They impress with their size, their calmness, and their gentleness with children.

Newfoundlands, Saint Bernards, and Leonbergers are admired for both their appearance and their temperament.

However, it's important to know that adopting a giant dog without understanding the real health constraints means exposing yourself to difficult situations, whether financially, emotionally, and especially if you want to ensure your pet's well-being.

Newfoundland, Saint Bernard and Leonberger (AI generated)

These three breeds share common biological characteristics: a high body mass (60 to 90 kg for the largest specimens), rapid growth over the first 18 months, and a permanent mechanical load on joints that don't always have time to consolidate.

The consequences are documented: hip dysplasia, elbow dysplasia, osteosarcoma, and a significantly shorter life expectancy than the canine average.

This article presents the data available in veterinary literature for each of these three breeds, in order to provide owners and future adopters with a clear and verified overview.

Why Size is a Joint Risk Factor

The link between body weight and joint pathologies in dogs is documented by several prospective studies.

A Norwegian cohort ( Krontveit et al., Preventive Veterinary Medicine, 2010 ) followed 501 dogs of four large breeds from birth until official dysplasia screening.

Biomechanics partly explains this phenomenon.

The heavier a dog is, the greater the forces exerted on the articular cartilage with each step.

In giant breeds, skeletal maturity is only reached around 18 to 24 months. Throughout this period, cartilaginous and bony structures are vulnerable to loads that exceed their remodeling capacity.

The survival study of the same cohort ( Krontveit et al., Veterinary Journal, 2012 ) shows that only 16% of Leonbergers were still alive at 10 years old, compared to 60% of Labradors in the same cohort.

These figures reflect a biological reality that owners of giant breeds must integrate.

Comparative Table of Documented Predispositions

The Saint Bernard: 

Hip Dysplasia

Data from the Orthopedic Foundation for Animals (OFA) place the Saint Bernard among the breeds most affected by hip dysplasia.

These statistics reflect dogs submitted for screening in the OFA database and do not represent a general population estimate, but they provide a useful order of magnitude for comparing breeds.

The breed's body mass (between 60 and 90 kg) mechanically exacerbates joint deterioration once dysplasia has set in.

Clinical signs can appear early, sometimes before 2 years of age.

Osteosarcoma: a documented predisposition

The Saint Bernard is among the breeds most frequently cited in the literature on canine osteosarcoma.

This malignant bone tumor preferentially affects the long bones of the limbs, often at the distal radius or proximal humerus.

In giant breeds, the rapid growth of long bones during the juvenile period is considered one of the predisposing factors.

The prognosis for osteosarcoma is guarded even with treatment.

Survival data vary depending on tumor location, stage at diagnosis, and treatment protocol.

This is information that owners of giant breeds should be aware of before adoption.

Life Expectancy: 8 to 10 years

The average life expectancy of a Saint Bernard is 8 to 10 years, which is typical for giant breeds.

Some individuals reach 12 years with good care.

Gastric dilatation-volvulus (GDV) is also a significant cause of mortality in this breed, particularly due to the characteristic deep chest.

The Leonberger:

25% Hip Dysplasia at 18 months

A Norwegian study published in Preventive Veterinary Medicine ( Krontveit et al., 2010 ) followed 180 Leonbergers from birth until official radiographic screening at 18 months.

25% showed radiographically detected hip dysplasia.

This figure is likely underestimated: only dogs that survived until screening were included.

The same study identified environmental factors modulating this risk: puppies exposed to stairs before 3 months of age had a significantly higher risk.

Conversely, outdoor exercise on soft, uneven ground during the juvenile period was associated with a reduced risk.

Hereditary polyneuropathy

The Leonberger is also affected by a hereditary polyneuropathy, of which several forms have been described.

Mutations in the ARHGEF10, GJA9, and CNTNAP1 genes have been identified, causing progressive degeneration of peripheral nerves.

Clinical signs include muscle weakness and coordination problems that can be confused with joint issues.

Genetic tests are available.

Osteosarcoma and survival

A Norwegian population study published in the Canadian Journal of Veterinary Research (Anfinsen et al., 2011, PMID 22210997) on 1,915 giant breed dogs showed that the Leonberger had the second highest rate of primary bone tumors after the Irish Wolfhound.

The survival study ( Krontveit et al., Veterinary Journal, 2012) indicates that only 16% of Leonbergers in this cohort were still alive at 10 years of age.

The Newfoundland:

Dysplasia and joint load

In the Norwegian cohort of 501 dogs ( Krontveit et al., 2010), the Newfoundland was among the breeds severely affected by hip dysplasia.

Its broad and deep morphology, combined with an average weight of 60 to 70 kg, creates significant joint stress.

OFA data also report a significant rate of elbow abnormalities in Newfoundlands presented for testing.

Gastric dilatation-volvulus

The Newfoundland is one of the breeds in which the risk of gastric dilatation-volvulus should be discussed with the veterinarian.

In some cases, preventive gastropexy may be considered.

Dietary precautions (several small meals, avoiding intense exercise after meals) are generally recommended for deep-chested breeds.

Life expectancy: 9 to 10 years

The average life expectancy of the Newfoundland is 9 to 10 years.

As with the Saint Bernard, joint diseases and oncological risks contribute to this limited life expectancy.

What this means concretely for an owner

Growth management is crucial

In giant breeds, growth rate during the first 18 months is directly correlated with joint risk.

An adapted diet (with a controlled calcium/phosphorus ratio and moderate energy density) is essential.

The most common mistakes are overfeeding during the juvenile period and using adult or large breed foods indiscriminately.

Intensive exercise, repeated jumping, and hard surfaces should be avoided until complete skeletal maturity, which is 18 to 24 months depending on the breed.

Regular and moderate walking on soft ground is preferred.

Joint screening: when and how

• Saint Bernard: hip radiography recommended at a minimum of 12-18 months, ideally PennHIP or OFA/SCC protocol

• Leonberger: hip radiography at 18 months (official protocol), polyneuropathy genetic test recommended

• Newfoundland: hip and elbow radiography, complementary veterinary check-up depending on the dog's profile

Veterinary costs to anticipate

Care related to giant breed diseases can represent significant expenses:

• severe dysplasia surgery (triple pelvic osteotomy, total hip replacement)
• cost of osteosarcoma treatment (amputation + chemotherapy)
• emergency GDV treatment
• or preventive gastropexy.

Amounts vary by clinic, region, and protocol.

Pet health insurance taken out before the onset of any pathology can cover a significant portion of these costs.

Choosing a reputable breeder for a giant breed

A reputable breeder of Saint Bernards, Leonbergers, or Newfoundlands exclusively provides hip radiography reports for their breeding dogs.

They perform available genetic tests (polyneuropathy for the Leonberger, cardiac tests for the Newfoundland).

They do not sell their puppies before 8 weeks of age and remain available after the sale.

Living with a Saint Bernard, Leonberger, or Newfoundland is also a rare experience.

These dogs are known for their emotional balance, their gentleness with children, and their ability to adapt to very different households.

The Newfoundland has historically been used as a water rescue dog, which demonstrates unusual practical intelligence and composure.

The Leonberger was selected for show and work, which gives it remarkable presence and sociability.

The Saint Bernard, an emblem of mountain rescue, is one of the most temperamentally stable dogs there is.

Knowing their vulnerabilities is precisely what allows us to offer them a long, comfortable, and well-supported life.

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Sources

1. Krontveit RI, Nodtvedt A, Saevik BK, Ropstad E, Skogmo HK, Trangerud C. A prospective study of hip dysplasia and growth in a cohort of four large canine breeds in Norway (1998-2001). Preventive Veterinary Medicine. 2010;97(3-4):252-263. PMID: 20956024
2. Krontveit RI, Trangerud C, Nodtvedt A, Dohoo I, Moe L, Saevik BK. Effect of radiographic hip dysplasia and breed on survival in a prospective cohort study of four large dog breeds followed for 10 years. The Veterinary Journal. 2012;193(1):206-211. PMID: 22093911
3. Krontveit RI, Nodtvedt A, Saevik BK, Skogmo HK, Trangerud C. Housing and exercise-related risk factors for the development of hip dysplasia as determined by radiography in a prospective cohort of Newfoundlands, Labrador Retrievers, Leonbergers, and Irish Wolfhounds in Norway. American Journal of Veterinary Research. 2012;73(6):838-846. PMID: 22620698
4. Anfinsen KP, Grotmol T, Bruland OS, Jonasdottir TJ. Incidence of primary bone tumors in dogs: a population-based study in Norway. Canadian Journal of Veterinary Research. 2011;75(3):209-215. PMID: 22210997