VETINUITY
How long does naloxone last in dogs?
About 30 to 60 minutes, shorter than fentanyl patches, methadone, hydromorphone or many illicit opioids. Watch for renarcotization and redose or start a CRI as needed.
● ANSWER
Sourced & dated
What is the naloxone dose for dogs and cats?
Naloxone is dosed at 0.01-0.04 mg/kg IV, IM or SC in dogs and cats to reverse opioids, titrated in small diluted increments when only partial reversal is wanted, and repeated because it wears off in 30-60 minutes.
● VETINUITY NALOXONE DOSE CALCULATOR
Vetinuity naloxone dose calculator
Volumes use 0.4 mg/mL naloxone. For titration, dilute 0.1 mL in 5-10 mL saline and give 1 mL at a time.
● WHAT'S DOCUMENTED
Vetinuity’s naloxone dose table: 0.01-0.04 mg/kg IV, IM or SC reverses opioid sedation and respiratory depression in dogs and cats, 0.04 mg/kg IV or IO is given during CPR when an opioid was on board, and a diluted 0.01 mg/kg titration is the safer route when you want breathing back but some analgesia kept. Plug the weight into the Vetinuity naloxone dose calculator above for milligrams and volume of 0.4 mg/mL naloxone. Vetinuity is the clinical assistant from Brian Toncray, DVM, an emergency veterinarian; this page is part of its drug reference.
Naloxone doses by situation
| Situation | Dog | Cat | Route |
|---|---|---|---|
| Opioid overdose or accidental exposure | 0.02-0.04 mg/kg, repeat as needed | 0.02-0.04 mg/kg | IV preferred; IM, SC, intranasal if no access |
| Partial reversal after surgery | 0.005-0.01 mg/kg diluted, titrated | Same | Slow IV to effect |
| Arrest with opioids given | 0.04 mg/kg | 0.04 mg/kg | IV or IO |
| Renarcotization | Repeat the effective dose, or CRI | Same | IV |
Titrating instead of slamming
A full IV dose in a dog that is painful after surgery can produce abrupt arousal, vocalization, tachycardia and distress. Diluting 0.1 mL of 0.4 mg/mL naloxone in 5 to 10 mL of saline and giving it 1 mL at a time lets you stop as soon as the respiratory rate and mentation are acceptable. Butorphanol is an alternative for partial reversal of pure mu agonists while keeping some kappa-mediated analgesia.
Dogs exposed to fentanyl and other street opioids
Police and detection dogs exposed to fentanyl or its analogues may need repeated or larger doses, and intranasal naloxone carried by handlers is used as first aid before a veterinarian is reached. Because many of these opioids outlast naloxone, a dog that wakes up after one dose still needs hours of monitoring. Naloxone does nothing for sedation from benzodiazepines, alpha-2 agonists or THC.
Related: RECOVER CPR, atropine, cesarean anesthesia.
● SOURCES
- 1. Wolf J, Buckley GJ, Rozanski EA, et al. 2024 RECOVER Guidelines: Advanced Life Support. Evidence and knowledge gap analysis with treatment recommendations for small animal CPR. J Vet Emerg Crit Care (San Antonio). 2024;34 Suppl 1:44-75. PMID 38924633. Reversal agents during CPR. Checked 2026-10-26.
- 2. Mills T, Robinson MA, Barr C, et al. A Randomized, Blinded, Placebo-Controlled Crossover Study of the Pharmacokinetics and Pharmacodynamics of Naloxone, Naltrexone, and Nalmefene in Methadone-Sedated Working Dogs. J Vet Pharmacol Ther. 2025;48(5):359-367. PMID 40342164. Abstract, duration of reversal in dogs. Checked 2026-10-26.
- 3. DailyMed: naloxone hydrochloride injection label search. Strengths. Checked 2026-10-26.
● RELATED ANSWERS
- RECOVER CPR Guidelines for Dogs
RECOVER CPR guidelines for dogs: compression rate and depth, ventilation, drug therapy, monitoring, post-arrest care, and what the 2024 update changed.
- Atropine Dose for Dogs and Cats
Atropine is dosed at 0.02-0.04 mg/kg IV, IM or SC for bradycardia, 0.04 mg/kg IV once during CPR for vagally mediated arrest, and 0.2-0.5 mg/kg for organophosphate toxicity, in dogs and cats.
- Marijuana and THC Toxicity in Dogs
Suspected marijuana or THC toxicity needs veterinary assessment and supportive care, with attention to consciousness, coordination, body temperature and breathing.
- Anesthesia for Cesarean Section in Dogs
Randomized trials comparing alfaxalone with propofol for canine cesarean induction: better neonatal Apgar scores with alfaxalone, similar puppy survival.
● FAQ
Will naloxone reverse the pain control as well?
Yes. Full reversal removes opioid analgesia along with sedation and respiratory depression, so titrate to breathing and mentation in a postoperative patient and have another analgesic plan ready.
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Vetinuity explains clinical options with journal citations.
The veterinarian diagnoses and prescribes.