The Kai Ken is still a relatively young breed, especially in the Western world where we are still learning about the issues and concerns that can affect the breed. Despite the common opinion that the Kai is a typically healthy breed, there are plenty of health conditions that breeders need to be screening for and disclosing to those interested in the breed. 

Kai Ken have the potential to be a long-lived breed, with individual dogs regularly reaching their late teens. That said, the current life expectancy is suggested to be between 12 and 15 years.

In order to promote a long and healthy lifespan in our dogs, ensuring breeders are testing their breeding stock through their countries’ health organisation is extremely important.

Here in the UK, the breed is not recognised and so far does not have any breed specific tests set out, so instead we can follow the suggestions from European and American breeders.

Kuro-go, a Kai Ken rumoured to have lived to be 28 years old. Kuro-go was born in January 1913, before the Kai Ken Aigokai was founded. Image from Okabe-San of Tenroukensha.

Health Screening

Under the Orthopaedic Foundation for Animals’ (OFA) Canine Health Information Centre (CHIC) scheme, the current requirements to achieve a CHIC number are:

To achieve CHIC, your Kai needs only three tests: A DNA test for PRA, a cardiac exam, and one other health elective of choice. 

However, this does not mean that these are the only conditions that the Kai Ken can be affected by. In fact, orthopaedic conditions are very common in the breed and should also be tested for outside of the possible single elective for CHIC.

Health Conditions

The following conditions can be found to affect the Kai Ken:

  • Hip & Elbow Dysplasia
  • Luxating Patella
  • Transitional Vertebra
  • Progressive Retinal Atrophy
  • Seizures
  • Heart Murmurs
  • Cancer
  • Allergies
  • Cryptorchidism
  • Hypodontia
  • Pacific Rimism

Hip & Elbow Dysplasia

Hip and elbow dysplasia refers to the abnormal formation of the hip and elbow joint and/or socket. It is typically developed from birth, though it can be caused by a traumatic injury to the joint. The condition is typically graded with mild causing minor orthopaedic changes to severe which can cause crippling arthritic joints and lameness.

Hip and elbow dysplasia can easily be screened for with x-rays taken by your veterinarian. In the UK most scoring is taken under full general anesthesia, but in the US and Europe it may be taken under sedation or even just physical restraint. Once the x-rays are taken, they are evaluated and scored. Each health board will have their own way of evaluating the x-rays, so an ‘OFA Good’ may return as a slightly worse score in the UK or Europe. It is important to know the average for your breed when taking into account the individual results of your dog.

Symptoms for Hip & Elbow dysplasia according to the BVA are:

  • Pain
  • Lameness on one or both limbs (hindlimbs for hips, forelimbs for elbows)
  • Stiffness
  • Intolerance or reluctance to exercise
  • Difficulty changing position (rising, sitting, laying)
  • Difficulty climbing stairs 
  • Abnormal gait or movement
  • Groaning or yelping while moving or getting up
  • Protectiveness of the joint during grooming or petting

Treatment for hip or elbow dysplasia can range from surgical intervention to medical management. In severe cases a total joint replacement may be necessary, though in many cases treatment with pain medication, weight management and physio or hydrotherapy can help. It is not recommended that dogs with hip or elbow dysplasia be bred from.

Luxating Patella

Luxating patella is a common condition in Kai Ken, where the kneecap dislocates out of its usual position within the groove of the stifle joint. The condition is very common in smaller breeds, but has been regularly noted in Kai Ken. 

Patella luxation is not typically scored in the UK under the BVA as hips and elbows are, though many breed clubs and veterinarians offer clinics to test the grade of the patellas similarly to the OFA or European vet schemes.

The condition is graded from 0 to 4, with zero being a normal healthy patella, and four being a severely, permanently luxated joint.

Symptoms of luxating patella include:

  • Pain
  • Lameness on one or both hind limbs
  • ‘Skipping’ motion when walking or running. This can be continuous or may return to normal after a few steps
  • Abnormal extension of the knee joint
  • Arthritic changes to the joint

Luxating patella can easily be tested for and diagnosed through a clinical manipulation of the joint by a veterinarian, though x-rays may be taken to determine the severity of the condition and the extent of damage caused.

Similarly to hip and elbow dysplasia, surgical or medical management are options for luxating patella. For a higher graded luxation, surgery is recommended, while with a lower grade it may be suggested to manage with pain relief when necessary and careful monitoring for any changes to the condition. 

Transitional Vertebra

To read my full experience with TV, please click here.

Progressive Retinal Atrophy

PRA is likely the most known health condition that affects the Kai Ken. At least two types of testable PRA are confirmed to affect the breed (PRA-PRCD and PRA CRD4/CORD1) though it is possible that there are untestable variants of the condition that may also affect the breed.

PRA is a genetic condition which affects the retina and causes progressive, non-painful vision loss with the gradual degradation of the retina and early loss of rod cells, one of the types of photoreceptors in the eye.

The condition is typically late onset, though there have been cases of young Kai showing symptoms from a young age. 

Symptoms include:

  • Poor vision in low light, which will gradually worsen to daytime vision too.
  • Bumping into things such as doors or stairs
  • Difficulty following without audio signals
  • Eventual complete blindness

There is no treatment for PRA, though the genes can be tested for using dog DNA tests such as Embark. The progression of the condition can also be checked with BVA or CERF Eye examinations, which are valid for one year.

In a breed with a small gene pool, it is difficult to justify completely ruling out the breeding of affected or carrier dogs, so it is important to continue genetic testing breed carriers or affected dogs to clear individuals where possible.


The exact cause of all types of seizures found in Kai Ken is unknown, but the most common cause of seizures in dogs is idiopathic epilepsy, a genetic condition with often unknown causes.

Seizures are also found in Shikoku Ken, and seem to be mostly isolated to specific lines of dogs, meaning affected animals and their direct relations should avoid being bred.

As well as diagnosed epilepsy, there are other reasons why a dog may develop seizures, including ingesting poison, blood sugar changes, brain tumours, head injuries and kidney disease. The most common form of seizures in dogs is known as a grand mal seizure, where abnormal electrical activity happens throughout the brain and the dog begins to convulse and may lose consciousness. Alternatively, dogs may suffer from focal seizures, where abnormal activity only occurs in parts of the brain and can present as unusual movements or spasms in limbs. Seizures can last from seconds to a few minutes.

Symptoms of seizures can include:

  • Vacant staring
  • Tremors
  • Convulsions, which can present as mild or violent
  • Aggression
  • Disorientation
  • Uncontrollable urination or defecation
  • Foaming at the mouth
  • Loss of consciousness
  • Temporary loss of senses
  • Vocalisations including barking, growling and whining
  • Biting tongues

Seizures usually cannot be cured but can be managed through medication and careful advice from a vet. The most important thing is for the owner to be prepared in case of the sudden onset of a seizure, which includes moving anything that could be dangerous out of the way of the dog and timing from onset to finish. It is important to stay calm and not to touch the dog as stimulation may cause more damage. It is recommended to always consult your vet after your dog has come out of a seizure, and if it continues for more than five minutes or your dog begins to have cluster seizures (multiple seizures back-to-back), this is a medical emergency and should be treated as such.

Heart Murmurs

Heart murmurs are not entirely uncommon in Kai Ken, and are usually found to be small grade and during puppyhood, where they are often innocent and may go away with age. An innocent murmur should have no effect on the dog’s health, though it is important to monitor the condition as your dog ages. They are graded from 1 to 6.

Symptoms include:

  • Coughing
  • Weakness
  • Intolerance to exercise

Heart murmurs can be diagnosed through auscultation with a stethoscope, though x-rays and echocardiograms may be recommended in affected dogs to determine the location and severity of the murmur. Most heart murmurs will not require treatment and prognosis is dependent on the grade as well as the cause of the murmur.


Cancer is unfortunately extremely common in all dog breeds, and Kai Ken are no exception. Cancerous tumours have been regularly found on eyelids, in mouths and in lungs of Kai Ken, though the most common and most invasive form of cancer seen in the breed is hemangiosarcoma, or HSA.

HSA is an extremely fast growing and invasive type of tumour filled with blood which may present inside or outside of the dog’s body. Dermal HSA, found on the skin, can often be found early enough and treated, though it may regrow or spread. Visceral HSA, found inside the body, are not normally discovered or diagnosed until the tumour has grown or ruptured, and are much more difficult to treat.

Symptoms include:

  • Pale, almost white mucous membranes 
  • Sudden collapse
  • Excessive panting and drooling
  • Irregular and abnormal heart rate
  • Bloated abdomen due to internal bleeding from a ruptured tumour

Surgery and aggressive chemotherapy are the only treatments for these types of cancers, and it should be noted that these types of surgery are usually considered palliative care and will not cure the dog of the condition, and the life expectancy of affected dogs is usually only three to seven months, with very few dogs surviving a year post surgery.


Allergies are very common in many dog breeds, and the Nihon Ken breeds are no exception. Allergies are an immune response due to exposure to certain environmental or food allergens, and they can be difficult to diagnose and treat, as your dog may be reacting to more than one allergen. 

Symptoms include:

  • Chewing, biting and licking, mainly in the feet but can be in other areas of the body
  • Skin and ear infections
  • Red or scaly skin
  • Hair loss
  • Tear staining
  • Rubbing or pawing at eyes and ears
  • Sores on the skin
  • Sneezing
  • Discolouration of the fur

Treatment for allergies can be difficult and may include allergen testing, dietary trials and antihistamine medication, or biological therapies like Cytopoint.


Cryptorchidism is where one or both testicles do not descend from the body. Cryptorchidism may be linked to infertility in male dogs, though it is possible for an affected dog to produce a litter, though the condition is thought to be hereditary.

Undescended testicles have a much higher chance of becoming cancerous, and as such it is recommended that affected dogs be castrated once they have reached sexual maturity. Dogs with cryptorchidism are otherwise healthy and can live normal, full lives.


Hypodontia, or congenital missing teeth, is a genetic condition where a dog has an incomplete set of teeth within the mouth. It can range from mild, with only one or two missing teeth, to severe, with further complications such as misaligned teeth and bite, damage to the gums and reduced ability to chew. Most dogs affected by hypodontia do not have any issues, and most dogs will cope well with missing teeth.

Pacific Rimism

Pseudohyperkalemia, or Pacific Rimism, named for its commonness in dogs from the Pacific Rim such as the Nihon Ken, is a condition where the potassium level in the blood appears to be highly elevated. In these breeds, this elevation can be completely normal. 

During routine blood tests, it is important to inform your vet as this condition is not well known, and high potassium levels may flag to indicate Addison’s disease, and your vet should run additional tests to ensure there is no misdiagnosis of the condition. 

Sources and Further Reading

Much of the above information was written in association with the Nihon Ken Network and the Association of Nihon Ken, it can also be found here: