The organs inside your own body are almost identical to those inside your dogs’ body. You may have friends who have suffered with gallstones, or you may know the pain first hand when these little stones get stuck in your bile duct. But what exactly is a bile duct, and why is it so important?

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When you eat, food enters your stomach and starts to get broken down (digested) into smaller fragments which can be absorbed across the gut wall into the bloodstream and used to give you energy. Each food type is digested differently, but fats need a liquid called ‘bile’ to break them down. 

The liver has many important jobs, and one of which is to make bile

The bile travels down tiny channels inside the liver which drain into the gall bladder – a small sac which sits between the liver lobes and stores the bile. The bile duct is a larger tube (but still only about 3mm wide in your dog!) which carries bile from the gall bladder to the first part of the small intestine, the duodenum. When food enters your stomach, the gall bladder squirts bile down the bile duct and into the duodenum where it mixes with the food you have eaten and helps digests the fats. 

How can the bile duct get blocked? 

‘Cholestasis’ is the term used to describe a blocked bile duct, and it can happen for several reasons. 

If we think of the bile duct like a hosepipe and the bile like the water flowing through it, obstruction can occur because of something that blocks the inside (like a stone being wedged in the hosepipe), or because of something blocking the hosepipe from the outside (like someone stepping on it). The bile duct runs next to another organ, the pancreas, before it reaches the gut, so problems with the pancreas can affect the bile duct too.

Cholestasis can be a result of problems inside the liver or bile duct itself:

  • Inflammation – swelling of the duct causing it to block itself
  • Infection – a build-up of infectious material causing a blockage
  • A mass in the liver (e.g. tumours, parasitic cysts, abscesses)
  • A mucocoele (a build-up of mucous in the gall bladder)
  • Gall stones (called choleliths) – although in dogs most never cause a problem

Or because of problems outside the liver:

  • Tumours in the pancreas or small intestine that press on the bile duct 
  • Inflammation of the pancreas (pancreatitis)
  • Inflammation or a blockage in the small intestine 
  • Trauma 

What happens if it gets blocked?

If the flow of bile from the liver to the gut is slowed down or stopped completely, the bile will ‘back-up’ into the liver and blood, making your dog very unwell. Bilirubin is a pigment contained in bile – it gives stools their characteristic brown colour. If it can’t escape into the gut, bilirubin builds up in the blood causing jaundice – a yellowing of the skin, gums and eyes. A high level of bilirubin in the blood is therefore often a sign of a blocked bile duct.

Symptoms 

These can vary depending on the underlying cause. They can be quite vague and ongoing, or very sudden and life threatening. 

They may include:

  • Lethargy
  • Reduced appetite
  • Weight loss
  • Vomiting
  • Jaundice 
  • Pale stools
  • Fever
  • Pain in their tummy

If you notice any of these signs in your dog, you should seek advice from your vet. If the signs develop very quickly or are severe, an emergency appointment should be made as life-threatening complications can arise quickly. 

What will my vet do if my dog gets a blocked bile duct? 

Because the signs are quite varied, your vet is unlikely to be able to make the diagnosis straight away. Unfortunately, there is no single way to diagnose a blocked bile duct. Rather, they will need to find all the pieces of the puzzle by carrying out tests, then put the pieces together to make the diagnosis. 

Remember, a blocked bile duct is not actually a diagnosis – it is a result of another underlying problem. It is critical to find the underlying cause for the blockage, as the treatment will depend on this. For example, if the cause is a tumour in the intestine, then treating it with antibiotics will never solve the problem.

How your vet will approach the case

Firstly, they will need to get the history by asking you detailed questions about the signs you have noticed at home.

The next step will be to do a thorough physical exam of your dog – including assessing his demeanour, hydration, heart rate, breathing, temperature, gums, and checking for any tummy pain.

A blood test will be the most likely next step. Based on the physical exam, if his signs are serious, your vet may admit your dog into the hospital to put him on a drip and carry out further tests immediately. If his signs are more mild, your vet may run a blood test as an out-patient. The blood tests will be checking for a number of things e.g. infection, inflammation, anaemia, liver and kidney function, blood proteins and salts. 

A urine sample is also likely to be useful to help your vet make the diagnosis. 

With all this information, your vet may have a high suspicion of a blocked bile duct. X-rays and/or an ultrasound scan (just like a pregnancy scan) of his tummy will probably be needed to confirm this. Sometimes, some sedation is needed to do the scan, but very well behaved (or often, very poorly) dogs, can be compliant enough to allow it whilst awake. 

Once a diagnosis is made, your vet will discuss treatment options for your dog which may be medical or surgical, depending on the cause.

Can it be fatal?

There are plenty of cases where a blocked bile duct can be treated successfully if treatment is started quickly enough, such as with infections or mucocoeles. But yes, a blocked bile duct can be fatal, either because of the severity of the underlying cause (e.g. a pancreatic tumour) or because of the damage caused to the body as a result of the blockage. It’s therefore vitally important that you seek timely advice from your vet if your pet is unwell.

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