What Is Hydrocephalus in Dogs?

Hydrocephalus in dogs is a medical condition in which abundant cerebrospinal fluid (CSF) accumulates in the ventricular system of the brain. This accumulation causes the cerebral hemispheres to increase in size. In puppies, the skull has not yet been fully formed and the bone of the cranium is relatively soft and malleable. For this reason, the increased amount of cerebrospinal fluid causes the brain to enlarge can deform the skull.

As the puppy develops, the cranium will harden. If left untreated, the dog's skull will remain large after they have matured into an adult dog. For this reason, dogs with hydrocephalus often have a characteristic head shape with some degree of the following features:

• Bulging skull
• Rounded shape
• Bilateral strabismus (misalignment of eyes)

Adult dogs can develop hydrocephalus also, something which is typically not related to genetic factors. As they are already developed physically and their cranium is not malleable like a puppy, they will have a different symptomology.

You can see a photo of a dog with hydrocephalus below displaying the typical head shape.

Types of hydrocephalus in dogs

The reason why puppies and adult dogs with hydrocephalus may have different symptoms is because there are different types of hydrocephalus in dogs. These include the following:

• Congenital hydrocephalus: congenital disorders are those that occur when the puppy is in the intrauterine state, meaning they are still developing in their mother's uterus. Since it happens at such an early stage of development, it is common for this developmental disorder to cause physical and behavioral abnormalities at birth or shortly after.
• Acquired hydrocephalus: this occurs in older dogs and it is not typically linked to genetics. This has various causes such as trauma or infection. It is less common than congenital hydrocephalus.
• Communicating hydrocephalus: this is a type of hydrocephalus in dogs which is classified by its mechanism rather than its onset. It occurs when the CSF is not properly reabsorbed by the bloodstream after being in the ventricles of the brain. This is because the tissues are not functioning how they should, rather than a blockage occurring.
• Non-communicating hydrocephalus: in this case, the flow of CSF fluid is blocked in the ventricles. This leads to a buildup of CSF and the resulting brain inflammation.

While the first two types of canine hydrocephalus are defined by how they develop in the animal, both communicating and non-communicating hydrocephalus can be either congenital or acquired. With this in mind, we look at some of the underlying causes of hydrocephalus in dogs.

The cause of canine hydrocephalus depends on whether they are congenital or acquired. While a veterinarian may not always be able to determine it exactly, the following are the known causes of hydrocephalus in dogs:

Causes of acquired hydrocephalus in dogs

• Brain tumors: whether benign or malignant, the proliferation of neoplasms in the brain can result in the cerebrospinal fluid being blocked in the ventricles. The size and extent of the tumor will largely determine the extent of the hydrocephalus.
• Trauma: dogs can experience various types of trauma in their life such as being in a traffic collision or fighting with another dog. The damage to the brain tissues can cause CSF to build up in the ventricles.
• Infections: viral, bacterial or fungal infections which affect the brain can result in inflammation which damages the ventricles and causes CSF buildup. Examples include meningitis, canine distemper virus and cryptococcosis. This can be exacerbated by abscesses on the brain.
• Parasites: parasitical infections such as toxoplasmosis and heartworm may result in hydrocephalus, but they are relatively rare causes.
• Autoimmune diseases: autoimmune diseases can cause water on the brain due to swelling. Various inflammatory conditions can also cause this.
• Idiopathic: the hydrocephalus is of unknown origin.

Causes of congenital hydrocephalus in dogs

The cause of congenital hydrocephalus is genetic. Certain genes predispose dogs to birth puppies which will then develop the condition. While acquired hydrocephalus results in spontaneous development due any of the above causes, congenital hydrocephalus has an early onset. Symptoms may appear at birth, but if a puppy is going to develop this condition, it will usually occur either shortly after birth or within a few months.

Breeds predisposed to congenital hydrocephalus

Acquired hydrocephalus can occur in any dog, but not all dogs will carry the genes which result in water on the brain in dogs. The breeds which are known to carry this gene include:

• Yorkshire Terrier
• Chihuahua
• Pekingese
• Boston Terrier
• Maltese
• Bulldogs
• Cairn Terrier
• Toy Poodle
• Pug
• Pomeranian

Wile hydrocephalus can cause the eyes to bulge, there are many different causes of this symptom. Learn more with our article on the common eye problems in dogs which can be either acquired or genetic.

As we have stated above, puppies with congenital hydrocephalus have softer skulls. This will result in a different symptomology than adult dogs with acquired hydrocephalus since the skull of the latter is already hardened. With this in mind, we can look at the symptoms of hydrocephalus in dogs:

Symptoms of congenital hydrocephalus in dogs

• Malformed head: the presence of cerebrospinal fluid in the ventricles of the brain puts pressure on the developing skull and causes its shape to malform. The result is a head shape which is typically bulbous.
• Open fontanelles: one or more holes in the skull may be present because the cranium has not been able to fuse together properly.
• Bulging eyes: a bilateral strabismus is common in hydrocephalic dogs because their skull cannot contain the eyeballs properly. They point in different directions and bulge out of the head. This is similar to brachycephalic dog breeds.
• Seizures: these are common in dogs with hydrocephalus because their brain is affected by the inflammation. They can vary in frequency and duration.
• Vision problems: it is common for a dog's vision to be affected, even leading to blindness.
• Cognitive dysfunction: the damage to the brain interrupts signals to the rest of the body. This results in various expressions of cognitive dysfunction such as the dog walking in circles. They will have difficulty responding to commands and their development is usually slower and more limited.

Symptoms of acquired hydrocephalus in dogs

With cognitive hydrocephalus, the dog will have never been able to develop fully. Their symptoms will begin between birth and after a few months of life. For acquired hydrocephalus, the dog will change due to the development of this condition. Symptoms include:

• Vomiting: physical symptoms are not as striking when compared to congenital hydrocephalus. Their head shape will not change dramatically, but the damage to the brain can cause vomiting due to nausea.
• Ataxia: a lack of coordination occurs because their brain signaling is impaired.
• Vision problems: this will deteriorate over time and can result in blindness.
• Seizures: will also vary in duration and frequency.
• Pain: the pressure the inflammation puts on the brain can be very painful and traumatic for the dog.
• Lethargy and irritability: the dog's personality can change significantly due to their brain functioning at reduced capacity, as well as the pain they experience.
• Cognitive dysfunction: they will no longer be able to respond to commands in the same way and they may lose education they had previously.
• Loss of appetite: this is common due to nausea and other symptoms resulting from brain damage.

Both congenital and acquired hydrocephalus in dogs share symptoms, especially in terms of cognitive function and behavior. The physical symptoms are more prominent in dogs with congenital hydrocephalus.

Learn about the different types of ataxia in dogs which may or may not be linked to hydrocephalus.

The diagnosis of hydrocephalus in dogs will largely depend on the type of canine hydrocephalus they have developed:

Congenital hydrocephalus in dogs

If dog develops congenital hydrocephalus, it will occur before 6 months of age. To reach a definitive diagnosis, the animal's clinical history, advanced imaging tests and the predisposition of certain breeds must be taken into account. In addition, it is necessary to check that the dog does not have any other congenital malformation.

Acquired hydrocephalus in dogs

When acquired hydrocephalus is suspected, the primary cause must be determined. This means they need to be assessed and tested for trauma, infections, parasites, tumors and any other potential cause. This will require imagining tests such as x-rays, as well as blood tests, cognitive tests and anything else deemed appropriate by the veterinarian.

Prevention of hydrocephalus in dogs

Congenital hydrocephalus cannot be prevented. It is due to the puppy's genetic code and cannot be cured. We will have to be very careful with puppies from breeds predisposed to hydrocephalus. The veterinarian will need to make appropriate assessments, so it is important they have a checkup early. Prevention of acquired hydrocephalus is based on ensuring overall health, i.e. proper diet, vaccination, deworming, avoiding exposure to pathogens, etc.

Dogs which are known to carry the gene responsible for hydrocephalus should not be bred. This will help reduce the onset of this disease in future generations. Learn more about the benefits of neutering a dog in our related article.

Many guardians will want to know if hydrocephalus in dogs can be cured. Unfortunately, there is no known cure for hydrocephalus in dogs. Treatment of the condition is based on symptom management to improve their quality of life. This will also differ slightly depending on the type:

Treatment of congenital hydrocephalus in dogs

• Surgery: various surgeries may be carried out to help the cerebrospinal fluid drain from the ventricles. These include a ventriculoperitoneal (VP) shunt placement, endoscopic third ventriculostomy (ETV) and a ventriculocisternal shunting. They can help control the amount of water on the brain, but do pose risks for over-drainage of the CSF.
• Medications: various drugs can be used to both help drain the ventricles of CSF, as well as manage the symptoms. These include diuretics to reduce intracranial pressure, corticosteroids to reduce inflammation and anticonvulsants to limit seizures.

Treatment of acquired hydrocephalus in dogs

In addition to those explained above, the treatment of this type of hydrocephalus will be determined by the underlying cause. For example:

• Tumors: if the hydrocephalus is caused by a tumor, surgical excision will be required.
• Bacterial infections: will need to be treated by antibiotics.
• Parasites: antiparasitic drugs or physical removal of the parasites by surgical intervention may be required.
• Trauma: may also require surgical intervention to stop intracranial bleeding or repair damage.

Generally speaking, we will need to manage the dog's symptoms, both physical and behavioral. For neurological symptoms, care and treatment focuses on stopping seizures, drowsiness, blindness, incoordination and others using drugs and/or surgical techniques. On the other hand, we will need to be careful to manage their daily care. This will require:

• Avoiding trauma or further damage to the head
• Controlling rough play with other animals
• Being careful with the skull during bathing and maintaining hygiene
• Providing environmental enrichment to improve cognitive function
• Avoidning the use of collars
• Ensuring proper diet
• Keeping vaccination and deworming schedules up to date
• Regular checkups

By using the symptom management and other treatment options explained above, we can best ensure the dog has a good quality of life. It is very important we monitor them regularly for signs of pain or discomfort. Some dogs may have such extensive brain damage that it is more humane to euthanize them.

The survival rate of the dog with hydrocephalus will depend on the extent of the condition. Generally speaking, dogs with congenital hydrocephalus have a reduced life expectancy. Dogs with acquired hydrocephalus may have a a similar life expectancy to other dogs, but it will depend on the extent of the damage and the underlying cause. Their overall health and response to treatment will also be important factors in their survival rate.

Learn more about congenital and acquired conditions affecting the dog's brain with our article on symptoms of neurological disorders in dogs.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to What Is Hydrocephalus in Dogs?, we recommend you visit our Neurological diseases category.