Oral electrolyte products for the treatment of horses in exercise

1. Purpose

The purpose of this guideline is to provide a template for the registration of a class of veterinary chemical products termed ‘orally applied dry-soluble-powder equine electrolyte products’, including parameters for:

• permissible constituents
• chemistry and manufacture
• use patterns and allowable therapeutic claims
• labelling, including instructions for use and handling.

In this guideline, electrolytes are minerals that are dissolved in the blood and cellular fluids, including sodium, potassium, chloride, calcium, magnesium and phosphate, as electrically charged salts or ‘ions’. Electrolytes or ‘body salts’ are involved in nerve transmission, muscle contraction, metabolic processes and water balance. They are lost in sweat, tears, digestive secretions, urine and faeces.

Equine electrolyte products require registration where they are represented as being suitable for, supplied or used to treat diseases or conditions in horses resulting from a deficiency of electrolytes, and/or to improve or modify the health, production, performance or behaviour of an animal.

Equine electrolyte products are usually administered in the horse’s feed or drinking water. In some situations, for example, to ensure that the horse has consumed the entire intended dose, aqueous solutions can be administered directly into the mouth using a delivery device appropriate for that purpose. In certain cases, it may be considered necessary to administer the electrolyte product by stomach tube under veterinary supervision.

If an electrolyte product conforms to this model, you may apply to the Australian Pesticides and Veterinary Medicines Authority (APVMA) to register the product by reference to the model.

If a product conforms to this guideline, we may be satisfied that it meets the statutory criteria in the absence of data, except where it is specified here that data should be provided. Such applications also do not require the nomination of an appropriate reference product, as the model sets the parameters for satisfying the criteria.

If you are applying for registration under this model, you should clearly indicate that the application references the APVMA Oral Equine Electrolytes Model.

If the electrolyte product contains bicarbonate or citrate ions, makes any claims other than those specified here, or does not otherwise comply with the model, you should not refer to the model in your application.

Note that certain stockfood supplements, including certain electrolyte products, are excluded from the requirements of registration. This model is only applicable to those electrolyte products that are required to be registered by the APVMA.

2. Which electrolyte products generally require registration?

Electrolyte products for use in animals generally do not require registration if all of the following apply:

• The product is presented in whole food or in a food premix for voluntary ingestion, as a block or a lick for voluntary ingestion, or with directions to administer in the feed for voluntary ingestion (not administered as a drench or by stomach tube)
• The only claim on the label consists of the words ‘to supplement diets where levels may be low’, or words to that effect
• The product is formulated in such a way that after following the label directions for use the intended recipient receives between 25% and 100% of the daily requirement of each electrolyte (from all sources) for maintenance, growth and exercise, as recommended by the National Research Council (NRC) of the United States National Academy of Sciences

The words ‘For Animal Treatment Only’ should not be included on the label of excluded stockfood supplements that do not require registration with the APVMA. Refer to the APVMA’s User guide: what is or isn’t a veterinary product for further information.

Electrolyte products for use in animals generally do require registration if either of the following applies:

• The product is to be administered parenterally, or enterally via a stomach tube or directly into the animal’s mouth, for the direct or indirect prevention or treatment of a disease or condition caused by an electrolyte deficiency
• Any claim in relation to the product beyond ‘to supplement diets where levels may be low’ (or words to that effect) is made, such as a claim to prevent or treat a disease or condition caused by an electrolyte deficiency or to improve and/or modify the health, production, performance or behaviour of an animal

Such products are considered to be represented as being suitable for, supplied or used for a purpose commensurate with the definition of a veterinary chemical product in the Agvet Code.

The registration model set out here relates only to those products requiring registration and which conform to the parameters set out below.

3. Use pattern parameters

The products to which this model applies may only be for the purposes listed here.

3.1. Target animal species

Healthy horses suitable for exercise and work.

3.2. Uses

Exercising horses have an absolute requirement to dissipate the heat generated by muscular activity. One of the most important mechanisms of heat dissipation in the horse is by evaporative cooling following sweating. Equine sweat is a hypertonic electrolyte solution, and significant quantities of both fluid and electrolytes are lost in sweat.

Equine electrolyte products are used to help replace the electrolytes lost in sweat. When provided in conjunction with freely available water, they allow the horse to rehydrate and replace water lost in sweat.

Quantitatively, the most significant electrolytes lost by horses in sweat include sodium (present at 3.0 to 3.7 g/L), potassium (present at 1.2 to 2.0 g/L) and chloride (present at 5.3 to 6.2 g/L). Equine sweat also contains relatively low levels of calcium (0.08 to 0.3 g/L), magnesium (0.024 to 0.14 g/L) and phosphate (<0.01 to 0.3 g/L).

3.3. Dose rate

Fluid and electrolyte loss in sweat during exercise is related to the speed and duration of work, the environmental conditions (temperature and humidity) and the training status and fitness of the horse.

The dose rates set out in the Labelling guidance section of this model for the heavy sweat and moderate sweat formulations have been determined by taking into account the NRC recommendations for the replacement of sweat losses, as estimated by body weight loss during exercise.

The dose rates set out in this model are considered to be appropriate and safe. However, as noted in the Labelling guidance section, veterinary or nutritionist advice should be sought on the appropriate use of electrolytes and to ensure that daily electrolyte intakes from the diet and electrolyte products match the daily requirements of each horse. This is consistent with normal industry practice and should be reflected in the label instructions.

4. Chemistry and manufacturing parameters

The products to which this model applies may contain only the constituents set out in this section. The concentration of any constituent should not exceed the limits specified here. Where no limits are specified, the allowable concentration of those constituents may be at the manufacturer’s discretion.

4.1. Active constituents

Products may contain the following active constituents:

BP = British pharmacopoeia; USP = United States pharmacopeia.

4.2. Non-active constituents

Equine electrolyte products to which this model applies may contain non-active constituents that perform a variety of functions, such as improving the physical characteristics of the formulation or enhancing its attractiveness.

Permitted non-active constituents are flavouring agents and those anti-caking and colouring agents listed in standards published by Food Standards Australia New Zealand as approved food additives.

The maximum total allowed concentration of all non-active constituents is 2%.

4.3. Formulated product details

The equine electrolyte products covered by this model are to be formulated as dry powders. They may be administered by addition to the feed or drinking water of the horse or prepared as a ready-to-administer aqueous solution for direct administration to the horse.

4.4. Formulation

The APVMA considers 2 formulation options under this model:

• Heavy sweat formulations: This type of formulation should contain at least 70% weight per weight (w/w) combined potassium and sodium chloride so that the ratio of potassium to sodium is 1.8 to 2.2:1.
• Moderate sweat formulations: This type of formulation should contain at least 70% w/w combined potassium and sodium chloride so that the ratio of potassium to sodium is 1:1.

These formulations may also contain any of the other constituents listed under Active constituents and Non-active constituents.

4.5. Shelf life

In the absence of stability data, we may be satisfied that the maximum shelf life for products that conform to this model is 36 months when stored below 30°C (room temperature). However, it is your responsibility to be satisfied that the shelf life shown on the label is appropriate. You may choose to nominate a shorter shelf life.

4.6. Maximum pack size

You should not propose any pack size greater than 25 kg.

5. Labelling guidance

You should review the APVMA’s Veterinary Labelling Code for information on how to set out your label. Claims and instructions should be consistent with those outlined in this section. Labels should also contain the following elements.

5.1. Active Constituent

Each kg of product contains:

[List the concentration of each electrolyte expressed as the ‘ion’]

x g/kg of sodium (Na+)

y g/kg of potassium (K+)’

[etc]

[Therapeutic claim]

[For heavy sweat formulations]

An aid in the prevention and treatment of dehydration and electrolyte imbalance caused by heavy sweat loss during prolonged exercise such as training, racing, competition or travelling, particularly in hot, humid conditions.

[Or]

[For moderate sweat formulations]

An aid in the prevention and treatment of dehydration and electrolyte imbalance caused by moderate sweat loss during exercise such as training, racing, competition or travelling.

5.2. Directions for use

Fluid and electrolyte loss in sweat during exercise is related to the speed and duration of work, the environmental conditions (temperature and humidity) and the training status and fitness of the horse.

Veterinary or nutritionist advice should be sought on the appropriate use of electrolytes and to ensure that daily electrolyte intakes from the diet and electrolyte products match the daily requirements of each horse.

[For heavy sweat formulations]

This product is intended for use after heavy sweat situations (such as an endurance ride) or for standardbred horses training in hot, humid conditions, where the horse’s bodyweight loss through sweat is typically above 4 per cent.

[Or]

[For moderate sweat formulations]

This product is intended for use after mild to moderate sweat situations where the horse’s bodyweight loss through sweat is typically less than 4%.

This product is for administration after exercise. It is NOT suitable for use just prior to or during exercise, such as during an endurance ride.

Always ensure that an adequate supply of clean, fresh drinking water is available after administration of this product. In addition to the salt provided by this product, free access to common salt (sodium chloride) as rock salt or salt block should also be provided.

5.3. Dosage

The exact dose will depend on sweat loss. The typical dose for a horse weighing 500 kg is 30 to 60 g per day (for other body weights, scale the dose directly on a body weight basis). One level measure/standard tablespoon is approximately x g. [Insert the amount in terms of the level measures (where there is an enclosed measure) or level standard tablespoons]

5.4. Administration

The product may be administered via the following methods:

• In feed
  Administer by mixing the required dose into the feed. It may be necessary to dampen the feed a little to avoid excessive dust and to prevent the product from settling to the bottom of the feed bin. If the horse is fed twice per day, mix half the dose in morning feed and half in night feed.
• In drinking water
  The dose may be administered by dissolving it in 25 to 50 L of drinking water.
• As a drench
  The dose may also be administered directly as a 2.5 to 5 L drench, making sure the horse is swallowing.

NOTE: Administration of electrolyte products by stomach tube is associated with a number of potentially serious adverse effects and should only be undertaken by or under the direct supervision of an appropriately qualified veterinarian.

Always ensure that an adequate supply of clean, fresh, untreated drinking water is available after administration by any method.

6. Other guidance

You should refer to the Make an application page for details about application requirements that are not specified in this guideline.