Hydrocephalus in dogs is a disease that affects the brain. It is more common in small and brachycephalic breeds but can occur in any dog. The severity of the problem will vary from dog to dog but it is a life-threatening condition that needs aggressive veterinary attention.
What Is Hydrocephalus?
Hydrocephalus occurs when cerebrospinal fluid (CSF) builds up in and around a dog's brain. It is often referred to as "water on the brain" since that is what the word hydrocephalus means. Normally, CSF flows around the brain and into the spinal cord and gets absorbed by the body. But in dogs with hydrocephalus, either too much of this fluid is being produced or it is not able to be properly absorbed into the body. Because there is too much fluid and not enough space to store it, it leaks into the skull which puts pressure on the brain.
This pressure results in the various symptoms pet owners may see in dogs with hydrocephalus. In dogs, hydrocephalus is classified as either congenital (primary) or acquired (secondary) and requires urgent veterinary attention.
Symptoms of Hydrocephalus in Dogs
- Swollen head
- Behavioral changes
- Slow to learn
- Eye issues
Since dogs with hydrocephalus are experiencing excess CSF in their head, it is not abnormal for them to have head swelling. The forehead or the entire skull may appear larger than usual due to the fluid pushing on it, especially if the dog is a young puppy.
A bubble or dome shape is often used to describe the head of a dog with hydrocephalus. Young puppies with hydrocephalus may have softer skulls that can expand to accommodate the fluid but, once the skull hardens, the brain is put under pressure. This pressure then causes the other symptoms of the disease.
Due to the increased pressure on the brain, seizures may occasionally be seen in dogs with hydrocephalus but they are not as common as once thought . Lethargy, as well as abnormal behaviors like head pressing and irregular walking patterns, are instead more often seen.
Puppies with hydrocephalus may also be especially slow at learning things. Finally, blindness, abnormal eye positioning, and other ocular issues are sometimes present in dogs with hydrocephalus.
Causes of Hydrocephalus in Dogs
Hydrocephalus is caused by an obstruction or decreased absorption of normal CSF flow. In dogs with congenital hydrocephalus, the problem is something the puppy is born with. What exactly causes this abnormality in puppies while they are developing is not always known. In dogs with acquired hydrocephalus, the obstruction or decreased absorption is the result of another brain disease like a brain tumor.
Diagnosing Hydrocephalus in Dogs
If you suspect your dog has hydrocephalus, a full physical examination by a veterinarian should be performed. Physical and neurological symptoms may lead your vet to recommend diagnostic testing.
If your dog has an abnormal opening in its skull called a fontanelle, an ultrasound may be performed, otherwise, a CT or MRI is typically recommended. Other tests including an EEG and an analysis of the CSF may also be obtained.
Treatment of hydrocephalus will vary depending on how severe the disease is. Neurological symptoms, like seizures, will need to be managed but the amount of CSF also needs to be addressed. A drug called omeprazole is commonly used to decrease CSF but steroids may also be used. Surgery to place a shunt to help drain the extra CSF from the brain may also be necessary if medications alone do not provide long-term relief. This surgery is not commonly done since it is costly and not many veterinarians perform it.
If treatment options do not help a dog with hydrocephalus or if surgery is not an option, euthanasia is often elected once the disease can no longer be managed.
How to Prevent Hydrocephalus in Dogs
Hydrocephalus is not a contagious disease so it is difficult to prevent it. The best thing you can do to prevent a dog from developing this disease or being born with it is to practice selective breeding and purchase puppies from reputable breeders. Dogs with hydrocephalus or those that have a familial history of hydrocephalus should never be used for breeding purposes.
While any breed of dog is capable of developing hydrocephalus, certain breeds are more prone to this disease. Toy breeds and brachycephalic breeds are especially at risk and they include:
- Cavalier King Charles Spaniels
- Boston Terriers
- Yorkshire Terriers
- English Bulldogs
- Toy Poodle
- Lhasa Apsos
Farke D, Kolecka M, Czerwik A, Wrzosek M, Schaub S, Kramer M, Failing K, Schmidt MJ. Prevalence of seizures in dogs and cats with idiopathic internal hydrocephalus and seizure prevalence after implantation of a ventriculo-peritoneal shunt. J Vet Intern Med. 2020 Sep;34(5):1986-1992. doi: 10.1111/jvim.15890. Epub 2020 Sep 12. PMID: 32918850; PMCID: PMC7517859.