Brain Injury in Cats
My cat was hit by a car. He seemed to be OK at first, even though he was dazed. He spent the night at the emergency practice, and I was called in the middle of the night to come to see him because he had taken a turn for the worse. In spite of excellent care, he died. The veterinarian said his cause of death was a brain injury. I would like better to understand what happened.
Brain injuries are devastating and, unfortunately, often fatal. There are both primary brain injuries that are the result of a direct insult to the brain, and secondary brain injuries that occur following the primary brain injury. These may include bleeding from a brain blood vessel or swelling of brain tissue.
"The overall function of the nervous system may be
altered/compromised in some way"
The typical signs of brain injury in a cat include altered consciousness that may signal bleeding in the skull, decreased blood flow to the brain, or fluid causing swelling within the brain itself. The cat may have seizures, some evidence of trauma to the head or other part of the body, bleeding into the eyes, or bleeding from the nose or ears. A cat with brain trauma may have difficulty regulating his body temperature, causing either too low a body temperature or fever. The heart may beat very slowly. The pupils of the eyes may be uneven in size and may react abnormally to light. The overall function of the nervous system may be altered/compromised in some way, and those abnormalities may change over time. That helps to explain how a cat who seems just dazed at first can have symptoms that progress in severity.
Besides a forceful trauma like being hit by a car, are there other causes of brain injury in cats?
There are many other potential causes of brain injury, and they include the following:
- Prolonged low levels of oxygen in the blood
- Decreased or lack of blood flow to the brain
- Severely low levels of sugar in the blood
- A prolonged seizure or multiple seizures over an extended time period
- Severe or extended fever
- Profound decrease in body temperature
- Altered concentrations in the blood of essential minerals, like sodium
- Profound or prolonged low blood pressure or high blood pressure
- Some infectious or immune-mediated diseases
- Cardiac arrest
- Blood clots that travel to the brain
- Respiratory arrest
- Bleeding into the brain from a blood clotting disorder
- Brain tumor
What are the risk factors for brain injury in a cat?
Risk factors for brain injury in a cat include unsupervised roaming outside that may result in trauma or exposure to toxins. As well, heart disease, lung disease, a blood-clotting disease or diabetes mellitus can be risk factors for brain injury.
If a cat survives the initial injury, how are brain injuries treated?
Treatment of a brain injury in a cat will always be determined and fine-tuned by the underlying problem that led to the brain injury. The initial goal of treatment is to maximize oxygen levels in the brain tissue. If the blood pressure is too low, then supporting blood pressure improves brain blood flow. If the blood pressure is too high, or if there is high pressure inside the skull for some other reason, then decreasing pressure in the skull is the priority.
"The head should never be lower
than the body in order to prevent
increased pressure inside the skull."
Any necessary intravenous fluid therapy must be administered carefully to avoid any fluid build-up in the brain, even if there is bleeding that requires fluid replacement. Your veterinarian will do her best to balance your cat’s blood pressure to prevent it from going either too low or too high. The head should never be lower than the body in order to prevent increased pressure inside the skull. Some cats with a brain injury do not blink their eyes normally, so lubricating the eyes may be a part of the treatment. It will also be important to prevent any urine or stool soiling if the cat is unable to position properly for elimination.
Are there any other treatments that are appropriate for a cat with a brain injury?
Any cat with a brain injury must receive adequate nutrition to support healing. This may require tube feeding at first if eating is difficult or impossible. Surgery may be necessary if there is a skull fracture, a foreign object penetrating the skull, or buildup of fluid or blood inside the skull.
"There may be a need for pain relievers, heavy
sedation, or even a temporary state of general anesthesia
to spare the brain from additional injury"
Medications may be needed to decrease pressure inside the skull by either helping the body eliminate extra fluid or by helping to “pull” extra fluid from the tissues of the brain. There may be a need for pain relievers, heavy sedation, or even a temporary state of general anaesthesia to spare the brain from additional injury. Adequate levels of oxygen must be provided, so a tube may be passed into the windpipe to assist breathing. If the cat’s blood sugar levels are too low, intravenous glucose may be needed. Alternately, if the cat’s blood sugar level is too high, intravenous insulin may be needed.
What about follow-up care for a cat with a brain injury?
Any cat with a brain injury should be tracked for the progress of his recovery. This may include measurements of blood pressure as well as laboratory tests to monitor blood levels of various substances like blood sugar and minerals.
Some potential long-term complications of brain injury in a cat include:
- Ongoing seizures
- Uncontrolled swelling of the brain
- Bleeding into the skull
- Progression of nervous system signs indicating permanent brain damage
- Malnourishment from difficulty eating enough
- Drying of the corneas from decreased blinking
What is the long-term outlook for a cat with a brain injury?
For a young cat with a minimal primary brain injury, and secondary injury limited to fluid buildup in the brain, the long-term outlook is favorable. If the cat experiences no additional nervous system deterioration over a 48 hour period, the prognosis also remains favorable. Finally, if blood pressure and blood sugar levels remain within normal limits, the prognosis is favorable.
In some cases, the cat’s nervous system signs may worsen before improvement begins. The extent of brain recovery may not be obvious for several days. The cat’s full level of recovery may not be apparent for up to 6 months or longer.
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