Four senses: a guide to recognising disease in your herd

Early recognition is the first step to successfully managing a disease outbreak or illness in your herd but how can you use the senses of sight, sound, touch and smell to detect the abnormal animal and to differentiate it from the rest of the herd?
calendar icon 26 September 2018
clock icon 7 minute read

Every day, a clinical examination of all pigs should be carried out. On a 100-sow farm, this could take up to half an hour per day and on a large farm, it becomes a major daily task but can be split between department levels. How many managers organising their farms allow such a time period for this function?

In this step-by-step guide, you will learn how to use all of your sensory resources to spot the sick pig the first time around.

What can you see?

The most obvious method of spotting a sick pig (or pigs) may be through visual cues: lethargy, inappetence, shivering and weight loss, are all easy clinical signs to spot in the individual pig by those who are experienced in noticing such changes. However, in a large group, identifying these clinical signs may be more difficult and may not be so obvious to less experienced stockworkers.

Changes in the herd

Daily, regular time should be set aside for the examination of all pigs. Allow at least 5-10 seconds to observe each pen of pigs. The environment of the house must also be assessed by noting the following:

• Temperature.
• Humidity.
• Ventilation.
• Smell.
• Pig behaviour.
• Appetite.
• Human reaction.
• Ammonia levels as experienced through breathing and the effect on eyes.
• Abnormal changes in slurry and bedding.

The pig is a social animal and in a healthy condition, remains part of a group. In disease however, it tends to rest on its own or often be rejected by the other pigs even to the extent of being attacked. Altered lying patterns in a pen must be monitored.

Conversely where a number of pigs are ill or the environment is inadequate huddling is common. The reluctance of pigs to rise or show an interest in the observer must always warrant a more detailed examination.

Changes in the individual pig


Inappetance is obvious where an animal is housed and fed as an individual, such as a sow in confinement, but in group housed animals this is not easy to detect. The failure to eat, or a drop in feed intake in a pen of apparently normal pigs, must immediately arouse suspicions. The initial check should be for lack of water which is usually the most important sudden cause of inappetance involving all pigs in a group. If the water supply is normal look for signs of disease.

Equally, inappetance alongside an increase in water consumption could indicate constipation.


Listlessness or a dull appearance is obvious when coming to move pigs. If a pig is reluctant to stand or move when it is normally comfortable doing so, or it continues to rest in a sitting position, this could be an indication of illness, leg weakness, or lameness.


Shivering and raising of hair over the body is an important clinical sign of disease. It could potentially be a sign of streptococcal meningitis or joint infections in the sucking pig. Look for this sign next time you examine each individual in a litter.

A pig laid on its belly and shivering with its hair on end while the rest of the group is comfortable is potentially suffering with scours (diarrhoea) or lame from a generalised septicaemia (bacteria in the blood stream).

Weight loss

Loss of body weight is a first indication of inappetance or dehydration due to diarrhoea or pneumonia. A simple body condition score can be recorded each time you visit a pen if illness is suspected and the visible signs aren’t obvious.


Discharges vary in their consistency and location, and hence will be indicative of different diseases.
Discharges from the nose or eyes could indicate an upper respiratory infection.

Excess salivation from the mouth could indicate an exotic disease such as vesicular disease.

In sows, a discharge from the vulva could indicate vaginitis, cystitis, pyelonephritis or endometritis.


Faecal changes can indicate a wide range of diseases, but sloppy faeces can also be quite normal. Look for signs of mucous or blood indicative of swine dysentery, salmonella infections gastric ulceration or proliferative haemorrhagic enteropathy.

Equally, look out for signs of constipation: humped up back; small, hard faecal balls; difficulty and straining during defecation; inappetance; and increased water consumption. This may be difficult to spot in larger herds but may be important in identifying the development of udder oedema and agalactia at farrowing.


Vomiting can be a sign of diseases such as transmissible gastro-enteritis, or in individual pigs it may indicate gastric ulceration. In the sucking pig, gastro-enteritis associated with E. coli infections is often seen. Injections with long-acting penicillin may also cause pigs to vomit.


Skin changes help in identifying diseases, typified by acute or chronic lesions of mange and lice although the latter are now uncommon.

Erysipelas may not be evident by sight but running the flat of the hand over the skin will indicate tell-tale lesions of raised areas.

A blueing of the extremities could indicate acute viral infections, acute bacterial septicaemia or a toxic state, as seen in flu, PRRS infections or acute mastitis and metritis. Acute pneumonia or pneumonia associated with heart sac infection can give a similar picture.

Respiration rate

If any of the above changes have been identified, cast your eye across the pen of pigs and compare the respiratory rates of both the normal and the suspect animals.

Assess, whether the breathing is a deep chest movement, due to consolidation of the lungs and a shortage of oxygen, or very shallow abdominal breathing indicative of pleurisy and pain.

Deaths in the herd

Finally, the circumstances surrounding the death of a pig is an important observation, especially when backed up by post-mortem examination. The timing and place where pigs die in a herd relative to clinical observations can often help in identifying and understanding a problem.

What can you smell?

The odour of a dead pig is one that we have all experienced from time to time. However, odours also occur with scour, bad feed or infected tissues.

The smell of piglet scour on outdoor sows can help detect affected litters. The quality of the air through the sense of smell will highlight poor ventilation rates, high levels of gases, or high or low humidity. What is uncomfortable for ourselves is also likely to be the same to the pig.

What can you feel?

It is essential to handle a sick pig, to detect changes in skin temperatures, the significance of abnormal fluids or lumps on the skin. The limbs should always be palpated in cases of lameness, for possible fractures or swellings in the joints. In the newly farrowed sow, always palpate the udder to detect any early changes of agalactia or mastitis.

What can you hear?

Be extremely wary if there are no pig noises when you enter a building. A disaster could have occurred due to electrocution, suffocation, or high levels of toxic gases such as carbon monoxide or hydrogen sulphide.

This is information is taken from the Managing Pig Health book. Click here to visit 5m Books

Emily Houghton

Editor, The Pig Site

Emily Houghton is a Zoology graduate from Cardiff University and was the editor of The Pig Site from October 2017 to May 2020. Emily has worked in livestock husbandry, and has written, conducted and assisted with research projects regarding the synthesis of welfare and productivity of free-range food species.

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