# Hydromorphone: veterinary dose and monograph

> Hydromorphone is a veterinary analgesic. Potent pure mu-opioid agonist (~5× the potency of morphine) for moderate–severe acute pain — a peri-operative and emergency analgesic given by IV/IM/SC bolus or CRI. Indications include moderate–severe acute / post-operative pain; premedication and balanced anaesthesia (opioid component); trauma / emergency analgesia. This monograph lists 8 reference doses for dogs, cats, horses, rabbits, ferrets and reptiles, each with route, frequency and source.

Source: https://vetmasterji.com/drugs/hydromorphone · Last reviewed: 2026-10-01

## At a glance

- **Drug class:** Analgesic
- **Also known as:** Dilaudid, Hydromorphone HCl
- **Species with doses:** Dogs, Cats, Horses, Rabbits, Ferrets and Reptiles
- **General dose range:** 0.05–0.2 mg/kg IV q2–6h (or CRI) — check the species tables for the indication
- **Routes:** IV, IM, Epidural, SC
- **Last reviewed:** 1 October 2026

## Indications

- Moderate–severe acute / post-operative pain
- Premedication and balanced anaesthesia (opioid component)
- Trauma / emergency analgesia
- Analgesic CRI in hospitalised patients

## Hydromorphone dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

### Dogs

*Hydromorphone doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Acute / post-op pain | 0.05–0.2 mg/kg | IV | q2–6h | — |
| Analgesic CRI | 0.01–0.03 mg/kg/h | IV | CRI after a loading dose | — |

- Acute / post-op pain: Papich 5e: 0.1–0.2 mg/kg IV repeated q2h, or 0.22 mg/kg IM/SC q4–6h; 0.1 mg/kg with acepromazine as a premedicant. Plumb’s p.623: 0.05–0.2 mg/kg IV, IM or SC q2–4h (Hansen; Hardie); 0.1 mg/kg IV or SC q2h (KuKanich 2008). Vomiting, panting and bradycardia are common; hyperthermia can occur.
- Analgesic CRI: Papich 5e: 0.01 mg/kg/h IV. Plumb’s p.623 (KuKanich 2008): 0.03 mg/kg/h based on pharmacokinetics.

### Cats

*Hydromorphone doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Acute / post-op pain | 0.05–0.2 mg/kg | IM | q2–6h | — |
| Epidural analgesia | 0.05 mg/kg | Epidural | single | — |

- Acute / post-op pain: Papich 5e: 0.1–0.2 mg/kg SC or IM, or 0.05–0.1 mg/kg IV, q2–6h. Plumb’s p.623: 0.05–0.1 mg/kg IM, IV or SC q2–6h (Wagner 2002); moderate–severe pain 0.08–0.3 mg/kg (Mathews). Opioid-associated hyperthermia in cats — monitor temperature.
- Epidural analgesia: Papich 5e: 0.05 mg/kg diluted in saline to 0.2 mL/kg (1 mL per cat).

### Horses

*Hydromorphone doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Epidural analgesia | 0.04 mg/kg | Epidural | single | — |

- Epidural analgesia: Papich 5e: 0.04 mg/kg diluted in 0.9% saline to 20 mL. No systemic horse dose reported.

### Rabbits

*Hydromorphone doses for rabbits*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Premedication / post-op analgesia | 0.05–0.1 mg/kg | IV | once; CRI 0.05–0.1 mg/kg/h post-op | — |

- Premedication / post-op analgesia: Plumb’s p.623 (Lichtenberger 2006): rabbits 0.05–0.1 mg/kg IV; post-op CRI after 0.05 mg/kg IV load at 0.05–0.1 mg/kg/h.

### Ferrets

*Hydromorphone doses for ferrets*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Premedication / post-op analgesia | 0.05–0.1 mg/kg | IV | once; CRI 0.05–0.1 mg/kg/h post-op | — |

- Premedication / post-op analgesia: Plumb’s p.623 (Lichtenberger 2006): pre-op 0.05–0.1 mg/kg IV; post-op CRI after 0.05 mg/kg IV load at 0.05–0.1 mg/kg/h.

### Reptiles

*Hydromorphone doses for reptiles*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Analgesia | 0.5–1 mg/kg | SC | q24h | — |

- Analgesia: Carpenter's 6th ed (Reptile analgesic table): 0.5–1 mg/kg SC q24h (red-eared sliders); 0.5 mg/kg SC (bearded dragons — PK supports q24h). Mu-opioid — more reliable reptile analgesia than butorphanol.

## Contraindications

Severe respiratory compromise without support. Head trauma with raised ICP (relative). Use reduced doses in geriatric/debilitated/hypovolaemic patients. Concurrent MAOIs/selegiline. Known opioid hypersensitivity.

## Species-specific warnings

> **Caution:** Cats: Cats are prone to opioid hyperthermia and dysphoria — use lower doses and monitor temperature after dosing.

## Adverse effects

- Dose-dependent respiratory depression
- Bradycardia (vagal — anticholinergic-responsive)
- Vomiting/nausea, panting (dogs)
- Hyperthermia in cats; sedation or dysphoria
- Reduced GI motility

## Drug interactions

- Other CNS depressants/anaesthetics/opioids: additive respiratory and CNS depression — reduce doses
- MAO inhibitors / selegiline: serotonergic/excitatory reaction
- Anticholinergics: used to manage opioid bradycardia
- Phenothiazines (acepromazine): enhanced sedation/hypotension (often combined deliberately)

## Pregnancy and lactation

Crosses the placenta — neonatal respiratory depression near parturition (have naloxone for neonates). Used peri-operatively when needed.

## Monitoring

- Respiratory rate/effort and SpO2/capnography
- Heart rate (bradycardia) and blood pressure
- Temperature — especially cats (hyperthermia)
- Sedation/analgesia/dysphoria scoring; controlled-drug records

## Toxicity and overdose

Overdose: marked respiratory depression/apnoea, profound sedation/coma, bradycardia, hypotension, miosis (dogs). Cats may show hyperthermia and excitation. Reversible with naloxone.

Management: Antidote: naloxone 0.01–0.04 mg/kg IV/IM, repeated as needed (may need re-dosing/CRI as the opioid can outlast naloxone). Support ventilation/oxygenation (priority), treat bradycardia with anticholinergics, IV fluids and warmth; actively COOL cats with opioid hyperthermia.

## Clinical pearls

- A strong, reliable, cardiovascularly stable opioid — an excellent morphine alternative with less histamine release (safer IV)
- Always have naloxone and the means to ventilate before dosing potent opioids
- Watch cats for opioid HYPERTHERMIA (check temperature post-dose) and dose at the lower end
- Bradycardia is vagal and anticholinergic-responsive; respiratory depression is the dangerous effect
- Account for every dose — controlled substance

## Mechanism of action

Pure mu-opioid receptor agonist acting in the brain and spinal cord (dorsal horn) to inhibit ascending nociceptive transmission and activate descending inhibition (G-protein coupling → reduced cAMP, decreased neuronal excitability and neurotransmitter release). Greater potency and less histamine release than morphine, with similar efficacy.

## Formulations and products

- Injection 2 mg/mL
- Injection 10 mg/mL (concentrated)
- Dilaudid / Hydromorphone — 2 mg/mL / 10 mg/mL injection; tablets, Injection / tablet (human-label)

## Storage

Injection: 15–30 °C, protect from light; SECURE controlled-drug storage and accountability records.

## Before you use this dose

> **Caution:** Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

## Other analgesics

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- [Fentanyl](https://vetmasterji.com/drugs/fentanyl)
- [Gabapentin](https://vetmasterji.com/drugs/gabapentin)
- [Lidocaine HCl](https://vetmasterji.com/drugs/lidocaine)
- [Methadone](https://vetmasterji.com/drugs/methadone)
- [Morphine Sulfate](https://vetmasterji.com/drugs/morphine)
- [Nalbuphine](https://vetmasterji.com/drugs/nalbuphine)

## Frequently asked questions

### What is the dose of Hydromorphone for dogs?

Reference doses for Hydromorphone in dogs: 0.05–0.2 mg/kg IV q2–6h (Acute / post-op pain); 0.01–0.03 mg/kg/h IV CRI after a loading dose (Analgesic CRI). Confirm against the label and the patient before use.

### What is the dose of Hydromorphone for cats?

Reference doses for Hydromorphone in cats: 0.05–0.2 mg/kg IM q2–6h (Acute / post-op pain); 0.05 mg/kg Epidural single (Epidural analgesia). Confirm against the label and the patient before use.

### What is the dose of Hydromorphone for horses?

Reference doses for Hydromorphone in horses: 0.04 mg/kg Epidural single (Epidural analgesia). Confirm against the label and the patient before use.

### When should Hydromorphone not be used?

Severe respiratory compromise without support. Head trauma with raised ICP (relative). Use reduced doses in geriatric/debilitated/hypovolaemic patients. Concurrent MAOIs/selegiline. Known opioid hypersensitivity.

### What are the side effects of Hydromorphone in animals?

Dose-dependent respiratory depression; Bradycardia (vagal — anticholinergic-responsive); Vomiting/nausea, panting (dogs); Hyperthermia in cats; sedation or dysphoria; Reduced GI motility.

## Sources

- Plumb's Veterinary Drug Handbook
- Merck Veterinary Manual, 11th edition
- Papich, Papich Handbook of Veterinary Drugs, 5th edition
- Carpenter, Exotic Animal Formulary

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VetMasterJi is a clinical decision-support and education platform for veterinary professionals and students. It does not provide veterinary advice, diagnosis or treatment for specific animals. All drug doses, calculators and differentials are references that must be independently verified before clinical use; the attending registered veterinarian remains solely responsible for every clinical decision.