Hydromorphone

What is this medication for?

• Sedative/restraint, analgesia, preanesthetic

How is it given?

Give exactly as your veterinarian prescribed — never change the dose or stop on your own unless your veterinarian has told you to.

What if I miss a dose?

• Give it as soon as you remember — unless it is almost time for the next dose (then skip the missed one; never double up).
• Call your clinic if you miss more than one dose in a row.

Side effects — what should I watch for?

Effects listed as common in this handout

• Sedation, panting, vocalization, vomiting, defecation (Common)
• Nausea, wobbliness/unsteadiness, hyperesthesia, overheating, behavioral change (Common)
• Bradycardia (Vagally mediated)

Worth a phone call to your veterinarian

• Any new symptom that worries you.

⚠️ Contact your veterinarian or an emergency clinic IMMEDIATELY if you notice

• Trouble breathing, collapse, seizures, severe vomiting or diarrhea, facial swelling, or pale gums

Before starting (or refilling), tell your veterinarian if your pet:

• has or has had: Hypersensitivity; toxin-induced diarrhea (until toxin cleared); suspected GDV/obstruction pre-anesthetic use (may induce vomiting)
• has or has had: Head injury/↑ICP, acute abdomen (may mask signs), respiratory disease, pre-existing bradyarrhythmia; cats — monitor for overheating, especially post-anesthesia

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • Butorphanol, nalbuphine
  • MAO inhibitors (amitraz, selegiline)
  • Phenothiazines
  • Tricyclic antidepressants

Storage and handling

Room temperature, protect from light. Schedule II — locked storage. Injection stable 24h in common into a vein fluids if light-protected. Incompatible with sodium bicarbonate or thiopental.

Good to know

• Significantly cheaper than oxymorphone with similar efficacy — has largely replaced it in practice.
• Cat overheating can be treated with naloxone if it occurs (reduces body temp rapidly).
• Contraindicated as sole preanesthetic if GDV/obstruction suspected — vomiting risk.