A subdural hematoma (SDH) is a type of bleeding in which a collection of blood—usually but not always associated with a traumatic brain injury—gathers between the inner layer of the dura mater and the arachnoid mater of the meninges surrounding the brain. It usually results from tears in bridging veins that cross the subdural space. Subdural hematomas may cause an increase in the pressure inside the skull, which in turn can cause compression of and damage to delicate brain tissue. Acute subdural hematomas are often life-threatening. Chronic subdural hematomas have a better prognosis if properly managed. In contrast, epidural hematomas are usually caused by tears in arteries, resulting in a build-up of blood between the dura mater and the skull. The third type of brain hemorrhage, known as a subarachnoid hemorrhage, causes bleeding into the subarachnoid space between the arachnoid mater and the pia mater. Signs and symptoms
The symptoms of a subdural hematoma have a slower onset than those of epidural hematomas because the lower-pressure veins involved bleed more slowly than arteries. Signs and symptoms of acute hematomas may appear in minutes, if not immediately, but can also be delayed as much as two weeks. Symptoms of chronic subdural hematomas are usually delayed more than three weeks after Injury.If the bleeds are large enough to put pressure on the brain, signs of increased intracranial pressure or brain damage will be present.
Enzootic pneumonia of sheep (and goats, with frequent intervention of M. haemolytica)
Fowl cholera (chicken and other domestic poultry and cage birds)
Enzootic pneumonia and atrophic rhinitis of pigs
Pasteurellosis of chinchillas
Pasteurellosis of rabbits
Pasteurellosis is suspected to be the cause of recurrent mass mortality of Saiga antelopes. See also
Hemorrhagic septicemia
Pasteurellaceae

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