In short, yes. Below is a revised version of an article I wrote a few years ago on the topic, but its something I get asked about a lot.
Since I was a kid the
lifespan of cats has increased massively – probably due to the availability of
excellent nutrition, advances in veterinary medicine and the move from cats as
primarily outdoor to primarily indoor pets (maybe this relates in part to
better flea control?).
Anyway, whereas cats in
their late teens and early twenties were relatively rare a decade ago, the
proportion of senior and geriatric cats seen in veterinary practice has grown
enormously. One study showed a 15 per cent increase in cats over the age of ten
in the US over the past ten years. Figures from the UK suggest that more than
30 per cent of the pet cat population can be classified as “senior”. [It does
depend on your definition. Laboratories tend to classify cats over 7 as senior
because that is when they tend to start to see laboratory changes that reflect
age-related conditions].
So…a longer life is super
news for cats and owners, and reflects in general their better care. BUT… there
is a down-side to the aging of the feline population. With age comes increased
prevalence of chronic diseases, cancer and dementia.
Dementia, or cognitive
dysfunction syndrome, is an age-related condition commonly associated with
behavioural changes in cats. Owners may report that their cat seems a bit
“senile” or “doddery”.
According to one study,
around 28 per cent of cats aged 11-14 years old showed signs of dementia. As
one would expect, this figure increased with age, and 50 per cent of cats aged
15 and over showed signs of dementia.
To put this into
perspective, as far as age goes, a 15 year old cat is roughly equivalent to an
85 year old person. According to some
scary stats, up to 50 per cent of us show signs consistent with dementia at
that age.
Underlying causes
There is still much to be
learned about senior dementia in cats and no single underlying cause has been
identified. We still don’t know if dementia is solely due to inevitable aging
of the brain, or whether it is due to a single, or multiple, treatable disease
processes.
There is evidence that
dementia is associated with pathological changes in the brain. These changes
include vascular disease, changes in the activity of neurotransmitters, a
decrease in brain mass, an increase in the rate and extent of free radical
damage to brain cells and the deposition of amyloid plaques – in other words,
the same types of processes that occur in people with dementia.
Another thing that we
don’t know is whether the extent and severity of these changes is associated
with the extent and severity of behavioural changes.
Obviously if we knew the
underlying cause we could develop a treatment to prevent or cure dementia. If
we knew how changes in the brain reflected changes in behaviour, we might be
able to use this information to give owners a more accurate diagnosis and
prognosis for their cat. Alas we do not.
Clinical signs
There are
numerous behavioural changes consistent with senior dementia in cats, but none
of them are specific to dementia. That means that there are other conditions that
can cause these signs, so diagnosis of dementia can never be made on the basis
of signs alone.
- Inappropriate
vocalisation, particularly at night. In my experience this is one of the most
common signs of dementia and can be very upsetting for owners who are trying to
sleep. Affected cats tend to emit a loud, guttural cry (sometimes for hours on
end), for no apparent reason, and may appear distressed.
- Changes in
social relationships. For example, cats that were once affectionate may become
very aloof, irritable or even aggressive. Some owners complain that their cats
incessantly demand attention.
- Confusion and
disorientation. This may manifest as forgetting where doors, walls and
furniture are located, forgetting the location of the food bowl or forgetting
where the litter tray is. Others may pace relentlessly, wander aimlessly or
stare at the wall. Some animals seem to forget that they have been feed…and
keep harassing owners (though its pretty hard to distinguish this from a cat
with an increased appetite, which can be a sign of hyperthyroid disease or
diabetes mellitus).
- Inappropriate
urination or defecation (i.e. doing it where one should not). This sign is
particularly upsetting to owners.
- Changes in
sleep-wake patterns. In particular, cats that once slept through the night may
get up at all hours. Some owners observe that their cat sleeps more or less
than usual.
- Decreased
response to visual and auditory stimuli. Some cats may show signs that they
have seen or heard something (looking or turning towards it) but may seem to be
confused about how to react.
- Change in
appetite. In my experience many affected cats show an increased interest in
food, but loss of interest is quite common too.
- Reduced
grooming behaviour. This may be evidenced by a dishevelled or rough looking
hair coat.
Signs may be
subtle at first, but they tend to become more pronounced over time.
Diagnosis
Diagnosis of dementia in cats is not easy because, as mentioned earlier, many other
medical conditions known to affect older cats result in similar clinical signs.
For example, cats suffering from arthritis may vocalise or avoid climbing in
the litter tray due to pain. Cats with diabetes or kidney disease may urinate
inappropriately or exhibit changes in their appetite. Cats with thyroid disease
may exhibit dramatic behavioural changes, including aggression and a ravenous
appetite.
Other
conditions that may cause behavioural changes in senior cats include high blood
pressure, urinary tract infection, diseases of the nervous system, loss of sight
and hearing, dental disease, brain tumours and any condition that causes pain.
And stress (for example regarding a new cat that moves in next door) can
manifest as all sorts of behavioural changes including some crazy litter tray
action.
 |
| A cat has blood pressure measured. |
Vitamin B1 (thiamine)
deficiency, common in cats fed fresh meat containing sulphur dioxide
preservatives, can also cause some dementia-like signs. Unfortunately it can be
difficult to tell which pet meats contain these preservatives or which don’t. Some
cats respond to thiamine supplementation and withdrawal of the offending diet,
but thiamine deficiency can cause permanent brain damage.
There is no
single diagnostic test for senior dementia. Rather, it is a diagnosis of exclusion. That is, your veterinarian will
need to rule out other medical conditions before determining that the changes
in your cat’s behaviour are due to dementia.
One
complicating factor is that older cats may have multiple medical conditions in
addition to dementia. In these cases it is difficult to determine what
proportion of behavioural signs are due to dementia and what proportion are due
to the other conditions.
Your
veterinarian will initially take a full history, including any medication your
cat is taking, previous medical conditions such as trauma, exactly what your
cat is eating and any recent environmental changes. You will be asked about the
behavioural changes you have noticed in your cat, and whether there have been
any changes in appetite, thirst, urination or defecation.
This is followed
by a full physical examination, which may include a neurological examination,
to determine whether there are physical signs of illness.
The next stage
involves running a panel of tests. This includes a complete blood count, a
biochemistry panel, thyroid hormone levels and urine analysis. These tests will
help identify the presence and extent of kidney disease, thyroid disease and
other conditions such as diabetes or liver disease – all of which may cause
apparently senile behaviour in cats.
In addition,
blood pressure measurements may be taken. Hypertension or high blood pressure
is reasonably common in older cats, although taking their blood pressure is not
as simple as it is in a human patient. The act of putting a blood pressure cuff
on a cat’s limb for the first time is often enough to send the blood pressure
off the scale – so your veterinarian may hospitalise your cat for the day and
take a series of blood pressure measurements, using the average of these. [And
even then the odd cat just doesn’t approve of having a cuff placed on its
limbs].
Depending on
the physical findings and the results of these tests, your veterinarian may
suggest your cat undergoes further tests if necessary. These might include
blood tests for feline leukaemia or aids, toxoplasmosis or cryptococcosis.
Ultrasound and
x-rays can be very useful in detecting some conditions which may be associated
with dementia, such as heart disease or cancer.
Finally, what
we can advanced imaging – the use of magnetic resonance imaging (MRI) or
computed tomography (CT) may be required. Advanced imaging may pick up things
such as brain tumours. One of the more common operable brain tumours in the feline
patient is the meningioma – but brain surgery is a specialist procedure. [One
prominent Sydney surgeon describes meningioma removal as a “brain spey”].
 |
Image showing a brain tumour in a cat (the big white mass marked with an asterisk).
Courtesy of Dr Katja Voss, University of Sydney. |
Treatment
Where no
underlying medical reason for behavioural changes can be found, your
veterinarian may make a presumptive diagnosis of senior dementia. It is likely
that as we learn more about the underlying causes of dementia in cats, targeted
treatment will become available.
Until then the
treatment options are based on extrapolation of data from people and dogs, and
it must be emphasised that there is currently no registered treatment
specifically for feline senior dementia available in Australia.
Other
treatment options include anti-depressant type drugs (particularly the
monoamine oxidase inhibitors), anti-anxiety drugs (such as some
benzodiazepines) and non-steroidal anti-inflammatory drugs. Because these drugs
may exacerbate other medical conditions it is important that they are
prescribed by a veterinarian after a thorough assessment of your cat.
Anti-depressant type drugs can take several weeks to take effect. A question we
are commonly asked is whether the cat can take the same medication that the
owner is taking. Generally NOT. Doses between cats and people vary, and again,
it is vital that every patient is assessed prior to medicating to reduce the
risk of adverse effects of medication.
Nutraceutical
dietary supplements containing antioxidants, essential fatty acids and
free-radical scavengers may reduce degenerative changes in the brain, although
there are no formal studies which show this is the case. It is important to
only use products designed for use in cats, as some products intended for use
in humans and dogs may be toxic.
What works for
one cat may not work for another. This may reflect an underlying variation in
the cause of dementia between cats.
In cats with
multiple medical conditions such as arthritis or diabetes, treatment of these
can improve your cat’s overall health and reduce dementia related behavioural
signs.
In addition to
treatment, making changes at home to keep your cat comfortable, such as
providing an extra litter tray (or two) and sticking to a routine when it comes
to feeding may help. These cats tend to get very stressed in the face of major
changes, so avoid rearranging the furniture or changing the position of their
bedding and bowls. These are not cats who would be thrilled with the
introduction of a new kitten or puppy.
Old cats with
dementia are not very quick on their feet. They are less able to retreat from
dogs, other cats or motor vehicles if they need to. Thus keeping them indoors,
or allowing them outdoors under supervision, may be the safest option.
Often cats are
not diagnosed with dementia until it is very advanced. This means that even
with the best veterinary care there may be little we can do to reverse or
reduce the behavioural changes associated with dementia.
