1. Right click on "Keyboard Right arrow is down".
2. Select "add"
3. Select "add another condition (C)"
4. Add another keyboard event for pressing "Down".
So now the event is made so that if both down and right is being pressed, the cow will move to the right. You could also have gotten to this point by clicking and dragging the "Keyboard Down arrow is down" that you had already made and merging it with the "Keyboard Right arrow is down".
5. Right click on the new conjoined event you just made and click the "Make 'Or' Block"
6. Thank me.
Also, you don't need two separate animations to make a object look like it's moving left or right. Use the "Mirrored" property to flip it around.