Salt intake Salt intake

Dogs with subclinical as well as clinical heart disease have impaired sodium regulation (Hamlin et al. 1967). Dogs with progressive valvular endomay have sodium retention during the prodromal (or compensated) phase of the disease. This is a reasonable conclusion because one of the body's compensatory mechanisms in the presence of reducing cardiac output is sodium and water retention by activation of the renin-angiapathway and aldosterone concentrations have been found to be increased in dogs with spontaneous heart failure.

Sodium retention increases preload on the heart and may lead to hypertension, oedema and ascites.

Plasma sodium concentrations may also be affected by two situations commonly found in geriatrics:

(1) Reduced daily water intake - the thirst centre is reported to be less sensitive to hyperosmolarity in older animals.
(2) Renal insufficiency - leads to sodium retention.

Contrary to popular belief, there is no documented evidence that dogs resist change from a high salt to a low salt diet. In one practice survey, only one client in ten reported any difficulty in getting their dog to accept a very low salt diet, and that was not due to poor palatability (Sauvage J. 1990, personal communication).

If changing from a high salt diet to a low salt diet is going to be a proit is likely to be so in:

(1) older dogs with an acquired taste for high salt diets which has been ~einforced over many years; and
(2) a dog which is inappetent due to the onset of congestive heart failure.

There is no evidence that high salt intake is beneficial to an animal with heart disease.

For these reasons the author believes that sodium intake should be reduced as early as possible in the progression of heart disease, i.e. during Stage 1.

The sodium contents of low sodium' diets available in the UK are listed in Table 2.4. All of these diets actually exceed the minimum daily sodium requirement, but compared with other available foods they reduce excessive sodium intake. Reducing sodium intake reduces preload on the heart.

The daily sodium intake is dependent upon the energy density of the food as well as the amount of sodium in the diet. The higher the energy density the less food is needed, so a high energy, low salt diet is recom

When changing from a relatively high salt diet, it is best to introduce the new food gradually over a period of 10-14 days, and tit-bits and snacks must be avoided as these are often high in salt content.

'Low salt' diets should not be given to animals that have hyponatraemia (rare), chronic debilitation or chronic diarrhoea.