Sure, that may be the next issue to deal with, but the eyes are in focus inside what appears to be about 4-5", so increasing DOF has to be resolved first. There is a 14" MFD on that lens, just over 1 foot.
Given the DOF being about 4-5", that puts the dogs out at about 5' from the subject at 50mm at f1.8. If the dogs were really right up on the lens, the DOF at 14"MFD would be less than 1". CLEARLY not the case here...
Questions to be answered:
1) Are the photos all the full frame, or are either/both cropped? (Assuming photo is cropped a bit to show the issue)
2) What AF mode is used? (Assuming all points)
3) What was the distance to the dogs on the first shot? (not all that pertinent, other to determine DOF values) (Assuming about 4-5 feet out)
Where did you get the DOF being 4-5"?
Moreover, where did you find the exif saying f1.8?