28. Forms of general anaesthesia in cattle, commonly used drugs, and drug combinations Flashcards
Types of anaesthetia?
Types of Anaesthesia
- Local: loss of sensation in a limited body are
- Regional: loss of sensation in a limited, but larger body area than for local anaesthesia.
- Epidural: on or around the dura mater, in particular (of an anaesthetic) introduced into the space around the
dura mater of the spinal cord.
• General: loss of consciousness decreased sensitivity and motor response.
General types?
General
- Intravenous
- Inhalation
General intravenous anaesthetia?
General Intravenous Anaesthesia
- Increases patient comfort
- Improves anaesthetic agents, analgesics, and equipment
- It requires increased experience and knowledge of veterinarians, veterinary anaesthesiologists, and veterinary
technicians.
Advantages of general anaesthetia?
Advantages
- Short induction time
- IV administration with minimal assistance
- Small volumes
- Some products can be administered intramuscularly
- Products are often combined
- Drug mixtures: decrease the dose and the negative effect of individual drugs
Disadvantages of general anaesthetia?
Disadvantages:
- The depth of anaesthesia is more difficult to control
- Slow recovery, especially when administered IM or SQ
- Drugs are not labelled for use in food producing animals
- Milk and slaughter withdrawal times
- Respiratory support is difficult
Complications of general anaesthetia?
Complications:
- Lung capacity of cattle is small, abdominal organs (dorsal or lateral recumbency)
- The cardiac sphincter relaxes during anaesthesia pushes the ruminal contents (reflux) into the pharynx which is
aspirated
• Rumen tympany
Other Considerations?
Other considerations
- Accurate weight of the patient
- Rate and dosage- many patient-related factors
o Excitement of the patient
o Renal or hepatic disease
o Metabolic rate
o Pregnancy
• Proper restraint and vein accessibility
o SC abdominal vein (milk vein) in the recumbent cow
Drugs types?
Drugs
- Sedative: narcotic agent used to calm a nervous or excited animal
- Analgesia: relief from pain
- Anaesthesia: the loss of sensation and loss of the ability to feel pain
- General anaesthesia: the loss of consciousness with decreased sensitivity and with reduced motor response
Acepromazine?
Acepromazine (phenothiazine-based tranquilizers)
- Mild sedation
- IM, IV, SQ or PO (higher doses are required for PO)
- Wait a minimum of 15 minutes for effect
- IV dose faster, but more time is required for IM, SQ, or PO use
- Cattle sedation
o IV 0.01-0.02mg/kg
o IM 0.03-0.05mg/kg
Diazepam?
Diazepam/ midazolam (phenothiazine-based tranquilizers)
- Sedation and muscle relaxant
- Cattle dose
o Sedation: 0.55-1.1mg/kg
Xylazine?
Xylazine (alpha 2 agonist)
- Potent sedative and analgesic effects
- Cattle: 10 times more sensitive to xylazine than horses
- IV, SQ, or IM
- Onset is longer: IM and SQ (min. 15 minutes)
- Dose and response of cattle depends on:
o Temperament of the patient
o Route of administration
- Higher dose: recumbent patient
- Doses:
o Mild to moderate sedation: 0.022 to 0.066 mg/kg
o Heavy sedation, possible recumbency: 0.11 to 0.165 mg/kg
Detomidine?
Detomidine (alpha-2 agonist)
- More potent sedative and analgesic agent than xylazine
- Causes more cardio and respiratory depression than xylazine
- Should not be used in cases to cause recumbency
- Dosage not well determined:
o IV dose range in cattle: 0.01 to 0.02 mg/kg
o IM dose range in Cattle: 0.02 to 0.05 mg/kg
Ketamine?
Ketamine (dissociative anaesthetic agent)
- Analgesic (painkiller) effect - administered in a subanaesthetic dose
- Commonly used in combination with xylazine
- Dose may be reduced when used in combination
- Recovery period
o Tremors, vomit or hypersalivation
• Cattle dose
o 2.2 mg/kg IV after sedation
Butorphanol?
Butorphanol (opiate)
- Analgesic (painkiller)
- Does not produce anaesthesia
- In combination with xylazine and ketamine
- In standing animals: + local anaesthetics (lidocaine) must be used
- Cattle dose:
o 0.02 to 0.025 mg/kg
o 30 to 40 mg total dose
o Best when used in combination with sedative
o Cattle may become excitable with butorphanol alone
Flunixin?
Flunixin meglumine (NSAID)
• Used as
o Anti-inflammatory
o Analgesic
§ To control visceral pain but not for musculoskeletal pain
o Anti-pyretic
o Anti-endotoxin
- No more than 5 days- abomasal ulcers
- Cattle dose 1.1-2.2mg/kg
o 1ml/100lb IV of 100mg/ml solution
