Needleless intradermal injections
The needleless applicator delivers a measured dose of formulation one millimetre into the skin – not through the skin, nor into the muscle. This causes necrosis (death of the skin cells) in the treated area. A bruise forms, followed by a scab which dries and falls off, leaving the stretched skin underneath.
The technology:
In the skin of wool bearing sheep the degree of intervention required is very high as the skin has amazing capacities to regenerate, resume follicle growth, and grow wool, particularly in young animals.
AWI commercial partner’s injection procedure involves the compound being delivered into the skin using needleless injection technology sourced from medical science.
The use of long (one to two centimetre) “nozzles” on the delivery head of the injector handpiece allow the face of the injector to be placed through the covering wool into contact with the skin surface.
Penetration into the skin is only possible when the face of each “nozzle” is in contact with the skin and depth of penetration is controlled by variation of the operating pressure, orifice size and dose delivered. The primary energy source is an inert compressed bottled gas or compressed air.
Progress:
A range of chemicals have been trialled.
An anionic surfactant developed by a commercial R&D company, with support from AWI shows the most promise. These chemicals are registered for human use on varicose veins – they dissolve veins and nerves very quickly.
Work is in its early stages, and although promising, it still has some way to go. The chemical is moving towards product registration is by 2009.
A number of other compounds have been evaluated and those which do not provide adequate flystrike protection or enhance the welfare of the sheep have been rejected – these include: cationic chemicals such as Cetrimide. The enzymes, including collagenase have been put on hold due to import restrictions. This is a normal process for a research and development program.
An injection “pattern” is being developed with the assistance of a plastic surgeon in conjunction with the field experience of professional mulesing operators, the aim of which is to achieve the desired area of skin stretch. On-going trial work plus field experience will provide operators with guidelines on how to apply the injection to accommodate the usual range of variations in sheep type, eg size, wrinkle score, skin thickness, skin movement, etc.
Best practice guidelines will be developed and it is the intention of the commercial partner that this technology will only be available via trained and accredited operators. The partner will manage the commercial release and will be responsible for the training and accreditation of operators. AWI will provide appropriate support in the training and accreditation process in consultation with the company.