Veterinary Anesthesia in Ruminants Quiz

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Questions and Answers

What is one of the validated pain scales for acute pain in cattle?

Cow Pain Scale (correct)

Paravertebral pain assessment

Sheep grimace scale

Flank block scale

Which regional analgesic technique is used for enucleation in ruminants?

Retrobulbar block (correct)

Petersen block

Cornual block

Inverted L block

What is a common challenge faced during anesthetic procedures in ruminants?

Difficulty in administering regional anesthesia

Regurgitation (correct)

Increased heart rate

Extremely high metabolism

What is a recommended practice to facilitate intubation in ruminants?

Use of a laryngoscope with a long straight blade Signup and view all the answers

What should be ensured to facilitate protection of the airway during anesthesia in ruminants?

Proper inflation of the cuff Signup and view all the answers

What is the recommended dosage of xylazine for sheep when administered intramuscularly?

0.2 mg kg -1 Signup and view all the answers

Which of the following statements about benzodiazepines in small ruminants is true?

Diazepam can provide excellent sedation when given IV. Signup and view all the answers

Which adverse effect may occur in some sheep given xylazine?

Pulmonary oedema Signup and view all the answers

What is the purpose of administering atipamezole after xylazine sedation?

To reverse sedation effects Signup and view all the answers

What is the main consideration when using NSAIDs for analgesia in small ruminants?

There are no opioids licensed for use. Signup and view all the answers

What is a major risk associated with the handling of ruminants during anaesthesia?

Inability to estimate body weight Signup and view all the answers

Which of the following conditions can lead to aspiration pneumonia in ruminants?

Regurgitation of reticuloruminal contents Signup and view all the answers

What is the recommended withholding time for food in ruminants before anaesthesia?

6 to 12 hours Signup and view all the answers

What is one of the goals of administering premedication to ruminants before anaesthesia?

Facilitate handling Signup and view all the answers

What is the typical dose range of xylazine for intravenous administration in cattle?

0.05 – 0.1 mg kg-1 Signup and view all the answers

Why should younger milk-fed animals not be starved before anaesthesia?

It poses a risk of hypoglycaemia and dehydration. Signup and view all the answers

Which drug is licensed for use in ruminant anaesthesia?

Xylazine Signup and view all the answers

What is the main effect of using xylazine in cattle?

Predictable sedation and muscle relaxation Signup and view all the answers

What is the primary reason to place a wedge under the neck if intubation is not possible?

To lower the mouth for better access Signup and view all the answers

What is a recommended method to address abdominal tympany during lengthy procedures?

Placement of a rumen tube Signup and view all the answers

What should be monitored to prevent hypoventilation and V/Q mismatch during anesthesia?

Respiratory muscle relaxation and depression Signup and view all the answers

What effect can intense hypoxic pulmonary vasoconstriction in cattle have during anesthesia?

Increased risk of hypercapnia and hypoxaemia Signup and view all the answers

What is a significant physiological response in adult cattle under anesthesia?

Production of up to 50L of saliva per 24 hours Signup and view all the answers

When should the endotracheal (ET) tube be removed during recovery in ruminants?

Late with cuff partially inflated Signup and view all the answers

What is a consequence of excessive use of anticholinergics in ruminants?

Viscid saliva that is difficult to clear Signup and view all the answers

Which volatile agent is approved for use as an anesthetic in ruminants within the EU?

Isoflurane Signup and view all the answers

What is a significant challenge in administering intravenous injections in pigs?

Jugular catheterization is very difficult. Signup and view all the answers

What anatomical feature contributes to the difficulty of intubation in pigs?

Narrow oral cavity and tongue. Signup and view all the answers

Which of the following breeds is NOT associated with a higher incidence of malignant hyperthermia?

Duroc. Signup and view all the answers

What is the primary biochemical abnormality associated with malignant hyperthermia?

Abnormal ryanodine receptor activity. Signup and view all the answers

What is a common clinical sign of malignant hyperthermia?

Blotchy skin. Signup and view all the answers

What should be administered to a pig experiencing malignant hyperthermia?

Dantrolene. Signup and view all the answers

What measure can help prevent hypothermia during anesthetic procedures in pigs?

Using active warming techniques. Signup and view all the answers

Which of these agents is a known trigger for malignant hyperthermia?

Succinylcholine. Signup and view all the answers

Study Notes

Anaesthesia in Ruminants

Anaesthetic Difficulties in Ruminants:
- Restraint and handling can be challenging.
- Body weight estimation may be inaccurate.
- Bloat and regurgitation risks.
- Aspiration pneumonia is a concern due to regurgitation.
- Hypoventilation, hypercapnia, and hypoxemia can occur.
- Hypotension is a potential complication.
- Neuropathy and myopathy can occur.
- Fluid and electrolyte imbalances can arise due to salivary losses.
- Limited number of licensed drugs available.
Legislation and Licensing:
- Few licensed products for ruminants – Xylazine, Detomidine, Ketamine.
- Cascade system must be followed when using drugs on food animals.
- Complex legislation regarding drug use.
- Drugs must be listed in the ‘Allowed Annex’ (EN 37/2010).
- Unlicensed drugs can result in animal withdrawal from the food chain.
Food Withholding:
- No consensus on withholding time.
- Withholding food for 18 to 24 hours reduces ruminal fermentation and bloating.
- Withholding food >24 hours can lead to ketoacidosis, reduced core temperature, and increased rumen fluidity.
- Recommended withholding time: 6 to 12 hours.
- Do not starve young milk-fed animals due to hypoglycemia and dehydration risks.
Premedication:
- Ruminants are generally docile.
- Licensed drugs must be considered.
- Goals of premedication: Facilitate handling, improve recovery, analgesia, balanced anesthesia, and reduce stress response.
- Xylazine and detomidine are licensed.
- Sedation is not always essential but can contribute to anesthetic sparing and analgesia.
Xylazine:
- Cattle are sensitive to xylazine.
- Predictable sedation.
- Use 1/10th the dose used in horses.
- Analgesic properties.
- Reversable with Atipamezole.
- Muscle relaxation, particularly when used with ketamine.
Xylazine Dosage:
- IV: 0.05 – 0.1 mg kg-1 (off-label).
- IM: 0.1 – 0.2 mg kg-1.
- Lower doses used for standing sedation.
- Often induces recumbency.
- Some animals can be intubated under xylazine alone.
- Positioning: Padded table, avoid pressure on superficial nerves.
Premedication in Small Ruminants:
- Restraint is usually not a problem.
- Premedication is often omitted.
- Premedication can prolong recovery.
Xylazine in Small Ruminants:
- 0.2 mg kg-1 IM for sheep.
- Goats are more sensitive: 0.05 mg kg-1 IM.
- Slow IV injection may be preferable.
- Up to 0.15 mg kg-1 IV for sheep.
- 0.01 mg kg-1 IV usually sufficient for goats.
Xylazine – Small Ruminant Considerations:
- Profound hypoxemia may occur.
- Pulmonary edema has been reported in some sheep due to pulmonary hypertension.
- Sedation is reversible with Atipamezole.
Benzodiazepines in Small Ruminants:
- Provide good and predictable sedation.
- Diazepam: 0.5 - 1 mg kg-1 IV or up to 2 mg kg-1 IM.
- Effective sedation in sheep and goats.
Common Small Ruminant Anaesthetic Protocols:
- Diazepam IV (0.2 - 0.5 mg kg-1) followed by Ketamine IV (2 - 5 mg kg-1).
- Xylazine (0.2 mg kg-1) + Ketamine (15 mg kg-1) mixed in a single syringe for IM administration.
Analgesia in Ruminants:
- Challenging due to limited licensed options.
- No licensed opioids.
- Some NSAIDs are licensed – check the Cascade and annexes.
- Butorphanol is the only opioid in the allowed annex (Regulation 37/2010).
- Regional techniques are recommended whenever possible.

Pain Recognition

Valid Pain Scales:
- UNESP-Botucatu unidimensional composite pain scale (cattle)
- Cow Pain Scale
- UNESP-Botucatu composite scale in sheep
- Sheep grimace scale

Regional Analgesic Techniques

Epidural analgesia and anaesthesia
Intravenous Regional anaesthesia (extremities)
Head blocks:
- Cornual (disbudding)
- Petersen (whole of ipsilateral face)
- Retrobulbar (enucleation)
Flank blocks:
- Line
- Inverted L (flank surgery)
- Paravertebral (flank surgery)

Ruminant Anaesthetic Challenges

Endotracheal intubation
Regurgitation
Abdominal tympany
Hypoventilation
Salivation

Intubation of Ruminants

Small ruminants and young calves:
- Can be challenging.
- Skilled assistance is essential.
- Use a laryngoscope with a long straight blade.
- Use a ‘bougie’ or stylet to guide the endotracheal tube.
Adult cattle:
- Relatively easier.
- Palpate the larynx orally.
- Guide the tube using fingers.
- Small hands are beneficial.
- Can be intubated blindly (50% success rate).
- Do not advance the ETT too deeply to avoid tracheal bronchus occlusion.

Regurgitation

Intubation strongly advised:
- Ensures airway protection.
- Inflate the cuff.
If intubation is not possible:
- Place a wedge under the neck to lower the mouth.
- Can also be done during recovery.

Abdominal Tympany

Will occur over time:
- Eructation is suppressed by anesthesia.
- GI motility is depressed by α2 agonists.
- More problematic during long procedures.
- Rumen tube placement can be used to release gas.
- Can affect the respiratory system.

Hypoventilation and V/Q Mismatch

Potential issue in conscious and sedated animals:
- Hypercapnia and hypoxemia may develop.
- Hypoxaemia is more likely when breathing room air.
- Caused by respiratory muscle relaxation and respiratory centre depression.
- Do not exceed peak inspiratory pressure of 25 cmH2O during positive pressure ventilation.
- Recumbency and splinting of the diaphragm can lead to atelectasis and hypoxaemia.
- Cattle and pigs have intense hypoxic pulmonary vasoconstriction, which can be exacerbated by inhalational anesthesia.

Salivation

High saliva production:
- Adult cattle: 50 L per day.
- Sheep: 16 L per day.
Anticholinergics:
- Not recommended, can make saliva viscous.
- Only indicated for bradycardia treatment.
Positioning:
- Head should be positioned to facilitate drainage.
Electrolyte derangement:
- Can occur with excessive bicarbonate loss.

Ruminant Maintenance

Choice of volatiles:
- Any volatile is suitable but only isoflurane is in the annexes (EU 37/2010).
Respiratory pattern:
- Respiration is fast and shallow during anaesthesia.
- Hypercapnia is common.
Blood pressure:
- Usually well maintained.
IV fluids:
- Required to replace salivary losses.

Ruminant Recovery

ET tube removal:
- Should be removed late with the cuff partially inflated due to the high risk of regurgitation.

Pig Anaesthetic Challenges

Similar licensed drugs:
- Similar to ruminants.
Restraint:
- Challenging – pigs are noisy and fast.
IM injection:
- Thick layer of subcutaneous fat.
- Use a long needle.
- Remote injection technique recommended.
- Inject behind the ears.
IV access:
- Relatively easy in the auricular vein.
- Jugular catheterization is difficult.
Intubation:
- Narrow oral cavity, difficult to open mouth.
- Thick fleshy tongue.
- Pharyngeal diverticulum.
- Small rima glottidis.
- Tilted larynx.
- Convoluted proximal trachea.
- Narrow trachea.
- Laryngeal spasm.
Respiratory depression:
- Common.
- Due to muscle relaxation.
Body temperature:
- Hypothermia is common due to vasodilation.
- Hairless and large skin surface area leads to heat dissipation.
- Active warming is essential during long anesthesia.
Malignant hyperthermia:
- Uncommon pharmacogenetic myopathy.
- Manifests during anesthesia.
- Overrepresented in certain breeds: Poland China, Pietrain, Landrace, Large White.

Malignant Hyperthermia

Abnormal receptor (ryanodine 1):
- Remains open for longer, leading to excessive intracellular calcium and increased muscle contraction.
Triggers:
- Halothane (other inhalants may also be involved).
- Succinylcholine.
Clinical signs:
- Generalized muscle rigidity (starts at the toes).
- Blotchy skin.
- Severe and sustained temperature rise.
- Hyperkalemia.
- Hypercapnia.
- Metabolic acidosis.

Malignant Hyperthermia - Treatment

Remove all inhalant anaesthetics:
- Replace breathing system, soda lime canister.
- Switch to total intravenous anaesthesia.
Promote mechanical ventilation:
- To reduce carbon dioxide.
- Active cooling.
Dantrolene:
- Post-synaptic muscle relaxant.
- Inhibits calcium release.
- 2-10 mg/kg IV.
Electrolyte monitoring:
- Hyperkalemia may develop.
- Treat as necessary.
Sodium bicarbonate:
- Administer if severe acidaemia, low bicarbonate, and low base excess.

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Description

Test your knowledge on veterinary anesthesia and analgesia practices for ruminants, particularly focusing on cattle and sheep. This quiz covers pain scales, analgesic techniques, and best practices for anesthetic procedures. Explore important considerations when using sedatives and NSAIDs in small ruminants.