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How to remember all about non barbiturates IV anaesthetics
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Here is a complete memory aid for Non-Barbiturate IV Anaesthetics from your veterinary surgery textbook (pages 138-139). The goal is to give you mnemonics, patterns, and key hooks so you stop having to re-read and start being able to recall.
🧠 Master Mnemonic: "C-C-E-P"
Chloral hydrate → Chloromag → Equithesin → Propofol
Think: "Cool Cats Enjoy Propofol"
1. CHLORAL HYDRATE - "The Sleep Drug"
Key hook: "Horses, cows, and buffaloes go wobbly then sleep - but it's NOT for sick or baby animals."
| Feature | Detail |
|---|---|
| Type | Hypnotic/narcotic - NO analgesia |
| Stages | First: locomotory incoordination → then: deep sleep |
| CVS effects | Hypotension + tachycardia (within safe limits) |
| Crosses | Placental barrier |
| Contraindications | Hepatic disease, renal disease, animals <1 month old |
| Onset / Duration | 20-30 min / 2-3 hours |
| Solution rule | Always prepare fresh before use |
Dose hook: "Horse = 6, Cattle = 5, Calf = 140, Camel = 100"
| Species | Route | Dose | Concentration |
|---|---|---|---|
| Horse (adult) | Per os | 6-10 g/50 kg | - |
| Horse (adult) | IV | 5-6.5 g/50 kg | 6-8% solution |
| Cattle/Buffalo (adult) | Per os | 40-60 g | - |
| Cattle/Buffalo (adult) | IV | 5 g/50 kg | 6% solution |
| Calf | IV | 140 mg/kg | 6% solution |
| Camel | IV | 100 mg/kg | 10% solution |
2. CHLOROMAG - "Chloral + Magnesium = Less Irritation, More Relaxation"
Key hook: "Mag takes away the sting and adds muscle relaxation."
- Mixture: Chloral hydrate + Magnesium sulphate in 1:1, 2:1, or 3:1 ratio
- Used as 10% solution
- Magnesium sulphate does two things:
- Reduces irritant effect of chloral hydrate
- Excellent muscle relaxation via neuromuscular blocking action
- Species: horses, cattle, buffaloes, camels
- Dose: 5 g/50 kg IV "to effect"
Memory trick: "Mag = Mellows + Muscles"
3. EQUITHESIN (Chloral-mag-pentobarbitone) - "The Horse Cocktail"
Key hook: "Three ingredients, one great horse anaesthetic - low drama induction, fast recovery."
Composition (memorize the 28-14-6.5 pattern):
| Ingredient | Amount | Role |
|---|---|---|
| Chloral hydrate | 28 g | Hypnosis |
| Magnesium sulphate | 14 g | Muscle relaxation (half of 28) |
| Pentobarbitone | 6.5 g | Sedation/narcosis |
| Sterile distilled water | to make 1000 ml | solvent |
| Ethyl alcohol | few drops | stabilizer |
Ratio trick: 28 : 14 : 6.5 = roughly 4 : 2 : 1. Also, 14 is exactly half of 28.
- Solution must always be prepared fresh
- Dose: 670 ml / 450 kg IV
- Advantages: low toxicity, negligible excitement during induction, excellent muscular relaxation, fast recovery
4. PROPOFOL - "The Modern Favourite"
Key hook: "Ultra-fast in, ultra-fast out - smooth for dogs and cats, safe in liver failure."
| Feature | Detail |
|---|---|
| Popularity | Most popular injectable anaesthetic - many species |
| Speed | Ultra-fast acting, cleared rapidly |
| Recovery | Smooth - can use as maintenance by constant infusion |
| Analgesia | Very mildly analgesic |
| Tissue effect | Non-irritant - but has little/no effect unless given IV |
| Liver | Suitable for animals with liver failure |
Administration pattern:
- Give first half rapidly, last half slowly "to effect"
- Anaesthesia appears within 8-13 minutes
- Rapid IV injection → temporary apnoea + reduced BP and cardiac output
Dose hook: "Horse = 2, Dogs with premedication = 4-6, Dogs without = 6.5"
| Species | Dose |
|---|---|
| Horse | 2 mg/kg IV |
| Dog (with premedication) | 4-6 mg/kg IV |
| Dog (without premedication) | 6.5 mg/kg IV |
Quick Comparison Table
| Drug | Species | Muscle Relaxation | Analgesia | Special Feature |
|---|---|---|---|---|
| Chloral hydrate | Horses, cattle, buffaloes, camels | No | No | Contraindicated <1 month age, hepatic/renal disease |
| Chloromag | Same as above | Excellent | No | Mag reduces irritation |
| Equithesin | Mainly horses | Excellent | No | 3-ingredient combo, fast recovery |
| Propofol | Dogs, cats, many species | Mild | Very mild | Safe in liver failure, constant infusion possible |
Exam Power Summary (30-second recall)
- Chloral hydrate = large animals, no analgesia, locomotory incoordination → sleep, crosses placenta, contraindicated in liver/kidney disease and neonates
- Chloromag = Chloral + Mag sulphate (1:1/2:1/3:1), 10% solution, Mag reduces irritation and gives muscle relaxation
- Equithesin = 28+14+6.5 g in 1000 ml + ethyl alcohol drops, fresh preparation, 670 ml/450 kg, horse specialty
- Propofol = ultra-fast, smooth recovery, constant infusion for maintenance, first half fast/second half slow, safe in liver failure, apnoea risk with rapid injection
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