Ursodiol (Ursodeoxycholic Acid) for Cats: Dosage, Safety, and Side Effects

Ursodiol is a bile‑acid medication that promotes healthy bile flow and offers protective benefits for the liver. This guide explains how ursodiol is used in cats, its dosing options, safety profile, and practical administration tips.

Quick Overview

• Medication type: Choloretic, bile‑acid, hepatoprotectant
• Form: Capsules and tablets (often compounded for small animals)
• Brand names: Actigall, URSO
• Available dosages: Commercial tablets (250 mg) and capsules (300 mg) are too large for most cats; veterinarians usually order a compounded preparation in a smaller, more manageable form.

What Is Ursodiol?

Ursodiol, chemically known as ursodeoxycholic acid (UDCA), is a naturally occurring bile acid produced in minute amounts by the liver. When given therapeutically, it helps:

• Increase bile flow (choloretic effect) by moving bile acids from liver cells into the ducts.
• Replace more toxic bile acids, reducing inflammation and cellular damage.
• Provide antioxidant, anti‑inflammatory, and immunomodulatory benefits.
• Protect liver cells from apoptosis (programmed cell death).

In cats, ursodiol is most valuable for managing cholangitis/cholangiohepatitis syndrome (CCHS), a complex disease that inflames the liver and bile ducts and often co‑exists with inflammatory bowel disease and pancreatitis (the triaditis complex). By improving bile flow and reducing inflammation, ursodiol supports the overall treatment plan for CCHS.

Unlike in humans, where ursodiol can dissolve cholesterol‑rich gallstones, it is ineffective against the calcium‑based stones that commonly form in dogs and cats; surgical removal remains the standard approach.

Dosing Information for Cats

Ursodiol is an off‑label medication in veterinary practice. The typical dose range is 10–15 mg per kilogram of body weight once or twice daily. For an average 10–11 lb (4.5–5 kg) cat, this translates to roughly 45–75 mg per day.

Because commercial capsules contain 300 mg and tablets 250 mg, precise dosing usually requires a compounded preparation—either a small tablet, flavored liquid, or chewable treat—tailored to the individual cat’s needs.

Veterinarians may split the total daily dose into two administrations (every 12 hours) to maintain steady blood levels.

How to Administer Ursodiol

When only commercial tablets are available, they must be cut into very small pieces (¼ tablet for once‑daily dosing or 1/8 tablet for twice‑daily dosing). The tablets are bitter, so palatability can be an issue.

Effective administration strategies include:

• Hiding the split tablet in a soft food treat or a pill pocket.
• Using a pill‑wrapper and placing it directly in the cat’s mouth.
• Having the medication compounded into a flavored liquid or a small, easy‑to‑swallow tablet.

For long‑term therapy, a compounded product is often the most practical solution.

Side Effects and Contraindications

Ursodiol is generally well tolerated because it mimics a bile acid the liver already produces. Reported adverse effects in cats are rare; occasional nausea or diarrhea have been noted in dogs.

Contraindications include:

• Complete bile‑duct obstruction (detectable via abdominal ultrasound).
• Severe ductopenia (absence of functional bile ducts), which can arise from advanced CCHS.

Routine laboratory monitoring typically shows no significant changes, except for a modest reduction in cholesterol levels.

Overdose and Emergency Care

Overdose is unlikely with properly compounded doses, but accidental administration of a full tablet or capsule could occur. Potential signs of overdose are:

• Excessive salivation
• Nausea or vomiting
• Diarrhea

These signs are nonspecific and may also reflect underlying liver or gastrointestinal disease. If an overdose is suspected, contact your veterinarian immediately or call one of the poison‑control hotlines:

• ASPCA Animal Poison Control Center: 1‑888‑426‑4435
• Pet Poison Helpline: 1‑855‑764‑7661

Potential Drug Interactions

Ursodiol may interact with the following medications. Use them together only under veterinary guidance:

• Aluminum‑containing antacids (e.g., aluminum hydroxide) – may bind ursodiol and reduce absorption.
• Cholestyramine – similar binding effect.
• Estrogens – in humans, can increase hepatic cholesterol secretion, potentially offsetting ursodiol’s benefit; relevance in cats is unclear.
• Fibrates (fenofibrate, gemfibrozil) – may counteract ursodiol’s cholesterol‑lowering action; animal data limited.
• Taurine – anecdotal concerns about long‑term taurine deficiency; not yet documented.

Storage Guidelines

Store ursodiol at room temperature (68–77 °F / 20–25 °C). Compounded tablets or liquids should be kept in a dry place and used within 28 days after splitting or opening.

References

1. Budde, J. A., & McCluskey, D. M. (2023). Ursodiol. In Plumb's Veterinary Drug Handbook (10th ed.). Wiley‑Blackwell.
2. Chen, I., & Cassaro, S. (2023). Physiology, Bile Acids. StatPearls Publishing.
3. Cifuentes‑Silva, E., & Cabello‑Verrugio, C. (2023). Bile acids as signaling molecules: Role of ursodeoxycholic acid in cholestatic liver disease. Current Protein and Peptide Science, 25(3), 206‑214.
4. Chandler, A. M., et al. (2019). Reference limits for hepatic bile duct‑to‑arteriole and bile duct‑to‑portal tract ratios in healthy cats. American Journal of Veterinary Research, 80(1), 15‑23.
5. Center, S. (2024). Feline Cholangitis/Cholangiohepatitis Syndrome. Merck Veterinary Manual Professional Version.
6. Černá, P., Kilpatrick, S., & Gunn‑Moore, D. A. (2020). Feline comorbidities: What do we really know about feline triaditis? Journal of Feline Medicine and Surgery, 22(11), 1047‑1067.