A short story that I wrote for school. Tell me what you think.

A wave of musty hot air hit Josh's face and his stomach turned. Another sleepless night over, he thought, I hope I at least have enough food for breakfast. He sat up on his cot and his feet pounded on the floor, startling Rambo who was sleeping on a mound of tattered blankets. "Easy boy, it's just me," his voice just came out in a whisper as Josh was still half asleep. Rambo laid his head back down on his paws and fell back asleep, pointed ears still twitching.
When he opened the pantry doors another battalion of musty air charged at him, making him cough. His eyes landed on a can of beans, the only thing left on the shelves except for a few cobwebs.
Josh muttered a few curses, "Hey Rambo, I guess where going to have to go back out there again. If we have time I'll go to the PETCO and get you an actual bed if they haven't all been looted yet." The soft pitter-patter of Rambo's paws shuffling across the wood floor filled Josh's ears, the sound of his only surviving companion. He laughed, "Don't worry boy you'll get some of this crap too."
The can of beans was gone in less than five minutes, and Josh walked across his hideout
to the ammo closet. He grabbed his trusty M16 and 9 mil sidearm which he snaked off of a fallen commando six months ago and suited up for his trek out to ground zero. A creak of his hideout door and six of the infected already shuffled out of the darkness of the alleys. He picked them off one by one and worked his way to the HUMVEE.
"Come on Rambo," He whistled, "Let's go boy." Rambo hopped up into the back and they where off. As they drove threw the war torn Milwaukee, the infected stupidly shuffled in front of the HUMVEE and where burst so smithereens.
"I'll tell you boy, I don't know how these things managed to take over the world if they will jump in front of a moving truck," A smirk emerged under his breath, "Zombies, they crack me up." He was now purposefully swerving into the infected townspeople. "Hey I think that one was my old history teacher," He stuck his head out of the window, "That's for giving me an F you cheap SOB! I'll tell ya boy, being one of the only people left has its perks." He skidded the HUMVEE into a telephone pole and killed the engine.
Josh looked into the rearview mirror, "Now Rambo, hey look at me, now stay here ok, I don't want you running off." He jumped out the door and slammed it shut. Three of the infected stumbled out of a building attracted to the noise, but they didn't get far. Josh jogged down to the convenience store with a duffel bag slung over his shoulder. As he got in he cleared the place of any remaining ghouls and raided what was left of the non-perishables and some candy. Then over to the beverages and got some water, Gatorade, root beer, and some Pepsi. Then his eyes hovered over to the bottles of Miller. I don't think the owner cares about the drinking age anymore; he's too busy trying to piece together his head. As he thought this he put 6 bottles in his bag and went over to the register. If I'm able to get to the market outside of town I'll be able to get something better than just beer. When the register clicked open, Josh cleaned it out, only about $200 but it was better than nothing. With a zip of the bag he was out the door, but his run didn't last long. His feet skidded to a halt as he saw the horror that was upon him, half the city was between him and his HUMVEE

Josh spun in a circle, he was surrounded. The undead where creeping in on all sides, groaning that awful grown at the smell of his warm flesh. With each shuffle they took the groaning got louder and louder, slowly turning him insane. As more magically popped out of the nooks and crannies of the ruined city, Josh realized he was loosing time, and fast. The only way out was to blast out. Quickly, he took a Grenade off his belt, yanked the pin and chucked it towards the horde that was closest to the HUMVEE. After the explosion and flying limbs settled Josh began his run, splitting undead heads as he went (living in ground zero for almost two years had made him a dead eye. The HUMVEE was only a block away, yet it seemed like fifty miles. Half way down the block he wasted two of his three clips. With every fallen ghoul three more popped out. The last shot rang out of the M16 and then nothing but clicks. He swung the rifle and pulled out his side arm and fired away at the undead skulls. The HUMVEE was about one hounded feet away, Time to make a run for it he thought and broke off into a full on sprint, but was soon brought down and the 9mm flew twenty feet in front of him.
"CRAP!" He yelled, pushing the jaws away from him, "GET OFF OF ME YOU GODDAM PIECE OF SH-" Before he could finish his sentence Rambo pounced onto the ghoul and started biting him.
"NOOOO Rambo don't!" He shot up and got his sidearm and fired a few rounds into the undead head. Josh could see the virus starting to take effect in his dog's eyes, the color draining from them.
"Rambo, just lay down...it'll be all right," Tears where running down his cheeks as the life left his best friend's eyes. Damn why does the virus have to work so fast? Josh lay with his dog in his arms for five minutes before Rambo's pupils began to turn red, the final sign before reanimation.
Josh could barley get his words out through the sobs, "I love you Rambo" He took his 9mm, pointed it towards his friends eyes, and pulled the trigger.