VetMaster startup settings:

Right click VetMaster startup icon (usually a dog), click properties, Advanced options
 
"Run as Administrator" must be NOT be checked 
Options tab
 
Quick Edit Mode must be not be checked for Logitech mouse support
  Use legacy console (requires relaunch) must be checked
Layout tab
 
Width 80 Height 25 for both Screen buffer size and Window size
  Let system position window must be unchecked

  Windows 10

If NTVDM component is not installed:

Right click Windows Start Button Flag in lower-left corner of Windows Desktop
Click Control Panel 
View by: Small icons instead of View by: Category 

Click Programs and Features
Click Turn Windows Features on or off
Click Legacy Components
Check NTVDM
Click OK