Inappropriate elimination behaviour or litter box use.
When your cat urinates or defecates outside the litter box, it could be a sign of an underlying health problem. Medical conditions associated with these behaviours include lower urinary tract disease, kidney disease, urinary tract infection, diabetes mellitus, and pain/arthritis.
Changes in interaction.
Cats are social. When the way they interact with family members or other pets changes, it could be a sign of disease, fear, anxiety or even pain.
Changes in activity.
A decrease or increase in activity can be a sign of a number of conditioners. Discomfort from joint disease or illness can lead to decreased activity; hyperthyroidism can cause an increase in activity.
Changes in sleeping habits.
The average cat may spend 16 to 18 hours a day sleeping. The key to differentiating abnormal lethargy from normal napping is knowing your cats sleeping patterns and noting any changes.
Changes in food and water consumption.
Look for changes such as a decrease or increase in consumption of food or water. An increase in water intake could be an early indicator of thyroid problems, kidney disease, diabetes or other illnesses.
Unexplained weight loss or gain.
Weight changes often go unnoticed because of a cats thick coat. A change in weight does not necessarily correlate with a change in appetite. If your cat goes to the food dish and then backs away without eating, nausea may be the source. At the same time, obesity has become a serious health concern in cats, with increased risk of diabetes mellitus, joint disease and other problems.
Changes in grooming.
Cats are typically fastidious groomers. A decrease in grooming behaviour can indicate a number of conditions, including fear, anxiety, obesity or other illnesses. An increase in grooming may be a sign of a skin problem or underlying joint pain.
Signs of stress.
Stressed cats may demonstrate an increase in grooming and social interaction, spending more time awake and scanning their environment. Or, they may hide more, withdraw and exhibit signs of depression. Stress may also cause changes (increased or decreased) in appetite.
Changes in vocalization.
More common in older cats, increased vocalization or howling could be the sign of an underlying issue. Many cats also have increased vocalization if they are in pain or are anxious.
Dental disease can lead to bad breath, pain, tooth loss and spread of infection to the heart and other organs. An early sign of an oral health problem is bad breath. Regular home teeth brushing and regular veterinary dental exams are the best way to prevent dental disease.