That is how England's welfare code for pigs puts it. They are driven to explore with their snouts, they cool off in mud because they barely sweat, and a sow about to give birth will try to build a nest.
Newborn piglets have only small fat reserves to make heat. A 2022 review says huddling is their main way to stop heat loss, taking up most of their time.
Pick a behaviour to see why pigs do it and what England's welfare code says about it. The bar shows how firmly the code ties it to something keepers must provide.
Based on Defra's Code of practice for the welfare of pigs (England) and the Wageningen review of wallowing. This is general information, not veterinary advice.
TWO NUMBERS WORTH KNOWING
Few sweat glands, lots of huddling.
One figure on why older pigs overheat, one on how newborns stay warm.
≈ 30 per cm²
Functional sweat glands in older pigs
A 2022 review says grown pigs are susceptible to heat stress because they have few functional sweat glands, and that wallowing is their first reaction to heat.
SWEAT GLANDS · FRONTIERS IN VETERINARY SCIENCE
61–74%
Share of time newborn piglets spend huddling
The same review cites figures of around 61.2 to 73.8 percent: huddling is the newborns' primary way to prevent heat loss.
HUDDLING · FRONTIERS IN VETERINARY SCIENCE
A 2010 Wageningen review of 48 papers on wallowing in pigs and wild boar found it serves mainly for cooling, sunburn protection and removing parasites, and possibly for scent-marking.
WHAT THE CODE EXPECTS
Four basics for a pig's behaviour.
These summarise points from Defra's welfare code for pigs in England. They describe what the code asks of keepers; anyone keeping pigs should read the code itself.
Material to root in
Straw, hay, wood or similar, available all the time and topped up so it keeps the pigs' interest.
A way to keep cool
Shade and wallows outdoors; in warm weather options such as misting, showers or floor cooling.
Nesting before farrowing
Suitable nesting material in the week before a sow gives birth, especially in the last 24 hours.
Care when mixing groups
Expect some fighting while a new ranking order forms, and separate pigs promptly if aggression becomes severe.
AI-generated image, not a photograph of a real person or place.
NESTS AND LITTERS
A nest before the piglets.
AI-generated image, not a photograph of a real person or place.
The code says nesting material should be provided especially in the 24 hours before farrowing, to satisfy the sow's need to build a nest and minimise stress. In free farrowing systems she should have room to nest build, turn around, rise and lie down.
Piglets need warmth from the start. The code requires a solid, matted or littered floor area large enough for the litter to rest together, and the 2022 review notes that newborns have only small fat deposits to make heat.
Questions
Questions people ask
Why do pigs roll in mud?
Mainly to keep cool. A Wageningen review says pigs lack functional sweat glands, so wallowing helps prevent overheating, and also protects against sunburn and helps remove parasites.
Do pigs sweat at all?
Hardly. A 2022 review in Frontiers in Veterinary Science says older pigs have few functional sweat glands, around 30 per square centimetre, which makes them vulnerable to heat stress.
Why do pigs root?
Exploring and foraging with the snout is a natural, highly motivated behaviour. England's welfare code says pigs must always have material such as straw or hay to investigate and manipulate.
Is nose-ringing allowed?
The code says ringing is a mutilation that should be avoided wherever possible because it interferes with natural rooting, and should only be done by a trained, competent person where necessary.
Are pigs social?
Yes. The code calls them inquisitive, social animals. Mixing groups changes the hierarchy and leads to some fighting to set a new ranking order.
