When to see a vet urgently
Seek immediate emergency assessment if your cat develops any of the following:
- An ongoing seizure or repeated seizures without normal recovery.
- Abnormal responses, collapse or inability to stand.
- Sudden loss of vision or pressing the head against a wall.
- Confusion with severe weakness or difficulty breathing.
Do not wait for the next planned liver or kidney check. You can find a vet near you.
Overview
When the liver or kidneys are damaged, the body loses its ability to remove waste products. These accumulate in the blood and reach the brain, causing behaviour changes, seizures and confusion. Two forms are most common in cats:
- Hepatic encephalopathy, with liver cirrhosis, a portosystemic shunt or liver failure.
- Uraemic encephalopathy, with chronic kidney failure.
These are complications of serious systemic diseases rather than independent conditions.
Encephalopathy means disturbed brain function. In the metabolic form, the cause lies in the body's metabolism and is not necessarily a disease originating in the brain. Alongside liver- and kidney-related forms, severe hypoglycaemia, or low blood glucose, can cause neurological symptoms, for example.
Hepatic encephalopathy has several interacting mechanisms. Ammonia is central, but one blood value does not describe the whole process. In a portosystemic shunt, some intestinal blood bypasses the liver through an abnormal vessel. Harmful substances can therefore enter the general circulation even when the original problem is blood flow rather than widespread destruction of liver tissue.
Causes
- Chronic kidney disease with uraemia.
- A portosystemic shunt.
- Liver cirrhosis and fibrosis.
- Acute liver failure from poisons or infections.
- Severe metabolic disturbances, including low blood glucose and electrolyte disorders.
In uraemia, reduced kidney filtration causes several harmful metabolic products to accumulate. Urea and creatinine help assess kidney status, but increases alone do not prove the cause of neurological symptoms. Confusion or seizures in a cat with kidney disease can also relate to blood pressure, electrolytes or another concurrent disease.
Severe hypertension can damage the brain, causing ataxia, seizures or behaviour changes, for example. Hypertensive eye damage can also explain sudden blindness. These symptoms should therefore not automatically be labelled uraemia because kidney disease was previously diagnosed.
Risk factors
- Older cats, which more often have chronic liver and kidney disease.
- Cats with congenital vascular abnormalities, such as a portosystemic shunt.
- Cats with chronic toxic exposure from medicines, food or poisonous substances.
- Cats with viral infections, including FIP and FeLV.
Risk factors describe situations in which underlying diseases are investigated, but do not confirm encephalopathy. A congenital shunt can cause symptoms in a young cat. Conversely, finding a viral infection alone does not establish that neurological symptoms result from a metabolic disturbance. Conditions such as FIP are also considered when investigating other neurological causes.
Typical symptoms
Metabolic encephalopathy causes neurological disturbances:
- Confusion and behaviour changes.
- Aggression or, conversely, apathy.
- Unsteady walking and ataxia.
- Drooling and jaw spasms.
- Tremors and muscle twitches.
- Loss of vision.
- Convulsions and epileptic seizures.
- Coma with severe toxic effects.
Symptoms may initially be intermittent: your cat may stare, wander aimlessly or seem slower than usual. In the hepatic form, signs are sometimes noticed after meals, but this relationship is not present in every cat. Do not carry out a feeding challenge at home to provoke symptoms.
Drooling or jaw movements alone do not distinguish hepatic encephalopathy from an epileptic seizure or another disease. Your vet needs an account of the event, its duration and recovery. Changes between episodes, such as poor appetite, vomiting, weight loss or increased drinking, may also help identify the cause.
Complications and consequences
- Status epilepticus, a series of seizures without regaining consciousness between them.
- Permanent brain damage.
- Multiple organ damage.
- Death if the underlying disease is not treated.
Status epilepticus can also mean one prolonged seizure, rather than only consecutive seizures without recovery of consciousness. It is an emergency. Not every case develops the severe consequences listed: some neurological changes can resolve when their cause is treated promptly.
Diagnosis at the vet
- Blood biochemistry, including liver enzymes, bilirubin, urea, creatinine and ammonia.
- A complete blood count for anaemia and inflammatory signs.
- Liver and kidney ultrasound.
- Viral infection tests for FIV, FeLV, coronavirus and FIP.
- Brain MRI or CT to rule out primary neurological disease.
Coronavirus and FIP investigations are not the same single test. A positive coronavirus result alone does not confirm FIP or explain all neurological symptoms. Infection testing is chosen according to clinical suspicion and suitable samples.
Blood glucose, electrolytes, hydration and blood pressure are also checked initially to identify rapidly treatable abnormalities. Neurological examination helps assess whether the symptoms fit systemic disease or need more detailed brain investigation.
Liver enzymes alone do not measure liver function. Suspected hepatic disease or a shunt may require bile acid and ammonia testing. However, normal ammonia does not rule out hepatic encephalopathy. Results are considered alongside history, other laboratory information and imaging.
Abdominal ultrasound may reveal liver or kidney changes and sometimes an abnormal vessel. Contrast vascular imaging or CT can locate a shunt more precisely. Brain MRI is considered if metabolic changes do not explain findings or concurrent structural disease is suspected. Stabilisation takes priority over imaging where necessary.
Treatment
In an acute situation, vital functions are supported and seizures and confirmed glucose, electrolyte or blood pressure disturbances are treated. Fluid treatment is planned according to dehydration, kidney function and overall health. Monitoring waste values alone is insufficient to assess care of a seriously ill patient.
For hepatic encephalopathy, your vet may use lactulose to reduce intestinal ammonia absorption. Some situations also require medicines affecting intestinal bacterial activity. Aggravating factors, such as constipation, dehydration or infection, are treated too. Home enemas or instructions prescribed for a person do not belong in home care.
Surgery for a single congenital shunt may be possible once your cat is stabilised and the vessel's anatomy established. However, not every abnormal vessel receives the same treatment. Closing multiple shunts caused by liver disease differs from correcting a single congenital shunt.
In a kidney-related case, treatment targets kidney disease severity and complications. If hypertension causes the neurological symptom, treating it may also ease those symptoms. Blood pressure and kidney function continue to be monitored during care.
Ensuring nutrition
Do not feed a cat with impaired consciousness by mouth before veterinary assessment. After stabilisation, nutrition is secured under a plan. In hepatic encephalopathy, protein quality and quantity are tailored individually; not every cat with liver or kidney disease has protein restricted in the same way. Not eating and muscle loss also require treatment.
Home care and prognosis
During a seizure, prevent falls and move dangerous objects aside. Do not put fingers or objects into the mouth. Record duration and film the event if safe without delaying help. Apparent settling does not establish whether the underlying cause has resolved.
After discharge, monitor appetite, drinking, walking, behaviour, defecation and successful medicine administration. A new drooling, confusion or seizure episode requires contact. Follow-up investigations depend on the diagnosed disease.
Prognosis depends on whether the cause is correctable, symptom duration and treatment response. A correctable shunt or metabolic disturbance can offer a different outlook from progressive liver or kidney disease. However, a severe seizure alone does not establish the extent of permanent damage.
Prevention
- Timely diagnosis and treatment of liver and kidney diseases.
- A vet-prescribed specialist diet for liver or kidney disease; cats still need enough good-quality protein, so do not restrict it yourself.
- Regular examinations for older cats, including blood tests and ultrasound.
- Avoiding poisoning and giving medicines without veterinary advice.
- Maintenance treatment to reduce toxic effects.
Maintenance treatment means following the plan for a confirmed disease and attending follow-up. It does not mean treating a new change in consciousness at home. A previous diagnosis does not replace reassessment when new neurological symptoms appear.
Important for cat owners
Metabolic encephalopathy is a serious complication of liver and kidney diseases that directly threatens life. Remember that sudden seizures, confusion and behaviour changes are reasons to seek veterinary care immediately. Only treating the underlying disease and reducing waste products in the blood can improve your cat's condition.
Urgent care also includes correcting seizures, low blood glucose and blood pressure disturbances where needed. Brain and whole-body function are therefore supported alongside treatment of the underlying disease.
This article provides general information and does not replace veterinary care. Contact a vet if you notice signs of illness in your cat.
Frequently asked questions
Does a seizure in a cat with kidney disease mean uraemia?
Not necessarily. High blood pressure, electrolyte changes or another neurological disease can also cause a seizure. Urgent assessment is needed.
Can a liver shunt cause symptoms in a young cat?
Yes. A congenital shunt can divert some blood around the liver, disrupting its detoxifying and metabolic functions. Diagnosis requires investigations.
Does normal ammonia rule out hepatic encephalopathy?
No. Ammonia can be normal in hepatic encephalopathy too. Your vet assesses symptoms alongside other test results.
Should protein be removed from the diet?
No. Cats need adequate nutrition, and protein quantity and quality are planned according to disease and nutritional status. Severe restriction without guidance can make the diet inadequate.
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
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- ACVIM Consensus Statement on the management of status epilepticus and cluster seizures in dogs and cats, ACVIM, Journal of Veterinary Internal Medicine, accessed 2026-11-03.
- Guideline for Feline Infectious Peritonitis, ABCD, accessed 2026-11-03.
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