Onsior (robenacoxib) is a COX-2 selective NSAID manufactured by Elanco, notable for being one of the few NSAIDs licensed for use in both dogs and cats. For cats, it is available for both short-term post-operative pain and — uniquely — for longer-term pain management under veterinary supervision.

Price Comparison

Onsior tablets (per pack/monthly equivalent):

  • Dog tablets (from vet): £20–£45 per month
  • Dog tablets (online pharmacies): £12–£28 per month
  • Cat tablets 6mg (from vet): £15–£35 per pack of 6
  • Cat tablets 6mg (online): £10–£22 per pack of 6

Savings of 35–45% are typical when purchasing from online pharmacies with a prescription.

What Does Onsior Treat?

Dogs:

  • Osteoarthritis pain and inflammation (long-term use)
  • Post-operative pain following orthopaedic and soft tissue surgery

Cats:

  • Pain and inflammation associated with musculoskeletal disorders (up to 6 days for the tablet form)
  • Post-operative pain following surgery (up to 3 days)
  • Chronic musculoskeletal pain in cats (under close veterinary supervision — an important option given limited alternatives in cats)

Species and Forms

  • Dogs: Flavoured tablets in 5mg, 10mg, 20mg, 40mg sizes. Dosed at 1–2mg/kg once daily
  • Cats: Tablets in 6mg size. Also available as an injection for vet use

Side Effects

  • Gastrointestinal: vomiting, diarrhoea, soft stools — less frequent than with non-selective NSAIDs
  • Kidney effects: monitoring required with long-term use, particularly in cats
  • Not for use in animals with kidney or liver disease, dehydration, or GI ulceration
  • Cats require blood tests before starting and regular monitoring during treatment

Prescription Requirements

Onsior is POM-V. Obtain a written prescription to buy from online pharmacies.

Why Onsior Matters for Cats

Cats have very limited NSAID options compared to dogs. Most NSAIDs are either not licensed for cats or carry significant kidney risks. Onsior's licensing for feline musculoskeletal pain — even if limited in duration — makes it a valuable tool. For longer-term cat arthritis pain, Solensia (anti-NGF injection) or gabapentin are now the primary alternatives.

How to Save

  • Written prescription: Save 35–45% by buying from online pharmacies
  • Compare with alternatives: For dogs, Metacam/Loxicom or Previcox may be cheaper for the same level of pain relief
  • Compare pharmacy prices: Use VetCost to compare across pharmacies

Last updated: March 2026. Sources: VMD product datasheet, CMA provisional decision (October 2025), VetCost pharmacy data.