Sodium Deficiency in Dogs

Hyponatremia, a sodium deficiency, occurs when the body’s sodium level drops below a normal level, causing an excess of water in the body’s cells. This offset of the sodium to water balance causes the cells to swell, including brain cells. The additional water in these cells causes many of the symptoms associated with this condition. While this condition is fairly common, it can be life-threatening if not treated.

Sodium deficiency is when the body is lacking a normal concentration of sodium (around 140 mEq/L). Due to the swelling of brain cells from an excess of water, a sodium deficiency will likely result in neurological symptoms. There are a range of causes of sodium deficiency, spanning from diarrhea to heart failure. If your pet exhibits symptoms of sodium deficiency, you should visit a veterinarian, where urine and blood tests will be done to determine and treat the cause of the condition.

Because the sodium deficiency leads to an increase of water in brain cells, a majority of the manifestations are neurological in nature, making it hard to narrow down without expertise. There are some noticeable symptoms that indicate a sodium deficiency:

• Lack of energy
• Vomiting
• Seizures
• Less alert
• Disorientation
• Loss of appetite
• Lowered muscle strength

Types

The types of hyponatremia are differentiated by causes of the water-sodium imbalance. There are three specific types of causes, all leading to a greater water content than sodium content:

• Euvolemic hyponatremia is a condition where the imbalance is caused by an increase in the overall water while the amount of sodium does not increase.
• Hypervolemic hyponatremia is a condition where the imbalance is caused by a greater water increase than sodium increase. What is different about this condition is that both sodium and water increase, water just increases by a greater amount.
• Hypovolemic hyponatremia is a condition where the imbalance is caused by a greater sodium decrease than a water decrease. Much like hypervolemic hyponatremia, both experience a change. The difference is that both decrease, and sodium decreases by a greater value.

There are a few different causes that initiate either an increase in water retention or decrease in sodium content.

• Significant burns on the body
• Diarrhea
• An increase of urine output, typically as a side effect of medication
• Heart failure
• Sweating
• Vomiting
• Pancreatitis
• Abnormal glucose levels
• Abnormal hormone creation
• Renal failure
• Fluid accumulation in abdomen

Because there are a number of differing causes of sodium deficiencies, diagnosis will require a complete physical examination, including a blood test and urine analysis. There are certain laboratory tests that can aid in the diagnosis of hyponatremia.

• Metabolic panel: This is a group of blood tests that will provide insight into your pet’s metabolism and overall chemical status.
• Osmolality blood test: Another blood test, this looks at concentrations of all chemical components found in the blood.
• Osmolality urine test: Similarly to the osmolality blood test, this test uses a urine sample to measure the concentration of chemical particles in the urine.
• Sodium urine test: The sodium urine test is helpful in determining sodium deficiency because it measures the amount of sodium in the urine. A concentration less than 140 mEq/L can be indicative of a sodium deficiency.

Once these laboratory tests are completed, the veterinarian will analyze the results and compare the concentrations of water and sodium to determine if hyponatremia is the cause of symptoms. These tests will also allow the veterinarian to rule out other possible conditions, or consider them if something else shows up.

The first focus of treatment will to be identify the cause of sodium deficiency and treat that problem first. If treatment of the cause does not bring the sodium and water levels back to equilibrium, the next step is to look at treatment options that increase the amount of sodium present to bring things back into balance.

• Patients with chronic hyponatremia are less likely to exhibit symptoms, probably because the body has had time to adjust to the condition. Treatment of these animals may actually be more dangerous than the condition itself. As a result, these patients are usually treated by restricting water and monitoring of the water to sodium concentration.
• Alternatively, patients that do exhibit symptoms are treated by attempting to stabilize the sodium to water ratio. This can be done through crystalloid solutions, fluids through a vein, and medication.

Ultimately, treatment of sodium deficiency depends significantly on what condition is causing the imbalance.

Post-treatment recovery and management depends largely on the underlying cause of the sodium deficiency. In regards to the deficiency itself, it will be necessary to have follow-up visits with your veterinarian in order to monitor the effectiveness of treatments.

The largest post-treatment focus will be on monitoring the overall water to sodium balance and ensuring that it is stabilizing with treatment. Instances where there is a quick onset of hyponatremia are significantly more dangerous than if it is a more chronic condition. It’s important, especially in quick onsets where symptoms are more likely to manifest, that monitoring of the sodium and water levels occurs. Being aware of your pet’s behavior and conscious of any of these effects post-treatment could save your pet’s life. It is possible, though, that in treating the underlying causes of the hyponatremia, the balance will be restored, and length monitoring of levels will not be required.