Hereditary nephritis: Samoyed hereditary glomerulopathy testing

Hereditary nephritis, also known as Samoyed hereditary glomerulopathy (SHG), is a serious hereditary kidney disorder found primarily in the Samoyed dog breed. This dominant genetic condition is caused by a mutation on the X chromosome that affects the collagen in the kidneys, leading to progressive renal failure, especially in male dogs.

The disease typically manifests early in life, with symptoms such as proteinuria (excessive protein in urine), foamy urine, lethargy, weight loss, increased thirst and urination, and can progress rapidly to fatal kidney failure. Female Samoyeds are also carriers but often exhibit milder symptoms and seldom develop renal failure.

Since there is no cure or effective treatment for this condition, the only prevention is careful breeding to avoid passing the mutated gene to future generations. DNA testing has become essential for responsible breeders to identify affected or carrier dogs to effectively reduce the incidence of this disorder in the breed's gene pool.

Understanding Samoyed hereditary glomerulopathy (SHG)

SHG results from a mutation in the COL4A5 gene, which affects the structure of the glomerular basement membrane in the kidneys. This defect impairs the filtering ability of the kidneys, causing leakage of proteins into the urine—a condition called proteinuria. Affected male puppies usually show signs from 2 to 4 months old, with slower onset possible in some cases.

The progression in males is aggressive, with many developing severe kidney failure and sadly passing away before two years of age. Females, carrying two X chromosomes, are typically less severely affected and may only show proteinuria without renal failure.

Which dogs are at risk?

The condition specifically affects the Samoyed breed and their direct crosses. Males are most severely affected due to the X-linked dominant nature of SHG, while females may be carriers or show mild symptoms. Because the gene mutation is dominant, any dog inheriting one copy of the mutation will be affected or a carrier, making early genetic health screening vital.

How is SHG inherited?

SHG is inherited in an X-linked dominant pattern:

• A male with the affected gene will pass it to all his daughters (carriers) but none of his sons.
• A carrier female has a 50% chance of passing the mutation to each pup, whether male or female.
• Mating an affected dog with a clear dog can result in litters that may carry or exhibit the condition depending on the parents' status.

Health testing for SHG

Health testing for SHG is crucial for breeders and prospective puppy buyers. Testing can involve:

• Urine protein screening to detect proteinuria as an early sign.
• DNA testing to detect the COL4A5 gene mutation definitively.

Veterinary blood or cheek swab samples are used for genetic testing. Knowing a dog’s clear or affected status before breeding helps prevent spreading the condition.

Responsible breeding and buying advice

Only breeding clear dogs or appropriate carrier combinations can effectively reduce SHG prevalence. Reputable breeders will have comprehensive health screening protocols, including official DNA test results for both sire and dam.

If you are looking to find a Samoyed puppy, always ask about the health testing status and request documentation. This responsible approach helps protect your new companion's health and the breed's future.

Conclusion

Samoyed hereditary glomerulopathy is a devastating inherited kidney disease, especially affecting males. Early diagnosis through urine and genetic testing is essential, along with responsible breeding to avoid perpetuating the gene mutation.

By supporting informed breeding choices and requesting health tests, owners and breeders contribute to healthier Samoyed generations ahead.