Glomerular disease in dogs is a common form of renal disease and a major cause of chronic renal failure. If the glomeruli — a network of tiny blood vessels that filter waste products as they pass through the kidneys — become inflamed due to the deposition and formation of toxins and enzymes in the glomerular capillary walls, the resulting impairment is glomerulonephritis.
Glomerulonephritis In Dogs
Glomerular diesase can also occur due to an infection or neoplasia, which are abnormal benign or malignant growths. Often discovered incidentally during a routine annual health screening, glomerulonephritis is known to be familial in several breeds of dogs including Bernese mountain dogs, bull terriers, Dalmatians, Samoyeds, Doberman pinschers, cocker spaniels, Newfoundlands, greyhounds, Rottweilers, and soft-coated wheaten terriers.
How glomerulonephritis occurs.
Healthy kidneys in dogs and humans remove waste and excess fluid from the blood and create urine which excretes the rest of the waste. In dogs, the glomeruli which are filtering units of the kidneys, absorb and filter water, protein, glucose, and electrolytes from the bloodstream. The kidneys reabsorb the glucose and electrolytes after filtration, and the rest is converted into urine. This process is necessary for dogs to absorb the essential nutrients they need and for their bodies to eliminate the unnecessary or harmful ones.
When antigens and antibodies build up in the blood vessels, the resulting inflammation is called glomerulonephritis.
The definitive clinicopathological characteristic of glomerulonephritis is proteinuria, the presence of abnormal quantities of protein in the urine. Proteinuria occurs when plasma proteins, principally albumin, leak across the damaged glomerular capillary walls. Renal disease patients with proteinuria, which exceeds 1 gm a day, will typically have a poorer prognosis.
Symptoms and signs of glomerulonephritis.
Presenting symptoms of glomerulonephritis are variable depending on the underlying cause — inflammation, an infection which can cause acute kidney disease, neoplasia, diabetes mellitus, long-term use of some drugs, and idiopathic (unknown) causes. Weakness and weight loss are the only signs in some dogs with chronic kidney disease ongoing for months who have not previously shown any overt signs of illness.
Diseases with gradual onset are often difficult to detect, sometimes not until extensive damage is done and a significant percentage of the kidney is diseased. By the time excessive protein is discovered in the urine, the dog may already have ascites, an abnormal collection of fluid in the abdominal cavity.
Once a renal disease is advanced, and in dogs suffering kidney failure, symptoms are:
- Increased thirst
- Frequency of urination
- Lack of appetite
- Elevated temperature
- Distension of the abdomen
In dogs with severe loss of the blood protein albumin, blood vessels in the lungs become blocked causing heavy panting and difficulty in breathing. The resulting high blood pressure may cause sudden blindness.
Diagnosis of glomerulonephritis.
Diagnosis of glomerulonephritis involves a thorough evaluation of the dog's health history, physical examination, assessment of symptoms since onset, and an exploration of any underlying issues or other possible causes of the condition.
To make a definitive diagnosis, a complete biochemistry profile including a chemical blood profile and complete blood count to check for anemia will be performed. This diagnostic indicator may show abnormally low levels of the blood protein albumin and high levels of cholesterol in the blood. The presence of proteins or lack of albumin may help the veterinarian determine an initial diagnosis. A urinalysis will also be conducted which will indicate the level of protein in the urine and the waste product creatinine, and any other corresponding changes in the urine in dogs with kidney failure. The ratio between urine protein and creatinine is calculated to determine the extent of kidney damage. Other tests include a comprehensive metabolic profile which expresses the ratio of blood urea nitrogen (BUN) and creatinine levels. The combination of these diagnostic tools aid the veterinarian in the short-term by guiding his treatment response, helps in the development of a longer-term treatment plan, and ultimately gives cues about the disease's progression or regression.
X-rays and ultrasound are also conducted to evaluate the condition of the kidneys and the extent to which they are impaired. This allows the vet to gauge the size of the kidneys and the condition of other abdominal organs. It's also helpful for less-invasive tissue biopsy purposes. Examination and testing of a sample kidney tissue through biopsy will help rule out other causes of kidney failure such as cancer. Diagnostic imaging is an invaluable part of the diagnostic arsenal and additionally indicates any concurrent diseases.
The discovery of a new indicator or biomarker of kidney disease in dogs and cats called symmetric dimethylarginine (SDMA) holds hope for diagnosing kidney disease at least 9.5-to-17 months earlier than BUN and creatinine levels tests alone.
Treatment, prognosis, and living with glomerulonephritis.
Reducing the workload of the functional kidney is the objective of treating kidney disease. Initially, pain medications, intravenous fluids, and anti-nausea drugs may be required.
While there is no cure for chronic kidney disease in dogs, the symptoms can be managed to give you and your dog more quality time together. Once stabilized, kidney disease if caught relatively early can be managed through regular monitoring and dietary changes that reduce protein, phosphorous, and sodium. The diet concentrates on sources of high-quality protein and carbohydrates enriched with antioxidants and fatty acids.
Antibiotics are used to treat bacterial infections, and kidney stones and blockages can be treated with surgery with subsequent dietary changes.
More severe cases may require periodic fluid therapy and medications to control the symptoms. In more advanced cases, kidney dialysis or kidney transplant may be indicated.