Ageing is “the process of growing older” and has recently become the focus of intense research in people. Geriatric medicine focuses on the progression and management of age-related diseases; healthy ageing is growing older in the absence of age-related disease. However, the difference between what changes constitute healthy ageing and what changes are the results of a pathological process can be difficult to determine. The average lifespan for cats has been reported as 14 years but, given that cats have been known to live to 30 years (AnAge database), there is scope for improving both the healthspan (period of healthy life) and lifespan of our feline companions.
The main causes of death in UK cats over five years of age include kidney disease (14 percent), non-specific illness (13 percent), neoplasia (12 percent) and mass lesion disorders (12 percent). Mass lesion disorders referred to conditions associated with a mass without further specific aetiology; there is likely overlap with neoplasia. The average age for cats that die of non-specific illness is 16 years. It is likely that many such cats are suffering from multiple co-morbidities and owners might be reluctant to pursue additional diagnostic investigations in cats they perceive as “old”.
While early recognition and diagnosis of these diseases might enable lifespan to be extended, this is not guaranteed; however, it should be possible to increase the quality of the life that remains – the so-called “healthspan” of the cat. Encouraging owners to bring their cats into the clinic for regular “senior clinics” is currently our best tool for achieving this.
Age of enrolment
Encouraging regular visits to the clinic will enable earlier recognition of signs of disease as well as preventative measures to be implemented for common conditions such as obesity or dental disease. The optimal age of enrolment is between 7 and 10 years of age. Although most owners would consider such cats to be in their prime, they are already “mature” cats in the human equivalent of middle age.
While age-related disease is not necessarily clinically apparent in this age group, the pathophysiological changes associated with these diseases are beginning to occur. Prevalence of renal disease and hyperthyroidism increase from 8 and 10 years respectively, while the risk of osteoarthritis (OA)/degenerative joint disease (DJD) increases from 34 percent to 90 percent between 6 and 15 years of age. Systolic blood pressure also increases with age, as does the risk of hypertension.
The prevalence of heart murmurs increases with age; the presence of a heart murmur and increasing age (over nine years) are also significantly associated with the presence of hypertrophic cardiomyopathy. Finally, obesity in cats peaks between 7 and 13 years, and 37.2 percent of cats aged 7 to 10 have current dental disease.
Visit frequency
The optimal frequency and timing of visits has not yet been confirmed. The current recommendation is for annual visits for a complete veterinary examination with interim six-monthly nurse clinics to monitor weight, blood pressure, dental status and mobility for mature cats. Geriatric cats usually need to visit the clinic more frequently, although this is determined by their current health and medical requirements, not their age.
For healthy seniors and super seniors, increasing the frequency of veterinary examinations to every six months is suggested, although this will depend on how the clinic’s nurse appointments are structured and what is contained in these appointments, as well as the experience and confidence of the nurse running them.
A well run and structured nurse clinic could pick up on changes in weight, body condition, blood pressure and dental health and changes to the heart. Any concerns can then rapidly be reported to the vet for further investigation. In this scenario, senior cats may only need to see a vet annually and super senior cats could have quarterly nurse appointments and biannual veterinary exams.
History
Making owners aware of what changes may start occurring as their cat ages is important. Many owners dismiss signs of disease as “normal” for older cats, especially changes in mobility. When taking a history in a senior health clinic, it is best to have a checklist of questions (Table 1). If you are regularly seeing the cats from seven years of age, repeating the same questions each year to have the owner thinking about what has changed will aid in the early recognition of potential disease processes.
Diagnosis of feline OA/DJD also often relies on owner-observed changes in combination with veterinary examination and further diagnostic investigations. Having a checklist of common signs of feline arthritis can also help to increase suspicion in a particular case (See Table 1 – activity and behaviour).
Currently, one of the best validated tools is the musculoskeletal pain index; an online tool has been created for this and is free to use at: painfreecats.org.
Physical examination
A general physical examination is advisable in every cat each time it is seen. However, there are particular aspects that should be prioritised in ageing cats. First, cats should always be weighed, since it is a useful measure of health in senior cats. It is important to ensure that the weight is always recorded on the clinical record. In addition to bodyweight, body condition score should be recorded, using a nine-point system, and muscle condition should be assessed, ideally using the four-category system recommended by the WSAVA.
Second, given that dental disease is a common problem in senior cats, veterinarians should always take time to examine in the cat’s mouth. In particular, try to observe the lower premolars as feline absorptive lesions are common on these (see Figure 1). Third, always palpate for a goitre, which would increase the suspicion for hyperthyroidism, and help in clinical decision making; for example, which blood tests might be required. Fourth, if possible, listen to the heart several times during the examination, since the presence and intensity of a heart murmur will vary during the examination and this will increase the chances of detecting a murmur. Fifth, examine the coat and make a note of areas of under- and over-grooming as this will help aid in the diagnosis of musculoskeletal pain and the interpretation of your orthopaedic examination.
Finally, try to observe the cat moving around the room to assess for possible orthopaedic disease. For cats that are too shy to move during the examination, owners can video record the cat walking and moving at home. Try to perform as much of an orthopaedic examination as the cat will allow. Of course, it can be challenging in cats to determine if any reaction to your manipulations is due to pain and discomfort or is just because the cat resents being handled. The advantage of starting to assess the orthopaedic system routinely during senior wellness examinations is that the prevalence of OA is likely to be lower, and signs less marked. Therefore, it is easier to be certain that any new reaction to manipulation is likely to be due to disease. This will make you more comfortable with making a diagnosis, especially if combined with owner-observed mobility changes.
Additional diagnostic testing Which diagnostic investigations you include for healthy senior consultations will depend on how you wish to run the clinics. It is strongly advisable to include a blood pressure measurement at least annually and, again, performing this regularly will make the cat more familiar and so reduce the potential of a white coat effect. High blood pressure readings can prompt you to investigate further, rather than waiting for clinical signs to appear. Untreated hypertension leads to target organ damage and/or hypertensive retinopathy, causing acute blindness; this is sufficient reason for including this in your plan.
Depending on the costs the client is willing to pay, further diagnostic investigations such as urinalysis, biochemistry, haematology and total thyroxine measurement can be included as part of an annual plan, or can be performed only if there is a clinical suspicion. See Table 2 and Table 3.
Summary
Ageing is an individual process of every cat and healthy ageing will be influenced by genetic and epigenetic factors. Regular health assessments enable earlier recognition and management of age-related disease, reducing the negative impact on the cat’s health. The best timing of these visits and additional diagnostics testing is still to be determined. The Feline Healthy Ageing Clinic at the University of Liverpool hopes to answer these questions and determine what factors influence the ageing process in cats. In the future, we may be able to manipulate the ageing process to extend both the healthspan and the lifespan of our feline clients.
A full list of references is available on request.
