When to see a vet urgently
Seek immediate assessment if a cat with kidney disease or suspected amyloidosis suddenly deteriorates:
- breathing becomes difficult or your cat breathes with its mouth open
- the hind legs suddenly become weak and your cat cannot walk
- your cat collapses and the gums are very pale
- vision suddenly deteriorates or your cat has a seizure
Repeated vomiting and failure to eat also require prompt contact. You can find a vet near you.
Overview
Amyloid is an abnormal protein complex deposited in organs in association with various chronic diseases and inherited disorders. In the kidneys, it accumulates in the glomeruli and tubules, disrupting blood filtration. This causes proteinuria, or protein loss into urine, and eventually chronic kidney insufficiency. Amyloidosis can remain symptom-free for a long time and become apparent only at a late stage, when kidney function is substantially impaired.
Deposits can also occur in the kidney medulla and tissue spaces, rather than only in the filtering units called glomeruli. The location of changes affects the urine findings. Declining kidney function therefore does not always appear in the same way in every cat. Deposits also do not mean that the cat's diet contained too much protein.
Blood proteins normally belong in the circulation. Damage to the filter can allow them into urine. Albumin loss in particular reduces the ability to retain fluid within blood vessels, allowing it to accumulate in tissues or body cavities. Proteins regulating blood clotting can also be lost.
Causes
Although the exact mechanism is not fully understood, several predisposing factors are known:
- genetic susceptibility, particularly in Abyssinian cats
- systemic amyloidosis affecting several organs
- chronic inflammatory processes that promote amyloid formation
- immune system disorders and abnormal protein metabolism
A common form in cats is AA amyloid, whose precursor is serum amyloid A, or SAA. In the disease, the protein's structure changes and it accumulates in tissues. However, a raised inflammatory marker or SAA level alone does not establish amyloid deposits: definitive identification relies on tissue examination. Not every cat with a long-term inflammatory disease develops amyloidosis either.
Risk factors
- Breeds with inherited susceptibility, such as Abyssinian and Oriental cats.
- Older age.
- Chronic inflammatory and infectious diseases.
- Systemic diseases involving the liver or spleen.
The age at onset varies, and inherited amyloidosis also occurs in young adults. Not every susceptible breed has the same main site of damage: liver deposits can be significant in Siamese and Oriental Shorthair cats, for example. A liver or spleen finding may therefore be part of the same disease and does not, on its own, identify the cause of kidney disease.
Breed does not exclude the disease in other cats. Amyloidosis has also been found in ordinary shorthaired shelter cats. Such study populations are limited and do not establish how common the disease is in the general pet cat population.
Symptoms
Early renal amyloidosis may cause no symptoms. As the disease progresses, signs include:
- increased urination, or polyuria
- increased thirst, or polydipsia
- weight loss with a maintained or reduced appetite
- lethargy and reduced activity
- nausea, vomiting and diarrhoea
- swelling due to protein loss
- declining coat condition
- signs of chronic kidney insufficiency, such as anaemia and toxic effects within the body
Increased urination may appear as larger-than-usual litter clumps. Your cat drinks more to replace water lost in urine, but can still become dehydrated. Do not restrict drinking water to reduce urination. These signs fit many other kidney diseases too, so increased thirst or a poor coat alone does not identify amyloidosis.
Possible complications
Renal amyloidosis almost always leads to serious complications:
- chronic kidney insufficiency
- dehydration and electrolyte loss
- toxic effects from metabolic waste products
- anaemia and reduced resistance to disease
- gradual wasting
The risk of severe consequences is high, but progression is not identical in every cat. A mildly affected cat may retain kidney function for a long time. The situation is assessed from test results and their changes, and a diagnostic label alone cannot establish remaining lifespan.
High blood pressure or a blood clot can also develop. Raised blood pressure can damage the retinas and cause sudden sight loss. Balance problems, confusion or seizures may be related to the same problem. Sudden symptoms must not be interpreted simply as slow progression of kidney disease.
Diagnosis at the vet
Diagnosis is based on several investigations:
- routine urine analysis showing proteinuria and reduced specific gravity
- blood biochemistry showing raised creatinine and urea
- kidney ultrasound
- tests to exclude infections and other kidney diseases
- kidney biopsy and histology with amyloid staining, the “gold standard”
What do the investigations show?
The amount of proteinuria can be assessed with the urine protein-to-creatinine ratio, or UPC. However, protein in urine alone does not prove amyloidosis. Urinary tract infection and other diseases of the kidneys' filtering structures, for example, must be considered. Urine culture and assessment of other sample findings help distinguish them. Normal kidney size on ultrasound does not rule out severe dysfunction.
Creatinine results are also affected by dehydration and muscle mass. In a cat that has lost weight, the result is therefore considered alongside other measurements, such as SDMA, urine concentration and previous samples. Blood albumin, electrolytes and a complete blood count help assess consequences. Blood pressure is measured calmly because anxiety during a veterinary visit can raise the reading.
A tissue sample distinguishes amyloid deposits from other kidney diseases through special staining. The decision to take one depends on the cat's situation. Amyloid-related proteins in urine have been studied as potential new markers, but small studies do not yet make them a generally valid replacement for tissue examination.
Studies have compared urine proteins with those of cats whose amyloidosis was confirmed in tissues after death. These observations help explain the disease but cannot be directly equated with a screening test for a symptom-free pet. Amyloidosis was also associated with scarring of the glomeruli and increased connective tissue in the kidney's interstitial spaces. Measuring protein amount alone does not reveal the precise extent of these tissue changes.
Glomerulonephritis can resemble amyloidosis because both involve protein loss into urine. Your vet therefore also investigates other inflammatory, infectious and tumour-related causes. The disease is not named from the fact that another cat in the family previously had kidney disease. Earlier investigation reports can still help establish whether a relative truly had amyloidosis or another kidney disorder.
Treatment and follow-up
There is no specific curative medicine for feline amyloidosis. Treatment supports remaining kidney function and, where possible, addresses underlying inflammation, infection or another disease. An unwell or dehydrated cat may need hospital care and intravenous fluids. High blood pressure and significant protein loss can be treated with medicines prescribed by your vet.
A kidney diet is selected according to disease stage and your cat's eating. Introduce new food gradually; do not leave your cat without food to force acceptance of a change. Wet food and several clean drinking places can support water intake. Any additional fluid therapy is given only according to individual instructions.
At home, record appetite, drinking, vomiting, alertness and weight changes. At the clinic, kidney values, proteins, urine findings, fluid balance and blood pressure are monitored. These guide treatment changes because concurrent hypertension can increase protein loss through the kidneys.
Successful blood pressure treatment cannot be inferred simply from your cat appearing bright. Changes at the back of the eyes may be detected before you notice a visual problem. Pressure is remeasured, and medication effects are assessed from both readings and possible organ damage. Existing retinal damage does not always resolve even when blood pressure is controlled.
Anaemia associated with kidney disease occurs partly because the kidneys produce less of the hormone regulating red blood cell formation. Unusual exhaustion and pale gums therefore need investigation even without poor appetite or vomiting. Finding anaemia can change supportive care needs.
Prevention
Because amyloidosis is often associated with inherited susceptibility and chronic inflammation, prevention focuses on maintaining general health:
- regular veterinary examinations in susceptible breeds
- kidney monitoring with blood and urine tests, particularly in older cats
- prompt treatment of chronic diseases
- a balanced diet
- monitoring and management of genetically susceptible breed lines
Monitoring can identify changes before visible symptoms, but examinations or a good diet do not reliably prevent inherited amyloidosis. Tell your vet about relatives' medical histories. An affected cat may help identify monitoring needs within the same family line, even if an individual cat's genetic background cannot be defined precisely.
This text provides general information and does not replace veterinary care. Contact a vet if your cat develops symptoms.
Frequently asked questions
Can a non-pedigree cat develop renal amyloidosis?
Yes. Breed susceptibility is particularly recognised in Abyssinians, but amyloid deposits have also been found in other cats. Breed or appearance is insufficient either to diagnose or rule out the disease.
Does amyloidosis show on an ordinary blood test?
A blood test can show kidney dysfunction or consequences of disease but cannot identify amyloid on its own. Some cats with tissue-confirmed disease have not had raised creatinine. Urine examination and a tissue sample where necessary complement investigations.
Can a kidney diet remove amyloid?
Diet does not remove existing deposits. Nutritional management of kidney disease can, however, support wellbeing and manage the consequences of insufficiency. Choose suitable food with your vet and maintain adequate eating while changing diets too.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
- Amyloidosis in Cats, VCA, accessed 2026-11-03.
- Renal Amyloidosis, Cornell University, accessed 2026-11-03.
- Renal amyloid-A amyloidosis in cats: Characterisation of proteinuria and biomarker discovery, and associations with kidney histology, Journal of Veterinary Internal Medicine / PubMed, accessed 2026-11-03.
- Renal alterations in cats (Felis catus) housed in shelters and affected by systemic AA-amyloidosis: Clinicopathological data, histopathology, and ultrastructural features, Veterinary Pathology / PubMed, accessed 2026-11-03.
- Chronic Kidney Disease, Cornell University, accessed 2026-11-03.
- Glomerulonephritis in Cats, VCA, accessed 2026-11-03.
- Hypertension, Cornell University, accessed 2026-11-03.