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Feline Hydrocephalus and “Hydro Cats” — 7 Facts

We’ve profiled several kitties with this rare disease. Learn how it affects cats and what treatments are available.

JaneA Kelley  |  Nov 4th 2015


Here at Catster, we love a good Monday Miracle kitty, and we’ve been fortunate enough to meet a bunch of them. A few of the felines we’ve profiled have a condition called hydrocephalus, also known as “water on the brain.” These cats are a real inspiration, and I’d encourage you to read the stories of Olaf, Super Hero, Zeke, and Bug A Boo to see what it’s like to live with a “hydro kitty.”

Bug-A-Boo, a longhaired brown tabby cat with hydrocephalus

Bug A Boo is one of the hydro kitties we’ve profiled. Her downward-facing eyes, due to the pressure caused by CSF buildup, are one of the outward signs of the disease. Photo from Bug A Boo’s Facebook page

You know me well enough by now to know that I love to get my geek on, so I’ve done some research and dug up some facts about the medical side of hydrocephalus. Check it out.

1. Why is there even “water” around the brain, anyway?

The brain and spinal cord are protected by cerebrospinal fluid (CSF), which acts as a kind of lubricant and shock absorber. CSF is actually produced in the brain and circulates through the brain and around the spinal cord, and is eventually absorbed into the blood. With hydrocephalus, the brain may produce too much CSF or the outflow of CSF may be blocked, which causes CSF to accumulate in and around the brain, resulting in excessive pressure.

2. What causes hydrocephalus?

The most common cause of hydrocephalus in young cats is a congenital defect that blocks the outflow of CSF. However, the condition can be caused by certain viruses (feline infectious peritonitis and the panleukopenia virus), parasite migration, bacterial and fungal infections, cysts, and tumors. Three cat breeds are known to be more at risk for developing hydrocephalus: the Siamese, the Persian, and the Manx.

Olaf, a Manx cat with hydrocephalus

Olaf is a Manx cat with hydrocephalus. Photo from the Olaf’s World Facebook page

3. What are the symptoms of hydrocephalus?

Symptoms vary depending on the severity of the condition. Cats with moderate to severe hydrocephalus may have oddly dome-shaped skulls or eyes that point outward and downward due to the pressure that the CSF is exerting inside the brain. Other symptoms can include hyper-excitability, spastic or irregular gait, visual or hearing impairment, circling, head pressing, and even seizures.

4. Does hydrocephalus cause pain?

I know humans with hydrocephalus who have said that when the fluid pressure in the brain builds up, it can cause headaches as well as other neurological symptoms. Because cats are mammals and have similar nervous systems, I think it’s safe to assume that untreated moderate to severe hydrocephalus causes pain.

5. How is hydrocephalus diagnosed?

Some diagnostic tests can be done right in your vet’s office, while others may require more advanced diagnostic equipment. The first thing a vet will do is order blood tests, because liver and kidney problems can cause seizures and other hydrocephalus-like symptoms. X-rays will be taken to see if there is evidence that the extra fluid has caused damage to the cat’s brain. CT scan, ultrasound (especially if the cat was diagnosed as a baby and his skull bones are still growing together), and an electroencephalogram (EEG) to monitor electrical activity in the brain are other tests that may be ordered.

Zeke the cat, wearing a superhero cape

Zeke and his brother Super Hero are hydro kitties with a cause. Photo from Super Hero and Zeke’s Facebook page

6. How is hydrocephalus treated?

Treatment depends on the severity of the CSF buildup and the symptoms it causes. Whatever treatment is used, the goal is to minimize the brain damage by decreasing the amount of extra fluid inside the skull. This is done by medications to increase the absorption or decrease production of CSF. Anti-seizure medication may be given if needed. If the hydrocephalus is caused by a tumor or malformation, surgery may be done to remove it, or a shunt may be placed that moves the extra CSF out of the skull and into the abdominal cavity, where it will be absorbed by the body.

7. What’s the prognosis for a cat with hydrocephalus?

Left untreated, hydrocephalus has a very poor prognosis. However, many cats can live good lives with appropriate treatment and home care. Kittens born with hydrocephalus can respond very quickly to appropriate treatment and live quite normal lives. “Hydro kitties” will need to be handled carefully to avoid head trauma. Regular vet care is especially important for these cats, because they need to be monitored for medications and possible progressive brain damage. Cats who received shunt surgery may require occasional revision procedures because the shunt can get blocked.

Super Hero, a hydro kitty, has started the Super Hero's Animal Hydrocephalus Society, an animal rescue society and sanctuary that specializes in hydrocephalus kitties.  Photo from Super Hero and Zeke's Facebook page

Super Hero, a hydro kitty, has started Super Hero’s Animal Hydrocephalus Society, an animal rescue society and sanctuary that specializes in hydrocephalus kitties. Photo from Super Hero and Zeke’s Facebook page

Do you have any questions about hydrocephalus? Do you have a cat with hydrocephalus? Is there any other kitty health or genetic condition you’d like to know more about? Please share your thoughts in the comments.

Read more by JaneA Kelley:

About JaneA Kelley: Punk-rock cat mom, science nerd, animal rescue volunteer and all-around geek with a passion for bad puns, intelligent conversation, and role-play adventure games. She gratefully and gracefully accepts her status as chief cat slave for her family of feline authors, who have been writing their award-winning cat advice blog, Paws and Effect, since 2003.