# Robenacoxib: veterinary dose and monograph

> Robenacoxib is a veterinary anti-inflammatory drug. Coxib NSAID with tissue-selective pharmacokinetics — it persists at inflamed tissue while clearing rapidly from blood, which underlies its feline safety profile. Indications include feline acute musculoskeletal / post-operative pain; feline osteoarthritis (repeat dosing); canine osteoarthritis and soft-tissue surgery pain. This monograph lists 4 reference doses for dogs and cats, each with route, frequency and source.

Source: https://vetmasterji.com/drugs/robenacoxib · Last reviewed: 2026-10-01

## At a glance

- **Drug class:** Anti-inflammatory
- **Also known as:** Onsior
- **Species with doses:** Dogs and Cats
- **General dose range:** 1–2.4 mg/kg PO q24h — check the species tables for the indication
- **Routes:** PO, SC
- **Last reviewed:** 1 October 2026

## Indications

- Feline acute musculoskeletal / post-operative pain
- Feline osteoarthritis (repeat dosing)
- Canine osteoarthritis and soft-tissue surgery pain

## Robenacoxib dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

### Dogs

*Robenacoxib doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| OA / surgical pain | 1–2 mg/kg | PO | q24h | — |
| Peri-operative (injectable) | 2 mg/kg | SC | once, ~30 min before surgery | — |

- OA / surgical pain: Plumb’s p.1045 (Onsior label): chronic osteoarthritis 1 mg/kg (range 1–2) PO once daily; stop after 10 days if no improvement; titrate to the lowest effective dose long term. Papich 5e: 2 mg/kg q24h PO.
- Peri-operative (injectable): Plumb’s p.1045 (Onsior injection label): 2 mg/kg SC about 30 minutes before orthopaedic or soft-tissue surgery. Papich 5e: 2 mg/kg q24h SC.

### Cats

*Robenacoxib doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Acute / chronic musculoskeletal pain | 1–2.4 mg/kg | PO | q24h, same time daily | up to 6 days |
| Peri-operative (injectable) | 2 mg/kg | SC | once, ~30 min before surgery; may continue PO | — |

- Acute / chronic musculoskeletal pain: Plumb’s p.1045 (Onsior label): 1 mg/kg (range 1–2.4) PO once daily at the same time each day for up to 6 days — 1 tablet for 2.5–<6 kg, 2 tablets for 6–<12 kg; do not split tablets; give without food or with a little food. Papich 5e: 1 mg/kg PO once daily.
- Peri-operative (injectable): Plumb’s p.1045 (Onsior injection label): 2 mg/kg SC about 30 minutes before surgery. Papich 5e: 2 mg/kg q24h SC for 3 days, first dose 30 min before surgery.

## Contraindications

GI ulceration, renal / hepatic disease, dehydration, hypotension. Concurrent corticosteroid or other NSAID. Cats < 2.5 kg or < 4 months. Pregnancy / lactation.

## Adverse effects

- GI: vomiting, soft stool / diarrhoea
- Renal compromise with dehydration / anaesthesia
- Elevated liver enzymes (occasional)

## Drug interactions

- Other NSAIDs or corticosteroids: additive GI ulceration risk — do not combine; allow a washout when switching
- ACE inhibitors / diuretics: reduced antihypertensive effect and greater renal risk in dehydrated cats
- Highly protein-bound drugs (e.g. cardiac, anticonvulsant): potential competition for binding sites
- Nephrotoxic anaesthetic protocols: ensure normotension and fluid support peri-operatively

## Pregnancy and lactation

Avoid in pregnancy, lactation and breeding animals — safety not established and NSAIDs may impair reproduction and foetal circulation.

## Monitoring

- Renal values and urine specific gravity at baseline and periodically (especially cats > 7 years)
- Hepatic enzymes on longer courses
- Appetite, vomiting and stool — discontinue at first GI sign

## Toxicity and overdose

Overdose risk is GI ulceration, acute kidney injury and hepatopathy, as with other NSAIDs; the short half-life is protective but not absolute. Cats with subclinical CKD are the highest-risk group.

Management: Stop the drug; GI protectants (omeprazole ± sucralfate), IV fluids for renal support, and monitoring of renal / hepatic values and faeces. Supportive care; no specific antidote.

## Clinical pearls

- One of the safest repeat-dose NSAIDs in cats — but still screen renal values and hydration first
- Give at the same time each day and away from a full meal for best absorption
- Injectable then oral lets you carry analgesia smoothly from theatre to home

## Mechanism of action

Coxib NSAID with tissue-selective pharmacokinetics. Selectively inhibits COX-2 to suppress inflammatory prostaglandins; uniquely it is highly protein-bound and persists in inflamed (acidic) tissue while clearing rapidly from blood and most organs, which underlies its short plasma half-life and relatively favourable feline safety profile.

## Formulations and products

- Onsior 6 mg tablet (cat)
- Onsior 5 mg tablet (dog)
- Onsior 10 mg tablet (dog)
- Onsior 20 mg / 40 mg tablet (dog)
- Onsior 20 mg/mL injection
- Onsior (Elanco) — 6 mg (cat); 5 / 10 / 20 / 40 mg (dog); 20 mg/mL injection, Tablet / SC injection

## Storage

Store at 15–25 °C in the original packaging, protected from moisture.

## Before you use this dose

> **Caution:** Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

## Other anti-inflammatory drugs

- [Nimesulide](https://vetmasterji.com/drugs/nimesulide)
- [Phenylbutazone](https://vetmasterji.com/drugs/phenylbutazone)
- [Piroxicam](https://vetmasterji.com/drugs/piroxicam)
- [Prednisolone](https://vetmasterji.com/drugs/prednisolone)
- [Tolfenamic Acid](https://vetmasterji.com/drugs/tolfenamic-acid)

## Frequently asked questions

### What is the dose of Robenacoxib for dogs?

Reference doses for Robenacoxib in dogs: 1–2 mg/kg PO q24h (OA / surgical pain); 2 mg/kg SC once, ~30 min before surgery (Peri-operative (injectable)). Confirm against the label and the patient before use.

### What is the dose of Robenacoxib for cats?

Reference doses for Robenacoxib in cats: 1–2.4 mg/kg PO q24h, same time daily for up to 6 days (Acute / chronic musculoskeletal pain); 2 mg/kg SC once, ~30 min before surgery; may continue PO (Peri-operative (injectable)). Confirm against the label and the patient before use.

### When should Robenacoxib not be used?

GI ulceration, renal / hepatic disease, dehydration, hypotension. Concurrent corticosteroid or other NSAID. Cats < 2.5 kg or < 4 months. Pregnancy / lactation.

### What are the side effects of Robenacoxib in animals?

GI: vomiting, soft stool / diarrhoea; Renal compromise with dehydration / anaesthesia; Elevated liver enzymes (occasional).

## Sources

- Plumb's Veterinary Drug Handbook
- AAFP guidelines
- Papich, Papich Handbook of Veterinary Drugs, 5th edition

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VetMasterJi is a clinical decision-support and education platform for veterinary professionals and students. It does not provide veterinary advice, diagnosis or treatment for specific animals. All drug doses, calculators and differentials are references that must be independently verified before clinical use; the attending registered veterinarian remains solely responsible for every clinical decision.