What are Cholestasis?
The liver plays an important role in digestion. When an animal begins digestion of food, the liver secretes bile acids, enzymes and bicarbonates that all aid in the breakdown and absorption of fats in food.
The gallbladder may also play an important in cholestasis. The main function of the gallbladder is to take the bile produced by the liver and store it during times when the animal is not consuming or digesting food. In doing so, water is taken out of the gallbladder and the bile becomes very concentrated. This can pose many problems as concentrated bile salts and acids can result in the formation of gallstones.
Cholestasis is a term that refers to the dysfunction of the hepatobiliary system, where the circulation of bile from the liver and gall bladder may be inhibited.
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Symptoms of Cholestasis in Dogs
- Polydypsia ( increased thirst)
- Abdominal pain (colic)
- Weight loss
- Acholic stool( this essentially means that the feces may have a pale appearance as a result of lack of bile excretion)
- Vomiting or regurgitation
- Discomfort may be seen as pacing, consistently trying to find a comfortable position
Often, veterinarians may have a hard time diagnosing the animal based on for either intrahepatic or extrahepatic cholestasis since the symptoms tend to overlap.
- Intrahepatic cholestasis refers to the cessation of bile flow within the liver; this can occur within the epithelial lining of the liver such that the canaliculi may be obstructed in some way
- Extrahepatic cholestasis often refers to the cessation of bile flow outside the liver; this may be associated with a physical obstruction of the bile duct system which may be either foreign bodies or inflammation
Causes of Cholestasis in Dogs
Intrahepatic cholestasis may be associated with:
- Liver cell carcinoma
- Tumors that metastasize
- Inflammation or infection within the liver canaliculi itself
Extrahepatic cholestasis may be caused by either an intraluminal or extraluminal block within the biliary system. These can include:
- Gallstone formation
- Pancreatic carcinomas
- Carcinomas of the duodenum (part of small intestine)
Diagnosis of Cholestasis in Dogs
A veterinarian may request a liver biopsy and blood chemistry report to be done on your dog. The aim is to identify for:
- Increased levels of bilirubin in the blood; this is referred to as hyperbilirubinemia
- Increased levels of ALP, and GGT which are enzymes of the liver
- As Vitamin K is fat soluble, any stagnation of bile may lead to a decrease in vitamin K absorption so levels must be evaluated
- Hypercholesterolemia, which is increase cholesterol levels due to lack of fat absorption
- Studies suggest that an increase in cholesterol may be more a more evident in dogs with extrahepatic cholestasis
- Bile acid concentration may rise as a result of cholestasis
Ultrasounds and radiographs may be done in order to identify any gallstone formation or ulcers that may be present in the duodenum of your canine.
Treatment of Cholestasis in Dogs
Treatment for cholestasis is dependent on the type of cholestasis and the potential secondary infection that may arise. Should secondary bacterial infection occur then inflammation of the hepatic duct may be prevalent. Veterinarians may choose antibiotics and steroids best suited to your pet’s need. Most commonly, prednisolone approximately 0.5-1 mg/kg may be administered to your dog every 12 hours to treat lymphocytic inflammation.
In regards to intrahepatic cholestasis, treatment will involve controlling inflammation and infection, and supportive care to stimulate bile flow and production. In this case, veterinarians may use Ursodiol which is a drug that may increase bile flow as a result of increased excretion of bile acids and bilirubin.
Should this be a case of extrahepatic cholestasis where obstructions of the biliary tract are prevalent, then surgery may be needed in order to decompress the build up in pressure with the gallbladder and bile duct.
Recovery of Cholestasis in Dogs
Because cholestasis may be caused by an array of factors it is hard to estimate the recovery time and specific management. Essentially, veterinarians will aim to treat the symptoms first and prevent them from worsening.
If your dog experiences symptoms such as diarrhea or vomiting during the course of antibiotics then your veterinarian may suggest routine subcutaneous fluids to be administered in order to prevent dehydration. Antiemetics may be administered as well should vomiting and nausea occur during the course of recovery.
If your dog’s immune system has been compromised as a result of bacterial colonization, the veterinarian may administer probiotics along with the broad range antibiotics. Furthermore, diet may be restricted to low fat foods in order to prevent the liver from doing extra work.