Neurological Problems of Cavalier King Charles Spaniels
The Cavalier King Charles Spaniel is one of my favourite breeds of dog to see in my surgery. They seem invariably to have a happy temperament, and a joyful outlook on life. This makes it even more heartbreaking that they are prone to so many serious diseases. The Cav has long been known to have a problem with heart disease, but more recently the spotlight has been shone on the breed's neurological problems. In the BBC's 2008 programme, Pedigree Dogs Exposed, the Cavalier was strongly featured due to their predisposition to a condition called syringomyelia. However, there are a number of other neurological conditions that are common in the breed, and this article describes the most important ones.
This complicated condition arises because of the shape of the Cavalier's skull. One of the bones at the back of the skull, the occipital bone, is shaped wrongly causing pressure on the back of the brain and the cerebellum (see link below for information on the parts of the brain). This is known as occipital hypoplasia, or caudal occipital malformation syndrome (COMS), and is similar to a condition in people known as Chiari malformation, a term that is often applied to dogs as well.
The result of this abnormality is a crowding of the back part of the brain, leading to the cerebellum protruding through the large hole at the back of the skull that allows the spinal cord to enter the brain (the foramen magnum). This alters the way the cerebro-spinal fluid (the fluid that bathes the brain and spinal cord) flows out of the brain, and although the exact mechanics of this are controversial, we know that this causes pockets of fluid to build up within the spinal cord. These pockets of fluid are called syrinxes, and mostly occur in the neck, although can occur further along the spinal cord.
People with syringomyelia report strange sensations such as neck pain, a burning sensation, or an intense itch, like insects crawling over the skin. It is likely dogs with the disease feel similarly, based on the signs they show - from mild neck pain through to frantic and persistent scratching.
The diagnosis of syringomyelia requires an MRI scan (see link below for more information on MRI in veterinary medicine). Treatment options include drugs such as gabapentin that act as pain killers for pain originating from the nerves, and certain surgical procedures.
Primary secretory otitis media
This condition, also called "glue ear", arises because of a failure of the eustachian tube (the tube that runs from the middle ear to the back of the throat to help equalise pressure changes) to open, allowing a thick viscous mucus plug to build up in the middle ear. This can lead to signs of head and neck pain, itching ears and neurological signs such as facial paralysis. This can be problematic to treat, although flushing the middle ear under general anaesthetic repeated times may be helpful.
In this condition, the ventricles of the brain which are normally filled with a small amount of cerebrospinal fluid become greatly enlarged. This will often happen very early in development, and can mean the brain will fail to develop properly. Affected dogs can be suprisingly normal, although some will show a number of signs of disease either from birth or as they get older, including seizures and ataxia (wobbliness).
Seizures can occur for a number of reasons, especially in this breed, but Cavaliers are also prone to an inherited epilepsy which is not related to any other identifiable diseases. Although all coat colours are affected, it is more common in lines originating from whole colours ancestors who were born in the 1960s.
Other neurological diseases
Cavaliers can also be prone to fly catching, thought to be a type of epilepsy, in which they snap at imaginary flies. Episodic falling is another neurological condition of Cavaliers which can involve them falling over when exercising. They also appear to be at an increased risk of strokes that affect the cerebellum, and as with most other small breed dogs, are prone to intevertebral disc disease.
Breeding out diseases
As some neurological conditions are inherited, schemes to eradicate the diseases from the breeding pool are sensible, although are more easily desired than achieved. In the UK the Cavalier Club runs a heart health scheme for Cavaliers in conjunction with the British Veterinary Association, and a scheme to help breed out syringomyelia is currently under discussion. More information can be found at the Cavalier Club website. http://www.thecavalierclub.co.uk
Not all Cavaliers will develop neurological problems, but it is worth being aware of these conditions. Early treatment is helpful in some of these diseases, while in others not recognising the disease is present could lead to suffering of which the pet owner is not aware.
The internet is not a substitute for a vet. If your animal is ill, seek qualified veterinary advice.
Rusbridge (2005) Neurological diseases of the Cavalier King Charles Spaniel. Journal of Small Animal Practice, 46, 265
Stern-Sertholtz et al (2003) Primary secretory otitis media in the Cavalier King Charles spaniel: a review of 61 cases. Journal of Small Animal Practice, 44, 253
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