Receipt for horse sale - what do I need to include?

[MissieSFW]

I've just sold my mare, and the buyer wants a receipt... what do I need to include? Obviously the purchase price and name of horse, passport number etc, date... Is there anything I've missed? Also as she has bone spavin would it be a good idea to include something like 'sold with preexisting medical condition as discussed with buyer'? In which case does the buyer need to sign it or just me?
Any advice/example wording gratefully received!!
thanks

 

[BigRed]

what you may want to put on the receipt and what they might want to see, could be different things. As a buyer, I'd like to see a description of the horse, name, sex, size and colour, and I'd also want to see "sold as good to hack, load, clip, shoe... whatever".

For your own protection it would be a good idea to state that you told them about the medical condition.