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Commercial Poultry Services

Sandhill Veterinary Services provides a comprehensive service for owners of Commercial Poultry

If clients wish to wait at the practice whilst birds are examined or wish to speak to the Veterinary surgeon it is advisable to make an appointment to ensure that the veterinary surgeon will be present.

Services offered by the practice include:

1) Laboratory testing

2) Post mortem examinations

3) Medicine and vaccine sales

4) Site visits and consultations

5) Routine flock monitoring

6) Vaccine programme advice

We are able to provide services for all these classes of commercial poultry with veterinary programmes specific to each individual site.


Under the Veterinary Surgeons Act we can only supply medication to birds under our care. To be under our care we need sufficient knowledge of the birds for the care to be actual and not merely nominal. In cases of disease we are required to make a clinical diagnosis (and hence will need to see the sick birds) before mediation can be dispensed. In addition we can only supply sufficient medication for the birds owned by that individual client.

Commercial Poultry Diseases

Hygiene and Biosecurity

Biosecurity is the science of reducing the spread of potentially harmful micro-organisms onto and within a site. Biosecurity practices are required in addition to vaccination programmes and planned antimicrobial treatments to reduce the levels of potential pathogenic organisms on a farm.

Disease Transmission 

Pathogenic organisms are transmitted by a variety of routes and an understanding of the ways organisms spread can be helpful in designing strategies to limit disease spread. 

Respiratory viruses               - spread by the birds coughing and sneezing

- carried by aerosol

Intestinal organisms              - spread via faeces

Oviduct infections                  - spread vertically via the egg 

Pathogenic organisms live for variable lengths of time in the environment and this also has implications in designing strategies to limit disease spread. eg 

Coccidia                    )

Many Bacteria           )           live for long periods outside the host in the environment

Aspergillus                 )

Respiratory viruses – generally live for short periods outside the host but can be carried several miles on wind currents

Methods of Spread of Infection


Wind                                                  - Respiratory viruses

Faeces                                               - Coccidia, Many Bacteria

Vermin                                                - Pasteurella, Salmonella

Human intervention                           - Newcastle Disease on lorries, Bacteria on footwear

Feed                                                   - Salmonella organisms

Equipment                                         - E.coli

Litter                                                  - Parasites


The quality of the housing available to livestock can have a significant effect on the effectiveness of Bio security programmes.


            Siting buildings near ponds or lakes utilised by migratory water fowl

            Poorly drained areas with standing water

            Areas with high concentrations of wild birds/vermin

            Major roads with poultry traffic 

Ensure there is the facility to dispose of litter effectively and well away from the site.

Concrete around houses will reduce surrounding vegetation to keep down vermin, and reduce contamination of boots and tyres with mud, litter etc. 


Keep vehicles entering the site to a minimum and consider spray disinfection of vehicle wheels at the entrance to the site.

Regularly refill foot-dips with a DEFRA approved disinfectant (ideally one which is effective in the face of organic soiling).

Keep overalls and boots for visitors on-site and insist that they are worn.

Supply hand-washing facilities for staff and visitors on arrival and departure

Maintain a record of ALL visitors to the site 

Carcase Disposal 

Ensure all carcasses are either removed or incinerated as soon as possible. Use containers with well-fitting lids to reduce vermin numbers.

Factors affecting Range Use

It is important for their wellbeing that free-range laying hens make good use of the range provided for them. In some surveys the average number of hens using a range were estimated at just 20% meaning that on some farms the number of hens using the range was much lower than this. 

Factors that have been observed to affect this figure include:           

1) Wind speed and the wind chill factor. This effect can be modified by providing the birds with wind breaks. It seems that temperature per se does not have an effect on a flock’s use of the range 

2) The indoor stocking density. The higher the density indoors the fewer birds use the range 

3) The age birds are first allowed onto the range. The earlier birds are let out the better is their range use 

4) Area of shelters on the range. The greater the area the better the range is used by the birds 

5) Bird’s confidence. The more fearful birds are the less they use the range 

6) Providing grit improves range usage 

7) Earth floor litter areas improve range use

Salmonella prevention in Laying Flocks

Salmonella infection in laying hens rarely leads to disease in the birds but it is a health threat to farm workers, visitors and consumers of eggs and poultry meat. It is this final threat that has made it so politically important.

Salmonellae are intestinal bacteria that can affect all animals and birds. The proper cooking of food will destroy the bacteria but in poultry it can also be transmitted in intact eggs so increasing the risk of human food poisoning infections.

More than 2500 types of Salmonella have been identified but only a very small proportion of these have been recorded in poultry.

Two types of Salmonella found in laying birds are of real concern in human health. They are Salmonella enteritidis and Salmonella typhimurium and they are of particular concern as they can be transmitted via the egg.

All commercial laying flocks are now routinely tested.

Transmission from breeding flocks to commercial flocks has been virtually eliminated and although the diseases could be introduced into laying flocks via infected pullets these are routinely vaccinated and tested before moving so should not pose a threat to laying flocks.

Potential sources of infection on layer farms:

  1. Pullets – unlikely if birds come from a reputable source.
  2. Other poultry units nearby – Salmonella may be introduced by wildlife and flies
  3. Human contamination on clothing, boots etc.  To reduce this likelihood:

Keep access restricted to only those who actually need access.

Visitor’s vehicles should be kept well away from the houses and if practicable disinfect the vehicle wheels.

Provide overalls and boots for visitors. (the  minimum provision should be a satisfactory boot wash with a disinfectant bath and brush available).

  1. Domestic animals – dogs and cats may carry salmonella so should not go into sheds or onto the range even if the houses are empty
  2. Wild animals – possibly these are greatest threat. Includes birds, insects and mammals.

Birds. Do everything possible to discourage wild birds particularly clean up any feed spillages promptly

Insects. Flies and mites can carry Salmonella so ensure these are effectively controlled.

Mammals. Especially rats and mice. An effective rodent control programme is essential. Note that there is a requirement in testing schedules for rodent droppings or swabs from bait boxes.

Other mammals such as foxes also need to be discouraged – correct disposal of carcasses necessary.

  1. Feedstuffs. Should be free of Salmonella if obtained from a mill who operates under the relevant DEFRA codes of practice for the control of Salmonella. Food can become subsequently contaminated if vermin have access to feed.
  2. Water. Should be safe if from a mains source. If from other sources have water tested and chlorinate it. It can become subsequently contaminated especially in the header tank if it is not enclosed.
  3. Catching gangs, cleaning gangs, equipment etc.

Routine testing of laying flocks: Designed to test for the actual presence of infection on the farm – must at all costs avoid false positives.

Sources of false positives:

  1. Testing kits / equipment – use kits from a known source
  2. Contamination of kits in storage – ensure that they are stored correctly
  3. Contamination of kits when in use / incorrect collection technique for samples – follow the guidelines for collecting samples.
  4. Laboratory error – all testing laboratories have to be DEFRA approved so there should be little likelihood of laboratory errors occurring. 


Always consult the relevant codes of practice for full details of sampling procedures.


A Veterinary Surgeon may prescribe medications only to birds that are under his / her care.

For the birds to be considered to be under his / her care a veterinary surgeon must have been given responsibility for the birds by the owner or the owner’s agent. In addition the veterinary surgeon must have acquired from personal knowledge and inspection an up to date picture of the current health status of the birds. Hence it is not legal for veterinary surgeons to supply medicines on demand for birds about which they have no detailed knowledge.

This discussion of medications is for information only, and is not to be used as an aid to diagnosis or treatment, nor as a replacement for Professional advice from your Veterinary Surgeon.

Vaccine Programme Advice

There is a wide range of vaccines available to commercial poultry producers in the UK to help protect against viral, bacterial and protozoal diseases.

The vaccination programme for a particular farm will depend on the class of livestock present, the clinical history of the site and diseases present in the surrounding area. This programme needs to be agreed in consultation with the veterinary surgeon responsible for the farm.

The source of vaccines may depend on their legal category -either POM-V or POM-VPS

Vaccines are classed as either live or inactivated with live vaccines usually being given orally (via the drinking water), by spray or by eye drop and inactivated vaccines usually being given by injection. The type of vaccine being given usually determines the route of administration.

Vaccines should be administered according to the manufacturer's instructions with additional veterinary advice as necessary.

The following general guidelines for oral and spray vaccination should be used in conjunction with manufacturer's advice. Most live vaccines can be damaged by the presence of chlorine, certain metals and water sanitisers.

Spray Vaccination.

When vaccines are to be dissolved in water to spray over the birds the vaccine can be protected from chlorine, metals, sanitisers etc. by using distilled or de-ionised water. The amount of water used will depend on the age and type of the birds and should be done according to manufacturer's instructions.

The size of the spray droplet is very important so it is necessary to use equipment that can deliver a set droplet size. The smaller the droplet the further down the respiratory tract it can travel. By using the correct size of droplet better immunity can be achieved and adverse reactions prevented.

In order to get a good take of the vaccine the ventilation system of the house needs to be switched off whilst vaccination occurs. In hot weather vaccination may need to be done early in the morning to prevent the birds becoming heat stressed. To keep the birds calm the lights can be dimmed for a period of fifteen minutes before and after the birds have been vaccinated.

Oral vaccination via the water system.

When vaccines are given orally via the water system it is important that all sanitisers are absent when vaccines are being given. To neutralise the effects of chlorine and certain elements in the domestic water, skimmed milk may be added (usually at a rate of 500ml of skimmed milk to 10 litres of water). This should be added about thirty minutes before the vaccine. Alternatively a product such as Vac-Pac Plus (R) may be used. This will instantly neutralise the effects of chlorine and heavy metals and it also contains a dye that will indicate when the water containing vaccine has come down the water lines and is available to the birds.

In order to achieve a good take of the vaccine it is necessary to ensure that all the birds drink the vaccine medicated water within two hours after which the viability of a live vaccine can rapidly decline. This may be achieved by withholding water for about thirty minutes before giving the vaccine to make the birds thirsty. As birds drink when feeding, vaccination should be timed to coincide with food being present in the feed tracks.

Following vaccination clean water should be again made available to the birds.

Advice on the use of Antibiotics

Antibiotics are effective only in treating bacterial infections. Antibiotics for flock medication can be administered either via the feed or water. Diseased birds are more likely to drink than eat so in-water medication is probably the desired route in the face of an infection. All antibiotic should be obtained either from your veterinary surgeon or on veterinary prescription.

Adequate medication of birds is dependent on ensuring the correct dose and duration of the treatment. Under treating, either by dose or duration, is likely to increase the incidence of resistant bacteria on a farm. The quantities of antibiotics to be used are calculated either using water consumption or total weight of the flock. Veterinary advice on dosage levels and duration should be followed at all times.

Choosing the correct antibiotic to treat a particular disease is dependent upon several factors: 

  1. The identification of the causative bacteria and its sensitivitv to the available antibiotics. 
  2. The body tissue infected. Antibiotics have varying abilities to penetrate various body tissues and the choice of a suitable antibiotic will depend on knowledge of these properties. 
  3. Previous treatments. Knowledge of an antibiotic’s previous effectiveness on a site may be taken into consideration when deciding on appropriate medication. 
  4. The Cascade System.  Ideally a licensed drug should be used for a particular species and for a particular disease. If no such medication is available veterinary surgeons are allowed to prescribe other antibiotics using a set formula known as the ‘cascade principle’. (Note that a minimum 28 day meat withdrawal period will then automatically apply) 
  5. Meat and egg withdrawal times must always be observed which may limit the use of certain medications.

Record Keeping. 

All antibiotics used in food producing animals must, by law, be recorded. The records to be kept are detailed in ‘The Animal, Meat and Meat Products (Examination for Residues and Maximum Residue Limits) Regulations 1997.



  Sandhill Veterinary Services 14 Long Street, Topcliffe YO7 3RW telephone 01845 578710 fax 01845 577685 email