Do you jump to conclusions?
This was the case for the people who brought their dog in last Friday night (challenging cases always happen on a Friday).
He was a Cocker Spaniel who doddered into the consult room looking at least 100 years old. It turned out he was only 8, but he hadn’t been himself for several days.
Within seconds, it became evident that the whites of his eyes were stained yellow. After lifting his lip, I wasn’t surprised to see that his gums were not pink but yellow, and on parting his fur I saw his skin had a yellow tinge. This dog was jaundiced.
His concerned humans had been watching my face and quickly demanded to know what I’d seen. Learning their dog was jaundiced, the mother immediately said, “That’s his liver, isn’t it?”
Most people jump to the conclusion that liver disease is the sole cause of jaundice, but it’s actually more complicated than that.
Other Possible Causes
The yellow staining of jaundice is caused by an excess of bilirubin in the bloodstream. The big question? How did the bilirubin get there?
This is where liver disease comes in: The liver processes bilirubin to form bile, so any condition that causes liver cell destruction releases bilirubin into the bloodstream.
The most common types of liver disease are:
- Infection, either bacterial or viral (what we call “hepatitis”)
- Toxins, such as poisonous plants or toxic chemicals
- Breed-specific liver disease, such as copper toxicosis in Bedlington Terriers
- Autoimmune disease, where the immune system attacks its own cells
- Adverse drug reactions
From the range of problems, you can see why using the label “liver” disease is pretty general. Treatment depends on identifying the exact nature of the liver disease.
But this is only part of the story because jaundice can arise from problems that occur before blood circulates through the liver or because of problems with bile as it exits the organ. This is what vets call pre-hepatic, hepatic or post-hepatic jaundice.
To understand this concept, think of the bilirubin in the bloodstream like cars on a road. When everything flows properly, there’s no problem. Now imagine there’s a massive traffic jam to get onto the freeway. It may be caused by a breakdown on the road (pre-hepatic jaundice), or only one lane is open on the freeway (hepatic jaundice) or an accident occurred on the off-ramp (post hepatic).
Problems Before the Liver
Pre-hepatic problems are due to the destruction of red blood cells, which sets bilirubin free. The most common reasons for this include:
- Autoimmune disease
- Adverse drug reaction
Treatment varies widely, depending on the cause, and ranges from high doses of steroids (autoimmune disease) to surgery or chemotherapy.
Problems After the Liver
Just like that accident on the freeway off-ramp, anything that prevents the gall bladder from draining out of the liver will cause bilirubin to build up in the liver and then overflow into the bloodstream.
The most common causes of this are:
- Gall bladder disease, such as gallstones or infection
- Trauma to the belly
Again, identifying the exact problem is crucial to correcting the jaundice.
Here’s Dr. Bob Payne, DVM, with more info in this quick video:
Identifying the Problem
So how does your vet know where the problem lies? Good question — it depends on running diagnostic tests.
A physical examination clues the vet in on body condition, fever or cancer but goes only so far. Blood tests are therefore necessary.
Screening blood tests help identify anemia (lack of red blood cells), raised white cell counts (sign of infection or cancer depending on the type) and liver enzymes. This gives pointers as to where the problem lies, but still further work is needed.
Anemia could be due to red blood cell destruction, and so the vet runs tests on the blood itself. This means looking at the blood cells under a microscope for changes consistent with cancer or autoimmune disease. In addition, they may run an “auto agglutination test” to see if the blood cells are sticking to themselves (a sign of autoimmune disease).
After that, imaging such as X-rays or an ultrasound scan helps troubleshoot for tumors. If it appears the liver is the site of the problem, then a needle biopsy gives a definitive diagnosis.
As it happened, my patient on Friday night had a liver infection, so the mother was right all along — but I’d call it a lucky guess because jaundice is far more complicated than just “liver” disease.
This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Oct. 11, 2018.