As the Department of Agriculture and Food issued a caution on heat stress to animals yesterday, the organic farm movement advised that free-range pigs should be kept indoors or covered in sunblock if left out.
One Clare-based organic farmer, Mr Hugh Robson, said he has also had to protect his ponies' noses from the sunshine with creams this year.
Dairy farmers were also warned by a leading vet to look out for sunburn on udders of milking cows, and check for photosynthesisation in lighter-coloured cattle.
This rash in pedigree cattle is caused by strong sunlight reacting to the toxins in some plants eaten by cows during very sunny weather.
Mr Robson, who farms organically on the Burren, Co Clare, said he was keeping his pigs in cover while the good weather lasted.
He said he had also provided wallow holes where the pigs could cover themselves with mud to protect them from sunburn.
"They sunburn very easily, and I would be advising those who have free-range pigs to keep them in. But if they cannot, they would need to protect their skin with sunblock." .
He said the ponies on his farm had been suffering chapping on their noses and lips, and he has had to apply cream to protect them in the heat.
Mr Sean Ó Laoide, of Veterinary Ireland, said animals had to be carefully tended during hot, summer weather and pigs, poultry and milk cows were very vulnerable to heat stress.
"It is advisable to keep cows in shelter, especially lighter-coloured cows which can get sunburned and can also suffer from photosynthesisation."
He said this caused a nasty rash on dairy cows, but farmers should also be careful to check that milking cows' udders were not sunburned if they were not in the shade.
The Department of Agriculture and Food yesterday reminded all farmers and transporters that farm animals suffered from heat stress during hot summer weather.
It said this was particularly true of pigs and poultry, while either housed or during transport, and it urged frequent checks on animals, reduction in stocking density during transportation, adequate ventilation, increased water supply and shade from the sun.
It warned that it was an offence to cause or allow unnecessary suffering of animals, both on-farm and during transport.