Chloride - Nutrition

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What is Chloride?

Chloride is the ionised form of the element chlorine and is the principal anion (negative ion) in extracellular fluids, where it is usually combined with the sodium cation (positive ion) to form sodium chloride (common salt). The approximate concentration of salt in blood is 0.9%.

Why is it Important?

The main function of chloride is in maintaining acid-base balance and contributing to the osmotic pressure found in extracellular fluids.

Roles in the Body

Chloride metabolism is very closely linked to sodium metabolism and factors that influence sodium balance also tend to have the same effect on chloride. Chloride is necessary to create a low pH (acid conditions) within the stomach, which is required for proteolysis and also provides some protection against bacterial colonisation. Stomach acidity is maintained by enhanced chloride secretion and increased sodium absorption.

Consequences of Chloride Deficiency


Naturally-occurring chloride deficiency in dogs is rare and there is very little information on the specific effects of sub-normal intakes of dietary chloride.

Recognised Syndromes Related to Chloride Deficiency

Signs of chloride deficiency were observed in puppies fed a milk substitute diet containing 0.021% chloride on a dry matter (DM) basis. After two weeks puppies developed low plasma chloride and potassium and a metabolic alkalosis. General weakness, ataxia and stunted growth were noted. In comparison, puppies fed a diet with a chloride content of about 0.3% DM showed normal growth and no abnormalities[1].


The occurrence of naturally-occurring chloride deficiency is very rare in cats and observations are confined to feeding trials of diets adjusted to contain low amounts.

Recognised Syndromes Related to Chloride Deficiency

Signs of chloride deficiency in cats are similar to those seen in dogs and result primarily from an associated secondary potassium deficiency. These signs were seen in kittens fed diets containing up to 0.07% chloride on a DM basis. Kittens fed diets with chloride concentrations of 0.1% DM or higher did not develop any signs associated with deficiency[2].  



There is little if any feeding trial information on the effects of excessive intakes of chloride in the dog. If extrapolation is made from the tolerable dietary content of sodium (1.5% DM) and an assumption made that the chloride intake is mainly or solely from the sodium salt, then an acceptable level of dietary chloride would be about 2.3% DM.


Feeding chloride at dietary contents of 1.1% DM to kittens or 1.2% DM to adult cats as the calcium salt did not result in adverse effects[3][4]. However, negative calcium and potassium balances were reported by Ching et al.[5] in adult cats fed a diet with a chloride content of 1.6% DM for five months. This value is substantially lower than the theoretical acceptable chloride content for dogs shown above. Nevertheless, these cats received the increased chloride mainly as the ammonium salt, which produces a greater degree of metabolic acidosis than occurs with calcium or sodium salts. This may have resulted in the adverse effects on calcium and potassium balances. It is clear, therefore, that the toxicity of excessive chloride in the diet depends crucially on the mineral salt that is delivering the increased amount. If the dietary chloride is mainly in the form of neutral salts (such as sodium), then the acceptable value for the dog will also be applicable to cats, since the acceptable dietary sodium content for cats is similar to that for dogs.

Dietary Sources

The best sources of chloride for dog and cat foods are animal products, including fish meals and meat meals, also milk and milk products. Cereals contain limited amounts of chloride. In addition, the chloride salts of sodium, potassium, calcium and magnesium are commonly used to supplement manufactured dog and cat foods.


  1. Felder, C, Robillard, J, Roy III, S, Jose, P (1987). “Severe chloride deficiency in the neonate: The canine puppy as an animal model”. Pediat. Res. 21:497-501.
  2. Yu, S, Morris, J (1999). “Chloride requirement of kittens for growth is less than current recommendations”. J. Nutr. 129:1909-1914.
  3. Pastoor, F, Van’t Klooster, AT, Beynen, A (1994). “Calcium chloride as urinary acidifier in relation to its potential use in the prevention of struvite urolithiasis in the cat”. Vet. Q. 16(suppl.):37S-38S.
  4. Pastoor, F, Opitz, R, Van’t Klooster, AT, Beynen, A (1994). “Substitution of dietary calcium chloride for calcium carbonate reduces urinary pH and urinary phosphorus excretion in adult cats”. Vet. Q. 16:157-160.
  5. Ching, S, Fettman, M, Hamar, D, Nagode, LA, Smith, K (1989). “The effect of chronic dietary acidification using ammonium chloride on acid-base and mineral metabolism in the adult cat”. J. Nutr. 119:902-915.