Sodium in Dogs: Function, Requirements, and Hyponatremia in

What is sodium in dogs?

Sodium (Na⁺) is the most important extracellular cation and an essential macromineral. It regulates osmotic pressure, extracellular fluid volume, and acid-base balance. Together with potassium (K⁺), sodium controls nerve and muscle conduction via the sodium-potassium ATPase.

Sodium enters the body through food and is excreted by the kidneys—renal sodium regulation is a key mechanism for controlling blood pressure. A balanced sodium homeostasis is essential for stable hemodynamics, neurological function, and hydration.

Background + Scientific Context

The NRC (2006, Nutrient Requirements of Dogs and Cats) defines sodium requirements: AAFCO minimum for adult dogs: 200 mg/kg dry matter (DM). NRC recommendation: 370 mg/kg DM. It is difficult to establish a defined upper limit for healthy dogs—in the short term, healthy dogs can tolerate high amounts of sodium (via renal excretion); however, in cases of impaired kidney function or heart disease, excessive sodium can become clinically problematic. Sodium and chloride are regulated as an electrolyte pair—a chloride deficiency also alters sodium balance.

Fascetti and Delaney (2012, *Applied Veterinary Clinical Nutrition*) describe nutritional therapy aspects: For heart disease and chronic kidney failure, a low-sodium diet is recommended—high sodium intake increases preload and worsens heart function in cases of pre-existing heart failure. The sodium content in commercial diet foods for heart and kidney patients is significantly lower than that in standard foods. A BARF diet consisting primarily of muscle meat contains sufficient sodium—specific supplementation is unnecessary.

Ettinger et al. (2017, *Textbook of Veterinary Internal Medicine*) describe the diagnostic significance of the sodium-potassium ratio in hypoadrenocorticism (Addison’s disease): Primary Addison’s disease leads to sodium loss and potassium retention due to a deficiency of mineralocorticoids (aldosterone) — clinical presentation: Hyponatremia (Na⁺ < 135 mmol/L), hyperkalemia (K⁺ > 5.5 mmol/L), Na:K ratio < 27:1. This electrolyte profile is considered the diagnostic hallmark of Addison’s disease in dogs and serves as the basis for screening prior to an ACTH stimulation test. Hypernatremia (Na⁺ > 155 mmol/L) occurs with dehydration or excessive salt intake and is less common but potentially dangerous (cerebral symptoms).

Vitomalia-Position

The sodium content in commercially produced dog food is formulated to meet a dog’s nutritional needs. Sodium becomes clinically relevant in cases of heart disease (restriction), kidney failure (restriction), and in dogs with Addison’s disease (diagnosis). Table salt in large quantities is toxic to dogs—table salt is not Supplement.

When does sodium become a factor?

• Heart disease: low-sodium food recommended by a veterinarian
• Chronic Kidney Disease: Monitoring Sodium Levels in the Diet
• Weakness, vomiting, collapse: Rule out Addison's disease (measure Na:K ratio)
• BARF: Never supplement with table salt — animal products meet the body's needs
• Heat exhaustion / intense endurance exercise: Check electrolyte balance, including sodium levels

Practical application

Sodium status — clinical interpretation:

Addison Screening — Electrolyte Panel: - Na⁺ < 135 mmol/L - K⁺ > 5.5 mmol/L Na:K Ratio < 27:1 - Confirmation: ACTH stimulation test (cortisol response)

Sodium content in common food sources:

Common Mistakes & Myths

• “A little salt in their food won’t hurt.” Table salt in small amounts on an occasional basis isn’t a serious problem for healthy dogs. Regular use or large amounts—especially for small breeds or dogs with heart or kidney conditions—can be harmful. Excess sodium increases thirst and puts a strain on the kidneys and heart.
• “BARF has too little sodium.” Lean meat contains enough sodium to meet a dog’s needs. Adding table salt to BARF is contraindicated and not recommended.
• “You can tell right away when a dog has Addison’s disease.” Chronic Addison’s disease can go on for years with nonspecific symptoms (lethargy, vomiting, weight loss). Addisonian shock (Addisonian crisis) is a medical emergency. Regular electrolyte checks are recommended for breeds predisposed to the condition.

Current State of Research (2026)

Sodium metabolism in dogs is well characterized. Diagnosing Addison’s disease using the Na:K ratio is standard practice in veterinary medicine. Current debates concern optimal sodium limits in heart disease diets—too strict a restriction can be counterproductive if the renin-angiotensin-aldosterone axis is stimulated by sodium deficiency. Dietary recommendations for heart disease are regularly revised.

Frequently Asked Questions

Is table salt toxic to dogs?

In large quantities, yes—sodium chloride can cause hypernatremia, dehydration of nerve cells, and neurological symptoms in dogs. Occasional exposure (such as a salty chip) is harmless, but regular consumption or large single doses are dangerous.

What does a low sodium level mean in dogs?

Hyponatremia (Na⁺ < 135 mmol/L) combined with high potassium levels is a warning sign of Addison’s disease. Other causes include chronic heart failure, severe diarrhea, and water intoxication. If Addison’s disease is suspected, a veterinary evaluation should be conducted using an ACTH stimulation test.

Does my dog need low-sodium food?

Only for specific conditions: heart disease (especially congestive heart failure) and advanced kidney disease. Healthy dogs do not benefit from a reduced-sodium diet—standard commercial dog food is properly formulated.

Related terms

• Minerals in Dogs
• Dog Nutrition
• Potassium in Dogs
• Kidney Disease in Dogs
• Addison's disease in dogs

Sources & Further Reading

1. National Research Council (NRC). (2006). Nutrient Requirements of Dogs and Cats. National Academies Press. ISBN 9780309086288.

2. Fascetti, A. J., & Delaney, S. J. (Eds.) (2012). Applied Veterinary Clinical Nutrition. Wiley-Blackwell. ISBN 9780813815688.

3. Ettinger, S. J., Feldman, E. C., & Côté, E. (Eds.) (2017). Textbook of Veterinary Internal Medicine (8th ed.). Saunders. ISBN 9780323312110.