Euthanasia Flashcards
At euthanasia what is the primary responsibility of the vet?
The welfare of the horse
When is euthanasia warranted in horses?
if the horse “sustains an injury or manifests an illness or disease that is so severe as to warrant immediate destruction” and “to relieve incurable and excessive pain and that no other options of treatment are available to that horse at that time.”
Typically used methods of equine euthanasia
Lethal injection
Captive bolt
Sedation and aortic cut (not very common)
Indications for free-bullet euthanasia
Owner preference
Poor venous access due to severe CV compromise or thrombophlebitis
Severe emergencies may limit time or positioning for catheter placement
Regulation surrounding free bullet euthanasia
EU regulation 1099/2009: regarding methods of stunning for slaughter of animals, it is permissible to use a firearm with free projectile to cause severe and irreversible damage to the brain in the case of slaughter
Firearm (amendment) act 1997: section 2. Slaughtering instruments permitted with a firearm certificate.
Procedure of free bullet euthanasia
Sedation minimises risk of poor placement
Brain is situated high in the head, middle of the forehead
- 2 imaginary lines: middle of the eye to contralateral ear base
- 2cm proximal to this imaginary cross over
Nead quiet location with no people in the vicinity
Complications of free bullet euthanasia
Agonal actions
Epistaxis
Lethal injection euthanasia
An intravenous overdose of barbiturates is the method of choice.
Reliably causes a quick loss of consciousness and death with the minimum amount of pain and distress for the animal.
What happens when you administer an overdose of barbiturates?
Barbiturates depress the central nervous system (CNS) in descending order beginning with the cerebral cortex and resulting in inducing a loss of consciousness, progressing to general anaesthesia.
With an overdose, apnoea due to depression of the respiratory centre is followed by cardiac arrest.
Most common drug used for lethal injection euthanasia
Somulose - Secobarbital sodium, cinshocaine hydrochloride
It’s only ever used IV; large volumes and the risk of losing IV access mean an intravenous catheter, IVC, should always be used.
Procedure for lethal injection euthanasia
Sedation with an alpha-2 agonist followed by euthanasia with barbiturate solutions.
Direct intravenous administration without prior premedication or induction of general anaesthesia does lead to loss of consciousness before induction of cardiopulmonary arrest, however it can cause induction of excitation and the horse to fall backwards abruptly.
However, the combination of pentobarbital with a neuromuscular blocking agent (NMBA) is not acceptable because of the potential for the NMBA to induce paralysis prior to the onset of unconsciousness
Alternatively, can induce anaesthesia then euthanise
Some vets do not sedate prior to euthanasia, e.g. if there are concerns for cardiovascular compromise.
Captive bolt euthanasia
The primary objective of captive-bolt stunning is to induce immediate insensibility by administering a severe blow to the skull of the animal.
The animal must then remain unconscious until it dies as a result of bleeding or pithing.
The horse must then be pithed to ensure brainstem death. Insert flexible wire or polypropylene rod through the hole in the head towards the tail through the brain to the level of the brainstem. If it is long enough, pass into the spinal cord.
Initially the animal will show violent muscle contraction, but then reflex muscle movement is inhibited.
Physical signs of an effective stun
Animal collapses
No rhythmic breathing
Fixed, glazed expression in the eyes
No corneal reflex
Relaxed jaw
Tongue hanging out
Can you repeat captive bolt stuns?
When a captive-bolt enters the skull, swelling ensues which will absorb impact, hence repeat stuns will be less effective.
Repeat shots shouldn’t be in the same location as the first for this reason, but as close to guideline positioning as possible, generally proximal and lateral or medial to the prior.
Once stunned, the animal should be bled or pithed without delay.
Complications to consider during euthanasia
upset owners, unsuccessful first attempts, catheter failures, agonal breaths; “He’s still alive!”
How to confirm death after euthanasia
Lack of a heartbeat (auscultation of the heart)
Lack of respiration (movement of thorax and airflow in nostrils)
Lack of corneal reflex (touching the surface of the eyeball for corneal reflex)
