We have used 3 whole lemons to 1.5 litres of water. (Or you can use 1 lemon to 500 ml of water)

Thinly slice the lemons.

Boil 1.5 litres of water.

When the water boils, turn off the flame.

Put in all the lemon slices.

Let it steep overnight.

The next day, strain into a spray bottle and the excess can be kept in the refrigerator for future use.
We have sprayed this lemon solution on Minnie and she smells fresh and it helps with her itch. She doesn't scratch as much.
Mummy has also used this solution to sponge all over Beckham's body for his skin problems. Beckham has body odor and this lemon skin tonic helps.
A word of caution, be careful not to spray into the eyes.