Liver disease in cats 

Why is the liver important?

The liver is a powerhouse of an organ that carries out many vital functions within the body. It sits within your cat’s abdomen just behind the diaphragm (thin muscle layer separating the chest from the abdomen). Some of the liver’s important tasks include:

• breaking down and using protein.
• producing and storing bile (to help digest fat).
• making hormones.
• filtering waste products from the blood.  
• producing immune factors (to fight disease).
• removing bacteria from the gut.
• making and storing glucose (sugar).
• storing vitamins and iron.  

As if all this isn’t clever enough, the liver can also regenerate and repair itself after damage. But despite this brilliance, there are a few toxins that break through the liver’s defences and cause irreparable damage. One reason this happens is due to the anatomy of the liver. Major blood vessels connect the liver directly to the intestines making it the first organ to come into contact with any toxins eaten by your cat.

Cats also lack some of the enzymes (chemicals) needed to deactivate certain toxins (for example many lilies are toxic to cats but not to other species).

Liver language - a quick guide

Hepatic = anything liver-related

Gallbladder = just like in humans, this tiny balloon-like structure stores bile and sits within the lobes (sections) of a cat’s liver.

Bile = a fat-digesting fluid made in the liver and stored in the gallbladder.

Bile duct = a tube carrying bile from the gallbladder and liver to the small intestine.

Hepatitis = inflammation of the liver.

Cholangitis = inflammation of the bile duct.

Cholangio-hepatitis = inflammation of the bile duct that spreads to the liver.

What causes liver disease in cats?

Fatty liver (hepatic lipidosis)

We usually see this condition in cats when they suddenly lose their appetite. Fat accumulates within liver cells causing them to swell and stop working. Overweight cats are the most likely to develop hepatic lipidosis, although it can affect all cats.

Bacterial infection (neutrophilic cholangitis)

Bacteria can move through the bile duct from the small intestine into the liver. Infected liver cells become inflamed and liver function reduces. Cats with neutrophilic cholangitis quickly show signs of being unwell.

Non-infectious inflammation (lymphocytic cholangitis)

Although not certain, vets believe lymphocytic cholangitis is when the liver becomes inflamed due to an abnormality within the cat’s immune (disease fighting) system. Recognising this condition isn’t straightforward as cats may have vague symptoms that come and go for months or even years.

Toxins

Most cat owners are aware of the dangers of lilies but there are other potential liver-damaging plants to look out for. Your local garden centre can advise and may even have a cat-friendly selection of plants. Common household and garden chemicals can be dangerous, as can medications prescribed for other species (most human and dog medicines aren’t suitable for cats).

Tumours

Cancer of the liver may be primary (the tumour just affects the liver) or secondary (tumours have spread to the liver from elsewhere in the body). Treatment (including surgery to remove a mass or part of affected liver) very much depends on the type of tumour your cat has.

Portosystemic shunt (PSS)

A PSS is a plumbing issue affecting blood vessels that connect the liver and small intestine. Blood bypasses the liver and enters the cat’s circulation without undergoing the liver’s usual filtering and cleaning. Toxins build up in the blood preventing nutrients from being absorbed. This nutrient deficiency limits growth causing cats with a PSS to be smaller than normal.

Cats are usually born with this condition (congenital), although very occasionally it develops alongside another liver-disease (acquired).

Endocrine (hormonal) conditions

Diabetes mellitus (sugar diabetes) changes how the liver metabolises fat making it more likely that cats develop hepatic lipidosis. Cats with hyperthyroidism (an overactive thyroid gland) often have higher levels of liver enzymes (chemicals) in their blood although liver function is unaffected.

Gallbladder and bile duct diseases

Gallbladder inflammation (cholecystitis) is usually due to a bacterial infection. This infection can also spread to the bile duct and within the liver. If the bile duct gets very inflamed it can block completely leading to severe disease (a bile duct tumour can also block this tiny tube).  Although rare, cats can develop stones within the gallbladder just like humans. 

What are the signs of disease?

There are a few common signs of liver disease although your cat’s exact symptoms will depend on the underlying cause of their condition.

Most cats with liver disease lose weight, stop eating, and become lethargic (seem very tired). More specific symptoms include:

• Pyrexia (a high temperature).
• Drinking more.
• Vomiting.
• Dehydration.
• Ascites (a swollen abdomen due to fluid accumulation).
• Jaundice (a yellow tinge to gums, skin, and inner eyelids).
• Abnormal behaviour or seizures (fits) if toxins build up and reach the brain.  
• Blood clotting problems (the liver makes proteins to help blood cells clot).

Diagnosing liver disease

If your vet suspects your cat has liver disease, they’ll carry out tests to confirm this and rule out other causes of your cat’s symptoms:

Blood tests

Damaged liver cells release enzymes (chemicals made within the cell) into the bloodstream. High enzyme levels indicate significant liver damage. Blood tests measure:

• ALT (alanine aminotransferase)
• ALKP (alkaline phosphatase)
• AST (aspartame aminotransferase)
• GGT (gammaglutamyl transferase)

The liver makes bile acids to help digest fat. High levels of bile acids within the blood indicate reduced liver function (whereas elevated enzymes indicate liver damage).

Cats with liver disease often have low protein levels in their blood because: 1. Damaged liver cells are unable to make protein and 2. Being unwell often reduces a cat’s dietary intake (they eat less protein). 

A full haematology screen checks your cat’s blood cells for signs of infection, inflammation, and anaemia (low levels of healthy blood cells).

Imaging the liver

If blood tests show that liver disease is present, your vet may advise X-rays and an ultrasound scan to show the extent of damage. By scanning your cat’s liver, vets can measure its size, asses the texture (disease processes change how liver tissue looks), and check for other abnormalities (such as a blocked bile duct).

Liver biopsy

A biopsy involves taking a small piece of liver tissue to send to a pathologist (specialist vet who studies how cells react to disease). Your cat will usually be asleep under a general anaesthetic throughout. Before taking liver tissue, your vet will check that your cat’s blood can clot normally. Bleeding problems occur if the liver can’t make enough important clotting factors (chemicals).

The pathologist provides important information to help plan your cat’s treatment (for example what antibiotics to use if infection is present).

Treating liver disease

Inpatient treatment

Cats who are very poorly can quickly become dehydrated and stop eating. To prevent further complications, they made need a stay in hospital as an inpatient. Supportive treatment includes intravenous fluids (a drip), assisted feeding (via a tube into the oesophagus) and injectable medications.

At home

Cats with mild disease (and those well enough to leave hospital) can be looked after at home. Your vet will guide you on how to give any prescribed medicines. They may also advise liver supplements to help the liver recover and to replace missing vitamins and antioxidants (substance to help prevent cell damage).

Some cats need anti-sickness medication and appetite stimulants to help them regain their appetite.

A prescription diet can also help with recovery, your vet can advise which may best suit your cat. Generally, liver diets are highly palatable with the right amount of good quality protein and energy. They often contain high levels of antioxidants and are very digestible to reduce the liver’s workload.

Living with liver disease

Some cats recover completely from liver disease whereas others need ongoing treatment — it very much depends on the underlying cause. It’s likely your cat will need regular vet checks and blood tests to identify and treat any further liver changes as soon as they arise.

It’s always hard finding out your cat has any health issues so speak to your veterinary team if you’re struggling and need more support (most are pet owners themselves who understand how you feel!)

Advances in veterinary medicine means more and more cats with liver disease can receive supportive treatment and lead good, happy lives.