I am sorry to hear you can't get Antepsin for Chloe.
My name is***** am a veterinarian, and will do my best to help.
Dicycloverine, the active ingredient in Kolanticon, is not anything like sucralfate, the active ingredient in Antepsin.
Sucralfate, Antepsin, acts like a protectant on the ulcers, covering them and reducing inflammation.
Dicycloverine, Kolanticon, affects the motility of the gastrointestinal tract. In my search to answer your question, I could not find it being recommended to give to dogs.
There really is nothing like sucralfate/Antepsin. If I could not get it for a dog with ulcers, I would treat with antibiotics (some ulcers are caused by bacterial infection) and acid reducers like famotidine (Pepcid AC is one brand name). A Rottweiler would take 10 to 20 mg of famotidine twice daily.
I would also try to find out the reason for the ulcers: kidney disease, the infection I mentioned before, liver disease.
I hope you can see what I am writing! I am not seeing responses from you.
I will try to connect with you another way, if I do not hear from you soon.