Merck Manual

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Selected Analgesics for Use in Dogs and Cats

Selected Analgesics for Use in Dogs and Cats

Class

Drug

Pain Category

Dosage for Dogs (mg/kg)

Dosage for Cats (mg/kg)

Route

Dose Interval (hr)

Epidurala (mg/kg)

Constant-rate Infusion (mg/kg/hr)

Opioids

Agonists

Morphine

Moderate to severe

0.1–2

0.1–0.5

IV, SC, IM

4–6

0.1–0.2

0.05–0.2

Hydromorphone

Moderate to severe

0.05–0.2

0.025–0.2

IV, SC, IM

2–4

0.01–0.03

Oxymorphone

Moderate to severe

0.05–0.2

0.025–0.1

IV, SC, IM

2–4

0.05

Methadone

Moderate to severe

0.1–1

0.1–0.5

IV, SC, IM

4–6

Fentanyl

Moderate to severe

0.005-0.01

0.0025–0.005

IV

15–20 min

0.004

0.002–0.05

Meperidine

Mild to moderate

3–10

3–5

SC, IM

1–2

Codeine

Mild to moderate

0.5–2

0.5–2

PO

6–8

Codeine 60 mg/acetaminophen 300 mg

Mild to moderate

1–2 (codeine)

Contraindicated

PO

6–8

Hydrocodone

Moderate

0.5

Reliable dosages not established

PO

6–12

Agonist-antagonist

Butorphanol

Mild (good visceral analgesia)

0.1–0.5

0.1–0.5

IV, SC, IM

1–2 (sedation up to 4)

0.25

0.14–0.4

Partial agonist

Buprenorphine

Mild to moderate

0.005–0.02

0.01–0.03

IV, SC, IM, buccal (cats)

6–12

0.005–0.03

0.001–0.005

Opioid-like

Tramadol

Mild to moderate

5–10

1–4

PO

6–8

α2-Adrenergic agonists

Xylazine

Sedative/analgesic, emetic effects in cats

0.05-1

0.1–1

IV, SC, IM

0.02–0.025

Medetomidine

Sedation longer than anesthesia

0.001–0.02

0.001–0.01

IV, SC, IM

0.001 (loading dose), 0.001–0.003

Dexmedetomidine

0.001–0.015

0.0025–0.02

IV, SC, IM

0.001–0.003

NMDA receptor antagonists

Ketamine

Adjunctive pain control

0.1–1

0.1–1

SC, IM, PO

4–6

0.5 (loading dose), intraoperative 0.01–0.02, postoperative 0.002–0.01

Amantadine

Adjunct drug for chronic/neuropathic pain

3–5

3–5

PO

Once daily

Calcium channel blocker

Gabapentin

Adjunct drug for chronic/cancer/neuropathic pain

5–15

2.5–20

PO

6–8

NK1 receptor antagonist

Maropitant

Visceral pain

2

1

PO

Once daily

Muscle relaxant

Methocarbamol

Intervertebral disc disease

15–20

PO

6–8

a Preservative-free formulations recommended.