


The sequence of events should go something like this: the brain – because it is surrounded by fluids, moves across the cranium and strikes the boney wall with tremendous force. This causes haemorrhaging and the development of a haematoma (like a blood blister). There is disruption of the blood supply to the damaged area and this, in turn, causes ischaemia (that is an acute decrease in the oxygen supply to the area)

Along with the haematoma, the area around becomes inflamed and starts to swell (as does your ankle when you twist it running). The damaged nerve cells start to dysfunction and the animal losses consciousness or starts to become sluggish with a decrease in cerebral activity.

If vital brain areas such as the heart regulatory centre become involved then the animal will die. If the animal is lucky enough not to be killed in the accident then the brain starts to undergo secondary changes due to changes within the skull or to the blood supply to the head area.

With the damaged brain cells comes to an increase in substances from the damaged cells that adversely affect other surrounding cells- these are called excitatory neurotransmitters and can cause the animal to fit or spasm.

But, the story does not stop with brain damage – as the brain cells stop their regulatory function then the rest of the body is also affected. One important area is the heart and blood supply – the brain damage causes a decrease in the ability of the heart to maintain normal blood pressure and the supply of the blood to the brain and this again causes a decrease in oxygen and nutrients to the brain. This, in turn, causes more damage to the already affected brain cells.

If the brain continues to swell from all the damage then eventually the brain can herniate out the back of the skull and then the animal will die

These events can take minutes (or days) to occur and that’s why it is paramount in importance that you get an injured animal to a veterinarian as soon as possible after a head injury accident

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