Temps here are running @ +35c at present so we have to take extra precautions with all the livestock ensuring none are dehydrated.
We make our own electrolyte solution:
4 Litres of water
2 tsp of salt
2 tsp bicarb
half a cup of pure honey
Syringe feeding any kids, lambs etc. and giving several bucketful's a few times a day to all the others.
I know temps are lower in the UK but we also use this mix when illness symptoms occur and it always helps so well worth keeping the ingredients in your animal first aid kit (our LSGD loves it).