.  Feeding an essential fatty acid supplement will help to keep the skin and coat more supple and healthy, and feeding a fatty diet is also recommended for dogs with cancer as cancer can’t feed on fat (but loves carbohydrates).

Mammary Glands

The mammary glands in female dogs may develop some hardening due to the infiltration of fibrous tissue, and mammary cancer may develop – this is the single most common tumour of the female dog.


The claws can become brittle and the footpads may thicken.  The claws will probably need clipping more often due to the dog being less active.


It is common for older, large breed dogs to develop calluses on their elbows.  Part of the reason for this is the tendency of older dogs to be less active and lay down more, especially on hard surfaces.  A soft bed (ideally with some form of support) should be provided, away from draughts.

Sensitivity to Temperature

Older dogs have increased sensitivity to temperatures changes as they are less able to regulate their body temperature.  They may need coats in the rain or cold, and to go out in the cooler times during the summer.

Skeletal & Muscular Systems


Dogs may develop arthritis in their joints, which causes swelling, stiffness and pain.  Symptoms may include difficulty in getting up, difficulty in finding a comfortable position to sleep in, limping or a change in gait, reluctance to move, aversion to stairs, difficulty standing or walking, and exhibiting pain when picked up.  A dog may lick or chew at the aching joint and can show irritability or aggression.  A soft bed with support should be provided out of draughts and in a warm, sociable part of the house.  Ramps can be provided to prevent the dog having to go up and down stairs or jump, and non-slip surfaces should be provided.  The dog may need to be lifted in and out of the car, or a car ramp used.  Supplements (particularly essential fatty acids, natural pain relief, glucosamine and chondroitin) can also be given to reduce swelling and pain and aid lubrication of the joints.

Body Fat

Dogs tend to store more fat as they get older, and this may result in fat infiltrating the bone marrow, causing anaemia.  For both the skeleton and the bone marrow it is vital to keep dogs lean into older age.


Dogs tend to lose muscle as they get older.  Exercise is critical to keep muscles toned and help prevent weight gain, as well as releasing endorphins to make the dog feel good.  Exercise will also help to keep the heart and digestive systems healthy.  Walks may need to become shorter and more frequent if the dog tires easily.  Swimming is great exercise as it reduces the stress on the joints and has great benefits for the whole of the dog’s body.  Massage will also relax and loosen the muscles and help with blood flow to the muscles, and will help them to relax.


Relaxation is important for any dog, but particularly a senior one, as they need quiet time to rest and recuperate.

Circulatory & Respiratory Systems


Particularly with smaller dogs, hearts can start to show stress leading to heart murmurs, enlarged hearts, heart disease and heart failure.  Medication can be provided to support the heart, and there are also herbs that support the heart in later life.  If a dog starts to show signs of heart stress then exercise needs to be adjusted accordingly.

Lungs & Respiratory Function

Lung capacity is decreased in the senior dog, as the lungs lose their elasticity during the aging process, and the ability of the lungs to oxygenate the blood may be decreased.  Again, maintaining exercise is critical, but adjusting the amount and intensity of exercise to the dog.

Older dogs may be prone to respiratory infections, and may tire more easily.


The dog’s bark can also become more gravelly and hoarse.

Digestive & Urinary Systems

Constipation & Diarrhoea

Older dogs can have problems with constipation, particularly if they don’t maintain proper hydration or the dog has arthritis which impacts on obtaining the correct posture for defecating.  The movement of food through their digestive tracts also slows, which can result in constipation.  They might not eat as much, leading to them not being as regular with their stools.  Adding more fibre to the diet can help, as will maintaining regular exercise.

Many older dogs can also suffer from diarrhoea or wind, as they may not digest their food as well as when they were young.  Feeding a good quality protein diet that is easily digested will help with the digestion process – feeding a raw diet will definitely help.


Older dogs can also suffer from incontinence, with them losing the ability to hold their urine.  They may leak a little whilst they are asleep or relaxed, and may need to go to urinate more frequently.  The main causes are kidney or urinary tract infections as the kidneys do not function as well in an older dog.  Spayed females can also have small quantities of urine leaking from the urethra whilst resting or sleeping.  Medication can be provided to help with some of the causes of incontinence, and the dog can also be provided with puppy training pads or a litter box.  If the dog loses total control of their bladder, then a vet can teach you how to express the bladder for the dog.  However, you need to be sure that normal bladder control will not return first, as once you start expressing the bladder you weaken the bladder muscles themselves.  If you express the bladder fully around 4-5 times a day you can prevent leaking from the urethra in between times.

Kidneys & Liver

Senior dogs can suffer from kidney disease, and when the kidneys lose their ability to perform properly waste and toxins can build up in the body – this can also occur if a kidney stone blocks the urinary tract, the bladder ruptures.  It is important to maintain proper hydration, and as kibble is dehydrated this is much harder on the kidneys - so where possible feed a raw, home-cooked or wet food diet.

Liver disease can also occur.  The liver can regenerate if the body is healthy enough, and this can be helped with herbs such as milk thistle.

Nervous, Endocrine, Immune & Lymphatic Systems


There are a number of conditions that can occur with the eye as the dog gets older.  Blindness can occur over time – deteriorating eyesight is part of the normal aging process for dogs.  As they rely more on hearing and scent than humans they can cope surprisingly well with permanent vision loss.  They adapt and get to know routes to take to the garden, etc.

A bluish tint to the eye that older dogs get is called Lenticular Sclerosis or Presbyopia.  The lens of the eye initially appears cloudy, but the dog can usually see quite well.  As the condition progresses the lens of the eye hardens and the dog struggles to focus up close and doesn’t see as well in the dark.

If there is a white film over the eyes or the dog starts to bump into furniture then you need to have the eyes checked by a vet as they may have Glaucoma or another treatable problem.

If the pupil becomes dilated then there can be other causes such as a tumour.

Any sudden changes in vision or appearance of the eyes could signal an emergency.


An older dog’s hearing does deteriorate.  Often it is the lower sounds that they lose the ability to hear first and they can still hear higher pitch sounds.  Talking in a higher pitch voice and using a dog whistle may make it easier for them to hear what you are saying.  If hand signals are taught along with voice commands then the dog can start to rely on these as his hearing deteriorates (providing his eye sight is OK).

Dogs can seem more aggressive as their hearing goes – if they don’t hear you coming a sudden touch can startle them.


Gingivitis (inflammation of the gum) is very common in older dogs.  It is a bacterial infection of the gums and usually precedes periodontitis (gum disease).  It can make eating painful for the dog, so if an older dog goes off his food it is worth checking his gums – symptoms are gums that bleed or are tender, red and swollen.  If left untreated the gums will loosed and eventually the teeth will drop out.  Gum disease can also spread infection to the bloodstream and cause serious damage to organs.  Dogs with heart problems are especially vulnerable.  Taking care of the teeth throughout the dogs’ life will help to keep the gums healthy – feed bones that clean the teeth and / or brush your dog’s teeth.  If there are signs of gingivitis then arrange a dental examination with your vet.

Note that dogs are able to eat perfectly well with few or no teeth – their gums are still strong enough to crunch bones.


Diabetes is more common in older dogs, as the production and function of insulin reduces.  It most commonly occurs in dogs at the age of 8 or 9 years, and can be hereditary.  I is more common in females.  Insulin injections can be given, although changing from a kibble to a raw food diet can also help.


Hypothyroidism can lead to skin and coat problems, weight gain for no good reason, loss of energy and mental dullness.  It can also lead to changes in behaviour and aggression.  It is easily treated with drugs.

Glandular Function

The older dog can also see changes in glandular function.  Some glands tend to produce less hormones as they age, and other glands may produce more (such as in Cushing’s Disease).  Advice should be sought from your vet.

Immune System

The immune system does not function as effectively in an older dog.  He will be more prone to develop infectious diseases and have a decreased ability to fight off disease.  Feeding a healthy diet (with probiotics) that supports the immune system will help.

Cognitive Dysfunction Syndrome

Cognitive Dysfunction Syndrome is an Alzheimer-like condition that some senior dogs develop.  It causes memory loss, personality changes, confusion and disorientation.  .  They can become disorientated and may not recognise familiar toys, where they are and who their owners are.  They may forget tricks or their name, and spend long periods of time staring blankly into space.  Pacing is also common, and other repetitive, compulsive behaviours such as walking in circles.  Their sleep patterns can also change and they may experience house training problems.  Cognitive Dysfunction Syndrome can be treated with drugs.  Food puzzles and trick training can help to keep the brain active, and feeding a good quality diet will also support the brain.

Reproduction System

Once an unneutered male dog reaches 8 years of age he has a much greater chance of developing prostate disease, but this is rarely cancerous.  In most cases the prostate just enlarges, but this may cause problems with urination or defecation.


As dogs age, the metabolic rate reduces, whilst at the same time exercise generally decreases.  If food is not adjusted accordingly, the dog will put on weight and may become obese.  The dog’s weight should be monitored and food adjusted accordingly.
It is also more common for the body to lay down fat as the dog ages.  Feeding a protein and fat diet will reduce this, as dogs more easily store excess carbohydrates as fat.


Cancer becomes more prevalent in dogs as they age, and it is the leading cause of death in senior dogs.  Signs of cancer are lumps and bumps on the body, changes in weight, sores that heal slowly, bleeding from the mouth, nose or ears, diarrhoea, constipation or blood and mucous in the stool, drooling, coughing, excessive panting, difficulty eating and extreme tiredness.  The most common cancers are lymphoma (cancer of the lymphatic system), osteosarcoma (bone cancer), soft tissue cancers, oral melanoma and mammary (breast) cancer.  Feeding a high protein, high fat, low or no carbohydrate diet helps keep cancer at bay.

Mental changes

Behaviour changes can arise due to any of the above physical changes.

Fears & Phobias

Fears and phobias can arise as a result of sensory decline, cognitive dysfunction and anxiety.  Phobias can relate to noise and thunderstorms, going outdoors, entering certain rooms, or walking on certain types of surfaces.  If you help the senior dog to cope with the physical problem, then this should also help with the fears and phobias.


Aggression can arise as a result of physical pain or a degeneration in mobility, cognition, senses or hormones, as well as a change in appetite.  By treating the underlying problem and allowing the dog to have his own space and plenty of rest you can reduce the amount of aggression.


Older dogs have a decreased ability to cope with stress, and this can lead to behavioural changes such as separation anxiety, aggression, noise phobias and increased vocalisation.  Try to help the older dog to relax and reduce the level of stress in his life.

Cognitive Dysfunction Syndrome

When dogs suffer from Cognitive Dysfunction Syndrome they are likely to have memory loss, personality changes, confusion and disorientation.  They can become disorientated and may not recognise familiar toys, where they are and who their owners are.  They may forget tricks or their name, and spend long periods of time staring blankly into space.  Pacing is also common, and other repetitive, compulsive behaviours such as walking in circles.  Their sleep patterns can also change and they may experience house training problems.  Cognitive Dysfunction Syndrome can be treated with drugs.


Other behavioural changes that can occur are pica (ingesting inedible objects), licking, sucking or chewing body parts, household objects or family members, scratching and digging.  Each may have a different cause.

One very important requirement when looking after a senior dog that is suffering with ill health is to listen to the dog – he will tell you when he’s had enough and the time has come to let him go.  One of the great blessings that we have with animals is that we don’t have to make them suffer once they have decided their bodies and minds are ready to rest that one final time.

One reference that I have found useful when assessing the quality of life that a senior dog has is the Quality of life scale.


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