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Wednesday, 13 May 2015

Sheep Medicines
Imperative to a successful sheep farming business is the control of disease and for efficient lamb production animal health and welfare are both essential. Treatment of disease is not as effective or economical as prevention.
Poor health status and subclinical disease can be a major cause of financial losses on many sheep farms. The impact of many diseases can be avoided or minimised by reducing exposure to disease pathogens (effective biosecurity) and implementing effective vaccination and parasite control programmes. These programmes will be designed for each individual sheep farm and included in the flock health plan by the farmer’s veterinary practitioner.
When treatments are necessary there is a joint responsibility between the veterinary surgeon and the farmer to ensure that all drugs, but especially all antimicrobial drugs, are used correctly and responsibly such that all legal requirements are met.

Prescribing Categories
Under 2005 legislation the categories for medicine prescribed for sheep are…
·  
       Prescription Only Medicine-Veterinarian (POM-V)

·         Prescription Only Medicine-Veterinarian, Pharmacist, 
Suitably Qualified Person (POM-VPS)

·         Authorised Veterinary Medicine-General Sales List (AVM-GSL)

·         Non-Food Animal-Veterinarian, Pharmacist, Suitably Qualified Person (NFA-VPS)

POM-V
POM-Vs can only be prescribed by vet surgeons for administration to animals under their care of a vet surgeon. The RVC require a number of criteria to be met…
- The vet surgeon should have been given responsibility for the animal’s health by its owner or guardian.
- The vet surgeon should have performed a clinical examination of the animal for the purpose of diagnoses or prescription, or have visited the premises in which the animal is kept sufficiently often and recently enough to have sufficient personal knowledge to make a diagnosis and prescribe for the animal in question.

POM-VPS
POM-VPS do not necessarily require clinical assessment prior to prescription. This category corresponds closely to the former PML (Pharmacy Merchants List) group of medicines. Medicines in this category can only be prescribed by a registered qualified person (RQP), which is:
-Registered Vet Surgeon
-Registered Pharmacist
-Registered Suitably Qualified Person (SQP).

AVM-GSL
Medicine products under this category may be supplied by any retailers (including supermarkets and pet shops) with no restrictions on supply.

Health and Safety
In addition to the considerations above, medicines are also controlled by the Control of Substances Hazardous to Health (COSHH) Regulations 2002. These regulations control and restrict the use of veterinary medicines in order to prevent damage to human health. Other substances produced by animals (blood, tissue, urine, faeces) are also considered under this act the employer must prevent or control exposure of employees to these substances by information, instruction and training.

Withdrawal Periods for Drugs
The Animals, Meat and Meat Products (Examination for Residues and Maximum Residue Limits) Regulations 1997 control residues of animal medicines in food producing animals. Maximum Residue Limits (MRL) is set which aim to avoid toxicity in man and technical problems for the food producing industries.
 EU legislation defines MRL as:
-Maximum concentration of residue that results from administration of an animal medicine which is legally permitted in the community or recognised as acceptable in or on a food.
Withdrawal Periods are defined as:
-The time between the last doses given to the animal and the time when the level of residues in the tissues (muscle, liver, kidney, and skin/fat) or products (milk, eggs, honey) is lower than or equal to the MRL.

Withdrawal periods are given for time after administration to slaughter (meat production). Where a withdrawal period is 
not given for a species a minimum of the following “standard” withdrawal periods should be adopted. 28 days for meat. Some organic schemes require doubling or tripling of the data sheet recommendations for withdrawal.

Storage of Veterinary Medicines
The main points are:
·         Store in accordance with manufacturer’s instruction
·         Refrigeration must be available and maintained between 2-8*C.
·         Should not be accessible to the public.
·         Storage areas should be kept clean and should be well ventilated. Eating/drinking forbidden.
·         Dates of delivery should be logged and market on products and for multi-use products date of first use should 
be marked.

Veterinary Medicines Regulations 2009 / Part 3 – Records
The keeper of a food producing animal must keep records of proof of acquisition of the medicine.
A veterinary surgeon who administers a vet medicinal product to a food producing animal must either enter the following information personally in the keeper’s records or give it in writing for the keeper to input themselves. The information must include:
(a) The name of the vet surgeon
(b) The name of the product and batch number
(c) The date of administration of the product
(d) The amount of the product administered
(e) The identification of the animals treated
(f) The withdrawal period

Parenteral Administration of Medicines
Medicines should be administered by intravenous, intramuscular and subcutaneous injection. A new sterile needle and syringe should be used on every occasion.
The only exception to single syringe/needle use is the admin of a vaccine to a number of sheep using an automatic syringe. In this situation it is also essential that the fleece is clean, free from contamination and dry. Vaccination of dirty or wet sheep should be delayed until the fleece is suitable; otherwise there is a risk of introduction of bacteria with the vaccine and the development of an abscess at the site of injection. A maximum of 20 – 25 sheep should be injected before the needle is changed; often the volume of the bottle corresponds to this amount.
For each weight of sheep there is a different type of hypodermic needles needed…
Lambs less than 10kg          21 gauge 5/8 inch
Lambs 10 – 20kg                   20 gauge     1 inch
Lambs 20 – 40kg                   19 gauge     1 inch
Adult sheep                           18 gauge     1 inch

Subcutaneous and Intramuscular injections

Sub-c injections are administered in areas where the skin is loose; mainly on the side of the neck or behind the shoulder.

To perform this type of injection, grasp a fold of skin and slide the needle through the skin, holding the needle at parallel the animal’s neck trunk. This method will avoid penetration of underlying muscle or injection into the chest cavity. The needle should be inserted several inches from the operator’s hand to avoid accidental self-injection. To ensure that the needle is not located in a blood vessel, pull back the plunger to check for any blood intake. Ensure that the needle point does not emerge from the other side of the skin fold. Slight resistance when depressing the syringe plunger will indicate that the solution is being injected under the skin and not through the fold and onto the skin surface.

Intra-m injections involve injecting a medicine directly into the muscle mass of the animal; the main site for this is usually the mass of the neck or the hind leg.

Insert the needle connected to the syringe into the muscle with a sharp action, not using too much power but ensuring a swift and sharp motion. Draw back and check for any blood, slowly inject the substance over 10 seconds. Do not inject too quickly as this may cause pain to the animal.

Intravenous injection
This is the fastest route for drug administration, bypassing absorption and is commonly used by vets. However, rapid injection of a drug solution may cause adverse reactions, such as collapse. Drugs administered intra-v includes some antimicrobials, NSAIDs and mineral solutions (e.g. Calcium Borogluconate). The jugular vein in the neck is the common site. Extravascular injection can lead to severe local tissue reaction overlying the site of injection. The use of dirty injection equipment introduces infection directly into the blood stream and can cause septicaemia with fatal consequences.

Drenching

Small volumes of liquid (less than 30mls) are frequently administered by mouth using a drenching gun (ie. Anthelminitcs/Anti-worming and flukicides and some trace element drenches). The animal is suitable restrained with the hind quarters secured (to prevent them moving away) and the head is tilted upwards by the chin, the gun placed into the mouth and aimed down the throat and the solution released. The head should be let go once the sheep has swallowed the solution.

Larger volumes can be administered by stomach tube (orogastric tube), most commonly to lambs.




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