Health Issues

The Pyrenean Mountain Dog is a relatively healthy breed with an average lifespan of 10 to 12 years. As with most large breeds however, there are some health concerns to be aware of. Responsible breeders undertake the tests that are available today for certain diseases. Though no one can provide a 100% guarantee that any puppy they produce will not have a problem, it is the responsible breeder who takes the extra steps in utilising the testing that is available. Without testing no breeder can honestly say that their bloodlines are clear or that a dog is not affected by a condition.

It should also be noted that there is a difference between a genetic and an acquired illness. Care, nutrition, age and environment can all be major factors in a dogs health and wellbeing. These factors can affect how a pup grows and develops as well as its health in later life. Some conditions can also be affected by both genetics and nutrition and environment. Bone and joint issues such as Hip Dysplasia can fall into this category. Both the heath of the parents and how the pup is raised can therefore be vitally important and play a part in a pups future health. Some of the conditions which can be found in the Pyrenean Mountain Dog are outlined below. For further reading see also the Great Pyrenees Club of America's page on Disorders Affecting the Great Pyrenees and the Canine Inherited Disorders Database.

Hip Dysplasia

Hip Dysplasia is an abnormal formation of the hip socket which in its most severe form can cause lameness and painful arthritis in the hip joints. Though found in many breeds, large and giant breeds can be particularly susceptible to Hip Dysplasia. The causes of Hip Dysplasia are considered to be genetic, but diet and environment can also play a role. Environmental influences can include things like overweight condition, injury, overexertion of the hip joint or a ligament tear at a young age, or repetitive motion on a forming joint (i.e. jogging or lots of long walks on lead particularly on hard surfaces with a puppy under the age of 1 year).

Dogs with Hip Dysplasia may exhibit signs of stiffness or soreness after rising from rest, reluctance to exercise, a bunny-hopping style of running or other abnormal gait, lameness, pain, reluctance to stand on rear legs, jump up, or climb stairs, or wasting away of the muscle mass in the hip area. While some dogs may show signs early on, many affected dogs do not show clinical signs until well into adulthood. No one can predict when or even if a dysplastic dog will start showing clinical signs of lameness due to pain. X-rays however, can confirm the presence of hip dysplasia and the degree of change in the hip joint often well before there are any outward signs. For this reason it is important that dogs to be used for breeding be x-rayed to determine the health of their hips.  Pyrenean Mountain Dogs intended for breeding are, under most assessment methods,  generally x-rayed at two years of age.

In Australia, scoring of hips is done on 9 different points of the hip joint anatomy, including subluxation, and it is necessary for the dogs pelvis to be x-rayed in the correct position for scoring by an experienced Veterinarian. The x-rays are then forwarded to a recognised veterinary radiographer for scoring. The score is expressed as two numbers e.g. 3:6 being the total for the right hip, then left hip. Both left and right scores can be added together to give an overall hip score for the dog, e.g. 3+6 = Total Hip Score of 9. The lowest score is 0 and the highest 106. The lower the score the better the hip.  A good explanation of how the hips are scored can be found here.

The current breed average for Pyrenean Mountain Dogs in Australia is 10.7. Over the years improvements have been made as a result of breeders x-raying and testing their dogs for this condition and taking this into account when making breeding decisions. Continued attention to the hip health of breeding dogs is required however, to ensure that progress in this area continues. To quote from the USA’s Orthopaedic Foundation for Animals “Hip dysplasia appears to be perpetuated by breeder imposed breeding practices, but when breeders and their breed clubs recognize HD as a problem and establish reduction of HD as a priority, improvement of the hip status can be accomplished without jeopardizing other desirable traits. Prospective buyers should check pedigrees and/or verify health issues with the breeder. If suitable documentation is not available, assume the worst until proven otherwise.” Unfortunately currently available Australian Veterinary Association statistics show only 9 Pyrenean Mountain Dogs as being hip scored in Australia (though the previous statistics released showed 27 dogs and it is unclear what time period the statistics cover). Lets hope that figure can be improved upon in future years.

Elbow Dysplasia

Three different conditions are generally grouped together under the more general term ‘Elbow Dysplasia’. These are: ‘fragmented medial coronoid process (FCP)’, ‘osteochondritis of the medial humeral condyle in the elbow joint (OCD)’ and ‘ununited anconeal process (UAP)’. These conditions are generally found in large breeds and often show a high rate of heritability. Elbow dysplasia is not discussed as much as hip dysplasia, but is just as important. After all, a dog has four legs.

Signs of elbow dysplasia include lameness, which may remain subtle for long periods of time. No one can predict at what age lameness will occur in a dog due to a large number of genetic and environmental factors such as the severity of changes in the elbow, rate of weight gain, amount of exercise, etc. The Orthopedic Foundation for Animals states that “It is very likely that using lameness as a guideline to accept the diagnosis of elbow dysplasia would permit an increased incidence of disease genes to proliferate in the breeding population”.  X-rays however, can confirm the presence of elbow dysplasia and the degree of change in the joint well before a dog shows any outward signs. For this reason it is recommended that dogs to be used for breeding be x-rayed to determine the health of their elbows .

Like hips, scoring in Australia is done on a number of points within the elbow x-ray. The score is expressed as two numbers e.g. 0:1 but each elbow can only score 0, 1, 2 or 3. 0 being a nil or perfect score, 1 being minimal, 2 being moderate and 3 being severe. The lower the score, the better the elbows.

Patella Luxation

The patella, or kneecap, is part of the stifle joint (knee) on the rear legs of the dog. In patellar luxation, the kneecap luxates, or pops out of place. Four grades of medial luxation are used to describe the disorder (dogs with completely normal patellas are not given a grade and are classed as 'normal'). Grade 1 is for the dog that usually has a normal condition, but which can be luxated by minor trauma or pushing firmly with the thumb and fingers. In Grade 2, the patella can be manually displaced by adequate finger pressure or can slip out when the leg is fully extended, though it can be pushed back by the owner or a vet. With the next two grades it is difficult (grade 3) or impossible (grade 4) to put the patella back in place. Older dogs with Grades 1 or 2 may seem ok until a sudden onset that may be triggered by trauma or arthritic changes. Dogs with higher grades may display more severe symptoms of pain and lameness. Treatment is generally by way of surgery.

Patella luxation is a simple condition for breeders to test for as the position of the patella can easily be palpated by a veterinarian. The dog does not need (and in fact should not be) sedated for the test. There is no formal testing scheme for Patellas in Australia.  However, breeders can participate in the scheme run by OFA in the US. Patella luxation is considered to be an inherited condition and it is generally recommended that affected dogs not be bred. 

Osteochondritis Dessicans (OCD)

Osteochondritis dissecans, commonly known as OCD, is a disease of the cartilage that can affect various joints in a dog. It most commonly affects the shoulder, but can also manifest in the elbows, hips or knees (stifle). OCD is a developmental condition that most frequently occurs in rapidly growing large and giant breed dogs, typically between 6 and 9 months of age and more often in male dogs.

The cause of OCD is considered to be multifactorial. It is thought that there are several factors that contribute to the formation of OCD lesions including trauma to the joint, genetics, rapid growth, hormone imbalances, and nutrition. Prevention includes careful selective breeding that avoids the breeding of animals with a history of OCD. Young dogs should not undergo strenuous activity that jars or impacts the joints, particularly jumping activities. Providing a good balanced diet that promotes even, sustained growth is also recommended.

Eye Problems

Progressive Retinal Atrophy (PRA) is the general name for several diseases that are progressive and lead to blindness. This inherited condition has been documented in over 100 breeds of dog and cross breeds as well. Normally, the photoreceptors in the retinas develop after birth to about 8 weeks of age. The retinas of dogs with PRA either have arrested development (retinal dysplasia) or early degeneration of the photoreceptors. Retinal dysplastic dogs are usually affected within two months of birth and may be completely blind by one year. Dogs with retinal degeneration are affected from one year to eight years of age and the symptoms progress slowly. Unfortunately, there is no treatment for PRA, and no way to slow the progression of the disease. Animals with PRA usually become blind. PRA is caused by an autosomal recessive gene.  At present there is no DNA test available for PRA in Pyrenean Mountain Dogs.  We can only hope that one will be developed in the near future.  As it stands, puppies from parents who have no history of the disease and have been certified free of PRA by specialist eye exam will have less risk of developing the disease. Affected animals should not be bred. The littermates or parents of animals with PRA should also not be bred.

Ectropian is when the eyelids are droopy and roll outwards. The droopy eyelid may collect debris such as dust, pollen and plant material from the environment. This may cause irritation to the eye which leads to discharge and a red eye. Dogs that have ectropion must be watched carefully by their owners for possible foreign bodies in their eyes, and the dogs' eyes must be cleaned and often medicated on a regular basis.

The opposite of ectropian is entropion which is when the eyelids roll inwards. If the eyelid is rolled inward sufficiently so that the hairs of the eyelid rub on the eye, much damage may be done to the eye. Dogs with entropion usually squint and have watery eyes. If the entropion is not corrected and the rubbing continues, ulcers often develop on the cornea and the cornea becomes pigmented. Vision may be lost. Dogs that have had surgery to correct entropion can not be shown.

Although entropion and ectropion are hereditary disorders, their mode of inheritance is complex. No single gene controls the development of eyelid conformation. Instead, it is a combination of genes that control eyelid size and shape, depth of the eye socket, size and shape of the eyes, head conformation and amount of facial skin. All of these genes work in concert to determine the relationship of the eyelids to the eye. Therefore if an eyelid conformation defect is to be eliminated, only those dogs without entropion or ectropion should be bred. This is particularly important if breeders are to maintain the correct close-fitting eyelids required by the breed standard for the Pyrenean Mountain Dog. Not too loose, but also not too tight. 

Canine Multifocal Retinopathy (CMR1) is a recently identified recessively inherited eye disease known to affect several breeds including the Mastiff, Bullmastiff,  Dogue de Bordeaux and the Pyrenean Mountain Dog. Early clinical studies in 1998 by Dr. Bruce Grahn at the University of Saskatchewan, Canada, first described CMR1 in the Pyrenean Mountain Dog.

CMR1 generally develops in young dogs before 4 months and might progress slowly, might appear to heal, or might even appear and then go away again. Some dogs affected with CMR1 do not show clinical symptoms of disease until later in life. Some lesions disappear with no remaining sign, while some lesions leave a wrinkled area – a fold. Some leave the lasting lesion of a blister formation. Most dogs exhibit no noticeable problem with vision despite their abnormal appearing retinas.

Due to the abnormal appearance of the CMR1-affected retina, ophthalmologist eye exam reports typically record these multi-focal lesions as “retinal dysplasia” or “retinal folds”, to denote a defect in formation of the retina. The genetic test for CMR1 is valuable for identifying the cause of a retinal deformation. Given the exact genetic diagnosis, an owner can be reassured that there probably will be little or no vision loss due to this condition. At the same time, future cases of the condition can be reduced or prevented by using the CMR1 test as an information tool for breeding. Affected dogs may be removed from a breeding program for example, or affected and carriers can be mated to non-affected dogs only with the aim of removing the condition from the line over subsequent generations.  DNA testing for CMR1 is not currently available in Australia, but can be tested for by some overseas companies with the sample provided via cheek swab.  To date we have tested 5 dogs this way through GenSol Diagnostics in the US.


While the mode of inheritance of dwarfism in Pyreneans is unknown, it appears to be tied to a simple autosomal recessive gene, possibly caused by a single ancestral mutation. It is not known when the earliest Dwarfism in Pyreneans occurred though there are references to the condition in the US in the 1970’s and possibly the 1960’s. The first scientific article on the condition in Pyreneans was published in 1994. To date there have been no known incidences of Dwarfism in Pyreneans in Australia. For more information on Dwarfism see this informative page on Dwarfism in Great Pyrenees.

Heart Problems

One of the main inherited heart conditions found in the Pyrenean Mountain Dog is Sub Aortic Stenosis (SAS). SAS is an inherited disease. However, the exact mode of inheritance still has not been proven. In simple terms though, it is believed that any affected dog can produce SAS in its offspring and there does not need to be a matching gene in the other parent. An affected dog should not be used for breeding. A clinically unaffected dog may produce SAS in its offspring if it carries the gene.

It is characterized by an obstruction (stenosis) or "lesion" near the aortic valve which causes turbulence or "noise" in the blood as it passes through the valve, manifest in most (but not all) affected dogs as a heart murmur. Diagnosis of SAS in its mildest form is extremely difficult. A dog affected with the mildest form of SAS will lead a full life of normal duration and quality, and will most likely be completely asymptomatic. Even those with moderate SAS can lead normal lives. However, dogs that are severely affected are at risk of sudden death. Heart failure is very rare except in the most severe cases. Medication can sometimes be helpful in managing the more severe forms of the disease.

This is an unusual congenital disease in that the definitive "lesion" is not present at birth and does not develop until around 3-4 weeks of age, and the resulting heart murmur may not be detected until approximately 6-8 weeks of age. In some of the mildest cases, the murmur may remain undetectable for several years. Many murmurs are detected at an early age. Some turn out to be "innocent" and disappear as the puppy matures. Those that linger on at 16 and 20 weeks can pose problems.  Any persistent murmur, especially one near or over the aortic valve, should be evaluated by an experienced cardiologist, and followed up with a Doppler echocardiogram. A murmur detected in an adult dog should be followed by an echocardiogram with Doppler.

Another condition which may be seen in Pyreneans is Cardiomyopathy. Cardiomyopathy refers to disease of the heart muscle without malformation of the heart or its valves. There is a breed predisposition to dilated cardiomyopathy in giant breeds though it can also develop as a result of some toxins or infections. The most common type is dilated cardiomyopathy where there is dilation of the chambers of the ventricles of the heart with some increase in the heart muscle mass, and a loss of the normal contracting abilities of the ventricles. The heart has to work harder as a result of the abnormalities in the heart muscle cells. This gives rise to irregular heart rhythms and congestive heart failure.

Signs of Cardiomyopathy may include weakness, loss of appetite, weight loss, depression, episodes of collapse, respiratory difficulties, a soft cough (especially at rest), and/or an enlarged abdomen. Dogs are generally affected in middle-age on average (I have personally known dogs who have become affected at 9 and 10 years of age), although they may be affected as early as a few months of age. Abnormalities may be seen on an electrocardiogram before there are any clinical signs. Treatment for dogs with signs of congestive heart failure involves rest, diet restrictions, and drugs to stabilize and support the failing heart as well as to control the arrhythmias. 


Hypothyroidism is a disorder of the thyroid gland. This gland has a number of functions, but is most well known for regulating your dog’s metabolic rate. In hypothyroidism, the thyroid gland is under active and unable to secrete enough thyroid hormone. Symptoms of hypothyroidism can include dry brittle ‘cottony’ coat, hair loss often in patches which are symmetrical on both sides of the dog, excessive skin pigmentation, scaly skin, weight gain and lethargy.  Liza Jane is an example of a Pyrenean who is hypothyroid.  You can see the classic hair loss and cottony coat in her photo.  Hypothyroid dogs can also sometimes show behavioural changes, for example increased anxiety and fearfulness. It can also result in infertility and reduced sex drive in entire animals. Hypothyroidism can be diagnosed via blood test. For breeders, information on classifying the thyroid status of breeding dogs can be found here.


The types of cancer that can affect Pyreneans can vary. According to health surveys conducted by the Great Pyrenees Club of America however, the two most common types of cancer seen in Pyrenean Mountain Dogs are Osteosarcoma and Hemangiosarcoma.

Osteosarcoma is commonly referred to as Bone Cancer. Large and giant breeds of dog are most at risk of this condition. Luckily the incidence in Pyreneans is not huge, but it is a condition to be aware of as it can occur. At this point there is no known genetic link in Pyreneans. Usually the first sign of bone cancer is when a dog develops lameness or pain, most often in a limb. A firm swelling may become evident as the tumour size increases. For most bone tumours, amputation of the affected limb has been the traditional form of surgical therapy. The condition will spread to other areas of the body, especially the lungs, very quickly so early diagnosis is valuable. All bone tumours are dangerous in the dog and should be treated as soon as possible. If concerned that your dog is exhibiting signs of pain or lameness, it is better to err on the side of caution and get your dog checked out by a veterinarian.

Hemangiosarcomas can occur anywhere on or in the body, but primarily in the spleen, liver, heart, and skin. It is a quite aggressive form of cancer. The skin form of hemangiosarcoma has a better prognosis and recovery rate than the internal forms. The internal form is usually diagnosed by the palpation of a large mass in the abdomen or with symptoms of sudden blood loss. The sudden blood loss results from the rupture of the fragile tumour and a resulting loss of blood into the abdomen. The symptoms would include weakness or collapse and pale mucous membranes. We do not currently understand why dogs develop hemangiosarcomas. Because of the increased incidence in several breeds, a genetic link appears to be one of several likely causes.

More information on cancer in Pyreneans is available on the GPCA website.    

Degenerative Myelopathy

Degenerative Myelopathy is a neurological disease occurring with increasing frequency in several breeds, including the Pyrenean Mountain Dog. The disease is chronic and progressive and is caused by the degeneration of the myelin sheath which insulates the neurons in the spinal cord. This results in a loss of communication between the nerves in the lower body of the dog and the brain and, as a consequence, the dog loses both sensation and control.
The condition usually manifests itself after the age of 5 years. Initially, the back legs are affected causing muscle weakness and loss of coordination. These cause a staggering effect that may appear to be arthritis. The dog may scuff one or both rear paws when it walks, wobble when walking, knuckle over or drag its feet, and may cross the feet. As the condition progresses, the limbs become weak and the dog begins to buckle at the knees and have difficulty standing. The dog begins to have considerable difficulties walking, and may loose control of elimination and front limb function. Eventually the back legs become useless, at which point euthanasia may be the only option.

DNA testing is now available for Degenerative Myelopathy in Pyrenean Mountain Dogs. Prior to the availability of the test, diagnosis of DM was gained by ruling out other potential conditions in affected dogs. As the condition was often late onset, there was limited opportunity for breeders to use this information when making breeding decisions. The DNA test now allows breeders to know if their dogs are clear of the gene, are carriers or if they are affected (carry two copies of the gene). Dogs that are carriers will not develop DM. It should  also be noted that dogs that test as affected may often appear phenotypically normal and it is not known at this stage what percentage of affected dogs develop the condition. It is more likely however, that a dog that tests as affected will develop Degenerative Myelopathy. Further information on DM and the implications of the DNA test results is available on the University of Missouri-Columbia website.
Neuronal Degeneration

Neuronal Degeneration is a condition which has only been identified in Pyrenean Mountain Dog relatively recently. It is a lethal condition which causes widespread degeneration in both the central and peripheral nervous systems.  Neuronal Degeneration causes symptoms such as muscular weakness an ataxia in the rear.  Affected dogs may also develop laryngeal paralysis. 

Neuronal degeneration first appears in pups at around 4 to 6 months of age and is a degenerative condition which means dogs who have the condition slowly get worse over time. The gene for Neuronal Degeneration is inherited in an autosomal recessive manner, which means dogs need two copies of the gene (one from each parent) to be affected by the condition. Dogs with one copy of the gene will not be affected, but will be able to pass the gene to their offspring.

A DNA test for the condition has been developed by the University of Minnesota in the US. DNA testing enables dogs which are carriers (having one copy of the gene and one normal gene) as well as dogs which are affected (carrying two copies of the gene) to be identified and assists breeders to breed responsibly so that affected dogs are never produced. To date there have been no cases of affected dogs in Australia, and the DNA testing of dogs used for breeding can help us to keep it that way. Further information on Neuronal Degeneration (NDG) can be found on the University of Minnesota website.