Bisphosphonates is a class of drug which prevents the loss of bone density in the racehorse.
These are substances are prohibited substances within the Rules of the NHA:
73.4.1 Substances capable at any time of causing an action or effect, or both an action and effect:
… 73.4.1.6 the musculoskeletal system;

There is now an allowance by which older racehorse are allowed to be treated for osteoporosis (which results in low bone density bones which are brittle and could break) which do occur with older horses.

The formal International Federation of Horseracing Authorities (IFHA) statement within Article 6 of the International Agreement on Breeding, Racing and Wagering is:

Any bisphosphonate is not to be administered to a racehorse:

• under the age of three years and six months as determined by its recorded date of birth; and
• on the day of the race or on any of the 30 days before the day of the race in which the horse is declared to run.

The bisphosphonate product administered must be licensed for use in horses in the country in which it is being used, and be administered in accordance with the label instructions.

There must be a diagnosis determined by a veterinary surgeon that supports the use of a bisphosphonate as an appropriate treatment, and such treatment must be administered by a veterinary surgeon.

There is the requirement that 

• Only local registered horse-approved drug substances are used.
  There is only one such licensed for use in horses in South Africa, called Tildren which contains Tiludronic acid (also known as Tiludronate).
   Other, locally available human preparations and non-licensed and non-registered products and other bisphosphonates may not be used.
• That the horse must be an older horse (not still a growing horse).
  the racehorses must be 3.5 years old at least (the age when osteoporosis may become problematic).
  There must be control by means of a veterinarian and a formal treatment regimen from a veterinarian (according to the recommendations for the     specific product).
• That younger racehorses (below the age of 3.5 years) may not receive this treatment (as osteoporosis treatment should not be required).
• It is specified that the use of such medication must be prescribed and controlled by a veterinarian and that such treatment must be well-detailed by   the veterinarian in the VTR of the corresponding horse and trainer.

It must be noted that

• a positive finding will result when it is detected in a racehorse younger than 3.5 years.
• that a positive finding will result if it is detected in a racehorse older than 3.5 years - if an official, corresponding diagnosis and prescription is not in     place.
• that a positive finding when result if it is detected on a race day in a racehorse older than 3.5 years - if a 30 day withdrawal period was not complied   with.
• There must be an official diagnosis determined by a veterinary surgeon that supports the use of a bisphosphonate (Tildren) as an appropriate   treatment.
• Tildren must administered in accordance with the product label instructions.
• Tildren treatments must be administered by a veterinary surgeon.

Flumethasone is a therapeutic substance which forms part of locally available veterinary injectable preparations. It is prescribed and administered to the racehorse for injury associated pain and inflammation.
Within international literature and NHA literature there is no publication of a detection time in the racehorse for this prohibited substance. The NHA laboratory conducts screening and confirmation for the presence of this substance in both urine and blood (plasma) to international guidance, at a level which is considered to have an effect on the horse.

• Flumethasone intravenous (IV) administration

Hereby notification is provided that following an intravenous (IV) administration of a typical therapeutic dose of Flumethasone to a racehorse, a detection period of a least 48 hours must be considered. A period of withdrawal which is longer than this period must be applied to prevent a level of Flumethasone which would result in a positive finding for this substance in either urine or blood (plasma).

• Flumethasone intra-articular (IA) administration

Rule 72.1.46 of the NHA specifies that it is a prohibited practise and a contravention to “race a horse within 7 days, calculated inclusively from the date of treatment, after the administration of any intra-articular corticosteroid treatment”. This rule applies for intra-articular treatment with the corticosteroid Flumethasone. 

Please note that irrespective of recent changes in local cannabis legislation the following NHA Rules still apply:

Prohibited substances in horses Rule 73.4.2  
Natural or herbal substances or remedies and/or drugs which have any of the following properties:  
73.4.2.1   antipyretic, analgesic and anti-inflammatory properties;

Banned substances in riders Rule 77.2.2  
Cannabinoids – a concentration in urine of 11-nor-delta 9 tetrahydrocannabinol-9-carboxylic acid (carboxy-THC) greater than 50 nanograms per millilitre;

It is cautioned that preparations produced from any Cannabis plant species contain tetrahydrocannabinoids (THC) which could result in a positive finding in horses and riders.

Methocarbamol is a muscle relaxant used to treat skeletal muscle spasms, with some effect on the central nervous system.  One of its actions is to block nerve impulses (such as pain sensations) to the brain. Methocarbamol is locally available as a human tablet preparation of commercial name “Robaxin”. It has therapeutic application in the horse and is used for the treatment of acute inflammatory and traumatic conditions of the skeletal muscle to reduce muscle spasm and effect muscle relaxation. Within the NHA Classification it is “Class 4 - substances which have a generally accepted veterinary (therapeutic) use in the racehorse but which have the potential to affect performance.”

Methocarbamol is a substance with an Asian Racing Federation screening limit and as member of this federation, the NHA has adopted this limit. This screening limit of 100 ng/ml in urine applies to: “Methocarbamol (restricted to single oral or IV treatment of no more than 5 grams)”

Within this guidance above it is clearly stated that it applies only to a single administration. The reason for this is that multiple dose of this substance have been reported to result in an accumulation of methocarbamol. This is non-predictable between different horses. This accumulation implies that multiple doses have an excretion time which is much longer than that of a single dose.

In oral studies there have been evidence of recycling during some trials. Recycling is when the preparation remains present in stable areas after administration (for example spilling, dripping or spitting by the horse), or when the substance is excreted in the urine and faeces and re-enters the horse. This can be reduced if the stable is frequently and thoroughly cleaned and with the realisation that it is not highly soluble in cold water. Recycling can be non-predictable between horses as well as in different stable environments.

It is recommended that Methocarbamol only be used as single dose treatment to the racehorse, with a detection time of about 48 hours (two days). With a detection of two days a withdrawal time period significantly longer than this must apply.  In isolation of this statement and guidance is the fact that a withdrawal period of several weeks must be applied when multiple doses are administered as part of a treatment regimen.

Consult your veterinarian with regards to suitable withdrawal periods. The NHA does not assume any legal, professional or other responsibility or duty whatsoever as to the accuracy of the data presented in this document. Please note that reliance on and use of the above information does not absolve or diminish a trainer or owner from being responsible for ensuring that the horse complies with the rules relating to the presence of prohibited substances when presenting a horse for a race.