Tramadol
Tramadol hydrochloride
Also known as: Ultram ER · Ryzolt · Rybix ODT · Ultracet · Tralieve · Tramadol ER · Zamadol · CG-315E · tramadoli hydrochloridum · U-26225A · Tramadol hydrochloride
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| General/Non-responsive pain | 5 mg/kg PO q6-8h and up to 10 mg/kg PO q6-8h | PO | q6-8h | — | 🌎 NA |
| Analgesic | 2-5 mg/kg four times daily | PO | q6h | — | 🌎 NA |
| Chronic pain | 2-5 mg/kg PO 2-3 times a day | PO | q8-12h | — | 🌎 NA |
| Mild acute and chronic soft tissue and musculoskeletal pain | 2-5 mg/kg | PO | q8h | — | 🌍 EU |
| Perioperative acute pain | 2 mg/kg | IV | single dose or as needed | — | 🌍 EU |
- General/Non-responsive pain: Maximum analgesic effects may not occur immediately and may be delayed up to 14 days for chronic pain conditions.
- Analgesic: Suggested starting dose.
- Chronic pain: Reasonable for mild pain; adjust for severe pain. Best used as multimodal therapy with NSAIDs or other analgesics due to erratic pharmacokinetics.
- Mild acute and chronic soft tissue and musculoskeletal pain: Chewable tablets are authorized for this use. Sustained-release tablets are unsuitable for once-daily dosing.
- Perioperative acute pain: Used instead of traditional opioids to provide analgesia for acute pain.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Starting dose | 2 mg/kg twice daily | PO | q12h | — | 🌎 NA |
| Current dosing recommendations | 1-2 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Chronic pain | 1-4 mg/kg PO 2-3 times a day | PO | q8-12h | — | 🌎 NA |
| Analgesia | 2-4 mg/kg | PO | q8h | — | 🌍 EU |
| Analgesia | 1-2 mg/kg | IV | as needed | — | 🌍 EU |
| Analgesia | 1-2 mg/kg | SC | as needed | — | 🌍 EU |
- Starting dose: Based upon the pharmacokinetics of tramadol and ODT in cats.
- Current dosing recommendations: Maximum analgesic effects may be delayed up to 14 days for chronic pain.
- Chronic pain: Reasonable for mild pain; dose and interval may need adjustment for more severe pain.
- Analgesia: Oral preparations are highly unpalatable to cats. Watch for dysphoria.
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Chronic laminitis pain | 5 mg/kg PO twice daily for seven days, alone or with ketamine at 0.6 mg/kg/hr IV during six hours each day for the first 3 days of treatment | PO/IV | q12h | 7 days | 🌎 NA |
- Chronic laminitis pain: Pain relief was enhanced.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Tramadol is a synthetic, centrally acting opiate-like analgesic used primarily for the management of mild to moderate pain and occasionally as an antitussive.
Key Clinical Highlights:
- Acts as a weak mu-opioid receptor agonist and inhibits the reuptake of serotonin and norepinephrine.
- Highly useful as part of a multimodal analgesic protocol (e.g., combined with NSAIDs, gabapentin, or amantadine) for chronic pain conditions like osteoarthritis or cancer.
- May take up to two weeks to reach full analgesic efficacy in chronic pain states.
- Clinical Pearl: While the monograph notes it is not a controlled substance, tramadol was reclassified as a Schedule IV controlled substance by the DEA in the USA in 2014 due to human abuse potential.
- Generally well-tolerated in dogs, with sedation being the most common side effect. Cats may experience dysphoria and find the medication highly unpalatable.
Mechanism of action
Tramadol provides analgesia through a dual mechanism of action:
- Opioid Activity: Tramadol and its active metabolite O-desmethyltramadol (M1) bind to mu-opioid receptors in the central nervous system.
- Monoaminergic Activity: It inhibits the synaptic reuptake of serotonin (5-HT) and norepinephrine (NE) → enhancing descending inhibitory pathways of pain transmission in the spinal cord.
Pharmacologic Pearl: The M1 metabolite is 6 times more potent as an analgesic and has 20 times greater affinity for mu-receptors than the parent drug. Dogs produce very little of the M1 metabolite compared to cats and humans, which explains why tramadol's opioid-mediated efficacy in dogs is often erratic and heavily reliant on its serotonin/norepinephrine reuptake inhibition. Naloxone only partially antagonizes tramadol's analgesic effects.
Safety & warnings
Contraindications
- Hypersensitivity to tramadol or other opioids
- Combination products containing acetaminophen (e.g., Ultracet) are STRICTLY CONTRAINDICATED in cats
- Concurrent use with MAOIs (e.g., selegiline, amitraz) due to risk of serotonin syndrome
- Patients with a history of epilepsy or seizure disorders
Adverse effects
- Dogs: Excessive sedation, agitation, anxiety, tremor, dizziness
- Dogs: Inappetence, vomiting, constipation, diarrhea
- Cats: Dysphoria, mydriasis, dose avoidance (unpalatability)
- Humans: Pruritus (approx. 10%)
- Injectable form: Respiratory and cardiac depression
- Sedation (especially at high doses in dogs)
- Dysphoria (more likely in cats)
- Nausea
- Behavioral changes
- Increased risk of seizures
Precautions
Important Warnings:
- Seizure Risk: Use with caution in animals with preexisting seizure disorders or those receiving drugs that lower the seizure threshold. Tramadol has caused seizures in humans.
- CNS/Respiratory Depression: Use cautiously with other CNS or respiratory depressants.
- Geriatric/Debilitated Patients: Use with caution; dosage adjustments may be needed for patients with impaired renal or hepatic function.
- Dependence & Withdrawal: Physical dependence can occur; withdraw gradually after chronic use.
- Formulation Warning: Extended-release tablets must not be broken, crushed, or chewed, as this can lead to rapid absorption and toxicity. Dogs do not absorb ER tablets well.
Drug interactions
Rarely linked to digoxin toxicity in humans.
Potential for fatal serotonin syndrome; concurrent use should be avoided.
May reduce the effectiveness of both drugs.
May increase tramadol concentrations and decrease M1 (active metabolite) concentrations.
Theoretically could cause additive serotonergic effects.
Pretreatment with tramadol reduced MAC values by approximately 30% in dogs and 40% in cats.
Can inhibit the metabolism of tramadol to its active metabolites, decreasing efficacy and increasing the risk of toxicity (serotonin syndrome, seizures).
Increased risk for seizures; amitriptyline may inhibit tramadol metabolism.
Increased PT and INR reported in humans (relatively rare).
Increased risk of serotonin syndrome
Increased risk of serotonin syndrome
Increased risk of serotonin syndrome
Increased risk of serotonin syndrome
Increased risk of serotonin syndrome
Increased risk of serotonin syndrome
Safe and synergistic multimodal analgesia
Safe and synergistic multimodal analgesia
Safe and synergistic multimodal analgesia
Monitoring
- Clinical efficacy (pain scoring, mobility, comfort levels)
- Adverse effects (excessive sedation, GI upset, dysphoria, agitation)
- Pain scores to assess efficacy
- Signs of sedation or dysphoria
- Signs of serotonin syndrome (hyperthermia, hypertension, agitation, tremors)
- Seizure activity in susceptible individuals
Pharmacokinetics
Half-life
Absorption
Dogs: PO bioavailability ~65% (significant interpatient variability); Rectal ~10%. Cats: PO bioavailability ~60% (high interpatient variability). Horses: PO bioavailability ~14% (adults), 53% (neonatal foals), 20% (weaned foals).
Distribution
Dogs: Vd ~3.8 L/kg. Cats: Vd ~2 L/kg.
Metabolism
Extensively metabolized via several hepatic pathways. The active metabolite O-desmethyltramadol (M1) has potent agonist activity but is a minor metabolite in dogs. Cats produce more of the M1 metabolite.
Elimination
Dogs: Total body clearance ~55 mL/kg/min. Cats: Clearance ~12 mL/min/kg.
Overdose
Acute oral overdoses may cause either CNS depressive signs or serotonin syndrome.
- Clinical Signs: Lethargy, mydriasis, ataxia, and vomiting are most common. Stimulatory signs such as tachycardia, tremors, vocalization, agitation, and seizures may also occur. Cats frequently show mydriasis, hypersalivation, and tachycardia.
- Treatment: Primarily supportive (maintaining respiration, treating seizures with benzodiazepines or barbiturates).
-
Important: Naloxone may NOT be useful in tramadol overdoses. It only partially reverses effects and may actually increase the risk of seizures. Cyproheptadine and phenothiazines can be used to treat stimulatory signs (serotonin syndrome).
Available products
Formulations
- Oral tablets (immediate release)
- Extended-release tablets
- Oral disintegrating tablets
- Injection (available commercially outside the USA)
- 50 mg tablets
- 100 mg, 200 mg, 300 mg immediate-release tablets
- 20 mg, 80 mg chewable tablets (veterinary)
- 10 mg, 25 mg tablets
- Sustained-release tablets (various sizes)
- 5 mg/ml oral liquid
- 50 mg/ml injectable solution
Veterinary
- None commercially available in the USA.
- Tralieve 20 mg, 80 mg chewable tablets
- Zamadol
Human-labeled
- Tramadol HCl Oral Tablets (film-coated) 50 mg (Ultram, generic)
- Tramadol HCl Extended-Release Tablets 100 mg, 200 mg, 300 mg (Ultram ER, Ryzolt, generic)
- Tramadol HCl Oral Disintegrating Tablets 50 mg (Rybix ODT)
- Tramadol HCl 37.5 mg / Acetaminophen 325 mg tablets (Ultracet) - WARNING: DO NOT USE IN CATS
- Tramadol ER
- 50 mg immediate-release tablets
Regulatory status
Authorized veterinary chewable tablets available for dogs.
POM-V, POM CD Schedule 3. Subject to safe custody requirements.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store tablets at room temperature 25°C (77°F); excursions permitted to 15-30°C (59-86°F). Dispense in tight, light-resistant containers.
Client information
For Pet Owners:
- Administration: Can be given with or without food. If your pet vomits after taking it on an empty stomach, try giving future doses with a small treat or meal.
- Taste: The medication has a very bitter taste. Cats, in particular, may drool excessively or resist taking it. Do not crush or break extended-release tablets.
- Behavioral Changes: May cause changes in alertness. Your pet might seem unusually sleepy, or conversely, anxious, restless, or vocal (especially cats). Contact your veterinarian if these signs are severe.
- Patience is Key: For chronic conditions like arthritis, it may take up to two weeks of consistent dosing to see the full pain-relieving benefits.
- Safety Warning: Keep out of reach of children and other pets. NEVER give your pet human medications containing tramadol combined with acetaminophen (like Ultracet), as acetaminophen is highly toxic and often fatal to cats.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.