Cholestasis is not a disease in itself; it’s a symptom of disease elsewhere.
Cholestasis is the inability of the gall bladder to empty bile into the small intestine. To understand what causes cholestasis, it helps to know the anatomy of the liver.
The gall bladder is like a tiny balloon full of bile. It sits in the liver and drains into the small intestine (the duodenum, to be precise) via a narrow tube called the bile duct.
If the bile duct becomes blocked, pressure builds in the gall bladder and causes bile to reflux in the wrong direction — back into the bloodstream. If this happens, the animal becomes jaundiced (jaundice can happen for reasons other than a blocked bile duct).
A bit like putting your foot on a hose, anything that compresses the bile duct stops the bile from flowing freely. Reasons for this include swelling in the liver, tumors, infection or inflammation of the bile duct, gall stones and foreign bodies within the small intestine.
The most obvious symptom is jaundice or yellowing of the skin. A good place to spot this is the cornea or whites of the animal’s eyes. Many animals also have pain in their tummies, and often refuse to eat.
Many times, cholestasis is linked to a primary disease, which is what is actually causing gall bladder issues. The signs of illness are linked to that condition and often include fever, appetite loss, increased thirst and vomiting.
The cause of cholestasis involves the search for another illness such as:
- A liver tumor — this puts pressure on the bile duct and stops it from draining into the small intestine
- Swelling in the liver — common causes include liver infections, either bacterial or viral. The generalized swelling narrows the bile duct and prevents it from working properly
- Inflammation of the gall bladder — this happens as a result of infection in the bile (cholecystitis)
- Gallstones — although relatively unusual in the dog and cat, they do happen; gallstones can move to plug the bile duct like a cork in a bottle
- A foreign body in the duodenum — an example of this is a dog that swallows a golf ball; if a ball gets stuck in a certain part of the small intestine, it can block the exit to the bile duct, a bit like putting a plug in a sink
The first step to diagnosis is a blood screen. Jaundice can occur for other reasons, such as damage to red blood cells, and a blood screen can help rule the latter out, indicate infections and give clues about liver disease.
Further investigation includes ultrasound scans of the abdomen to look for tumors and foreign bodies, checking the health of the gall bladder and allowing ultrasound guided samples of bile to be taken for culture.
Just as stagnant water invites contamination, so a gall bladder unable to drain attracts infection. Antibiotics are a wise precaution to prevent secondary infection if your pet has cholestasis. Usually a combination of 2 antibiotics is necessary to kill the full range of bugs linked to bile.
Equally important is to search for and treat any underlying problem that stops the gall bladder from working properly. This includes surgical removal of gallstones and antibiosis for liver infections.
There is no preventive care for cholestasis other than being vigilant when your pet is unwell and taking him promptly to the vet.
- Diseases of the gallbladder and biliary tree. SA Center. Vet Clin North Am Sm Anim Pract, 39 (3): 543–598.
- Manual of Canine and Feline Gastroenterology. Thomas, Simpson & Hall. Publisher: BSAVA Publications.
This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Jan. 2, 2016.