Anti-inflammatory · Drug monograph

Robenacoxib: veterinary dose and monograph

Q: What are the side effects of Robenacoxib in animals?

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

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.

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

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.

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?