**7.4 Spinal anesthesia**

238 A Bird's-Eye View of Veterinary Medicine

Effects of local anesthetics on calcium and potassium ion channels and local anesthetic induced inhibition of cyclic adenosine monophosphate (cAMP) production may also

Bupivacaine is more cardiotoxic than lidocaine. It is always important to draw back on

General overdose depends on blood levels, therefore is influenced by total dose and speed

As a very rough guide, the toxic dose of lidocaine would be 8 mg/kg and 4 mg/kg of

In very small animals such as small mammals (goat kids) and birds this amount can be easily exceeded using solutions of standard concentration, so it must be diluted carefully

Signs of overdose are initial sedation, followed with increasing dosage by twitching,

Reports implicate prilocaine, benzocaine, lidocaine and procaine as causative agents to

This refers to the use of local anesthetics in solution sprays as well as in various creams and ointments; drops into the eye; sprays or brush in laryngeal area, infuses into the nostrils,

Used in joints, bursa, and tendon sheaths. Useful for both diagnosis of lameness, and for general pain relief. The local anesthetic chosen must cause minimal irritation, and great care

By this method the nerve endings are affected at the actual site of operation. Most minor surgery can be done this way, excluding surgery on teats in cattle or small animals digits.

in sterility is necessary as infection in these sites occurs easily.

syringe to check to be not in vein before injecting local anesthetics.

contribute to cardiac toxicity.

of uptake from the tissues.

and used with caution.

convulsions, coma and death.


**7.1 Surface (topical) anesthesia** 

**7.2 Intrasynovial anesthesia** 

**7.3 Infiltration anesthesia** 


urethra, or rectum.


produce methemoglobinemia in some animals.

**7. Methods of producing local anesthesia**  Common methods of producing local anesthesia are:

bupivacaine.

Spinal anesthesia is the injection of local anesthetic around the spinal cord. When local anesthetics such as lidocaine or bupivacaine are used, all the segmental nerves (sensory and motor) which pass through the anesthetic are paralyzed, although when opioids are used only sensory block occurs.

Spinal anesthesia is divided into two types: epidural and true spinal.

Epidural (or extradural) anesthesia refers to depositing of local anesthetics into the extradural space. The needle enters the spinal canal, but does not penetrate the meninges. The anesthetic is therefore limited to the canal outside the dura mater.

True spinal anesthesia refers to the subarachnoid access in which the needle penetrates the dura mater, and the analgesic is injected into the cerebrospinal fluid.
