Cholangitis

Cholangitis — inflammation centred on the bile ducts and the surrounding liver tissue — is the second most common liver disease in cats, after hepatic lipidosis (fatty liver). Because the liver is the body's chemical factory, filtering toxins and producing bile to digest fat, even modest inflammation here produces wide-ranging illness. The hallmark sign is jaundice: as inflamed ducts back up, bile pigment (bilirubin) spills into the blood and stains the gums, the whites of the eyes and the skin a tell-tale yellow.

Vets recognise two main forms. The acute, or neutrophilic, form is essentially a bacterial infection — gut bacteria travel "upstream" from the intestine into the bile duct, triggering a sudden, feverish illness with vomiting and a painful, swollen liver. It tends to strike middle-aged cats and, caught early, often responds well to a course of antibiotics. The chronic, or lymphocytic, form is slower and more puzzling: rather than infection, it appears to be an immune system that has turned against the cat's own bile ducts. This version smoulders over months, causing gradual weight loss, a fluctuating appetite and intermittent jaundice, and is managed by damping the immune response rather than with antibiotics.

A crucial feature of feline anatomy explains why cholangitis rarely travels alone. In cats, the bile duct from the liver and the duct from the pancreas merge into a shared channel before emptying into the small intestine. Inflammation in one organ readily spreads to its neighbours, so cholangitis, pancreatitis and inflammatory bowel disease frequently occur together — a trio vets nickname "triaditis." This is why a cat being investigated for liver disease is often also tested for pancreatic and intestinal problems.

Diagnosis usually combines blood work showing raised liver enzymes and bilirubin, an abdominal ultrasound to image the liver and bile ducts, and ideally a liver biopsy to distinguish the bacterial form from the immune form — because the two are treated quite differently. Alongside the specific treatment, supportive care is vital: cats that go off their food are at high risk of developing fatty liver on top of the cholangitis, so vets prioritise getting calories in, sometimes via a temporary feeding tube. With prompt, accurate treatment many cats — particularly those with the acute bacterial form — recover well, while the chronic form is usually a manageable, long-term condition.