Welcome to this short video demonstrating epidural anaesthesia in the dog
Epidural anaesthesia provides optimal pain relief for surgery of the hind legs such as
cruciate ligament surgery or fracture repair.
In dogs an epidural injection is usually performed at the lumbosacral junction.
You may recall the anatomy of the spinal cord in this area - the spinal cord itself usually
ends at approximately L5 and the spinal nerves to the hindlimbs and tail emerge as the cauda equina
These spinal nerves are blocked with an epidural anaesthetic to prevent transmission of pain
sensation from receptors in the hindlimbs and tail to the brain.
An epidural produces optimal pain relief during the perioperative period and can last for
up to 24 hours depending on the drugs that are being used.
The reference at the end of this video discusses the different drugs and doses further.
When performing an epidural, the iliac crest serves as a useful landmark for the lumbosacral junction.
To perform an epidural, aseptic technique is required, with clipping and surgical preparation
of the injection site, isolation of the prepared area with a sterile drape, use of sterile
surgical gloves and use of drugs in single-use ampoules.
A spinal needle with a short tip and a stylet is used, rather than a conventional needle.
With the 5kg dog in this video, I am using a 22 gauge needle, larger dogs may require
a 20 gauge needle.
I usually perform an epidural by palpating for the cranial tip of the iliac crest, moving
to the midline and palpating for the depression that separates the 7th lumbar vertebra and
the sacrum to locate the lumbosacral junction as shown here.
Placing the dog in ventral recumbency, with the hind limbs extended forward, helps open
up the lumbosacral space.
The spinal needle is inserted through the skin and the stylet removed.
A small amount of the anaesthetic solution is dripped into the end of the needle to form
a meniscus.
When the needle penetrates the epidural region, the negative pressure draws this fluid down
the needle as can be seen here in slow motion.
This is a reliable indicator that the needle is located in the correct position.
Once the needle is located correctly, the syringe with the anaesthetic is attached and
its contents slowly injected over 30-60 seconds before the needle is removed.
There should be no resistance felt as the anaesthetic is injected.
If blood or csf is apparent, the injection should be abandoned.
Side effects of an epidural include blockade of the autonomic nerves.
The sympathetic nerves, located in the thoraco-lumbar region may be affected by the anaesthetic
resulting in vasodilation and a consequent reduction in heart rate - this is a common finding.
Intravenous fluids and monitoring of blood pressure are recommended for all epidurals.
Blockade of the parasympathetic nerves in the sacral region may result in urinary retention
and the patient should be monitored for urination post-operatively.
After surgery, the dog will be unsteady and weak on its hind feet until the effect of
the anaesthetic has worn off.
Care should be taken to ensure the dog does not stumble as it comes out of the cage post-surgery.
Before performing an epidural, please read this reference which goes into more detail
regarding drugs, doses and side-effects.
It is always safest to perform this technique for the first time under the supervision of
an experienced vet.