Partial opioid agonist · For Cats

Buprenorphine dosage reference for cats (Buprenex)

This page's standard weight-based reference is 0.02 mg per kg (0.0091 mg per lb), with every 6-12 hours recorded as the reference frequency. Use the calculator to see the arithmetic for your cat's weight, then confirm the indication, product, and actual dose with a veterinarian.

Onset: 15-30 minutes (transmucosal), 5-15 minutes (injectable)
Duration: 6-12 hours (0.3 mg/mL buprenorphine); about 24 hours per Simbadol injection
Class: Partial opioid agonist

Weight-based calculator estimate from the references listed on this page. This page has not been independently DVM-reviewed — see our methodology .

This information is for educational purposes only. Always consult your veterinarian before giving medication to your pet. Do not use this calculator for emergencies, overdoses, pregnancy, very young animals, very old animals, pets with liver/kidney disease, or pets taking multiple medications.

Sources and review process

Each medication page lists the references recorded for its data. The calculator math and editorial presentation are maintained by PetDosageChart; a page is independently DVM-reviewed only when a named reviewer byline appears. See our methodology and limitations.

Buprenorphine (often known by brand names such as Simbadol and Buprenex) is a partial opioid agonist commonly used in veterinary medicine for moderate pain relief, post-surgical pain, oral pain, and trauma pain management. Understanding the correct dosage, administration, and potential side effects of Buprenorphine is critical for your cat’s safety and well-being.

Buprenorphine comes in two very different strengths for cats, and the dose depends on which one your cat receives:

0.3 mg/mL buprenorphine (Buprenex-type) is the product veterinarians most often send home, as small syringes to squirt into the cheek. It is dosed at about 0.01-0.03 mg/kg (0.02 mg/kg is this page’s standard reference) every 6-12 hours. The calculator below applies only to this product.
Simbadol (1.8 mg/mL) is six times more concentrated. Its FDA label dose is 0.24 mg/kg injected under the skin once daily for up to 3 days, and the label says it must not be dispensed for home use. It is given only by your veterinary team.

Never use this calculator to measure Simbadol, and never substitute one product for the other.

Calculator Warning: This calculator uses the 0.3 mg/mL buprenorphine reference only; it does not apply to Simbadol. Use it only as an educational estimate. Your veterinarian may prescribe a different dose based on your pet’s condition, age, weight, other medications, and medical history.

What the source establishes

Lists buprenorphine 0.3 mg/mL for cats at 0.005–0.03 mg/kg IM, IV or sublingual, every 6–12 hours, and notes that sublingual absorption is reported to be excellent in cats. At the every-6-hours end of that range, 0.03 mg/kg per dose is 0.12 mg/kg per day, the daily maximum this page records.

This applies only to the standard 0.3 mg/mL product. It does not apply to Simbadol (1.8 mg/mL), and it is not a home pain plan for an individual cat.

MSD Veterinary Manual: Opioids Used in Emergency Practice (table) — Buprenorphine row; cats, 0.3 mg/mL formulation.

Simbadol contains 1.8 mg/mL buprenorphine. Its label dose is 0.24 mg/kg (0.11 mg/lb) under the skin once daily for up to 3 days, with the first dose about 1 hour before surgery, and it says not to dispense Simbadol for administration at home by the pet owner.

This is why the page treats Simbadol as clinic-administered and keeps it out of the calculator. It does not set doses for other buprenorphine products.

SIMBADOL (buprenorphine injection) FDA-approved label (Zoetis, DailyMed) — Dosage and Administration; Human Safety (revised September 2022).

Buprenorphine Dosage Calculator for Cats

Enter your cat’s weight below to estimate the dose of 0.3 mg/mL buprenorphine from the 0.02 mg/kg guideline. Your veterinarian may adjust it for your cat’s age, condition, and other medications, so treat the result as an educational starting point, not a prescription.

Dosage Calculator · 01

Enter your cat's weight

Which product this applies to: This reference applies only to 0.3 mg/mL buprenorphine (Buprenex-type) given in the cheek, dosed at about 0.01-0.03 mg/kg. It does not apply to Simbadol (1.8 mg/mL), which is injected under the skin by your veterinary team only (label: 0.24 mg/kg once daily for up to 3 days). Never use this number to measure Simbadol.

Quick Dosage Chart

Typical amounts of 0.3 mg/mL buprenorphine for common cat weights, for quick reference (not for Simbadol):

Dosage Chart · 02

Buprenex weight-based reference chart for cats

Scroll sideways to see full table

Buprenex weight-based reference chart. Educational arithmetic, not a prescription.
Weight	Lower Reference	Standard Reference	Upper Reference	Frequency
3 lbs (1.4 kg)	0.014 mg	0.027 mg	0.041 mg	every 6-12 hours
4 lbs (1.8 kg)	0.018 mg	0.036 mg	0.054 mg	every 6-12 hours
5 lbs (2.3 kg)	0.023 mg	0.045 mg	0.068 mg	every 6-12 hours
6 lbs (2.7 kg)	0.027 mg	0.054 mg	0.082 mg	every 6-12 hours
7 lbs (3.2 kg)	0.032 mg	0.063 mg	0.095 mg	every 6-12 hours
8 lbs (3.6 kg)	0.036 mg	0.073 mg	0.11 mg	every 6-12 hours
9 lbs (4.1 kg)	0.041 mg	0.082 mg	0.12 mg	every 6-12 hours
10 lbs (4.5 kg)	0.045 mg	0.091 mg	0.14 mg	every 6-12 hours
12 lbs (5.4 kg)	0.054 mg	0.11 mg	0.16 mg	every 6-12 hours
14 lbs (6.3 kg)	0.063 mg	0.13 mg	0.19 mg	every 6-12 hours
16 lbs (7.3 kg)	0.073 mg	0.15 mg	0.22 mg	every 6-12 hours
18 lbs (8.2 kg)	0.082 mg	0.16 mg	0.24 mg	every 6-12 hours
20 lbs (9.1 kg)	0.091 mg	0.18 mg	0.27 mg	every 6-12 hours
25 lbs (11.3 kg)	0.11 mg	0.23 mg	0.34 mg	every 6-12 hours

Parenthetical tablet amounts are arithmetic comparisons only. They do not account for scoring, release type, concentration, product labeling, or whether this medication is appropriate for an individual animal.

By Weight

Buprenex reference by cat weight

Choose a common weight to open its optional reference page. Use the main medication calculator for a different exact weight.

Common-weight pages are convenience views of the same educational reference, not separate medical recommendations.

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How to Give Buprenorphine to Your Cat

Buprenorphine is uniquely well-suited for cats because it can be absorbed through the oral mucosa (inside the cheek). For transmucosal dosing, use a syringe to squirt the liquid between the cheek and gum — do NOT let the cat swallow it immediately, as oral absorption through the gut is poor. Hold the head gently and let it absorb for 1-2 minutes. Simbadol is a different, concentrated injection (1.8 mg/mL) that is given only at the clinic, once daily for up to 3 days; it is never sent home for owners to give.

It may interact with other opioids, benzodiazepines, CNS depressants, and MAO inhibitors.

Side Effects and Safety

Common side effects include sedation, dilated pupils, euphoria or purring, and mild decrease in appetite. More serious side effects can occur, such as respiratory depression, severe sedation or unresponsiveness, hypothermia, and bradycardia (slow heart rate).

Cautions · 12

When Buprenex should be used with caution or avoided

Some cats should not take Buprenex, or need a different dose and closer monitoring. Tell your veterinarian about your pet's full health history and every other medication or supplement they take before giving Buprenex.

severe respiratory disease
head trauma with increased intracranial pressure
known hypersensitivity
pregnancy

Interactions · 13

Buprenex drug interactions

Buprenex can interact with other drugs. This list is not complete — always give your veterinarian a full list of your cat's medications and supplements.

other opioids

benzodiazepines

CNS depressants

MAO inhibitors

Calculator Limits · 14

When not to use this calculator

This calculator gives a general educational estimate for a healthy adult cat at a known weight. Do not rely on it in these situations — talk to your veterinarian instead:

In an emergency, or after accidental ingestion or a suspected overdose
For pregnant or nursing pets
For very young or very old cats
For pets with liver disease, kidney disease, or another chronic illness
For pets taking several medications at once
When you are not sure of your cat's current, accurate weight
For combination products that contain additional active ingredients

Overdose · 15

Suspected overdose: what to do

If you think your cat had too much Buprenex, or swallowed any medication by accident, act right away. Do not wait for symptoms to appear.

Call your veterinarian or the nearest emergency animal hospital.
ASPCA Animal Poison Control Center: (888) 426-4435
Pet Poison Helpline: (855) 764-7661

A consultation fee may apply to the poison hotlines. Have the medication packaging ready, and note how much your pet may have taken and when. Do not try to make your pet vomit unless a veterinarian tells you to.

When to Call the Vet

If your cat experiences any of the following, contact your veterinarian or an emergency clinic immediately:

Very slow or shallow breathing
Extreme sedation or inability to rouse your cat
Collapse or inability to stand
Persistent vomiting
No pain improvement or worsening signs of pain

Frequently Asked Questions

Frequently Asked · 07

Questions about this medication

Why is buprenorphine considered the best pain medication for cats?

Buprenorphine is widely regarded as the gold standard for moderate pain in cats because of its excellent transmucosal absorption (squirted inside the cheek), long duration of action, wide safety margin, and the calm sedation it produces. Cats tolerate it much better than many other opioids, which can cause excitation in felines.

Can I give buprenorphine to my cat at home?

Yes, veterinarians often prescribe 0.3 mg/mL buprenorphine for at-home administration in the cheek after surgery or dental procedures. You will receive small pre-measured syringes to squirt inside your cat's cheek. It is a controlled substance, so it must be prescribed and dispensed by a veterinarian. Simbadol (1.8 mg/mL) is different: its label says it must not be dispensed for home use, so it is only given as an injection at the clinic.

How long does buprenorphine last in cats?

Standard 0.3 mg/mL buprenorphine is usually repeated every 6-12 hours in cats. Simbadol, a concentrated 1.8 mg/mL injection, is labeled for once-daily injection under the skin (0.24 mg/kg) for up to 3 days and is given only by your veterinary team.

Does buprenorphine make cats act strange?

Buprenorphine commonly causes mild sedation, dilated pupils, and sometimes euphoria (purring, kneading). These effects are normal and expected. Some cats may seem "spaced out" or unusually affectionate. These effects are temporary and generally resolve as the drug wears off.

Is buprenorphine safe for older cats?

Yes, buprenorphine is considered safe for senior cats and is commonly used for pain management in older cats with arthritis, dental disease, or post-surgical pain. Dose adjustments may be made for cats with significant liver or kidney disease. Your vet will determine the appropriate dose.

Use This Guide Safely · 08

What weight alone cannot tell you

The calculator performs one narrow job: it multiplies your cat's weight by the lower, standard, and upper mg/kg values recorded for Buprenex. It cannot decide whether this drug, indication, formulation, or schedule is appropriate for an individual animal.

Context in this medication record

Commonly listed uses: moderate pain relief, post-surgical pain, oral pain, trauma pain management
Recorded forms: 0.3 mg/mL oral transmucosal solution (Buprenex-type; calculator reference), 0.3 mg/mL injection (clinic), Simbadol 1.8 mg/mL injection (clinic only)
Reference timing: every 6-12 hours; onset 15-30 minutes (transmucosal), 5-15 minutes (injectable); duration 6-12 hours (0.3 mg/mL buprenorphine); about 24 hours per Simbadol injection

Individual checks a calculator cannot perform

Confirm the diagnosis and the reason this medication is being considered.
Match the exact product, concentration, route, and whether a tablet may be split.
Account for age, pregnancy, organ function, genetics, allergies, and prior reactions.
Review every prescription, over-the-counter product, and supplement your pet takes.

Recorded cautions

severe respiratory disease; head trauma with increased intracranial pressure; known hypersensitivity; pregnancy.

Recorded interactions

other opioids; benzodiazepines; CNS depressants; MAO inhibitors.

These lists reproduce the structured record used by this page and may not be exhaustive. Show your veterinarian the product label and your cat's complete medication list before acting on a number.

Sources · 09

Sources & references

The structured medication record behind this page names the references below. The links open the publisher or official resource; they do not turn this page into a prescription for an individual animal.

MSD Veterinary Manual: Opioids Used in Emergency Practice (table)
Buprenorphine row; cats, 0.3 mg/mL formulation. Supports the specific claim described above; it is not a review of the entire page.
SIMBADOL (buprenorphine injection) FDA-approved label (Zoetis, DailyMed)
Dosage and Administration; Human Safety (revised September 2022). Supports the specific claim described above; it is not a review of the entire page.
Plumb's Veterinary Drug Handbook — listed in this medication's source record.
Merck Veterinary Manual — listed in this medication's source record.
DailyMed label search for Buprenorphine — check current product and formulation labels; some veterinary uses may be off-label.

Specific citations above support the identified claims. Other source names remain record-level references; further claim review is still needed. Read our methodology and limitations.

Transparency · 11

How this page was made

This page's structured medication record includes Plumb's Veterinary Drug Handbook among its source names. PetDosageChart applies the record's mg/kg values to the entered weight and presents the arithmetic result. A source record is not the same as an individualized prescription or an independent clinical review.

Sources cited: Plumb's Veterinary Drug Handbook
Merck Veterinary Manual
Calculator formula: Doses scale linearly from a standard basis of 0.02 mg per kg (0.0091 mg per lb) of body weight, given every 6-12 hours. The calculator multiplies that basis by your cat's weight and shows an arithmetic comparison with recorded tablet sizes. That comparison does not determine whether a tablet is scored, splittable, or appropriate for your pet.
Editorial owner: Prepared and maintained by the PetDosageChart editorial team, a software-led publisher and not a veterinary practice.
DVM review status: Not independently DVM-reviewed. A named reviewer and review date appear here only after a confirmed review.

More on our methodology and editorial process — how we source, calculate, and review cats dosage data.

Safety · 10

More resources

Pet Medication Safety Hub — What's safe, what's dangerous, and emergency signs
How we calculate dosages — Our sources, math, and review process
Printable emergency checklist — One-page reference for your fridge or first aid kit