Can a rabbit be scared to death?
I have heard several times about rabbits being kept in outdoor cages where, a dog or other predator barked and/or scratched at the cage. The person came out and found the rabbit(s) dead in a still secure cage.
The assumption generally relaid in this scenario is that the when the predator came up, the rabbit was scared to death (implying a quick death).
Another possibility is that the predator had made multiple threats to the caged rabbit, and it died of long term stress (or other) health related issues.
I am looking for to prove or disprove that a rabbit can be suddenly "scared to death". Where death follows with seconds or at most a few minutes of from an initial encounter.
It can really be fatal to any animal, so far as I know. For example, heart attacks.
It sounds reasonable given that rabbits would normally flee in that situation. It is likely that the rabbits brain gives instructions to make lots of adrenaline for equipping the body for the flight, but escape is actually not possible due to the cage. The high adrenaline dose without adequate physical activity can give raise to a heart attack .
If it helps during a thunderstorm my rabbit died. He jumped in fear and threw himself at the cage and broke his back. He died hours later.
This condition is called Exertional or Capture Myopathy.
Specifically, according to the Manual of Common Diseases and Parasites of Wildlife in Northern British Columbia
Exertional or capture myopathy (disease of the muscle) is a non-infectious disease of muscles that is characterized by damage to muscle tissues brought about by physiological changes, usually following extreme exertion, struggle and/or stress.
It may be seen peracutely (immediately), acutely (within minutes) or chronically (in hours, days or weeks).
The House Rabbit Society of Georgia describes the mechanics of the disease in rabbits over long term:
The perception of a dangerous or frightening situation causes the release of chemicals called neurotransmitters from the pituitary gland at the base of the brain. These neurotransmitters affect many tissues in the rabbit’s body, but most notably the adrenal glands that release epinephrin (adrenaline) and, with protracted periods of stress, glucocorticosteroids.
Epinephrine causes the rabbit’s heart rate and blood pressure to increase. Blood flow is directed to vital muscles and organs and away from those that are nonessential in this dangerous situation. The rabbit’s respiratory rate increases, his eyes dilate, and his blood sugar (the fuel for the bodies tissues) soars. Other neurotransmitter and hormonal effects of fear not as easily understood are that they cause an ileus of the gastrointestinal (GI) tract-that is, they cause the GI tract to stop moving.
....when these physiological conditions exist for a long period, they affect the rabbit negatively. Restriction of blood supply to “nonessential tissues” leads to their dysfunction. Ileus results in changes in GI tract bacterial balance and potentially can lead to gut stasis, diarrhea, enteritis or even enterotoxemia. Exhaustion of liver energy stores leads to a starvation of body tissues that may be lethal.
For the short term, death seems to be caused by what we intutitively expect - adreneline's effect on the heart. A study conducted on rabbits and rats reports (in the abstract):
Arterial hypertension, hypotension, and heart failure are the reactions typical of the stress-sensitive animals. The main cause of sudden death under emotional stress is the abrupt decrease in peripheral vascular resistance. Adrenal hormones are crucial to the mechanisms of sudden death under emotional stress.