METAL GEAR SOLID V: THE PHANTOM PAIN

D-Dog is one of the more useful allies in the game immediately from the get go. You obtain him as a puppy in main missions 3-5 usually at the main landing zone for those three missions. Extract him once you see him. Once you do finish whatever mission you did and go back to Mother Base and you'll encounter a cute cutscene. A few mission later (for me it was two or three) and you'll encounter another cute cutscene with D-Dog. Finally you'll return at some point prior to mission 11 and when you leave you'll take D-Dog with you after another cutscene. He is now available for deployment.
Now this is quite an easy achievement to get, it just takes some time to do. Please note that this is a similar solution that I'm posting in the other two bond achievements as well.
Now how do you increase the bond of a buddy (sans D-Walker as it is a robot)? Well you do main missions with them as well as side-ops running around the overworld of Afghanistan and Africa. Now you can see their progress at the end of main missions as well as at the sortie screen. IF in fact you do have the meter all filled up but the achievement didn't pop because you got all your buddy progress (or got the last bit needed by doing a side-op) you need to redeploy and then extract yourself inside of freeroam via helicopter, do not just return to ACC after you hit a checkpoint because the achievement will not unlock. Once the game gets back to the loading screen the achievement should unlock.
Do note that you can decrease the bond if you get your buddies "killed", as they will be extracted, by either enemy fire or friendly fire primarily from explosives.

You can find DD as soon as you get off the chopper at the start of Mission 4. He'll be a puppy running around where you start. You should get a call when you are close to him. Fulton him away, and he'll return to Mother Base. From there, Ocelot will train him. After completing missions, return to Mother Base until he is fully grown. After that, he will be able to be used as a buddy.

Once you have him as a buddy, simply take him with you on every mission, side op, or free roam you do. As with the other buddies, using him will increase his bond with you. Once you max his bond rating, the achievement will unlock.

You can check your bond level with your buddies by highlighting them on the Select Buddy option in the Mission Prep screen, or upon completing a Mission on the bottom left of the ranking screen.

As you increase his bond, you will unlock more commands and equipment to use with him. To use his commands, hold and use the to choose a command. Click the to issue that command.

How to increase d dog bond


Watch a cutscene at Mother Base involving D-Dog. +2

Visit D-Dog. Once per stay on Mother Base. +0.5

Convert a provisional marker from D-Dog into a permanent marker. Up to ten times per mission/free-roaming sequence. +0.3

Clear a mine sensed by D-Dog. Up to ten times per mission/free-roaming sequence. +0.3

Collect a medicinal plant sensed by D-Dog. Up to ten times per mission/free-roaming sequence. +0.3

Whistle to call D-Dog or tell him to wait. Up to five times per mission/free-roaming sequence. +0.3

Use the Keep 'Em Busy command. Up to five times per mission/free-roaming sequence. +0.3

Have D-Dog kill an enemy with the "Do it (kill enemy) command. Up to five times per mission/free-roaming sequence. +0.3

Have D-Dog incapacitate an enemy with the "Do it (knock out enemy)" command. Up to five times per mission/free-roaming sequence. +0.3

Have D-Dog critically wound an enemy with the "Do it (wound enemy)" command. Up to five times per mission/free-roaming sequence. +0.3

Have D-Dog extract a soldier or animal with the "Get it" command. Up to five times per mission/free-roaming sequence. +0.3

Have D-Dog bark. Up to five times per mission/free-roaming sequence. +0.3

Use the command "DD" and D-Dog reacts. Up to five times per mission/free-roaming sequence. +0.3

Pet D-Dog. Up to five times per mission/free-roaming sequence. +0.3

Stare at D-Dog in first person view for at least five seconds while inside the ACC. Once per visit. +0.5