# Robenacoxib for Animals: Mechanism, Doses by Species & Brands

> Robenacoxib is a highly selective COX-2 inhibitor of the coxib class. Under the US Onsior labels cats get 1 mg/kg by mouth once a day for up to 3 days, and dogs…

- Source page: https://wevet.in/active-ingredients/robenacoxib/
- Type: Active ingredient
- Publisher: WeVet
- Updated: 2026-11-02
- Medically reviewed by: Dr. Ravi Baraiya, B.V.Sc. (2026-11-02)
- Audience: veterinarians and veterinary students

Robenacoxib is a highly selective COX-2 inhibitor of the coxib class [1]. Under the US Onsior labels cats get 1 mg/kg by mouth once a day for up to 3 days [2], and dogs and cats get 2 mg/kg by subcutaneous injection once a day for up to 3 days [3].

- Class: Non-steroidal anti-inflammatory drug (NSAID, coxib — highly COX-2 selective)
- Brands: Onsior, Robenatail, SeamiCox

## Dose by species

| Species | Use | Dose | Route | How often | Basis |
|---|---|---|---|---|---|
| Cats | Post-operative pain (tablets) (Cats ≥ 2.5 kg and ≥ 4 months old.) | 1 mg/kg [2] | PO | Once daily · Maximum 3 days | Label |
| Cats | Post-operative pain (injection) (First dose about 30 minutes before surgery.) | 2 mg/kg [3] | SC | Once daily · Maximum 3 days | Label |
| Dogs | Post-operative pain (injection) (First dose about 45 minutes before surgery.) | 2 mg/kg [3] | SC | Once daily · Maximum 3 days | Label |

## Uses

- Cats: post-operative pain and inflammation after orthopedic surgery, spay and castration — tablets and injection, maximum 3 days (US labels) [2][3].
- Dogs: post-operative pain and inflammation after soft-tissue surgery — injection, maximum 3 days (US label) [3].

## Mechanism of action

NSAIDs reduce prostaglandin production by inhibiting the cyclooxygenase (COX) enzymes [1]. Robenacoxib is highly selective for COX-2 [1].

## Safety

- Do not use the tablets in cats under 2.5 kg (5.5 lb) — they cannot be dosed accurately [2].
- Robenacoxib has been shown to prolong the QT interval [2].
- Do not give with any other oral or injectable NSAID or corticosteroid [3].


## Frequently asked questions

### What is the robenacoxib dose for cats?

1 mg/kg by mouth once a day for up to 3 days with the tablets, or 2 mg/kg under the skin once a day for up to 3 days with the injection (US labels) [2][3].

### How long can cats take robenacoxib?

The US labels allow a maximum of 3 days [2][3].

## References

[1] Nonsteroidal Anti-inflammatory Drugs in Animals — Merck Veterinary Manual — S. H. Edwards (updated Sep 2024) (2024). https://www.merckvetmanual.com/pharmacology/inflammation/nonsteroidal-anti-inflammatory-drugs-in-animals
[2] ONSIOR (robenacoxib) 6 mg tablets for cats — FDA labeling — Animal Drugs @ FDA — US label, Elanco (2026). https://animaldrugsatfda.fda.gov/adafda/app/search/public/document/downloadLabeling/743
[3] ONSIOR (robenacoxib) injection — FDA labeling — Animal Drugs @ FDA — US label, Elanco (2026). https://animaldrugsatfda.fda.gov/adafda/app/search/public/document/downloadLabeling/745

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Numbers in [brackets] cite the references above. For veterinary professionals. Information supports — never replaces — clinical judgement; always check the current product label and local regulations.
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