Swelling of the brainstem and brain can be dangerous for cats, necessitating immediate, emergency treatment.

Swelling of the brain or brain stem in a cat is not a stand-alone illness. Instead, these are symptoms of either illness or head trauma. Swelling of either the brain or brain stem leads to symptoms that can be alarming. If a cat has been hit in the head, has begun to develop brain tumors, or has contracted meningitis or encephalitis, brainstem and brain swelling can develop.

The symptoms of a swelling of the brain can include:

If the cat suffered a head injury, the cat’s owner and vet may notice several symptoms:

Cats can develop a swollen brain or brain stem for several reasons, which may include:

Illnesses unique to cats, such as FeLV, FIP or feline nonsuppurative meningoencephalomyelitis, also called staggering disease, can cause brain symptoms and paralysis. 

If the cat’s brain has begun to swell, this can develop because of a lack of oxygen, lowered blood flow to the brain, toxins, brain tumors, and metabolic disorders (diabetes, for instance).

If the cat suffered a head injury, causes may include:

Because swelling of the brainstem or brain is serious, and potentially deadly, it’s important to get a veterinary diagnosis as fast as possible. Once the vet knows the cat is suffering neurological symptoms, they will take a full health history and conduct a full examination of the cat. the vet will also run several neurological exams, looking at brain function. They will be looking for where damage has taken place.

The vet determines the cat’s level of consciousness, looks at its pupils and how they respond to light. If the cat is comatose, a deeper, more complete neurological exam will have to wait until it is more alert.

The vet also looks for illnesses as the cause of the edema (swelling) of the brain or brain stem. If the cat was injured, the vet looks for other injuries, such as to bones, its chest and abdomen.

The cat will be X-rayed and may also undergo a CT scan as the vet looks for spinal or skull fractures. 

In a neurological exam, the cat’s gait (walk), forelegs, neck, hind legs, torso and tail are closely examined. The vet tests the cat’s reflexes as well to determine where the injury or illness within the brain have taken place.

Blood will be taken so the cat can be tested for metabolic disorders such as diabetes. Lead poisoning and some infections that affect the brain are also considered. A biochemical profile and urinalysis will also be conducted.

The vet may need to order an electroencephalogram, which records the electrical activity in the brain. This test can help the vet narrow down the cause of the injury or illness. Finally, the cat will undergo an MRI of the brain, which helps identify brain abnormalities or tumors.

The treatment of cerebral edema (swelling of the brain or brain stem) should be started just as soon as underlying causes have been narrowed down. The cat may need supplemental oxygen and regular monitoring of its neurological status. Medications for edema include mannitol, which is a diuretic. This helps to bring brain swelling down. It also helps to lower the pressure within the cat’s skull. This should only be given to cats with a poor neurological assessment. If mannitol doesn’t help, hypertonic saline can be given through a slow IV. Steroids can decrease the level of inflammation of the tissues of the brain. Even though they can be helpful, their use for brain edema is controversial.

Barbiturates work to slow the brain’s metabolic rate, making them useful for animals suffering from head injuries that cause seizures.

If the cat has a head injury, surgery to reduce compression of brain tissue may be helpful. The vet wants to prevent hypoxia, or lowered oxygenation of the cat’s brain and body. The cat may also receive fluid therapy, which helps to maintain the normal fluids that surround the brain and brainstem.

If the cat received immediate veterinary treatment, its prognosis can be good, depending on what the vet has found. During recovery, the cat should be kept indoors so it doesn’t suffer more injuries from other animals. 

Depending on the severity of the swelling of the brain or brain stem, the cat may need to stay in the animal hospital until it has recovered. It may not be aware that water and food are close by, so a feeding tube may be necessary. Because the cat can’t bathe or groom itself, frequent bathing will also be necessary.

The cat’s owner should closely monitor the cat, making note of its mental attitude, alertness and behaviors. Anything out of the ordinary should be reported to the vet.

Some illnesses that affect the brain, such as FIP, are usually fatal. The cat with FIP needs at-home nursing care and should be made as comfortable as possible.