Jaundice in dogs: causes, tests and treatment

Overview

Bilirubin forms partly through the breakdown of haemoglobin from ageing red blood cells. The liver processes bilirubin and passes it into the intestine in bile. Increased production or impaired elimination allows the pigment to accumulate in blood and tissues.

Jaundice and raised blood bilirubin do not themselves confirm liver disease. Extensive red blood cell destruction can also cause yellowing without primary liver damage. Visible jaundice generally appears when total bilirubin exceeds around 2.5–3 milligrams per decilitre. Yellow discolouration may appear in a blood sample before your dog's skin or mucous membranes become yellow.

Processing in the liver makes bilirubin water-soluble, allowing elimination in bile and partly in urine. The physiological jaundice typical of human newborns is not recognised in dogs, so yellowing in a puppy also needs investigation.

Causes

Red blood cell destruction increases bilirubin production

In haemolysis, red blood cells are destroyed so rapidly that the liver cannot process all the released haemoglobin. A common cause in dogs is immune-mediated haemolytic anaemia, or IMHA. The body's immune response then targets its own red blood cells. Red blood cell infections, adverse medicine reactions and poisoning can also cause haemolysis. Babesia infection and zinc poisoning, for example, are possible causes in a jaundiced, anaemic dog.

Less commonly, a large haematoma or blood leaked into the abdomen can increase bilirubin production. This differs from immune-mediated destruction of red blood cells.

Red blood cells can break down within blood vessels or be removed by cells in the spleen or liver.

Impaired liver processing and blocked bile flow

Liver cell damage can impair bilirubin processing or secretion into small bile ducts. Causes include hepatitis, toxic exposure, a tumour or advanced liver disease. Sepsis can also impair bilirubin transport without a major liver enzyme increase.

With obstruction outside the liver, bile cannot flow normally from the gallbladder and bile ducts into the intestine. Gallstones, pancreatitis, a tumour or thick gallbladder contents may obstruct flow. In a gallbladder mucocoele, thick mucus can impair emptying and cause obstruction. A ruptured gallbladder or bile duct can allow bile to leak into the abdomen.

Cholestasis, meaning slowed bile flow, can also develop within the liver's small ducts.

Risk factors

Jaundice risk depends on the risk factors for the disease causing it. Gallbladder mucocoeles occur particularly in middle-aged and older dogs. Predisposed breeds include Shetland Sheepdogs, Miniature Schnauzers and Cocker Spaniels.

In one study from northern Europe, 97 dogs with mucocoeles had an average age of 9.5 years. IMHA is diagnosed more often in females than males. Hypothyroidism, Cushing's disease and lipid metabolism disorders may predispose dogs to mucocoeles. Dogs with IMHA have an average age of around 6 years. A recognised genetic change is associated with inherited copper accumulation in Bedlington Terriers.

Breeds at risk of IMHA also include Cocker Spaniels, Finnish Spitz and Miniature Schnauzers.

Typical symptoms

Yellowing is easiest to see in pale gums, the whites of the eyes or the ear flaps. Dark skin or mucous membrane pigmentation can make the change harder to notice. Other signs you see at home depend on the underlying disease.

• Your dog eats less or becomes subdued.
• Vomiting or diarrhoea may accompany the illness.
• Your dog's abdomen is tender and painful.
• Urine may become darker than usual.
• Your dog breathes rapidly or tires more readily during exercise.
• The abdomen may enlarge because of fluid accumulation.

Haemolytic anaemia can cause weakness and fainting. Chronic liver disease may cause weight loss and increased drinking and urination. The intensity of the yellow skin colour alone cannot identify its cause.

Complications and consequences

The underlying disease causes the danger

Severe haemolytic anaemia reduces tissue oxygen delivery and may require a blood transfusion. Venous blood clots are a major life-threatening complication in IMHA. Bile leakage can cause bile peritonitis, inflammation of the abdominal lining caused by bile. Gallbladder rupture and associated sepsis increase the risk of death around surgery.

Advanced liver damage can cause ascites, clotting disorders and hepatic encephalopathy. The outlook depends on the underlying cause and disease severity. Persistent, unchanging jaundice in chronic liver disease is associated with a guarded outlook.

Yellow colour may outlast the original problem

In prolonged cholestasis, bilirubin binds to blood albumin, forming delta-bilirubin. Neither the liver nor the kidneys can directly remove this form. During recovery, delta-bilirubin may account for up to 90% of total bilirubin. Jaundice may therefore persist for 7–14 days in some patients after successful treatment of the cause. Delta-bilirubin gradually disappears as albumin breaks down.

Diagnosis at the vet

Blood counts, liver tests and urine guide investigation

Investigation begins with the history of signs, medication and possible toxic exposures. A blood count shows whether your dog has anaemia, meaning too few red blood cells. A blood smear is examined for altered red cell shape and abnormal clumping. Diagnosing IMHA requires anaemia, evidence of immune-mediated destruction and evidence of haemolysis.

Total bilirubin is measured with a blood test. Liver enzymes, albumin and other biochemical tests help assess the cause. Dividing blood bilirubin into direct and indirect fractions does not reliably distinguish haemolysis from a liver cause.

Bilirubin passed in urine is water-soluble bilirubin processed by the liver. Small amounts can also occur in concentrated urine from a healthy dog. Urine bilirubin is therefore interpreted alongside blood results and urine concentration. Urine bilirubin can increase before blood bilirubin rises.

Even without other signs, an unexplained ALT increase lasting more than 2 months is investigated for chronic hepatitis.

Cholestasis-related bilirubin increases also raise blood bile acids. Normal blood ammonia does not exclude encephalopathy associated with impaired liver function. Albumin can also be lost through the kidneys or intestine, so the cause of a low result needs separate investigation.

Ultrasound assesses the bile ducts

Abdominal ultrasound examines the liver, gallbladder and bile ducts for possible obstruction. Mucocoele contents typically remain stationary when your dog changes position. Ordinary loose biliary sludge, in contrast, may move with gravity. Ultrasound does not always reveal a gallbladder rupture that has already occurred.

Bilirubin can be measured in abdominal fluid if bile leakage is suspected. A fluid bilirubin concentration more than 10 times the blood concentration confirms bile leakage and indicates a surgical emergency.

Establishing the precise cause of liver disease may require a biopsy. This assesses changes such as inflammation, fibrosis and copper accumulation. Clotting is checked beforehand to assess procedural bleeding risk.

Fine-needle cytology does not show liver tissue structure in the same way as a biopsy. Infection tests can be selected according to the signs and diseases occurring locally. Direct sampling through the skin into the gallbladder is avoided when a mucocoele is suspected.

Treatment

Anaemia, liver disease and bile duct obstruction need different treatments

Your vet plans treatment according to the disease causing bilirubin accumulation. In severe anaemia, a red blood cell transfusion can restore the oxygen transport tissues need. Transfusion need depends on signs and how rapidly anaemia developed, rather than a single blood result alone.

IMHA is treated with immunosuppressive medicines and treatment to prevent blood clots. An identified underlying disease is also treated where possible. Corticosteroid treatment for IMHA is often prolonged. The overall course of immunosuppressive treatment is also often prolonged. These treatment requirements concern IMHA, rather than every disease causing jaundice.

In copper-associated hepatitis, copper intake is reduced and medication removes copper accumulated in the liver. Other hepatitis treatment is selected according to the cause of inflammation and tissue sample findings. Not every dog with liver disease needs protein restriction.

A symptomatic gallbladder mucocoele or rupture often requires gallbladder removal. Simply emptying the gallbladder is not recommended because mucocoeles generally recur. With bile peritonitis, the abdomen is flushed and drains are used if needed. Bacterial infection requires antimicrobial medication chosen by your vet.

A liver biopsy may be taken during gallbladder removal to investigate concurrent disease.

Clinical condition and laboratory changes are monitored together

Products protecting liver cells may support treatment of chronic hepatitis. A mild gallbladder mucocoele can sometimes be managed with medication and close monitoring. Blood tests and ultrasound may then be recommended at intervals such as every 6 weeks. Worsening signs, blood results or imaging findings may require a switch to surgery.

After gallbladder removal, liver ultrasound monitoring may be needed because of associated changes. Identified hormonal diseases and abnormal blood lipids are also treated as part of the overall plan. Reduced yellowing does not replace monitoring of the underlying cause and response.

Prevention

No single measure prevents every disease causing jaundice. Accidental exposure to medicines and toxic substances that may damage liver cells or red blood cells should be prevented. A diet for copper accumulation belongs only in the treatment plan of a dog that needs it.

Lipid metabolism disorders and hormonal diseases predisposing dogs to gallbladder mucocoeles are identified and treated. Follow-up of a diagnosed mucocoele may detect progression before rupture. New signs need attention even when previous gallbladder changes caused few signs.

Important for dog owners

Check the colour of the mucous membranes and eyes if your dog's condition changes, especially with darkly pigmented skin. Record appetite, vomiting, urine colour and energy levels for the appointment. Also report medicines used, travel and possible exposure to unfamiliar substances.

After treatment, monitor general condition as well as colour, because delta-bilirubin can sustain yellowing for 7–14 days. Rapid deterioration, severe pain or fainting requires urgent reassessment. Planned follow-up depends on the underlying disease: IMHA and a gallbladder mucocoele need different overall treatment plans.

Frequently asked questions

Does jaundice always mean liver disease?

Jaundice may result from liver disease, but also from extensive red blood cell destruction or bile duct obstruction. Visible yellowing therefore does not establish the cause. A blood count, biochemical tests and ultrasound when needed help distinguish these conditions.

Can a healthy dog have bilirubin in its urine?

Small amounts of bilirubin can occur in a healthy dog's concentrated urine. The finding is therefore assessed alongside other investigations. Increased urine bilirubin can also precede a blood bilirubin rise, so investigation of an unwell dog does not end with the urine finding alone.

Does a jaundiced dog always need surgery?

The need for surgery depends on the cause of jaundice. IMHA, for example, is treated with transfusions and immunosuppressive medicines. A symptomatic gallbladder mucocoele or bile leakage, however, may require surgery. The bile ducts and blood count are therefore assessed before choosing treatment.

How quickly should the yellow colour disappear with treatment?

Resolution of jaundice depends on correction of the underlying cause. Albumin-bound delta-bilirubin can maintain yellowing for another 7–14 days after successful treatment. Response is therefore also assessed through clinical follow-up and tests. Rapid deterioration needs urgent assessment.

Can a bilirubin result alone identify the cause of jaundice?

Blood bilirubin confirms an abnormal pigment increase but does not establish its underlying cause. Red blood cell destruction is assessed with a blood count and smear. Examining the bile ducts often requires ultrasound. Investigating the precise liver disease may instead require a biopsy.