Oral drenches administer a set volume of chemical to the mouth/throat of cattle. This can be done with either a drench gun or a drench hook.
A parasite population can develop resistance to a chemical through:
Pour-on applications can be susceptible to under-dosing (see points above) plus caked mud, lesions, wet skin etc can reduce chemical uptake. Social licking may also decrease the actual dosage received.
Everyone working in the rural industry has a ‘duty of care’; a legal obligation to provide a safe workplace for everyone on the property.
Oral drenching requires use of a purpose manufactured hand piece or drench gun to deliver a set volume of drench to the bovine throat. A drench gun connects by a hose to the drench container or backpack and uses hand compression of a lever to deliver a set volume of drench to each animal.
Drench guns must be calibrated at the beginning of the drenching procedure by setting the required drench volume on the gun cylinder and then measuring over a number of deliveries that the correct volume of drench is being delivered. A calibrated measuring cylinder is used to measure the volume delivered by the drench gun.
Cattle should be restrained in a head bail. The operator stands in front of the bailed bovine and passes the drench gun horizontally into the mouth, and gently but firmly, over the back of the tongue, taking care to avoid damage to the mouth teeth and gums. Care must be taken to avoid directing drench liquid into the trachea. Cattle occasionally spit or cough the drench from their mouths. If this occurs the animal should be partially or completely re-drenched depending on whether the dose was partly swallowed or not at all.
A drench hook is effectively a drench gun extension or a further attachment to the drench gun in the style of an elongated tubular metal hook. This device enables oral delivery of drench to cattle confined in a raceway, without head bailing. The hook is caught into the commissures of the lips of standing cattle. Once in place with the hook opening comes to rest at the level of the rear molars. Hand compression of the drench hook lever rapidly delivers liquid drench to the back of the throat from where it is swallowed.
A drench hook is best used by an operator walking on a raised platform putting him or her at an ergonomically correct height for easy access to the mouths of cattle in the raceway. Use of a hook removes the need to head bail each animal.