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Ursodiol (ursodeoxycholic acid) is a bile acid medication used for liver and gallbladder disease in dogs. It makes bile less harmful to the liver and helps it flow.1 The usual dose is 10 to 15 mg/kg a day by mouth, given with food, either once a day or split into two doses.1,2 It's a human medication, sold in Canada as Urso and Urso DS and as generic ursodiol.3
Key Takeaways
Call your vet the same day if your dog turns yellow, vomits repeatedly, stops eating, or has a painful or swollen belly while on ursodiol. These can be signs of a blocked bile duct or a gallbladder problem getting worse.4,5 Hold the next dose until your dog has been checked. Call us at (519) 896-0532, or use our emergency page after hours.
Ursodiol is a bile acid. The liver makes bile acids to help digest fat, and they work a bit like detergents in the gut. Bile naturally contains a small amount of ursodiol. Giving it as a tablet raises that amount until it becomes the main bile acid.3
Urso is a 250 mg tablet and Urso DS a 500 mg tablet.3 Generic ursodiol is also sold as a 300 mg capsule.1 For small dogs, a compounding pharmacy can make it in smaller doses or as a flavoured liquid.
When bile can't drain from the liver properly, a problem called cholestasis, bile acids build up inside it. Many bile acids are harsh detergents, and at high levels they damage liver cells.3,6 Ursodiol is a much gentler one. Once it's the main bile acid, the bile that backs up does less damage.3 It also increases bile flow, which helps clear bile out of the liver, and it protects liver and bile duct cells from injury and inflammation.1,2,3
Most of what's known about these effects comes from people and lab animals. The ACVIM specialist panel notes ursodiol has been little tested in dogs, but still recommends it for some liver diseases because it's safe.1
Ursodiol is used when bile isn't flowing well or the bile ducts are inflamed. It's given alongside whatever treats the underlying cause.
| Condition | What it is | Where ursodiol fits |
|---|---|---|
| Chronic hepatitis | Long-term inflammation of the liver | Added when bile flow is reduced or the bile ducts are involved1 |
| Cholangitis | Inflammation of the bile ducts, often with a bacterial infection | Given with antibiotics, and often with SAMe and vitamin E2 |
| Gallbladder mucocele | A gallbladder packed with thick, mucus-filled bile | Tried in dogs with no sign of leakage or blockage; surgery if it progresses4 |
| Gallstones | Stones in the gallbladder or bile ducts | Keeps bile flowing, but rarely dissolves stones in dogs6,7 |
For chronic hepatitis, the ACVIM consensus recommends ursodiol when the hepatitis comes with cholestasis, inflamed bile ducts or a suspected infection in the bile.1 Copper-associated hepatitis also needs copper removed from the liver, and immune-mediated hepatitis may need a drug such as prednisone.1
Cholangitis, also called cholangiohepatitis, is inflammation of the bile ducts. Bacteria are often involved, so antibiotics treat the infection while ursodiol increases bile flow through the inflamed ducts.2
A gallbladder mucocele is most common in middle-aged and older dogs, especially Shetland Sheepdogs, Miniature Schnauzers and Cocker Spaniels.4 A dog with no signs of leakage or blockage may be managed with ursodiol first. If the mucocele gets worse on bloodwork or ultrasound, the gallbladder needs to be removed, and most dogs that are already unwell need surgery.4 Mucoceles rarely go away with medication alone.4
Ursodiol dissolves gallstones that contain cholesterol,6 but most gallstones in dogs are made of calcium and bile pigment,7 so it isn't expected to break them down. We use it to keep bile moving. A stone blocking the bile duct needs surgery.7
The usual dose is 10 to 15 mg/kg a day by mouth, with food. It can be given once a day or split into two doses about 12 hours apart.1,2 For gallbladder mucoceles and gallstones, some vets use a higher dose of up to 25 mg/kg a day.4,7
| Dog's weight | Daily dose at 10 to 15 mg/kg |
|---|---|
| 5 kg (11 lb) | 50 to 75 mg |
| 10 kg (22 lb) | 100 to 150 mg |
| 20 kg (44 lb) | 200 to 300 mg |
| 30 kg (66 lb) | 300 to 450 mg |
| 40 kg (88 lb) | 400 to 600 mg |
Your vet rounds the dose to a tablet size that's practical to give. Small dogs often need less than any tablet, so we have their ursodiol compounded. The 500 mg Urso DS tablet is scored and can be split in half.3 Keep split tablets apart from whole ones, because the cut surface is bitter and the taste rubs off.3
Most dogs with chronic liver or gallbladder disease stay on ursodiol long term, often for life. According to the ACVIM panel, safety studies have found no harmful effects on dogs' health or bloodwork.1
Tell your vet if your dog also takes cyclosporine (Atopica), which is used for allergies and some immune diseases. In people, ursodiol can change how the body processes cyclosporine, so blood levels may need checking.3
Nausea and diarrhea, and both are rare. They're the only side effects the ACVIM panel lists.1 We see them occasionally, usually mild and soon after a dose. If your dog's stomach is upset, I recommend splitting the daily dose into two smaller doses with meals.
Facial swelling, hives or trouble breathing after a dose can mean an allergic reaction.3 That needs an emergency vet right away.
An overdose mostly causes diarrhea. In toxicity studies, very high doses made dogs drool and vomit.3 If your dog gets into the bottle, call us or the nearest emergency clinic.
Ursodiol isn't used when the bile duct is completely blocked.3 It pushes more bile toward a duct that can't drain, so the blockage has to be relieved first.2 Gallstones, a mucocele and pancreatitis can all block the duct.5 With a partial blockage, vets use it with caution.3
It's also avoided in these situations:
Liver supplements are often paired with ursodiol, because they work in different ways. SAMe raises glutathione, the liver's main antioxidant, and vitamin E protects cell membranes from oxidative damage.1 Milk thistle (silybin) comes combined with SAMe in products such as Denamarin, though its benefit in dogs is less clear.1
They're added to ursodiol rather than used in place of it. SAMe goes on an empty stomach and ursodiol with food,1 so the two are usually given at different times of day.
Your vet will recheck liver enzymes regularly. Once things are stable, we usually check every 6 to 12 months, and sooner after a change in treatment or if symptoms come back. Dogs being managed for a mucocele also need repeat ultrasounds, because any progression means it's time for surgery.4
A bile acid test can read slightly high while a dog is on ursodiol. In a study of 20 healthy dogs given ursodiol for 6 to 8 weeks, a few had bile acid results above the normal range. Every repeat test was normal 3 days after stopping.10 That's why we stop ursodiol for 4 to 5 days before the test.
If your dog is due for a recheck on ursodiol, or you're unsure of the dose, call us at (519) 896-0532.
Yes, if your vet prescribes it. Dogs take the same ursodiol people do, usually as a generic tablet or capsule, at a dose set for their weight. Avoid human liquid versions unless the ingredients have been checked, because some contain xylitol, which is toxic to dogs.
Often for life. Dogs with chronic hepatitis or gallbladder disease usually stay on it long term, and safety studies in dogs have found no harmful effects. Bloodwork every 6 to 12 months once things are stable confirms the liver disease is under control.
Rarely. Ursodiol dissolves gallstones that contain cholesterol, but most gallstones in dogs are made of calcium and bile pigment. Vets use it in dogs to keep bile flowing. A stone that blocks the bile duct needs surgery.
Not usually. A dog with a mucocele and no signs of leakage or blockage may be managed with ursodiol and repeat ultrasounds, but mucoceles seldom go away with medication alone. If it gets worse, or your dog becomes unwell, the gallbladder needs to be removed.
Ursodiol is a prescription bile acid that protects the liver from harsher bile acids and helps bile flow. Denamarin is a supplement that combines SAMe and silybin (milk thistle), which act as antioxidants. They're often used together. Ursodiol is given with food and SAMe on an empty stomach, so give them at different times of day.
Not for routine bloodwork. In a study of healthy dogs, ursodiol didn't change liver enzymes or bilirubin. Before a bile acid test, we stop it for 4 to 5 days, because it can push the result up. In that study, every repeat bile acid test was normal 3 days after stopping.
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