VETINUITY
How hot do cats get after hydromorphone?
Postanesthetic hyperthermia is recognized in cats given hydromorphone, with some cats exceeding 40 C. Check temperature for several hours after recovery.
● ANSWER
Sourced & dated
What is the hydromorphone dose for dogs and cats?
Hydromorphone is dosed at 0.05-0.1 mg/kg IV, IM or SC every 4-6 hours in dogs and 0.025-0.05 mg/kg IV or IM every 4-6 hours in cats, or as a 0.01-0.03 mg/kg/h CRI in dogs.
● VETINUITY HYDROMORPHONE DOSE CALCULATOR
Vetinuity hydromorphone dose calculator
Hydromorphone 2 mg/mL. CRI row shows the hourly amount.
● WHAT'S DOCUMENTED
The Vetinuity hydromorphone dose table puts dogs at 0.05-0.1 mg/kg IV, IM or SC every 4 to 6 hours, or 0.01-0.03 mg/kg/h as a constant rate infusion, and cats at 0.025-0.05 mg/kg IV or IM every 4 to 6 hours. The Vetinuity hydromorphone dose calculator above returns the milligrams and the volume of 2 mg/mL stock, including the hourly CRI amount.
Dose table
| Indication | Dog | Cat | Route and frequency |
|---|---|---|---|
| Premedication | 0.05-0.1 mg/kg | 0.025-0.05 mg/kg | IM or IV once |
| Moderate to severe pain | 0.05-0.1 mg/kg | 0.025-0.05 mg/kg | IV, IM or SC q4-6h |
| Constant rate infusion | 0.01-0.03 mg/kg/h | 0.01-0.02 mg/kg/h | IV, after a loading bolus |
Vomiting, reflux and panting in dogs
Hydromorphone is one of the more emetic opioids, especially IM or SC in a dog that is not yet in pain. That matters before induction in a dog with an airway problem, an esophageal foreign body or raised intraocular pressure. Costa and colleagues studied gastroesophageal reflux and regurgitation in anesthetized dogs premedicated with hydromorphone alone or with acepromazine or dexmedetomidine. Expect panting and a lower body temperature in dogs during the first hour.
Hyperthermia in cats
Cats behave differently: Niedfeldt and Robertson found postanesthetic hyperthermia more often in cats given hydromorphone than in cats given buprenorphine, with some reaching dangerous temperatures. Monitor rectal temperature for several hours after recovery, and treat with active cooling and, when needed, low-dose naloxone or butorphanol to partly reverse the opioid. Lascelles and Robertson measured thermal antinociception in cats after hydromorphone, butorphanol and the two combined, which is useful when deciding whether to add butorphanol on top.
Cautions
Respiratory depression and bradycardia are dose-dependent. Use the low end in geriatric, hepatic or head-trauma patients. Hydromorphone is Schedule II in the US and comes as 2 mg/mL and 10 mg/mL injections, so read the vial before drawing up.
This table lives in Vetinuity, the clinical assistant from emergency veterinarian Brian Toncray, DVM, and links to the pancreatitis and heatstroke pages. Opioid alternatives: methadone, butorphanol. Reversal: naloxone.
● SOURCES
- 1. Niedfeldt RL, Robertson SA. Postanesthetic hyperthermia in cats: a retrospective comparison between hydromorphone and buprenorphine. Vet Anaesth Analg. 2006;33(6):381-389. PMID 17083610. Abstract. Checked 2026-10-26.
- 2. Lascelles BD, Robertson SA. Antinociceptive effects of hydromorphone, butorphanol, or the combination in cats. J Vet Intern Med. 2004;18(2):190-195. PMID 15058769. Abstract. Checked 2026-10-26.
- 3. Costa RS, Wetmore LA, Stein A. Randomized, blinded, controlled clinical trial to assess gastroesophageal reflux and regurgitation in dogs undergoing general anesthesia after hydromorphone premedication with or without acepromazine or dexmedetomidine. Am J Vet Res. 2021;82(9):695-700. PMID 34432514. Abstract. Checked 2026-10-26.
● RELATED ANSWERS
- Canine Acute Pancreatitis: Management
Canine acute pancreatitis care centers on fluid support, analgesia, antiemetics and nutrition, with treatment adjusted to severity and complications.
- Methadone Dose for Dogs and Cats
Methadone is dosed at 0.2-0.5 mg/kg IV, IM or SC every 4-6 hours in dogs and 0.2-0.3 mg/kg IV or IM every 4-6 hours in cats, and rarely causes vomiting.
- 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.
- Butorphanol Dose for Dogs and Cats (Torbugesic)
Butorphanol is dosed at 0.2-0.4 mg/kg IV, IM or SC in dogs and cats for sedation and mild pain, lasting about 1-2 hours, and at 0.05-0.1 mg/kg SC as an antitussive in dogs.
- Heatstroke in Dogs: Cooling, Fluids and Plasma
Vetinuity's heatstroke table: cool with room-temperature water and moving air, stop active cooling at 39.5 C (103.1 F), give crystalloids to effect and plasma for coagulopathy.
● FAQ
Does hydromorphone cause vomiting?
Yes, commonly in dogs when given IM or SC before pain is present. IV dosing and pretreatment with maropitant reduce it.
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