"Holy shit."
You wasted a few moments trying futilely to understand just what your horse was doing and why, but quickly came to the instinctual decision to act now and reason out those problems later. By the time you had come to your senses, the only working dog you had on the farm was now stuck up your trophy horse's rear up to it's back legs. Your mare seemed to be having a lot of trouble sucking up the poor dog's back legs due to their stubbornly vertical nature. Now's your chance.
"Rosie! No! Let him go!" You yell commandingly, drooping the baseball bat and flashlight and grabbing onto the dog's back legs and pulling with all your might. She looks back at you with surprise for a moment, as if shocked that she had been caught red-handed, but stubbornly tightened her sphincter's grip on the dog, refusing to release her prey. You were shocked at how strong of a grip that was. You were pretty strong yourself, but you were able to make no progress in pulling the dog from the mare's massive rear. However, you were able to stop her from sucking the dog in even further.
It quickly became a stalemate, with both of you trying your hardest to maintain your grips while waiting for the other one to slip up. Of course, being so close to the horse's rear, it was only a matter of time before the smell hit you- and while you thought you would be ready for it, it hit much harder then you thought you would. You couldn't help but choke on the disgusting scent as it hit you in the face, and you gagged, your grip loosening a bit. Your mare saw her chance, and suddenly stepped backwards, bumping into you and knocking you onto your back.
As you lay on the ground coughing, Rosie put all of her energy into her task. You watched in horror as the dog's back legs were bent at an unnatural angle to more easily slide into the mare's greedy rear, and you faintly hear light snapping sounds as the horse's muscles readjust to fit their unexpected guest. By the time you got back up, it was already too late.
To your horror, you watched as the rear half of the mares gut bulged and pulsated, realizing the poor, poor dog was still alive inside. You desperately tried to wedge her anus back open and drag the dog out, but her sphincter still wouldn't give up it's prey. "Let him out! Let him out!", you were still screaming, the smell no longer affecting you.
As the bulges coming from her abdomen slowed and eventually ceased, you laid your head on your horse's back, shocked and dejected, still slightly in disbelief that your average-sized horse could fit the whole dog up it's rear. Rosie looked back at you, looking sorry at how it had affected you, but not necessarily remorseful at what she had done.
It was time to call the vet.
***
"Mmhm. And just how big was this dog?"
"I don't know, uh, 50 pounds or something." You replied, your voice still shaking.
"Did the horse display any signs of discomfort or pain following the... insertion?"
"Uh, no. Not at all, that I've seen. Could you just tell me how to get the dog out?"
"It's been around fifteen minutes or so from the time of the incident, as you said, correct? In that case, the dog would've already been moved into the horses stomach. You don't have to worry, your horse's stomach is fully capable of digesting the husky and no retrieval will be necessary."
"Yeah, well... I kind of want the dog back. Alive."
"I apologize, but in enclosed, airless spaces, the average animal suffocates within minutes. It is likely too late for the dog."
You lean back into the couch, squeezing your eyes shut, trying not to let yourself cry.
"So, has your horse displayed any other relevant unusual behavior lately?" The veterinarian asked, interrupting your moment of sorrow, which you were rather relieved by.
"What? O-oh, no... I mean, kind of. They never really liked each other. The horse and the dog, I mean." You state, keeping yourself under control, under you finally exclaim in exasperation, "Doctor, please! Why... why did she do this? How did she do this? Is there something wrong with her?"
"No, don't worry, there's nothing wrong with her physically. All horses of her size have this kind of... 'ability'." The vet consoled you. You heard a crack, as if he was leaning forward in his chair, before he came out and fully explained the situation to you.
"See, your horse is enduring a phenomenon common among large animals, which is the urge to insert smaller, suitable animals into the anus- and, in turn, the stomach- as opposed to a more conventional dietary choice, as they find it more healthy and pleasurable. This was a common occurrence in prehistoric time, but as humans domesticated the native species, we bred this natural urge out of their gene pool. However, this urge can come flooding back to many horse species if they happen to 'swallow' a smaller animal accidentally somehow. Some of the more common original incidents include things like small birds crash-landing, desperate squirrels thinking they've found a place to hold up for the winter, or, in one case, an unlucky boy in a tragic skateboard-related accident. The chances are your mare has been doing things like this for quite a long time."
You choked up in shock and surprise as he explains this all to you. Could this be real? Was this all some kind of horrible, horrible joke?
"S-shes my signature trophy horse. I can't have her doing... this. Is.. is there any way to stop this urge?"
"Well, yes. If you keep her under constant surveillance and isolation for a period, feeding her only artificial and more natural horse food, to wean her off of her new 'diet', the urge will eventually subside."
"And how long will this take?"
"One or two months."
Your eyes widen.
"Two months? Racing season is right around the corner! I had a critical competition scheduled in a week!"
"Now slow down, now. This 'diet' isn't necessarily unhealthy for your horse. Quite the opposite, in fact. Some of the most successful racing horses practiced this almost exclusively for it's benefits to nutrition and morale. If you decide to support this diet, at least until racing season is over, your horse will continue to be at tip-top shape unabated. The question is, are you willing to face the moral consequences?"
You paused, considering it. You didn't want to support... whatever this 'diet' was, but Rosie was your signature race horse, and your primary point of pride and profit. You couldn't afford to miss this racing season.
After a few minutes, you make your decision.