Hereditary nephritis in dogs is a genetically inherited disorder that affects the kidneys. This condition is analogous to Alport syndrome in humans. It is primarily characterized by structural abnormalities in the glomeruli — the microscopic filtration units within the kidneys. Over time, these abnormalities impair the kidneys’ ability to filter waste products from the blood, leading to a buildup of toxins and subsequent renal failure.
Here’s what you should know about the symptoms, causes, and treatments of the condition.
Symptoms of hereditary nephritis in dogs
The onset of clinical symptoms in hereditary nephritis varies depending on the dog breed and the severity of the genetic mutation. Generally, affected dogs begin to exhibit symptoms between six months and two years of age. Common signs include:
- Excessive protein in the urine (proteinuria)
- Presence of blood in the urine (hematuria)
- Weight loss
- Lethargy
- Decreased appetite
- Increased thirst and urination
- Edema
As the disease advances, dogs may develop signs of chronic renal failure — such as vomiting, diarrhea, oral ulcers, and halitosis. Eventually, uremia — a buildup of waste products in the blood due to kidney failure — can occur, leading to severe systemic effects and potentially life-threatening conditions.
Causes of hereditary nephritis in dogs
Hereditary nephritis is caused by mutations in genes responsible for the structural integrity and function of the glomerular basement membrane (GBM). In dogs, mutations in the COL4A3, COL4A4, and COL4A5 genes, which encode for type IV collagen, are commonly implicated. These mutations result in defective collagen production, compromising the stability and filtration capabilities of the GBM.
Certain dog breeds, such as English Cocker Spaniels, Bull Terriers, and Samoyeds, are more predisposed to hereditary nephritis due to their genetic makeup. The inheritance pattern of this disorder varies among these breeds. Typically, it is inherited in either an autosomal recessive or autosomal dominant manner, although the recessive form is more common. In recessive inheritance, both parents must carry a defective gene to pass the condition on to their offspring. In contrast, with dominant inheritance, a single copy of the mutated gene from one parent can result in the disease.
Given the hereditary nature of this condition, genetic counseling and responsible breeding practices are crucial for preventing its transmission to future generations. As such, it is advisable not to breed affected dogs and carriers. Genetic testing can also help identify carriers and guide breeding decisions to reduce the incidence of hereditary nephritis in at-risk breeds.
Diagnosis of hereditary nephritis in dogs
If you suspect your dog may be suffering from hereditary nephritis, consult with your veterinarian immediately. Your vet will likely begin with a thorough physical examination and then recommend a series of diagnostic tests. These tests may include blood work to check for elevated levels of blood urea nitrogen (BUN) and creatinine — which are indicators of kidney function — as well as a urinalysis to detect proteinuria, hematuria, or other abnormalities in the urine.
To confirm a diagnosis of hereditary nephritis, your veterinarian may recommend more specific tests. Genetic testing can identify mutations known to cause hereditary nephritis in certain breeds, providing definitive evidence of the disease. If genetic testing is unavailable or inconclusive, a renal biopsy might be necessary. This involves collecting a small tissue sample from your dog’s kidney, usually under general anesthesia. Your vet will then examine the tissue histopathologically to identify characteristic changes such as glomerular basement membrane abnormalities.
Treatments for hereditary nephritis in dogs
Once diagnosed, it is essential to work closely with your veterinarian to manage the condition and improve your dog’s quality of life. Since hereditary nephritis in dogs has no cure, treatment mainly focuses on providing supportive care and slowing the progression of kidney damage. Some management strategies include:
- Dietary modifications: Specialized renal diets with reduced protein and phosphorus levels can help reduce the workload on the kidneys.
- ACE inhibitors: Your vet may prescribe angiotensin-converting enzyme (ACE) inhibitors — such as enalapril or benazepril — to reduce proteinuria and slow the progression of renal damage.
- Supportive care: Based on the severity of the symptoms, your vet may also recommend additional supportive treatments such as fluid therapy, antiemetics, appetite stimulants, and phosphate binders.
- Dialysis: In severe cases where the kidneys are no longer able to filter toxins effectively, dialysis is an option. This treatment can be either hemodialysis or peritoneal dialysis, depending on your vet’s recommendation.
The prognosis for dogs with hereditary nephritis largely depends on the severity of the disease and the age at which symptoms first appear. Dogs diagnosed at a younger age tend to have a more severe form of the condition. Under such scenarios, the progression of the disease can be rapid, often leading to kidney failure within months to a couple of years.
While early detection and intervention can help slow disease progression, most affected dogs eventually develop end-stage renal disease, which can be life-limiting. In advanced cases, some pet parents may consider humane euthanasia to prevent undue suffering. Remember, each case is unique, so have a thorough discussion with your veterinarian to determine the best course of action for your dog’s specific needs.