Multimorbidity in Senior Cats: 84% Have Two or More

Only 9 of 209 cats finished a seven-year study without a single chronic condition. That is 4%. Eighty-four percent developed two or more, and 103 cats — 49% — carried the same trio: dental disease, an abnormal orthopedic examination and a heart murmur.

The numbers come from the Cat Prospective Ageing and Welfare Study (CatPAWS): 209 client-owned cats in north-west England, enrolled at 7 to 10 years and examined every six months from 2017 to January 2024, median follow-up 4.4 years across 1,241 visits. It moves the practical question: not whether an older cat has a second disease, but which disease in front of you is doing the damage this month.

What the cohort measured

Each visit scored eight conditions from 0 to 8: chronic kidney disease, neoplasia, hypertension, hyperthyroidism, heart murmur, diabetes mellitus, dental disease and any orthopedic abnormality. Median age at enrolment was 8.1 years; the median age across all visits was 10.3 years. Fifty-nine cats (28%) died during follow-up, and median life expectancy in the cohort was 15.2 years, against roughly 14 years for UK primary-care cats overall.

Two design details matter. Every cat had a full oral and orthopedic examination at every visit, so mild disease that a ten-minute wellness check misses was recorded; and a condition counted once it appeared, so these are lifetime figures, not a snapshot.

Dental disease, joints and murmurs: the 49% trio

Condition	Cats affected	Median age at diagnosis	New cases per cat-year
Dental disease	84%	9.3 years	0.40
Orthopedic abnormality	82%	10.1 years	0.38
Heart murmur	59%	10.4 years	0.16
Hypertension	20%	12.0 years	0.05
Chronic kidney disease	11%	11.6 years	0.02
Neoplasia	9%	11.7 years	0.02
Hyperthyroidism	8.6%	11.1 years	0.02
Diabetes mellitus	1.9%	12.2 years	0.004

Eighty-four percent depends on the definition: a gingivitis score of 2 or worse, any tooth resorption lesion, or stomatitis — the point at which dental work under anaesthesia is advised. 129 cats already qualified at enrolment, aged 7 to 10. Radiographic osteoarthritis tells the same story: 61% of cats have it in at least one appendicular joint, 48% in two or more.

Hypertension never arrives alone

Forty-one cats developed hypertension, diagnosed when systolic blood pressure stayed at or above 160 mmHg on repeated measurement. Twenty-eight of them (68%) also had a murmur, 9 (22%) had hyperthyroidism and 9 (22%) had chronic kidney disease. Not one cat that developed hypertension, hyperthyroidism, diabetes or kidney disease had that condition in isolation.

The age curve is not smooth: predicted probability rose steeply in male cats after 10 years, far more than in females, and the eye is often where it is found first — a sudden bleed, or a pupil that stops reacting.

The thyroid and kidney trap

Hyperthyroidism affected 18 cats (8.6%), diagnosed on a total T4 of 60 nmol/L or above, or above 50 nmol/L with a raised free T4. Between 15% and 50% of hyperthyroid cats have kidney disease that the thyroid is hiding: high thyroid hormone raises glomerular filtration, so creatinine looks acceptable until the cat becomes euthyroid and filtration falls.

That is why the order of tests matters more than the order of drugs. Before choosing methimazole, an iodine-restricted diet, surgery or radioiodine, ask for creatinine, urine specific gravity, ideally SDMA, and blood pressure, then recheck creatinine four to eight weeks in. A rise from 150 to 230 micromol/L after treatment does not mean the treatment caused harm; the kidney disease was always there and is now visible.

What the pile-up costs in survival

In 178 cats with a score at enrolment, four or more conditions carried six times the hazard of death during follow-up (HR 6.30, 95% CI 1.5 to 26.1). The score climbed by a factor of 1.09 for every year of age, and no cat over 12 years had a score of zero.

Two findings are more actionable than the headline. Mild muscle loss at middle age — the 20 to 29 band out of 30 — doubled the hazard of death (HR 2.01). A body condition score of 7 to 9 out of 9 at enrolment raised the hazard fivefold once the cat passed 11 years (HR 5.04), while 3 to 4 roughly doubled it at any age (HR 2.48). Pedigree cats died at twice the rate of mixed breeds, median life expectancy 12.7 years against 15.8.

Which problem goes first

Four rules cover most sequencing decisions. Pain and blood pressure come before anything elective. The thyroid is stabilised before kidney treatment is judged. Hydration and blood pressure come before any NSAID for arthritis. Dental work waits until anaesthetic risk is acceptable, not until the mouth is perfect.

Situation	Treat first	Why
Grade 3 murmur, mouth pain, no breathlessness	Dental work after a cardiac review	Untreated dental disease keeps driving inflammation and weight loss
Blood pressure 180 mmHg, T4 80 nmol/L	Blood pressure today, thyroid plan this week	Pressure damages eyes and kidneys within weeks
T4 high, creatinine 200 micromol/L	Thyroid treatment, then kidney staging	Kidney values are only interpretable once euthyroid
Arthritis plus kidney disease	Fluids, then a reviewed analgesic plan	Dehydration is the main avoidable trigger for kidney injury

A 12-month schedule and what it costs

The 2021 AAHA/AAFP life-stage guidelines put mature cats at 7 to 10 years and senior cats over 10, and set a minimum of one examination a year for every cat, rising to at least every six months once a cat is senior. In practice that is two to three visits a year, alternating a full check with a nurse weight and blood-pressure check. Each full visit covers weight, body and muscle score, blood pressure, dental chart, bloodwork with total T4, and a yearly urinalysis.

Item	United States	China
Senior wellness examination	$180 to $260	¥320 to ¥560
Bloodwork with total T4	$120 to $220	¥870 to ¥1,600
SDMA alone	$40 to $80	¥290 to ¥580
Anaesthetic dental cleaning	$350 to $750	¥800 to ¥2,000
Echocardiogram with report	$220 to $450	¥600 to ¥1,200

What to record between visits

The exam finds what the history points at, so bring numbers rather than a feeling. Weigh the cat monthly on the same scale. Measure a 24-hour water intake twice a month; over 50 ml per kg per day deserves a call. Count resting breaths, and note whether the cat still jumps onto the third shelf — and when it stopped.

Weight: a fall of 5% in 30 days is the line, not a trend you wait out.
Water: rising intake precedes visible kidney signs by months.
Breathing: 30 breaths a minute at rest is the referral line.
Jumping: the first sign of joint pain is a change in route, not a limp.
Appetite: a cat that eats but loses weight needs T4, glucose and a kidney panel on the same visit.

This article does not replace a veterinary diagnosis. Doses, drug choices and anaesthetic decisions have to be made by a veterinarian who has examined the cat, and several of the conditions above change how the others are treated.

Terms mentioned in this article

T4 SDMA

Frequently asked

My 12-year-old cat has three diagnoses. Is that unusual?

No. In the CatPAWS cohort, 37% of cats developed three chronic conditions and a further 25% developed four or more; only 4% finished with none. Three conditions is the middle of the distribution, which is why treatment order matters more than the count.

Will treating hyperthyroidism make the kidneys fail?

It can unmask kidney disease that was already there. Between 15% and 50% of hyperthyroid cats have masked chronic kidney disease, because high thyroid hormone raises filtration and flatters the creatinine. Check creatinine, urine specific gravity and blood pressure before treatment and repeat creatinine four to eight weeks after starting.

How often should a cat over 10 be examined?

Every six months under the 2021 AAHA/AAFP life-stage guidelines, with blood pressure and a urinalysis at each full visit and bloodwork including total T4 at least yearly. In the cohort, no cat over 12 years had a multimorbidity score of zero, so a normal examination is a reason to keep the schedule, not to skip it.