Pain in pregnant or lactating patients

WSAVA guideline

Key findings

• Maternal physiology alters pharmacology: ↓GI motility, reflux/vomiting; ↑cutaneous blood flow; ↑body water/fat; ↓serum albumin; altered hepatic enzymes; ↑renal function; placenta = lipoprotein barrier → polar/ionised/protein-bound/water-soluble drugs cross poorly (sheet).
• Opioids in pregnancy: commonly used; methadone, morphine, hydromorphone used in human pregnancy; fentanyl, pethidine, butorphanol, nalbuphine more lipid-soluble → higher foetal levels (sheet).
• Caesarean: most neonates deliver vigorous; if depressed → warmth, stimulation, O₂, suction ± a drop of naloxone sublingually (repeat doses may be needed) (sheet).
• ⚠️ Buprenorphine caused lack of milk production in animal studies — problematic post-caesarean (sheet).
• ⚠️ NSAIDs not given to pregnant animals (teratogenicity/development-interfering effects); ketamine crosses the placenta rapidly with no foetal effects observed in rats/mice/rabbits/dogs but increases uterine tone → avoid in pregnancy; α2-agonists reduce uterine blood flow — xylazine should not be used, no data for medetomidine/dexmedetomidine (sheet).
• Lactation: opioid milk transfer follows lipid solubility (pethidine > sufentanil > fentanyl > morphine > hydromorphone) — prefer hydrophilic morphine; suckle after peak levels wane; pethidine/butorphanol/nalbuphine not recommended; monitor dam + offspring. Local anaesthetics safe/non-teratogenic — highly recommended; if analgesia essential with toxicity concern, pump and discard milk 12 h and bottle-feed; herbals avoided (sheet).

Drugs named in WSAVA’s own guideline text

As printed in WSAVA’s document, not this app’s own extracted data — see “Related drugs in this reference” below for that.

• Opioids — methadone, morphine, hydromorphone

  Pregnancy: Commonly used — Lactation: Prefer morphine (hydrophilic, least milk); suckle after peak wanes — Monitor dam + offspring

• Naloxone

  Pregnancy: A drop sublingually for depressed neonates, repeat as needed — Lactation: — — With warmth/stimulation/O₂/suction

• NSAIDs / paracetamol

  Pregnancy: ⚠️ Avoid — teratogenic/development-interfering — Lactation: Single doses only, with caution (no lactating dog/cat studies) — Haemorrhage concern with non-COX-/COX-1-selective NSAIDs right after birth; paracetamol safe in dogs, never cats

• Ketamine

  Pregnancy: ⚠️ Avoid — increases uterine tone — Lactation: Expected in milk (no reports) — Crosses placenta rapidly

• α2-agonists — xylazine / medetomidine / dexmedetomidine

  Pregnancy: ⚠️ Xylazine contraindicated (uterine blood flow); no evidence for the others — Lactation: Not addressed — —

• Local anaesthetics (lidocaine)

  Pregnancy: ✅ Safe, non-teratogenic — highly recommended — Lactation: Small milk levels; incision-line infiltration highly recommended — —

• Herbal analgesics

  Pregnancy: ⚠️ Avoid (no information) — Lactation: ⚠️ Avoid — —

Recommendations

• Opioids acceptable in pregnancy; prefer less lipid-soluble agents

  Stated verdict (sheet)

• No NSAIDs in pregnancy; avoid ketamine (uterine tone); xylazine contraindicated

  Stated verdict (sheet)

• Local anaesthetics highly recommended (pregnancy; incision-line in lactation)

  Stated verdict (sheet)

• Depressed neonate post-caesarean: support + drop of naloxone sublingually

  Stated protocol (sheet)

• Lactation: prefer hydrophilic opioids; NSAIDs single doses only (haemorrhage risk)

  Stated verdict (sheet)

• If concern: pump-and-discard milk 12 h, bottle-feed; avoid herbals

  Stated protocol (sheet)

Related drugs in this reference (0)

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