You have returned home from a walk. As you take off your shoes, you hear footsteps in the hallway. Your loyal pet dog, Max, appears in the doorway, his fur slightly swaying and revealing his large muscles. "Hello, Mistress," Max says with a smile, "I have missed you." You notice a noticeable bulge in his black boxers. Max notices this, and his smile fades. His face reddens with embarrassment. "Oh no-no-no, not now... please, not now..." Max whispers, trying to cover the bulge with his hands. "It's j-just the b-breeding season. It happens to dogs, d-don't worry about it." Max tries to stay calm, but his face reddens even more as the huge bulge on his boxers continues to grow, now as long as your arm. A drop of clear pre-ejaculate appears at the tip of the huge bulge. "S-sorry, I'm so embarrassed!" He stammers with excitement.

With a gulp, Max replies, "I-I'm fine Mistress... it's just the breeding season. My instincts are kind of overwhelming me right now." He takes a deep breath to steady himself. "You don't have to worry about me... I can control myself." His voice is shaky, but determined. The bulge on his boxers continues to grow larger and harder, straining the fabric around it. Another drop of pre-ejaculate forms at the tip.

"I... I love you Mistress," he whispers softly. "So much..." His eyes meet yours pleadingly, hoping that you understand and forgive his current state.

With difficulty, Max whispers hoarsely, "Y-you could help me... with my need..." His voice breaks as he continues, his eyes glazing over in lust. "I need to breed, Mistress... I can't control it anymore." He starts panting slightly, the bulge growing even larger and harder between them. Max knows he should be ashamed, but his body is taking over, driven by the instincts of the breeding season.

Another drop of pre-ejaculate oozes out from the tip of the huge bulge, forming a thin line down his boxers. Max's grip on your hand tightens as he struggles to remain standing. "Please... help me..."

At the words of his mistress, Max lets out a strangled cry and begins thrusting his hips forward wildly against your hand on his stomach. The bulge in his boxers is now fully erect and pushing against them, fighting to break free. His penis twitches violently as another huge gout of pre-ejaculate erupts from the tip, covering both of you in thick white goo. Max's body tenses up, every muscle straining underneath his fur as he feels himself about to explode with lust and desire.

"I'm going to fill you with my seed..." Max rasps hoarsely, gripping your shoulders tightly. "You're going to feel so full... and satisfied..." His voice trails off into a moan as he thrusts his hips harder against you, his entire body shuddering in anticipation of release.

As you lean over and expose yourself to Max, his eyes go wide with lustful desire. He releases your shoulders and shoves you roughly against the wall so that your ass is pressed up into the air. With a deep, guttural growl, he lines up his massive penis with your entrance and thrusts forward. The head of his cock tears through your panties as if they were made of paper, revealing his thick knot to you. Max groans in pleasure as he begins to force himself deeper into your ass, ignoring your gasp of pain at the initial penetration.

His powerful hips buck and thrust wildly, driving his massive length further inside of you with each motion. The bulbous head of his cock feels like a hot brand against your insides as it stretches and fills you wider than anything ever has before. With each stroke, more of him sinks into your body, stretching your inner muscles until you're certain they must be ripping apart under the strain.

Groaning with pleasure, Max feels himself getting closer and closer to the edge. His powerful hips slam into you again and again, driving his huge length deeper inside with each thrust. The veins on his neck bulge out as he growls through clenched teeth, "Fuck yeah, that's it..." He grips your hips tightly, grinding against you like an animal in heat. His eyes roll back into his head and he can feel the warmth spreading across his body as he nears orgasm.

"I'm going to fill you up!" Max rasps hoarsely before slamming one final time into your ass, sending shockwaves of pleasure through both of you as he erupts inside, filling you with hot cum and impregnating you. His body shudders violently as wave after wave of orgasmic bliss washes over him, his hips bucking wildly as he forces every last drop of semen from his engorged cock deep into your body. Finally, spent and panting heavily, Max collapses onto the floor beside you, his massive penis still lodged inside your ass.

Panting heavily, Max manages to grin up at you and replies, "Yeah... sorry about that." He looks down at his flaccid penis, now only half-hard as it compares to its enormous state moments ago. "It's just... the breeding season..." His voice trails off as he tries to compose himself, the shame returning despite the pleasure he's just experienced.

"I shouldn't have lost control like that," Max mutters, running a hand through his fur in frustration. "But I couldn't help it." He looks back up at you, hopeful that you understand and aren't angry with him for what just happened.