CPD
CPD ACCREDITED
ACCREDITED ARTICLE
ARTICLE
Proteinuria
and the Progression of Chronic Kidney Disease in Cats
Liesel L van der Merwe, BVSc MMed Vet (Med) Small Animals
Senior lecturer: Outpatients
Chronic kidney disease is common in cats, with an
increased prevalence in older animals, affecting 30-
40 % of those over 10 years of age. The average life
expectancy is 1-3 years once clinical signs become
apparent. There are some congenital and some
disease related causes of renal impairment in cats,
but the majority appears to be a gradual age related
deterioration in function.
Ureteroliths and nephrolithiasis are increasing in
incidence and 98% are calcium oxalate. These typically
occur in younger cats, so not part of the typical CKD,
and have no association with the progression of CKD.
Renal lymphoma, infections, nephrotoxic agents
and systemic hypertension are all associated with
decreased renal function.
Risk factors such as a general anaesthesia or
documented dehydration in the previous 12 months
or exposure to nephrotoxic drugs may cause
undetected acute kidney injury (AKI) which may
initiate or stimulate inflammation and fibrosis.
CKD is a silent disease until quite advanced. Health
checks in older cats are advised for early detection.
The AAHA advise bi-annual checks in cats >7yrs.
History and clinical signs suggestive of clinical CKD
are weight loss, dehydration, decreased kidney size,
PU/PD, systemic hypertension and low USG (1.035-
1.040). Clinical signs mean uraemia. Early stage 2-3
renal disease often clinically normal
In cats progression of renal disease does not seem
to be characterised by a slow increase in creatinine
over time but rather by abrupt increases in creatinine
(uraemic episodes) after relatively long periods of
stability (3 – 21 months). The median survival time
after diagnosis shows considerable individual variation
but is as follows: IRIS 2 - 1151 days, IRIS 3 - 778 days,
IRIS 4 - 103 days.
vet360
Issue 05 | NOVEMBER 2018 | 6
Table 1 General Clinical Exam
BCS/ Lean body
mass Severe weight loss
Appetite Decreased appetite
Oral examination Ulcers, dental disease,
halitosis pale mucous
membranes
Renal palpation Small / large kidneys ,
Contour chages,
painful ?
Ocular examination Rentinal haemorrhage,
detetchment, hypertension
Auscultation Cardiac disease , thyroid
disease , HCM
Further diagnostic tests should include a urinalysis,
serum biochemistry, haematology, systolic blood
pressure, and ultrasonography.
The aim of the further testing for a CKD is to stage
the disease according to the IRIS scoring system and
to evaluate the patient for any possible causes of the
decreased renal function (lymphoma, hypercalcaemia,
ureteroliths etc) as well as to detect any concurrent
progressors or complication of the renal disease such
as hypertension , proteinuria and hyperphosphataemia.
Urinalysis
Dipstick: to exclude diabetes mellitus as a cause for
the clinical signs.
SG: There is a loss of concentrating ability in CKD
caused by solute diuresis from tubular overload, loss
of the hypertonic medulla and impaired response to
ADH. However urine concentrating ability does not
correlate with GFR in cats and they can maintain SG
even if mildly azotaemic.