Marissa, a mid-30's anthro cat, lounges on the couch with the family dog, Rex. She checks her phone quietly while the golden retriever rests its head on her lap and pants happily.
In the corner of the room is her infant daughter, Mary, who moves around quietly in her baby bouncer. The little tabby has an orange pelt and green eyes just like her mother's.
Despite the calm scene, Marissa's heart is racing. There's something she's been preparing herself for all day, silently, in anticipation. Her husband is away for a few days on a business trip, and she's going to have sex with the family dog.
She responds to one last text from her husband confirming that he's arrived at his hotel two states away, wishing him a nice night with a little heart emoji at the end, and she puts her phone away. There's nothing left to wait for.
Finally, she gets up and walks silently into the bedroom she usually shares with her husband. Adrenaline is pumping through her and her heart beats rapidly in anticipation of what's to come. There's nothing to do but steel herself and begin undressing.
Meanwhile, the dog hops off the couch and trots down the hall. It glances at the closed door and tilts its head curiously before losing interest and returning to the living room.
"Ba blahblaufh," a little vocalization from Mary draws Rex's attention to the baby. His paws tap on the ground as he trots over to the infant in the baby bouncer.
SCLIK LAP SHLICK
The dog licks the baby's face affectionately, prompting high-pitched giggles from the infant. It then presses its nose up against the baby kitten's face and sniffs. It can't help but notice how delicious the child's face was.
GRRWRRGLE
A hunger pang strikes the dog at just that moment, and it decides to satisfy it right away. There's something very tasty right in front of it, after all.
OMFGH-
In one swift motion, the dog stuffs the baby's head into its maw before little Mary has any time to react, not that she could do anything but scream and cry.
SLURPFH GULP BUUULCHH
Rex gulps the child down swiftly and without any resistance, then lets out a burp right after. Mary slides down the dog's throat into its stomach helplessly. The much larger dog's gut is more that capable of containing the infant, and the bulge in its stomach isn't noticeable at a glance.
GGRRRRRRWWWWLLLL GLRRP
Marissa looks at herself in the mirror over her dresser. She's fully nude now, and she's silently hyping herself up to do something truly depraved. She could hardly be more excited, but she could hardly be more nervous.
With nothing left to postpone her plans, she slowly opens the bedroom door and heads down the hall. 
She finds Rex laying on the floor half-asleep. The dog looks over to her and gets up eagerly when it sees her, tail wagging behind it. He sure seems happy today.
"Alright, boy," Marissa hesitantly crouches down and gets on her knees. She leans forward and reaches for the dog's sheath, stroking it gently and sticking one finger inside.
Rex's red rocket erects rapidly at her touch, and the dog begins to pant already.
"Fuck, we're really doing this..." Marissa says under her breath, not noticing the slight bulge in the dog's belly or the unusually loud gurgling of its gut. She gets on her knees and elbows and spreads her legs wide, ass sticking up in the air, pointed at the dog, "Come get me, you sexy thing~"
GRRGGGLE
The dog's gut lets out another groaning noise as the dog investigates what its owner is doing. The golden retriever sniffs Marissa's backside and catches a potent smell wafting from her exposed sex. He decides there's no better place to satisfy his raging erection, and so he mounts her.
PLAP PLAP PLAP
"Rrwrrfff," the dog vocalizes as it presses its knotted cock into the woman, its forepaws up over her shoulders. Rex's tail wags eagerly as he plows his owner, and his infant-filled belly rubs against her rump.
Marissa notices the strange bulge now, but she's unsure what exactly it is. It's the last thing on her mind, though, exhilarated as she is by what she's doing. With each thrust of the canine's cock into her bare pussy, she feels herself getting closer and closer to an orgasm, spurred on by sheer arousal at the degenerate deed more than the actual pleasure she's experiencing.
Rex pants in her ear and drools over her head as he continues to hump her, and he keeps going as Marissa moans loudly, achieving her first orgasm of many for the night.
PLAP SLAP SMACK GWWRRRRGGG
By now, much of little Mary's soft, tender flesh has been stripped away by the dog's stomach acid. As a result, the large feline skull begins to press more potently against Marissa as it rams into her again and again. Her mind getting over the first orgasm and not yet lost in the pleasure leading up to the second, she finally pays it some mind.
Her eyes wander as she questions what the object inside her scandalous canine lover could be, and she has a striking realization as she notices the empty baby bouncer. But she's in too deep already, and there's nothing she can do. She can't help but find the situation all the more arousing.
"Huff... I'm not a very good mother," she admits aloud as the skull of the infant she'd neglected presses against her bare ass in the gut of the family dog.
PLAP PLAP PLAP
After nearly an hour of fucking and numerous orgasms on Marissa's part, the copulation ends with a burst of canine cum deep into her pussy. The former mother gasps for breath as the dog knots her and pants heavily in her ear.
Bent over on the ground with her dog's bone still buried inside of her, she reaches for her phone on the coffee table next to the couch. It's a bit of a stretch to get it, but she manages. She has a new text waiting for her from her husband.
"I love you, sweetheart. Hope everything's going good back at home. How's Mary doing? <3"
GLLRRRRGGLLLE GROOAN GLORRP
Her attention is drawn back to the bulge in her dog's gut that used to be her child. She's going to have to break the news to him eventually, but for a now a lie will have to suffice.
"We're doing good! Just put Mary to bed. I love you, too."
PFFFFRRRRRRR... CRRLLFHBLRRK SPLURCH
It's been two hours since Marissa finished her canine endeavor, and Rex is squatting over a newspaper set up in the kitchen. Marissa strokes his back gently as he passes log after log of massive, bone-filled dog turds.
Each one presses slowly out of his backside and lands on the paper with a splat, forming a growing pile. If the mess were smaller and lacked the infant bones, it'd look like any other mound of dog shit.
Huff... Huff... CRRSFFHRLPBLRRFHKK SPLT SLOUGH
Rex grunts with effort as he passes the little skull out of his rectum and pants heavily as it sloughs down into the brown mound. Finally finished pooping, the dog then gets up and lifts a leg to urinate on the mess of former baby.
FSLSHHRHSHHHHHPBLRRTLTLRLSHH
Marissa can't help but lightly finger herself, watching the dog piss on the remains of her daughter. She gets some of Rex's cum on her fingers as she does.
"Fuck, you turn me on too much, boy..."
Later that night, she lounges on the couch with Rex held close in her arms. She absent-mindedly takes in some late night programming she doesn't much care about while Rex enjoys the affection.
The elephant in the room that is her daughter's steaming remains has yet to be cleaned up. She'll need to decide how to dispose of them shortly, and of course how to tell her husband. It's waited all night, though, and it can wait a little longer. She has days before he'll be home again.
Rex whines a little and licks her face, demanding Marissa's attention. She notices his member growing erect again. She pets the dog's head, "Alright, boy, you know I can't resist you~ Nothing to lose now, after all."