Health Issues

Cavaliers can notably be prone to mitral valve disease, which leads to heart failure. This appears in many Cavaliers at some point in their lives and is the most common cause of death. Some serious genetic health problems, including early-onset mitral valve disease (MVD), the potentially severely painful syringomyelia (SM), hip dysplasia, luxating patellas, and certain vision and hearing disorders are health problems for this breed. As today's Cavaliers all descend from only six dogs, any inheritable disease present in at least one of the original founding dogs can be passed on to a significant proportion of future generations. This is known as the founder effect and is the likely cause of the prevalence of MVD in the breed. Additionally, bad breeding increases the chance that a Cavalier will develop MVD, so it is important to find a responsible breeder who uses dogs with healthy hearts rather than use the first breeder you come across. The health problems shared with this breed include mitral valve disease, luxating patella, and hereditary eye issues such as cataracts and retinal dysplasia. Cavaliers are also affected by ear problems, a common health problem among spaniels of various types, and they can have such other general conditions as hip dysplasia, which are common across many types of dog breeds.

In 2022, the Oslo District Court made a ruling that banned the breeding of Cavalier King Charles spaniels in Norway due to their propensity for developing health problems. In its verdict the court judged that no dog of this breed could be considered healthy, therefore using them for breeding would be a violation of Norway’s Animal Welfare Act.

Mitral Valve Disease

Nearly all Cavaliers eventually have mitral valve disease, with heart murmurs that may progressively worsen, leading to heart failure. This condition is polygenic (affected by multiple genes), and therefore all lines of Cavaliers worldwide are susceptible. It is the leading cause of death in the breed. A survey by The Kennel Club of the United Kingdom showed that 42.8% of Cavalier deaths are cardiac related. The next most common causes are cancer (12.3%) and old age (12.2%). The condition can begin to emerge at an early age and statistically may be expected to be present in more than half of all Cavalier King Charles Spaniels by age 5. It is rare for a 10-year-old Cavalier not to have a heart murmur. While heart disease is common in dogs generally – one in 10 of all dogs will eventually have heart problems – mitral valve disease is generally (as in humans) a disease of old age. The "hinge" on the heart's mitral valve loosens and can gradually deteriorate, along with the valve's flaps, causing a heart murmur (as blood seeps through the valve between heartbeats) then congestive heart failure. The Cavalier is particularly susceptible to early-onset heart disease, which may be evident in dogs as young as one or two years of age.

Syringomyelia

Syringomyelia (SM) is a condition affecting the brain and spine, causing symptoms ranging from mild discomfort to severe pain and partial paralysis. It is caused by a malformation, commonly known as Chiari Malformation, in the lower back of the skull that reduces the space available to the brain, compressing it and often forcing it out (herniating it) through the opening into the spinal cord. This blocks the flow of cerebral spinal fluid (CSF) around the brain and spine and increases the fluid's pressure, creating turbulence that in turn is believed to create fluid pockets, or syrinxes (hence the term syringomyelia), in the spinal cord. Syringomyelia is rare in most breeds but has become widespread in the Cavalier King Charles Spaniel, with international research samples in the past few years consistently showing over 90% of Cavaliers have the malformation, and that between 30–70% have syrinxes. However, most dogs with syrinxes are not symptomatic. Although symptoms of syringomyelia can present at any age, they typically appear between six months and four years of age in 85% of symptomatic dogs, according to Clare Rusbridge, a research scientist. Symptoms include sensitivity around the head, neck, or shoulders, often indicated by a dog whimpering or frequently scratching at the area of his neck or shoulder. Scratching is often unilateral – restricted to one side of the body. Scratching motions are frequently performed without actually making physical contact with the body ("air scratching"). The scratching behaviour appears involuntary and the dog frequently scratches while walking – without stopping – in a way that is very atypical of normal scratching ("bunny hopping"). Scratching typical of SM is usually worse when the dog is wearing a collar, is being walked on a leash, or is excited, and first thing in the morning or at night.

Not all dogs who show scratching behaviour appear to be in pain, though several leading researchers, including Dr Clare Rusbridge in the UK and Drs Curtis Dewey and Dominic Marino in the US, believe scratching in SM Cavaliers is a sign of pain and discomfort and of existing neurological damage to the dorsal horn region of the spine. If onset is at an early age, a first sign may be scratching and/or rapidly appearing scoliosis. If the problem is severe, there is likely to be poor proprioception (awareness of body position), especially with regard to the forelimbs. Clumsiness and falling results from this problem. Progression is variable though the majority of dogs showing symptoms by age four tend to see progression of the condition

Episodic Falling (EF)

Episodic Falling causes "exercise-induced paroxysmal hypertonicity" meaning that there is increased muscle tone in the dog and the muscles cannot relax. Previously thought to be a muscular disorder, it is now known to be neurological. EF is caused by a single recessive gene, and a genetic test is available. Except for severe cases, episodes will be in response to exercise, excitement or similar exertions. Although EF is often misdiagnosed as epilepsy, which typically results in loss of consciousness, the dog remains conscious throughout the episode. Severity of symptoms can range from mild, occasional falling to freezing to seizure-like episodes lasting hours. Episodes can become more or less severe as the dog gets older and there is no standard pattern to the attacks. The onset of symptoms usually occurs when a dog is between 4 months and 4 years of age. It is similar to Scotty Cramp, a genetic disorder in Scottish Terriers. About 1% of Cavaliers are affected by the condition, with 19% being carriers. Dogs with whole coloured coats were more likely to be affected than dogs with parti-coloured coats.

Thrombocytopenia and macrothrombocytopenia

As many as half of all Cavalier King Charles Spaniels may have a congenital blood disorder called idiopathic asymptomatic thrombocytopenia, an abnormally low number of platelets in the blood, according to recent studies in Denmark and the United States. Platelets, or thrombocytes, are disk-shaped blood elements that aid in blood clotting. Excessively low numbers are the most common cause of bleeding disorders in dogs. The platelets in the blood of many Cavalier King Charles Spaniels are a combination of those of normal size for dogs and others that are abnormally oversized, or macrothrombocytes. Macrothrombocytosis is also a congenital abnormality found in at least a third of CKCSs. These large platelets function normally, and the typical Cavalier does not appear to experience any health problems due to either the size or fewer numbers of its platelets.

Hip and knee disorders

Hip dysplasia is a common genetic disease that affects Cavalier King Charles Spaniels. It is not present at birth but develops with age. Hip dysplasia is diagnosed by X-rays, but it is not usually evident in X-rays of Cavaliers until they mature. Even in adult spaniels with severe hip dysplasia, X-rays may not always indicate the disease.

Cavaliers can be subject to a genetic defect of the femur and knee called luxating patella. This condition is most often observed when a puppy is 4 to 6 months old. In the most serious cases, surgery may be indicated. The grading system for the patella runs from 1 (a tight knee), to 4 (a knee so loose that its cap is easily displaced). If a Cavalier has a grade 1–2, physical rehabilitation therapy and exercise may reduce the grading and potentially avoid surgery. The grades 3–4 are most severe where surgery will most likely be needed to correct the problem to avoid the development of arthritis and lameness in the limb.

Eye problems

A disorder commonly found in Cavaliers is keratoconjunctivitis sicca, colloquially known as "dry eye". The usual cause of this condition is an autoimmune reaction against the dog's lacrimal gland (tear gland), reducing the production of tears. According to the Canine Inherited Disorders Database, the condition requires continual treatment and if untreated may result in partial or total blindness. This disorder can decrease or heal over time. A 1999 study of Cavaliers conducted by the Canine Eye Registration Foundation showed that an average of 30% of all Cavalier King Charles Spaniels evaluated had eye problems. They include hereditary cataracts, corneal dystrophy, distichiasis, entropion, microphthalmia, progressive retinal atrophy, and retinal dysplasia.

Ear disorders

Primary Secretory Otitis Media (PSOM), also known as glue ear, consists of a highly viscous mucus plug that fills the dog's middle ear and may cause the tympanic membrane to bulge. PSOM has been reported almost exclusively in Cavaliers, and it may affect over half of them. Because the pain and other sensations in the head and neck areas, resulting from PSOM, are similar to some symptoms caused by syringomyelia (SM), some examining veterinarians have mis-diagnosed SM in Cavaliers that actually have PSOM and not SM.

Cavalier King Charles Spaniels may be predisposed to a form of congenital deafness, which is present at birth, due to a lack of formation or early degeneration of receptors in the inner ear, although this is relatively rare. In addition, more recent studies have found Cavaliers that develop a progressive hearing loss, which usually begins during puppy-hood and progresses until the dog is completely deaf, usually between the ages of three and five years. The progressive nature of this form of deafness in Cavaliers is believed to be caused by degeneration of the hearing nerve rather than the lack of formation or early degeneration of the inner ear receptors.