Environmental medicine tool box for Pig Vets

John Carr

Murdoch University/Portec Australia



Poor performance on pig farms is too often blamed only on pathogens.  The farm staff and veterinary team spend too much time and emphasis on treating these “diseases” relying on identifying the bug and finding a suitable “medicine” to heal the pigs.    However, in practice it is often better to promote health rather than treat disease.  In production medicine, once an animal actually expresses clinical signs of disease, too much money has already been lost.  In addition, the animal’s welfare and well-being has suffered – a major concern to the veterinarian.


This article discusses a systematic approach and details basic equipment to assist the veterinarian’s ability to assess a pig’s well-being and welfare and then change the pig’s environment where deficiencies are identified.  The bigger challenge to today’s veterinarian is understanding animal husbandry sufficient depth to suggest meaningful changes.


When we start our clinical examination we quietly look over the “stable door” and observe.

The environment can be broken down into four major categories:

Water; Food; Floor and Air

Pen design draw 1 label copy

environmental anlaysis 5 label copy

The basic pig pen’s environmental components

A simple tool kit used in environmental medicine


Approach to environmental medicine

The first approach is to ask the pig whether it is comfortable and is displaying behaviour within normal parameters.

Possible abnormal pig behaviour can be considered in two broad patterns:


Clinical exam preentry 1

Before the clinician enters a building, the pigs should be examined in an undisturbed natural state to determine their acute welfare situation.

Using the four categories, it is possible to note various normal and abnormal behaviours, which then can be examined in more detail.



Water short nursery 3 arrow

Feed insufficient grower arrow

Inadequate water space with aggressive actions between pigs – arrowed.

Inadequate feed space – every feeder is working and there are signs of aggression – pig arrowed.

Grower varanda overstocked arrow

Air chilled piglets

Inadequate sleeping accommodation, some pigs have to sleep in the defecation area

Inadequate air quality.  The pigs’ lying patterns  indicate they are cold; note the piglets do not place their stomach onto the cold floor



The pig’s defecation pattern indicates the area where the pig will not select to sleep.  It is vital to examine the defecation pattern.


The two pens shown below are on the same farm.  Why would some pigs defecate over the slatted area and sleep on the appropriate solid area whereas another group defecate over the solid area and thus sleep over the inappropriate slated area?

Air draught lying au1

Air defecation pattern poor au 1


The pigs are lying on the solid portion of the floor and defecating over the slats


Pigs defecating on the solid area and sleeping on the slatted area.


The pigs throughout the farm failed to sleep in the human designated solid sleeping area.  Examination of the air flow within the building revealed the cause:


Cross-section of the building and air flow patterns:

The building was designed with a central slurry system.  The pen is slatted above the slurry system with solid flooring area in the rest of the pen.  The pigs are supposed to sleep on the solid portion and defecate over the slatted area.  To encourage the pigs to defecate over the slatted area the drinkers are placed in this area. 


Unfortunately, the ventilation system utilized a cross-flow automatic curtain sided system which has a low air speed.  When the air flow was examined, the cold entry air entered the building and fell into the building into the passageway and solid floor area.  The air then moved into the centre of the house at a speed greater than 0.2m/s – a draught.  This encouraged the sleeping pigs to move away from the solid area to the more comfortable slatted area, despite the drinker wetting and cooling the slatted area.  The pigs then choose to defecate in the cool solid area.  This in turn caused the solid area to become wet and smelt of faeces.  This encouraged more defecation.  The fact the air at entry was not attached to the ceiling, potentiated the problem.

The building, while good for the farm accountant (a single slurry system is cheaper than two channels), totally ignored the natural requirements of the pig.   The solutions would be:



Tools required to examine the water supply

Water measure collapsableWater measure collapsable 1

Collapsible 250 ml water cups

Water stopwatch


Floor tape measure

Measuring cup


Small tape measure

Water Wrench

Water multipurpose tool

Water TDS tool


Multipurpose tool

Total dissolved solids meter


Systematic approach:

Observe the pigs using the drinkers

Observe the type of drinkers

Observe the position of the drinkers in the pen and their locality in relation to the feeders

Note the distance between the drinkers

Count the number of drinkers in the pen and number(s) available per pig

Note any drinkers which are dirty – this probably indicates that the drinker is not working

Measure the flow rate of water.  In troughs note the depth of the water.  In the farrowing area check every drinker

Note any environmental impact – frozen or hot water supplies

Measure the height and angle to the drinker

Note any drinker which is leaking

Determine the water quality – taste; salt concentration; faecal contamination and/or temperature for example

Where failures are determined, remove the drinker and examine in detail



Simple examples where there were problems with the water supply:

The farm problem accompanying the picture is highlighted in blue

Water Drinkers too high

Water blocked au 2 arrow

The drinkers are too far from the feeders and the floor management results in variable height

The farm suffered from a variety of vice issues and poor growth

A dirty drinker (arrow) should always raise alarm and needs to be urgently checked in detail.

The reduction in water availability resulted in variable growth, increased aggression over the drinkers which became more acute as the pigs got bigger

Water none sp

Water frozen hospital arrow

water hopeful

There is no water flowing from the drinker – in any circumstance a severe welfare problem.

Unfortunately both drinkers in the pen failed resulting in death from “salt” poisoning

Environmental conditions can impact the water supply

The pigs in the hospital pen failed to recover before this freezing issue was realized – this is a serious welfare failing

Drinkers height must be corrected for the pigs

The lack of water accounted for greasy pig disease on this farm

Water drinker turned leaking

Water taste1

Water drinker poor au8

The drinker is twisted making water difficult to access and they are leaking

The farm produced excess slurry and demonstrated variable growth rates and pneumonia

The quality of water should be acceptable for man to drink.  If you are unwilling to drink the water, why should pigs?

The palatability of the water restricted lactating sow feed intake.

Drinkers which are inadequate should be immediately fixed

The damaged drinker was not used by pigs reducing their water availability



Tools required to examine the feeding system

Floor tape measure

   >3mm         >2 mm    >1mm    <1mm

Feed analysis no mids

Feed Weigh balance copy

Tape measure to calculate feeder space

Feed sieve to measure particle size – Bygholm kit

Scale to measure weight of feed being feed


Systematic approach:

Examine the feed bin or feed storage area

Observe the pigs using the feeders

Observe the type of feeders

Observe the position of the feeders in the pen and their locality in relation to the drinkers and defecation area

Calculate the feeding space and the space available per pig

Note any feeder where feed is unavailable or is overflowing

Note any feed bin, pipeline or feeder which is leaking feed, particularly through the slats

Are the rough/sharp edges to the feeder which may cause injury to the pigs?

Determine the feed quality – particle size and palatability.  Taste the feed.  There should be no pig feed that should be harmful to man

Estimate age of any fly population in soiled feed to provide time basis for stockmanship observance

Note any feeder which is vulnerable to vermin attack

Examine if the correct feed weight/volume is being used

Simple examples where there were problems with the feeding supply

The farm problem accompanying the picture is highlighted in blue


Feed open bin lids

feeder close 1

Feeder blocked weaner au

Feed bins where the filling point was left open, exposing many tonnes of feed to the rain

Over 30 tonnes of feed had to be disposed of after going mouldy

Feeders which are too close together.

Restricted feed access and growth in the pigs over 30 kg resulting in a misdiagnosis of PMWS

Feeder blocked

Increase in gastric ulceration and a misdiagnosis of pneumonia occurred on this farm

Feed brokendownpipe

Feed Weevils au a1

Feed holes au a4

Broken feed bins, pipes and feeders all contribute to wasted spilt feed

The sow in the stall was losing weight before this error was noted

Rhyzopertha dominica and other vermin can result in considerable loss of feed

These insects resulted in many bags of spoilt feed and reduced FRC

Sharp edges to corroded holes in a feeder – which may injure the pigs and is wasting feed

The FCR on the farm was higher than expected and was not resolved until the feeders were fixed


Evaluation of stockmanship/feeder management using the fly (Musca domestica) in soiled feed

fly eggs arrow

feed fly maggot arrow

Eggs – less than 1 day

Maggots – 1 to 10 days

fly pupae


fly lifecycle

Pupae - 10 to 20 days

Hatched pupae – greater than 20 days

Estimation of fly lifecycle in days at 20°C



Tools required to examined the floor

The floor includes any surface where the pig has contact and the slurry system

floor tape measures 2 arrow

Floor calculator

Floor slope measure 20degree arrows

Tape measures are essential to measure flooring conditions.  The arrowed measure uses ultrasound

Calculator is useful to calculate stocking densities

An angle measure for loading area assessments – many countries have a legal 20° maximum slope


Systematic approach:

Calculate stocking rate (m2/pig)

Examine location, size and suitability of sleeping area

Examine pens for sharp and projecting edges, especially at bottom of doors and gates

Examine floor conditions for rough areas and holes. Pay particular attention to the floor under drinkers and feeders.  Where different floor materials meet (e.g. metal and concrete) corrosion is common.

Check any bedding especially for mould

Check slat condition especially edges.  Note solid and void widths.

Examine steps and gate separations

Examine building supports for damage by the pigs

Examine hygiene of pens, especially empty pens

Note the degree of unused floor space – such as passageways

Review the slurry system and hygiene cleaning programmes

On the outside of the building note condition of guttering and wall security


Simple examples where there were problems with the floor

The farm problem accompanying the picture is highlighted in blue


Floor overstocking shelters au 2

Floor finisher last  pig

Floor broken 2 arrows

Overstocking in a serious health problem and a cause of serious welfare reduction

The farm suffered from significant pneumonia and poor growth rates

Under-stocking can also be a problem resulting in cold pigs

Placing the end pigs in a pen results in the cold pigs eating but not putting on weight stalling of their growth

Sharp projections may occur even in the pen, here the floor is falling apart (arrow)

One of the pigs impaled itself on the damaged floor requiring stitching

Floor Skin trauma drinker 3 arrow

Floor hole in floor with hand

Floor Mouldy straw 3

Examine the pigs for signs of injury – scar from a wall projection (arrowed)

This pig tore itself on a mis-positioned drinker.

Holes in the floor resulting in serious leg injuries

A mating sow and boar both suffered injury when they slipped into this hole

Mould on bedding

The farm had a significant abortion storm after this straw was used as bedding for pregnant sows

Floor damaged slats

Floor high step kr

Floor head stuck gate

Roughened slats, especially in front on feeders or drinkers

The farm reported numerous lame pigs and several pigs were euthanased as unfit for transport increasing post-weaning mortality

Steps can limit access to feeders by small pigs

Small pigs were unable to reach the feeders and wasted significantly, resulting in a misdiagnosis of PMWS

Gating incorrectly hung can result in pigs getting caught between the bars

Pigs caught by gates often die through strangulation. This pig was lucky

Floor support post yards

Floor cleaning poor ca 1

FLoor layout poorsows arrow

The building supports (especially when wooden) can be destroyed by pigs over time

The building had to be abandoned as the pigs had weakened the roof supports

Poor cleaning between batches. 

This was part of an eradication programme and the farmer believed the farm was clean. Even this degree of feaces can spread dysentery  (Brachyspira hyodysenteriae)

Poor layout design. 

In this particular case: note solid part of slat (arrow) within stall, sow’s faeces are more difficult to remove – more vulval discharges observed




The air includes all aspects of ventilation and lighting regimes.

Tools required to examine the air


Air temperature and humidity pen

Air Intrared temperature meter

Air gas concentrations

Ambient air temperature and humidity pen

Infrared thermometer

Pollutant analysis – gas concentration immediate and time based.  NH3, H2S, CO2, CO

Air light meter

Air Tachometer

feed tape measure

Light meter

Tachometer for fan speed

Tape measure for fan size

Air smoke bombs1

air windvane 1   Air wind vane

air temperature monitor

Smoke emitters come in a variety of sizes

Anemometers (and wind vanes) to measure air speed

Remote sensors to record changes over time


Systematic approach:

From the outside of the building: visually check air inlets and outlets for hygiene and maintenance.  This might necessitate climbing into the attic space

Observe and account for the lying patterns of undisturbed sleeping pigs

From the inside of the building: visually check air inlets and outlets for hygiene and maintenance. 

Check ambient air temperature and humidity at the: air inlet; pig height in the sleeping area and at the air outlet.  This provides a minimum/ideal and maximum temperature range in the house

If floor heated areas are used, record the infra-red temperature emitted from the floor and variations in temperature over the surface

Examine any heat lamps.  If gas heating is used note hygiene of heater and the colour of the flame

Examine the cooling system.  Note if the water sprays into any feeder. Note distribution of water over evaporative cooling systems

Note any insulation failure issues

Note any signs of condensation

Note any pollution issues – gases, dust or endotoxin concentrations

Record the light intensity and patterns

Examine any automated ventilation systems for hygiene, maintenance and fan efficiency – sound, speed and size of fan

In pressurized rooms note pressure differences and changes in fan speed when door opened

Note any recording or alarm systems and check that they work within expected parameters

Note any open doors and holes in the walls

Review vermin control through the ventilation system

Expose and record air movement throughout the house by the use of smoke.  Note the differences between hot and cold smoke when assessing air movement.  It might be necessary to move outside the building to assess air movement between rooms and buildings

Record the air speed in the sleeping area and at air inlet

Note the time it takes the smoke to dissipate – room air exchange times

Examine any evidence of poor electrical maintenance

If necessary, set up time analysis of temperature and pollutant variations


Simple examples where there were problems with the air and ventilation systems

The farm problem accompanying the picture is highlighted in blue


Air sofit blocked arrow

Air outlet broken

Air farrowing cold au 3

Winter inlet (Soffit) blocked – the building is starved of air

The pigs were suffering from a severe APP outbreak before this was resolved

The louver protecting the building is broken allowing draughts to enter the building

The pigs post-weaning demonstrated significant diarrhoea problems

The heated floor is too cold in the farrowing house.

The chilled piglets had E. coli scour before this was resolved.  Heated floors pre-weaning should run at an infrared temperature of 36-42°C

Air inlet eco au3 arrow

Air dripper dirty

Air evap cooling poor

Ventilation system impaired by other equipment (arrow)

The performance of the pig’s were suboptimal before this was resolved

Cooling system clearly not working

The finishing performance was poor until proper cooling was provided

Poor water distribution over an evaporation panel (dark/wet normal)

Poor temperature control in the farrowing area with reduced feed intake in sows and poor weaning weights


Air inlet stuck arrow

Air insulation bird nest

Air light dirty off au

Variation in inlet openings (arrow closed)

The performance was variable over the house and between pens

Insulation area used for nesting

As the farm aged, its performance deteriorated, in particular pneumonia increased

Poor lighting associated with electrical failure and fly dirt

Gilt cycling was poor after arrival until a proper lighting regime implemented

Air dust weaner 1

Air checking sensors 2 au no reaction label

Air curtain hole

High dust levels can damage pigs’ respiratory systems

The post-weaning performance was poor and coughing very noticeable in these pigs

Alarms and sensors need to work also note side panels (A and B) are not working together

An APP problem was diagnosed on the farm, but proper ventilation control resolved the issues

Holes in curtain result in draughts

Poor room ventilation controls and variable growth throughout the house was noted

Air draught eco au 5

air building close tw

Air Electrical short k2

Smoke revealing high air speed

The draught resulted in pigs having no sleeping area and increased vice and pneumonia

Ventilation between rooms and buildings need assessment

This farm has no all-in/all-out as each room's ventilation was passed into the next room.  Pneumonia was a serious problem.

Electrical failure can result in a farm fire

The poor wiring resulted in a small electrical fire, but the ventilation failure resulted in the suffocation of 200 finishing pigs

farm finisher sa general

Air trees around building

Air weed building

External position of building

Particularly with cross-flow ventilated barns it is necessary to consult a wind-rose to correctly orientate building

Obstructions to the whole farm ventilation

The trees in the background restricted air movement to the farm and cause air vortexes which interfered with air flow

Obstruction to a buildings ventilation

This building suffered from chronic pneumonia problems until the vegetation blocking the vents was removed


Most under-utilized tool set- YOU

The veterinarian

The veterinarian comes already equipped with a complex tool set allowing detailed examination of the pig’s environment through hearing, sight, smell, taste and touch.  Combined with a trained analytical approach, and a knowledge base (PDA), the veterinarian is ideally situated to improve the welfare and well-being of pigs under his/her care.


Combination of problems

Environmental medicine should encompass the whole farm including the outside of the building and the general layout.  Many times, farms have illustrated multiple problems at the same time.

For example, what problems can be seen in the photograph below?

Airr inoutpoorsiting

Answers -at the end of the article

Examples of common disorders which have been resolved solely by manipulation of the environment


Water issues

Feed issues


Gastric ulceration


Variable growth rates

Vaginitis/vulval discharges

Vices in general – tail biting

Greasy pig disease

Greasy pig disease

Vices – vulval biting

Colitis issues

Milking reduction

Milking problems – reduction

Facial necrosis

Facial necrosis

Non specific colitis

Post-weaning diarrhoea


Mycotoxins – abortions/reproductive issues

Gastric ulcer

Regular and irregular returns

Enzootic pneumonia – tracheitis/bronchitis


Variable growth rates


“salt” poisoning


Atrophic rhinitis – bent snout


Floor issues

Air issues

Lameness general

Enzootic pneumonia – NH3 dust and endotoxin

Torn claws

Pneumonic conditions


Atrophic rhinitis – NH3 and dust

Septic arthritis

Sneezing and coughing – dust and endotoxin


Vices in general


Scouring pre-weaning - draughts

Pulmonary abscessation

Scouring post-weaning - draughts

Pneumonia – overstocking

Sudden death – H2S pneumonia

Colitis – under-stocking/chilling

Greasy pig disease

Vices in general

Milking problems due to heat

Greasy pig disease

Reproductive disturbances – heat and cold

Reproductive issues/mating injuries

Poor cycling in gilts – light issues

Teat and udder damage

Meningitis – CO and other gases

Teat necrosis in piglets


Overlaid piglets


Splayleg in piglets




After 25 years of practising veterinary medicine the lesson I have learnt is that (excluding PMWS) almost all of the day to day conditions/disorders of the pig can be traced back to problems with stockmanship and man’s manipulation of the pig’s environment.  Even in cases of PMWS a biosecurity breach lies at the bottom of the problem.  There is no excuse for pre- or post-weaning diarrhoea, pneumonia or lameness issues on most farms.  The majority of reproductive issues lie at the stockpersons feet to resolve.  The veterinarian must recognise the impact of the environment in management of stress of pigs under their care and take positive holistic action to resolve the underlying issues, rather than just reaching for a convenient quick fix of medicine.

Combination of problems - answer

Airr inoutpoorsiting label copy


All of this would have been missed if the veterinarian stayed inside the building

 and only looked at the pig’s clinical signs