Conditional Formatting a range of numbers

I have body weight sheet for dogs that tells me what their weights are daily. I had previously set the Conditional Formatting to highlight the cell for a particular dog's weight if they lost 10% body mass and a second one for 20% body mass. However, the format only told me what the weight loss was based on the very first time that animal was weighed.
(Current Formula) Cell Value - Less than or Equal to - C$4-(C$4*0.1) - highlight Yellow
What I want is a formula that will take into account ALL of that particular dog's body weight, including increases, and highlight based on the Greatest weight they have achieved. For example, Dog #1 the percentage is based on his first weight 25.8 on Day 09/15/15 because the formula uses the first cell in the row. I want the formula to select the highest weight for it's calculations, so the percentage weight loss will actually be based on the 26.5 weight of day 09/16/15.

I have included an image of an example using my current formulas.

Thank you very much for the information. I tried it and I'm not sure I have it set correctly because it didn't work. Here is the original file.

try

=MAX(C4:G4)-(MAX(C4:G4)*0.1)

and

=MAX(C4:G4)-(MAX(C4:G4)*0.2)