Health and Behaviour 81
A disease is any disorder or abnormal condition of a body part, organ or system.
Diseases can have many causes including inflammation, infection (bacterial, viral,
fungal or parasitic), trauma, toxins or just simple ‘wear and tear’. There are numerous
feline diseases, many of which can cause behavioural changes, either directly by
affecting the brain and/or neurological system or indirectly by causing other physio-
logical changes that may, in turn, influence the animal’s behaviour.
Diseases that directly affect the central nervous system can cause symptoms such
as seizures, tremors, disorientation, incoordination, circling/pacing, and/or uncharac-
teristic mood changes such as unexplained fear, anxiety and/or aggression.
As well as the behavioural changes associated with pain or discomfort as
described previously, the physiological effects of disease that might influence behav-
iour indirectly can include:
● Increased frequency and/or urgency of urination or defecation, potentially leading
to house-soiling problems.
● Increased appetite that might lead to increased competition and conflict with
other cats or other household pets.
● Pruritus (itching) leading to over-grooming and irritability.
● General malaise and ‘feeling unwell’ that might lead to irritability and anxiety.
As cats increase in age they become more vulnerable to weakness, sensory decline
and poor health in general, plus the strength of their immune function can
decrease making them increasingly prone to infections. The prevalence of diseases
such as hyperthyroidism, renal failure and degenerative joint disease also increases
with age, all of which can increase anxiety, irritability and generally reduce the
cat’s overall coping abilities (see the next section on stress). Behaviour problems
linked with pain, discomfort and disease are therefore more likely to be seen in
Cognitive dysfunction syndrome (CDS) can also occur in elderly cats (see Box 6.1)
and can be responsible for a severe decline in cognitive ability and associated
Fig. 6.1. A cat may become aggressive if
being touched causes or increases pain, or
if it anticipates pain when touched or about
to be touched.