As pets get older, similar to humans, various things start to deteriorate.
Cats live past 15 years and dogs live longer (12-18 yrs), than they used to now due to better quality foods and improved health care
Many specific problems do affect the different animals . This can be picked up by a simple examination but sometimes needs a blood test or even blood pressure analysis.
At this stage they should have a blood test , sick or not to gauge wether there is any problem smouldering away in the backround. Diagnosis is the precursor to improvement. Once identified food types can be changed or improved and medication can be designed to improve your animals life for the next few years
Cats get high blood pressure and I check every cat older than 10 years of age. They do suffer arthritis although not as frequently as an energetic active dog breed e.g. Collies .
Thyroid issues also affect both cat and dog although in opposite directions . Cats become hyperthyroid due to a slow growing growth in their thyroid glands that produces too much thyroid hormone that sends metabolism into hyperdrive so you get a hungry cat but still loosing weight. Dogs on the other hand get a hypothyroid condition similar to humans where the body attacks the thyroid gland (autoimmune thyroiditis) that results in lethargy, weight gain, skin conditions and may be seen as puffy ankles and face . Both conditions cause heart damage so early intervention is needed. Routine blood tests pick these conditions up easily even before I can see clinical signs .
Cats often suffer kidney damage and failure more than dogs . This may be due to chronic infection most commonly seen in the mouth with dirty teeth & Gum infection. When we see kidney damage in the blood test we can say that 75% of the kidneys are damaged beyond repair and we have to manage the remaining 25%. Saying that there are some excellent treatments and food changes that will improve the situation and provide a happy final couple of years of life.