What exactly happens when a cat is humanely euthanised? What physiological processes take place? The infographic summarises the answers to these questions.
When a domestic cat is humanely euthanized, the process is typically carried out using an intravenous (IV) injection of a euthanasia solution, most commonly a barbiturate such as pentobarbital. This drug rapidly induces unconsciousness, followed by complete loss of brain and bodily function. Here’s what happens metabolically and anatomically:
1. Injection and Absorption
- The euthanasia solution is usually administered via an IV catheter, most often in the front leg.
- If intravenous access is not possible, it may be injected into a major organ (intracardiac or intrahepatic), though this is less common.
- The drug quickly enters the bloodstream and is distributed throughout the body.
2. Nervous System Effects: Rapid Unconsciousness
- Pentobarbital acts as a central nervous system (CNS) depressant.
- It enhances the effects of gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter, which causes neurons to become less active.
- This results in sedation, unconsciousness, and loss of awareness within seconds.
- The cat does not experience pain or distress beyond the initial needle prick.
3. Cardiovascular and Respiratory Depression
- As the nervous system shuts down, it affects the brainstem, which controls vital functions like breathing and heart rate.
- Respiratory depression occurs as neurons controlling breathing in the medulla oblongata stop firing. The cat stops breathing within seconds to minutes.
- The heart slows and then stops beating as cardiac muscle function ceases due to extreme CNS depression and lack of oxygen.
4. Metabolic Shutdown and Death
- As oxygen supply to the brain and body ceases, cells begin dying due to lack of ATP (energy – see below).
- The body enters a state of global hypoxia (oxygen deprivation).
- Once the brainstem is fully non-functional, death is irreversible.
Post-Mortem Changes
- Some cats may experience involuntary muscle twitching or gasps after death due to residual electrical activity in nerves and muscles.
- The bladder and bowels may empty as sphincters relax.
- Rigor mortis (muscle stiffening) sets in after a few hours as ATP depletion prevents muscle relaxation.
Final Outcome
- The cat passes peacefully, without pain, as consciousness is lost almost instantly, followed by the cessation of all vital functions.
- This method ensures a humane and stress-free passing.
What is ATP? ATP (adenosine triphosphate) is the primary energy carrier in cells. It stores and provides energy for cellular processes, including muscle contraction, nerve signaling, and metabolism.
Structure and Function
- ATP consists of adenine (a nitrogenous base), ribose (a sugar), and three phosphate groups.
- Energy is stored in the high-energy phosphate bonds.
- When ATP is broken down into ADP (adenosine diphosphate) and an inorganic phosphate (Pi), energy is released for cellular activities.
Role in Euthanasia and Death
- ATP is crucial for maintaining normal cellular functions, including heartbeats and respiration.
- When euthanasia causes oxygen deprivation, ATP production stops, leading to cellular failure and death.
- Lack of ATP also causes rigor mortis because muscles need ATP to relax after contraction.
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