WHAT IS HYDROCEPHALUS?

Hydrocephalus is the accumulation of fluid within the deep cavities of the brain, or ventricles. The excess fluid increases the size of the ventricles and puts pressure on the brain.

Cerebrospinal fluid usually flows through the ventricles and covers the brain and spinal cord. However, pressure from excess cerebrospinal fluid can damage brain tissues and cause a range of symptoms related to brain function.

SYMPTOMS OF HYDROCEPHALUS

Clinical signs of hydrocephalus in dogs can vary depending on the part of the brain that is being compressed, the extent of brain damage, the age of the dog when the condition arose, and the cause of the fluid accumulation. Some dogs can live a normal life with the condition, while others suffer debilitating neurological symptoms.

Signs of hydrocephalus in dogs may include:

• Large dome-shaped skull and persistent fontanelle (soft spot on the head).
• Wide open eyes and abnormal eye position (fixed downward and outward).
• Learning and training difficulty
• Difficulty in drinking
• Difficulty in drinking and eating
• Personality and behaviour
• Personality and behavioural changes
• Head pressure
• Inappropriate vocalisation
• Blindness
• Seizures
  
  

CAUSES OF HYDROCEPHALUS

Cerebrospinal fluid (CSF) surrounds the brain and spinal cord, protecting the delicate tissue and providing nutrients. It is produced in the ventricles of the brain and is reabsorbed by the body as it completes its necessary tasks. However, excess CSF can accumulate in the brain if:

• The flow or absorption of CSF is obstructed.
• Too much CSF accumulates in the brain.
• Too much CSF is produced
  
  

In dogs, obstruction is much more common, and there are two basic types: congenital and acquired. Although the results are the same, the causes are different.

CONGENITAL HYDROCEPHALIA: Dogs with congenital hydrocephalus are born with a defect in the structures that normally facilitate the flow or absorption of CSF. When dogs are born with hydrocephalus, the skull remains soft enough to expand as the brain swells with fluid, resulting in a large dome-shaped head and often an obvious open fontanelle.

Certain dogs are predisposed to congenital hydrocephalus, especially toy and brachycephalic breeds such as:

• Chihuahua
• Yorkshire terrier
• Boston terrier
• Pomeranian
• English puppy
• English Bulldog
• Pomeranian
• Lhasa Apso
• Pomeranian
• Pug
• Pekingese
• Maltese
• Pekingese
• Maltese
  
  

ACQUIRED HYDROCEPHALIA: Acquired hydrocephalus can occur in any breed and at any age. Dogs with acquired hydrocephalus are born with normal brains, but develop an obstruction that interferes with the flow or absorption of CSF. The most common development is a brain tumour, but there are other possibilities.

Causes of acquired hydrocephalus include:

• Brain tumour
• Traumatic brain injury
• Brain haemorrhage
• Traumatic brain injury
• Bacterial or viral brain infection
• Inflammatory brain disease
• Vitamin A deficiency
• Exposure to certain medications
• Brain problems.
• Exposure to certain drugs, chemicals or toxins.
  
  

HOW IS HYDROCEPHALUS DIAGNOSED?

Because hydrocephalus can lead to the death of brain tissue, early diagnosis is important.

Congenital hydrocephalus can cause death of brain tissue.

Congenital hydrocephalus can often be recognised only by the distinctive head shape and symptoms. However, a veterinarian will usually order tests to confirm it. In addition, many breeds of dogs predisposed to hydrocephalus are predisposed to other conditions, so it is also important to rule these out.

Hydrocephalus is a disorder that affects all dogs.

Testing should include physical and neurological examinations, blood and chemical profiles, haemogram, electrolyte panel and urinalysis. Once other conditions have been ruled out, MRI and CSF analysis can be used to obtain a definitive diagnosis.

MRI is the most reliable and comprehensive method of diagnosing hydrocephalus in dogs. Not only can we see the enlarged ventricles, but we can also see what is causing it. In some cases, a lumbar puncture is performed after an MRI scan to check for infection.

HOW IS HYDROCEPHALUS TREATED?

Treatment of hydrocephalus depends on the severity, type and cause. However, in most cases, hydrocephalus in dogs is managed and not cured. For mild to moderate hydrocephalus, treatment will usually begin with medication:

• Corticosteroids reduce swelling and pressure.
• Proton pump inhibitors
• Proton pump inhibitors decrease CSF production.
• Diuretics can increase CSF output and decrease CSF production.
• Anticonvulsant drugs reduce the frequency, duration and severity of seizures.
• Unfortunately, medical treatment often provides only a temporary solution. More definitive treatment requires surgery with a highly specialised neurosurgeon.
  
  

For severe or unresponsive hydrocephalus, ventriculoperitoneal (VP) shunting is recommended. A specialised tube is surgically placed under the skin to redirect fluid from the brain to the belly. Shunt placement is a complex procedure that carries considerable risk, but it is a long-term solution with a high success rate in the right hands, such as those of the experts at Southeast Veterinary Neurology. Patients still require close follow-up and may need subsequent surgeries to replace shunts that have become undersized, moved or otherwise failed.

CONCLUSION

Hydrocephalus is a serious and often life-threatening condition. For dogs with mild symptoms and dogs that respond well to treatment, outcomes can be positive. For dogs with severe symptoms, dogs that do not respond to treatment and dogs with underlying untreatable causes, the prognosis is less optimistic.