Use the Trenchgun for dogs instead of any other gun. It is the only one to reliably kill dogs quickly at higher rounds. Bouncing Betties will also kill dogs so use these intelligently.

If you opened up all doors, then put the Bouncing Betties in the unused area between Storage and the Doctor's Quarters. If you never opened Storage, put BBs in front of the storage door and the area around that. Start a dog round in one of the 3 available corners there, preferably the one farthest from the Storage door. After the dogs explode the BBs there, move to the next corner and finally to the corner in front of the Storage door. At that point, the dog round should be over.

I usually open the Fishing Hut, followed by DQ, followed by Storage (if still needed). This will allow you to defend from the Comm room alcove until you need to open Comm up to start the 'loop'.

Note that if you are terrible at 'camping' here, just open the Comm room swamp area (but not Comm room itself if possible) and just do the 'loop' with whatever weapons you have available. Do the loop 2-3 times and then, as you exit the second small shack, turn and gun the zombie crowd as best as you can, switch to the Trenchgun, run a few feet and then reload your better gun when you are at a safer distance/repeat.

Remember to drop your BBs inside between each round and keep your eyes open for dropped items.

I used this strategy 4 times by myself, I got to levels 29, 28, 30, and then I got to round 50, beat the round and then killed myself because I ran out of time (I had a prior engagement).