Hydrocephalus
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
Hydrocephalus is abnormal accumulation of cerebrospinal fluid within the brain’s ventricular system. The increased fluid enlarges the ventricles and can compress surrounding brain tissue. In kittens it is usually congenital, although acquired obstruction of cerebrospinal fluid flow can occur later from inflammation, bleeding or a mass.
Congenitally affected kittens may have a domed skull, persistent open fontanelle, abnormal eye position, poor coordination, behavioural changes, difficulty learning or seizures. Some remain small or fail to thrive. Severity varies depending on how much functional brain tissue is compressed and whether pressure continues to increase.
A large head alone does not diagnose hydrocephalus, especially in brachycephalic breeds where skull shape is naturally rounded.
The condition must also be distinguished from other congenital neurological diseases that produce poor coordination or developmental delay. If signs begin later in life, investigation for an acquired cause is particularly important.
Hydrocephalus can be static or progressive. Mild congenital cases may remain functional with limited intervention, while severe pressure can cause worsening neurological disability. Prognosis is therefore highly individual and depends on the amount of remaining normal brain tissue and whether pressure can be controlled.
The presence of an open fontanelle is also not diagnostic on its own. Some young kittens can have a small fontanelle without clinically important hydrocephalus. Careful interpretation avoids both over-diagnosis and missed progressive pressure.
A markedly domed skull, persistent open fontanelle, abnormal eye position, seizures and delayed neurological development can accompany clinically important hydrocephalus. Littermate comparison can be helpful because affected kittens may stand out in movement, behaviour or growth. Early detection is important when neurological signs are progressive because increasing intracranial pressure can cause permanent damage. Some cats remain stable for years, while progressive hydrocephalus can be life limiting.
Screening & Early Detection
Neurological examination determines whether signs are consistent with forebrain dysfunction. In young kittens with an open fontanelle, ultrasound may demonstrate enlarged ventricles. MRI provides the most detailed assessment and is especially useful before surgery or when other brain malformations are possible.
Blood tests are used mainly to assess general health and exclude metabolic problems; they do not diagnose hydrocephalus. In an older cat with newly developed ventricular enlargement, imaging is used to search for inflammation, tumour or another obstruction.
There is no general screening programme for healthy cats. Seizures, sudden deterioration, marked lethargy or loss of consciousness require urgent veterinary care rather than waiting for routine developmental monitoring.
Neurological signs and imaging are needed. Ultrasound can sometimes examine the brain through an open fontanelle in a young kitten, while MRI or CT provides better definition of ventricular enlargement and other brain abnormalities. Neurological function and imaging determine whether ventricular enlargement is truly causing disease, which prevents skull shape alone from driving prognosis.
Treatment & Management
Medical treatment can reduce clinical signs in selected cats. Medication may be used to decrease cerebrospinal fluid production or control associated inflammation, and anticonvulsants are prescribed when seizures occur. These measures do not correct a severe anatomical obstruction permanently.
A ventriculoperitoneal shunt can be considered for suitable cases. The device diverts cerebrospinal fluid from the brain to the abdomen, relieving pressure. Shunt surgery requires specialist expertise and can have complications including blockage, infection or over-drainage, so careful case selection and long-term follow-up are essential.
Kittens with mild stable signs may be managed conservatively with a safe environment, assistance with feeding or mobility where needed and regular neurological reassessment. Cats with severe cognitive impairment or inability to perform basic functions may have a poor quality of life despite treatment.
The prognosis is variable. Treatment decisions should be based on neurological function and trend over time rather than skull shape alone. Any rapid change after a period of stability warrants repeat imaging or specialist review.
Any implanted shunt requires lifelong awareness of possible blockage or infection, and sudden neurological deterioration after surgery should be treated as urgent.
Treatment aims to reduce signs and, in selected cases, divert excess fluid.
Breeds or species affected
Abyssinian
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American Bobtail
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American Curl
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American Shorthair
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American Wirehair
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Arabian Mau
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Aegean
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Australian Mist
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Balinese
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Bengal
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Birman
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Bombay
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British Longhair
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British Shorthair
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Burmese
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Burmilla
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Chartreux
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Chausie
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Colorpoint Shorthair
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Cornish Rex
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Cymric
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Devon Rex
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Domestic Longhair
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Domestic Medium Hair
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Domestic Shorthair
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Donskoy
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Egyptian Mau
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European Shorthair
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Exotic Shorthair
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Havana Brown
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Highlander
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Himalayan
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Japanese Bobtail
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Khao Manee
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Korat
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Kurilian Bobtail
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LaPerm
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Lykoi
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Maine Coon
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Manx
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Minuet
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Minskin
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Munchkin
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Nebelung
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Norwegian Forest Cat
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Ocicat
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Oriental Longhair
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Oriental Shorthair
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Persian
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Peterbald
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Pixiebob
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RagaMuffin
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Ragdoll
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Russian Blue
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Savannah
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Scottish Fold
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Scottish Straight
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Selkirk Rex
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Siamese
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Siberian
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Singapura
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Snowshoe
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Somali
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Sphynx
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Thai
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Tonkinese
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Toybob
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Toyger
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Turkish Angora
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Turkish Van
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Bambino
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Cheetoh
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Dwelf
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Elf Cat
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Genetta
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Kinkalow
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Lambkin
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Serengeti
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Skookum
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Ukrainian Levkoy
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