Candalan Cavaliers - Health Testing

Cavalier Health

Breeding better pedigree dogs for the future of the breed and conformation showing

Health testing does not provide a guarantee that your puppy won't develop a hereditary disease down the track. However, routinely checked dogs over generations do prove that health screening does work and helps to maintain and improve the health of our pedigree breeds when bred responsibly. The standard accepted health tests for Cavaliers are heart screening and DNA testing for curly coat dry eye (CCDE) and episodic falling (EF).

At Candalan, we heart screen our dogs yearly by a cardiologist for mitral valve disease and other heart conditions such a pulmonic valve stenosis. We have also started to eye screen our dogs by an ophthalmologist and will be commencing a breeding program for Syringomyelia via MRI, maintaining generational screening of our dogs into older age.

We also routinely DNA test for a number of conditions which might affect Cavalier KCSs:

Episodic falling Syndrome (EFS): EFS affects some Cavalier King Charles Spaniels, starting between 3 and 7 months. The main sign is stiff or locked muscles that may cause a dog to jerk, hop like a bunny, or walk stiffly with what is sometimes called a 'deer stalker' gait. These episodes are usually brief, lasting less than 5 minutes, and go away on their own. However, the length of time they last can vary. Episodes may be triggered by exercise, excitement or stress.

Testing for a mutant form of the BCAN gene which causes EFS, can inform breeding choices. Testing can also help confirm or correct diagnoses, as the condition has similar symptoms to other disorders and could be misdiagnosed. EFS requires two copies of the mutant BCAN gene, one from each parent, to develop in dogs. It affects both males and females equally. Carriers (one copy) won't have EFS, but can pass the gene on to offspring.

Curly coat/dry eye (CCDE): CCDE is an inherited syndrome in some Cavalier King Charles Spaniels pups. It's also called congenital keratoconjunctivitis sicca and ichthyosiform dermatosis (CKSID). It causes serious health problems that affect the eyes, skin, coat and paws from birth, getting worse as the puppy grows. Eye and skin problems may cause vision issues and itchy skin, respectively. Paw issues can be painful for the puppy and make it hard to walk. Unfortunately, there's no cure for this syndrome and it is difficult to manage it. Testing for the mutant form of the FAM83H gene, which causes this syndrome, can help breeders avoid producing affected pups. This syndrome requires two copies of the mutant FAM83H gene, one from each parent, to develop in dogs. It affects both males and females equally. Carriers (one copy) won't have this syndrome, but can pass the gene on to offspring.

Canine degenerative myelopathy (DM): this is a disorder that occurs relatively late in a dog's life, usually around the age of eight. Dogs that have two copies of the DM gene are at risk of developing DM. However, it must be kept in mind that the currently available test for this disease relies on a "marker", which in itself is not causing the disease. Results therefore have to be considered carefully and a diagnosis should also be based on pedigree history, clinical signs, history (incidence) of the disease and the specific genetic test for the disease. Penetrance of a disease will always vary, not only from breed to breed but within a breed, and will vary with dierent diseases. Factors that influence penetrance are genetics, nutrition and environment. It is important to consider the specific test used, and temperament and phenotype should also be considered when making breeding decisions.

ge of hereditary diseases continues to increase and we see some that are relatively benign and others that can cause severe and/or fatal disease.

Medium-chain acyl-CoA dehydrogenase deficiency (MCADD): MCADD is a condition in Cavalier KCSs, which affects how they break down certain fats for energy. If a dog has MCADD, they may not be able to get the energy they need when they need it. This may result in low blood sugar, seizures, coma or even sudden death. MCADD can be managed by changing diet (avoiding certain oils), so it's crucial to find out if your dog has the mutant form of the ACADM gene. Testing will also help to make informed breeding choices. MCADD requires two copies of the variant ACADM gene, one from each parent, to develop in dogs. It affects both males and females equally. Carriers (one copy) won't have MCADD but can pass the gene on to offspring.

Congenital macrothrombocytopenia (CKCS type)(CM): This condition means that an affected dog has large platelets in their blood (clumping cells that help stop bleeding) that are fewer in number than in most other dogs. These large platelets still work normally and don't cause any bleeding problems for the dog. CM does not require treatment and is not a disease as such. However, CM can make it look like a serious bleeding disorder on a blood test. You should tell your vet if your dog has the mutant form of the α1-tubulin gene which causes CM to avoid misdiagnosis and unnecessary treatments. CM requires two copies of the mutant α1-tubulin gene, one from each parent, to develop in dogs. It affects both males and females equally. Carriers (with one copy) won't have the large size platelets in their blood, but can pass the gene on to offspring.

Myxomatous mitral valve disease (MMVD): This test is based on recent research that identified genetic variants associated with increased risk of early-onset myxomatous mitral valve disease (MMVD). It determines a dog's genotype for the genetic variant referred to as NEBL3 in the Axelsson paper referenced below. Dogs with a G G or A G test result are less likely to be diagnosed with MMVD early in life compared to dogs with an A A result. Very few Cavalier King Charles Spaniels have the G variant, and identifying these dogs could help breeders who want to produce healthier pups. The test was developed based on data from Cavalier King Charles Spaniel and Dachshund dogs and should not be used on other dog breeds. The test is likely to be updated if further research suggests other genetic variants are more useful predictors of MMVD severity or time of onset.

Degenerative myelopathy and Myxomatous mitral valve disease tests are marker tests. A marker test indicates a statistical association with a trait but does not directly cause it. This means that, in some cases, an animal may test negative yet still develop the trait, or test positive without actually having it. Additionally, some marker tests may require specific environmental factors to trigger the expression of the trait. It's important to note that these tests are still relatively new, and much more data is needed before their results can be fully understood and considered meaningful in all cases.

It is important to make informed breeding decisions based on health testing, but it is also important to remember that the Australian context of breeding pedigree dogs is heavily influenced by what new bloodlines can be brought into Australia and the rules that must be followed when importing a dog or frozen semen. Whilst it is important for breeders to test, it is also important that the genetic diversity is not lost in Australia.

There are no enforced tests that breeders must complete prior to breeding cavaliers here in Australia. ANKC dogs do have to be healthy prior to breeding and there are rules by which we must follow. Having a pedigree does help ANKC breeders but be mindful that even backyard breeders can do testing including the DNA of their breed. A test through Orivet can give me the exact percentage of my breed. ANKC breeders would have dogs that are 100% their chosen breed.