Veterinary Anesthesia and Seizure Management

Contraindicated Drugs in Cases of Seizures

• Ketamine and xylazine are contraindicated in animals with a history of seizures.
• Acepromazine was previously thought to decrease seizure thresholds, but this is now known to be incorrect.
• Thiopental is contraindicated in animals with a history of asthma because it can cause apnea and in Greyhounds because they have prolonged recoveries with this drug.
• Thiopental is currently unavailable in the U.S. and Canada.
• Morphine should not be used in cases of high intracranial pressure.
• Diazepam and phenobarbital are used to treat seizures.

Anesthetic Breathing System Flow Rates

• Nonrebreathing systems have no remixing of inhaled and exhaled gasses.
• Nonrebreathing systems operate at high fresh gas flows of 100-300 ml/kg/min.
• Closed rebreathing systems only deliver enough fresh gas to meet an animal's metabolic needs.
• Closed rebreathing system flow rates are approximately 5-10 ml/kg/min, depending on animal size.
• Semi-closed and partial rebreathing systems are the same and run at intermediate flow rates of approximately 10 ml/kg/min (large animals) and 30 ml/kg/min (small animals).

Ketamine Contraindictions

• Ketamine can cause seizures in some dogs and should not be used in dogs with epilepsy.
• Ketamine is contraindicated in dogs with increased intraocular pressure (like glaucoma).
• Ketamine can cause respiratory depression.
• Other contraindications for ketamine use include prior hypersensitivity reactions, animals to be used for human consumption, ketamine used alone for general anesthesia, and increased CSF pressure or head trauma.
• When using ketamine in cats, protect their eyes with ophthalmic ointment because they remain open.

Endotracheal Tube Placement

• If an endotracheal tube is inserted too far into the airway, it can direct ventilation to only one lung, cutting the gas administration in half and making it difficult to keep the patient sedated.
• An endotracheal tube that is too long can increase mechanical dead space.

Auriculopalpebral Nerve Block

• The auriculopalpebral nerve, located along the dorsal zygomatic arch, provides motor innervation to the upper orbicularis oculi muscle.
• Anesthesia of this nerve prevents the horse from blinking and allows for a complete ophthalmic examination.
• The frontal nerve provides sensory innervation to the upper eyelid.

Preventing Laryngospasms in Cats

• Laryngospasms can be prevented by applying lidocaine gel or spray to the larynx before attempting intubation.
• Topical lidocaine requires 15-20 seconds to take effect.
• Laryngeal spasm can occur in cats, small ruminants, and swine.

Minimum Alveolar Concentration (MAC)

• MAC is the minimum concentration of inhalant anesthetic in the alveolar gas necessary to prevent a physical response to surgical stimulation in 50% of animals.
• MAC is a measure of anesthetic potency.
• Desflurane has the highest MAC.

Neuropathic Pain

• Neuropathic pain (NP) is a painful response caused by damage to neural tissue.
• NP can result from direct injury to nerve tissue or indirectly from the inflammatory and neurochemical response to injury of non-neural tissue.
• Symptoms of NP include burning, shooting, or stabbing pain.
• NP is often associated with chronic pain, but is now believed to also develop as an acute pain.
• Many medications are used to treat NP, including gabapentin.

Gabapentin Side Effects

• Sleepiness is the most common side effect of gabapentin, generally at higher doses.

Hyperalgesia

• Hyperalgesia is an increased response to a stimulus that normally produces pain.
• Damaged areas develop an exaggerated response or hypersensitivity to painful stimuli.
• Inflammatory mediators, like bradykinins, cytokines, serotonin, and histamine from activated inflammatory cells, amplify the inflammatory response and resulting pain.
• Allodynia is the triggering of a painful response by stimuli that are not normally painful.
• Hypoalgesia is a decreased response to normally painful stimuli.

This quiz covers important guidelines regarding contraindicated drugs in cases of seizures and the effective use of anesthetic breathing systems. Test your knowledge on veterinary pharmacology and anesthesia principles essential for safe clinical practices. It's a must for veterinary professionals and students aspiring to understand essential anesthetic protocols.