Article — Metacam Dosage Calculator for Cats
Metacam dosage calculator for cats: mg and mL by weight
The standard Metacam dose for cats is 0.1 mg/kg by mouth on day 1, then 0.05 mg/kg once daily as maintenance. A 4-kg cat gets 0.4 mg on day 1 (0.8 mL of 0.5 mg/mL suspension) and 0.2 mg on subsequent days (0.4 mL). The single preoperative SC injection is 0.3 mg/kg. Meloxicam (the active ingredient in Metacam) carries an FDA boxed warning in cats — repeated use causes acute kidney injury and death. The calculator above gives the exact mg and mL for any cat weight, but the dose must be confirmed by a veterinarian.
Cats process NSAIDs more slowly than dogs. The cat half-life of meloxicam is 15 to 36 hours, versus 12 to 24 in dogs. The narrow safety margin in cats is why FDA requires the boxed warning and why most veterinarians limit oral Metacam to 3 to 5 days unless the cat has stable kidney function on regular bloodwork.
Metacam dose for cats
The published doses come from Boehringer Ingelheim (the manufacturer) and the FDA label for Metacam injectable. Oral dosing of Metacam in cats is off-label in the United States, though the manufacturer publishes a recommended protocol that veterinarians commonly follow.
Day 1 oral 0.1 mg/kgDay 2+ oral 0.05 mg/kg/daySC injection 0.3 mg/kg single onlyLong-term oral 0.025 mg/kg/dayCat oral concentration 0.5 mg/mLInjectable concentration 5 mg/mLFor a 4-kg cat: day 1 oral is 0.4 mg = 0.8 mL of 0.5 mg/mL suspension. Maintenance is 0.2 mg = 0.4 mL once daily. The single SC injection is 1.2 mg = 0.24 mL of 5 mg/mL — given before surgery. The injection cannot be repeated within 24 hours.
How Metacam dosage is calculated
Metacam dosing is body-weight scaled. The two inputs are the cat's weight (in kg or lb) and the suspension concentration (0.5 mg/mL for the cat-label oral, 5 mg/mL for the injectable). The dose in mg equals weight times the mg/kg dose. The volume in mL equals the mg dose divided by the suspension concentration.
The math is the same as any liquid medication: you cannot dose 0.4 mg of a drug without knowing how concentrated the liquid is. A 0.4 mg dose of 0.5 mg/mL suspension is 0.8 mL; the same 0.4 mg dose drawn from the dog-label 1.5 mg/mL suspension is only 0.27 mL. Mixing up the bottles delivers a 3× overdose, which is the single most common Metacam-related kidney injury in cats.
Boehringer Ingelheim makes Metacam in two oral concentrations: 0.5 mg/mL for cats, 1.5 mg/mL for dogs. Both bottles look similar. Always confirm the bottle says it is the cat product (or use the dog product only with dose volume recalculated). The 3× difference in concentration is the difference between a therapeutic dose and a toxic one.
Oral vs injectable Metacam for cats
The Metacam injection (5 mg/mL) is the only FDA-approved Metacam product for cats in the United States, and only for a single preoperative dose at 0.3 mg/kg subcutaneously. It is used for surgical pain control in cats undergoing spay, neuter, dental work, or other procedures. The injection cannot be repeated, even at the same dose, without exceeding the FDA-approved indication.
The oral suspension (0.5 mg/mL) is used off-label for postoperative pain at home or for chronic osteoarthritis. Off-label use is legal under the Animal Medicinal Drug Use Clarification Act (AMDUCA) when prescribed by a veterinarian with a veterinarian-client-patient relationship. Off-label does not mean unsafe, but it does shift legal responsibility to the prescribing vet.
Metacam FDA boxed warning
In 2010, the FDA added a boxed warning to Metacam labels stating that "repeated use of meloxicam in cats has been associated with acute kidney injury and death." The warning followed adverse event reports of cats developing kidney failure after multiple doses, especially in cats with preexisting kidney disease, dehydration, or hypotension. The boxed warning is the FDA's highest safety alert.
The FDA boxed warning is the same regulatory category used for human medications like opioids, immunosuppressants, and chemotherapy drugs. In veterinary medicine, it is rare — Metacam is one of only a handful of veterinary drugs carrying a boxed warning. The warning does not ban use; it requires informed consent from owners and careful monitoring during use.
The mechanism is the same as in humans: NSAIDs inhibit cyclooxygenase (COX-1 and COX-2), which normally maintains kidney blood flow through prostaglandin signaling. In dehydrated or hypotensive cats, NSAID-induced loss of prostaglandins drops kidney perfusion below the level required for normal filtration, causing acute tubular injury. Cats with chronic kidney disease tolerate even less margin.
Side effects of Metacam in cats
The most common side effects are GI: decreased appetite, vomiting, soft stool. These usually appear within the first 1 to 3 doses and resolve when the drug is stopped. More serious effects include GI ulceration and bleeding (black tarry stool, vomiting blood), acute kidney injury (increased thirst, increased or decreased urination, lethargy), and liver injury (jaundice, lethargy, anorexia).
Any cat on Metacam that shows decreased appetite for more than 24 hours, increased water intake, or behavior change should stop the drug and be evaluated by a veterinarian. Bloodwork (creatinine, BUN, SDMA, ALT, packed cell volume) and urinalysis confirm or rule out kidney and liver involvement. Early intervention reverses most cases; delayed intervention does not.
When to stop Metacam
Stop Metacam immediately for: vomiting more than once, refusing food for over 24 hours, soft black stool, lethargy not explained by the underlying condition, jaundice, or increased thirst and urination. Call the veterinarian the same day. Do not restart Metacam after a side-effect episode without bloodwork and direct veterinary instruction.
Take a photo of the bottle label and the calculated dose volume before the first dose. If you give the wrong amount or have to call poison control, the photo confirms exactly what concentration and dose were involved. ASPCA Animal Poison Control (888-426-4435, fee per case) is available 24/7 for medication exposures.
Metacam alternatives for cats
For acute pain, robenacoxib (Onsior) is FDA-approved for cats and has a similar mechanism with a slightly better safety record. Gabapentin is widely used for both acute and chronic pain in cats — it is not an NSAID and does not carry the renal risk. Buprenorphine (under the tongue, transmucosal) is an opioid alternative used in postsurgical settings. For osteoarthritis, monoclonal antibody therapy (frunevetmab, brand name Solensia) is a newer cat-specific option that avoids NSAIDs entirely.
Metacam storage and handling
Metacam oral suspension is stored at room temperature (15 to 30°C) away from direct light. Once opened, it remains effective until the printed expiration date. The dropper or syringe should be rinsed after each use to prevent residue contamination. Do not store in the refrigerator unless the label specifies — cold suspension is harder to dose accurately. Keep the bottle upright between uses to avoid leaks. Discard at the expiration date even if liquid remains.
- Day 1 oral = 0.1 mg/kg
- Maintenance = 0.05 mg/kg/day
- SC injection = 0.3 mg/kg single only
- Cat suspension = 0.5 mg/mL
- Half-life in cats = 15–36 hours
- FDA boxed warning = repeated use, kidney injury risk
- 4-kg cat day-1 dose = 0.4 mg (0.8 mL)
- Max ongoing use = 3–5 days without bloodwork