Ageing and it’s Effects on the Brain

As with humans, there is an increasing number of pets living to an advanced age.

This means we are seeing more age related diseases in our pets including age related brain

problems. This often leads to behavioural changes and behavioural problems in the older pet population. Our aging pets often show a decline in cognitive function i.e. memory, learning,  perception and awareness. The way this manifests may be by forgetting previously learned behaviours such as housetraining; the onset of new fears and anxiety; disorientation; changes in sleep/waking patterns; decreased recognition of people and  places; and deterioration of memory and learning ability.

Obviously not all the behavioural changes we see in older pets are just from brain changes, there may often be underlying medical conditions. Pain related problems such as dental disease and arthritis may lead to increased fear or irritability when handled, if mobility is affected it may lead to problems accessing elimination areas. Some other diseases such as hyperthyroidism or Cushings will cause major changes in attitude or eating and drinking behaviours.

A lot of the changes seen in the brain are similar to those seen with Alzheimer’s in humans.

There is a reduction in brain mass (in the number of neurones, atrophy of ganglia and increased size of the fluid filled spaces in the brain -the ventricles), there is accumulation of material (amyloid and mineralisation) and reduced blood perfusion of the brain.

Unlike humans, dogs do not get tangled neurofibrils.

With age, the brain becomes more sensitive to damage from free radicals. A small amount of oxygen that is used for normal energy production is converted to reactive oxygen species (also known as free radicals) such as hydrogen peroxide, superoxide and nitric oxide. As cells age they produce more free radicals and less energy; and at the same time the body is less able to clear these. The net effect is an increase in free radicals which damage cells and the brain is particularly susceptible to the toxic effects of free radicals.

So what should we do for our aging pets with brain issues?

A combination of environmental management, nutritional and sometimes drug therapy is used.

Environmental management- keeping a regular, predictable daily routine may help to reduce anxiety. As eyesight and hearing decline, adding new odour, tactile and sound clues can also help them navigate around the environment. Studies show that continued enrichment in the form of walking outside the home environment, training, play and novel toys (or rotating toys around) can help maintain cognitive function (use it or lose it). A new canine companion may sometimes help also.

Dietary management- the use of antioxidants in the diet is the main dietary strategy. Some studies have shown that high intakes of fruit and vegetables, and vitamin E and C have decreased the risk for cognitive decline.

A commercial diet Hills canine b/d is supplemented with antioxidants and studies have shown that animals on this diet do better with respect to cognitive function than those on other diets, though the best responses are seen when both dietary and environmental strategies are used.

Drug therapy- depending on the problem there are some useful drugs which may be used.

For anxious animals medications such a clomicalm can be used or more natural therapies such as pheromones, bach flower remedies and so on. There are some drugs which improve the circulation in the brain and others which increase the duration of action of neurotransmitter substances in the brain.

Sadly, cognitive dysfunction in our older pets is a real problem and sometimes is the final reason euthanasia is considered.