Meloxidyl for Dogs and Cats: Complete Guide to Dosage, How Long the Bottle Lasts & Why the Cat Formulation Is Non-Negotiable

Meloxidyl is one of the most commonly prescribed veterinary NSAIDs for managing pain and inflammation in dogs and cats. It comes in two completely separate formulations — 1.5mg/ml for dogs and 0.5mg/ml for cats — and understanding why those two products cannot be swapped is the most important thing this guide will cover.

What Is Meloxidyl?

Meloxidyl is a brand of meloxicam oral suspension manufactured by CEVA Santé Animale. It is available in two formulations:

• Meloxidyl 1.5mg/ml — for dogs (32ml)
• Meloxidyl 0.5mg/ml — for cats (15ml)

Both formulations are often also referred to by the brand name Metacam — Meloxidyl is the generic equivalent of Metacam, with the same active ingredient at the same concentrations. Many vets and pharmacies use both names interchangeably.

How Meloxicam Works

Meloxicam belongs to the NSAID (non-steroidal anti-inflammatory drug) class. It is described as a COX-2 preferential NSAID, meaning it preferentially inhibits the COX-2 isoform of cyclooxygenase enzymes over COX-1, though it inhibits both.

Cyclooxygenase enzymes are responsible for producing prostaglandins — the chemical messengers that trigger and sustain inflammation, pain, swelling, and fever. By suppressing prostaglandin synthesis, meloxicam reduces all the signs of inflammation at the affected joint or tissue, providing pain relief and improved mobility.

COX-2 preferentiality matters because COX-1 also produces prostaglandins that protect the stomach lining. Non-selective NSAIDs that inhibit both equally (like aspirin) produce more GI irritation. Meloxicam’s preference for COX-2 over COX-1 reduces — but does not eliminate — this risk.

⚠️ Why Cats Cannot Use the Dog Formulation

This is the most critical safety point about meloxicam in veterinary medicine, and it bears explaining in full.

Cats have a fundamental metabolic difference from dogs: their livers have severely reduced activity of a family of enzymes called UGT (UDP-glucuronosyltransferases). These enzymes are responsible for glucuronidation — the primary metabolic pathway by which meloxicam (and many other drugs) is broken down and eliminated from the body.

In dogs, meloxicam is metabolised and cleared within 24 hours, which is why once-daily dosing works. In cats, because the metabolic pathway is so much slower, meloxicam is cleared far more slowly. This means:

• Doses that are safe and effective in dogs rapidly accumulate to toxic levels in cats
• The therapeutic margin in cats is extremely narrow — there is very little difference between an effective dose and a harmful one
• The cat formulation (0.5mg/ml) was specifically developed at one-third the concentration of the dog formulation precisely to allow accurate dosing at the tiny volumes cats require

Using the dog formulation (1.5mg/ml) in a cat would deliver three times the meloxicam concentration per ml. Even if you tried to give a proportionally smaller volume, accurately measuring one-third of a very small cat dose using a dog syringe is essentially impossible. The risk of fatal overdose is real and documented. This is not a theoretical concern.

Reported consequences of meloxicam overdose in cats include: acute kidney failure, severe gastrointestinal haemorrhage, hepatic failure, and death.

Meloxidyl 1.5mg/ml for Dogs — Full Guide

Indications

• Osteoarthritis (the primary use — chronic joint inflammation and pain)
• Acute musculoskeletal disorders (sprains, strains, injuries)
• Post-operative pain and inflammation following orthopaedic or soft tissue surgery

Dosage

A loading dose is given on day 1 only, followed by a lower maintenance dose from day 2 onwards. The dosing syringes provided are calibrated for the maintenance dose.

Use the blue-print small syringe for dogs under 15 lbs. Use the green-print large syringe for dogs 15 lbs and over. Never use the large syringe for small dogs — it cannot accurately measure small doses.

How Long Does the 32ml Bottle Last?

Key Contraindications for Dogs

• Cats — never
• Dogs under 6 months
• Pregnant or lactating dogs
• Pre-existing GI disease, ulceration, or bleeding
• Liver or kidney disease
• Bleeding disorders
• Dehydration (increases renal risk significantly)

Critical Drug Interactions (Dogs)

Never combine Meloxidyl with other NSAIDs or corticosteroids — the combined GI and renal toxicity risk is severe. Allow at least 24 hours washout between switching from one NSAID to another. Also avoid concurrent use with diuretics, ACE inhibitors, anticoagulants, and nephrotoxic drugs.

Meloxidyl 0.5mg/ml for Cats — Full Guide

Indications

• Post-operative pain and inflammation after orthopaedic or soft tissue surgery (as oral follow-up after initial injectable)
• Chronic musculoskeletal disorders — osteoarthritis in cats

Dosage

Weight-Based Maintenance Dosing (Cats)

Monitoring for Long-Term Meloxicam Use in Cats

Long-term use is appropriate under veterinary supervision with regular monitoring:

• Baseline kidney function, liver enzymes, and urine analysis before starting
• Repeat bloodwork every 3–6 months
• Watch for: reduced appetite, vomiting, increased thirst/urination or reduced urination, weight loss, lethargy, mouth ulcers
• Discontinue immediately if any of these develop and contact your vet

Meloxidyl vs Rimadyl vs Onsior for Dogs — When to Use Which

Meloxidyl’s liquid format is a significant advantage for dogs with arthritis because it allows precise weight-based dosing down to the pound, unlike tablet formulations where dose increments are limited to tablet fractions.

Key Safety Rules — Summary

• Never give the dog formulation (1.5mg/ml) to cats
• Never combine any NSAID with another NSAID or corticosteroid
• Always use the lowest effective dose
• Ensure access to fresh water at all times during treatment
• Do not use in dehydrated animals — stop treatment and contact your vet if the animal becomes dehydrated during therapy
• Perform baseline and regular blood/urine monitoring for any course lasting more than a few weeks