Hello, my name is***** and I have over 20 years of experience as a veterinarian.
I am sorry to hear that your new fellow is panting more then usual, and seems unable to settle tonight.
Is he unable to stop panting or is he panting on and off and seems restless?
Is he eating a normal amount?
Did you change his diet from what he was being fed?
Are you feeding him lots of table food or treats?
Is he drinking and urinating noticeably more than usual?
If you look at his gums and tongue are they bubble gum pink in color, white or gray?
Does his abdomen seem like it is rapidly bloating?
Panting can be a sign of pain, lack of oxygen or anxiety.
If his gum color is nice and pink then I suspect that his panting is related to abdominal pain or anxiety. If you have changed his diet or he's been given lots of treats those things can lead to stomach upset.
But if his abdomen seems to be rapidly swelling, he is trying to vomit but is unable, retching and unable to settle, then I recommend he see a veterinarian immediately as this can also be a sign of bloat, a rare occurrence but life threatening if allowed to progress.
If he isn't retching repeatedly and his abdomen size looks normal then to try and settle his stomach today you can try either:
1) Pepcid-ac (famotidine) at a dose of one 10mg tablet per 20 to 40 pounds of body weight every 12 hours.
2) Prilosec (omeprazole) at a dose of one 20mg tablet per 40 to 80 pounds of body weight every 24 hours.
These will reduce stomach acid and should help if this is related to simple nausea and gastrointestinal irritation.
I would not feed him any food for 24 hours after the acid reducers are started. This should help stop gut spasms and restore normal gut motility and help decrease his gas.
Small amounts of water or ice cubes given frequently are fine as he needs fluids.
If he has any loose stools you can start Kao-pectate at 1ml per pound or 1 tablespoon per 15 pounds of body weight every 6 to 8 hours. This is quite safe and will coat his irritated gastrointestinal tract as well as absorbing bacterial toxins. You can use it for several days until his stools look normal. You can find kao-pectate at the drug store.
If he has a tense painful abdomen, continues to have diarrhea after being on kao pectate for 24 to 48 hours, becomes very lethargic, begins vomiting or runs a fever greater than 103.5F then he really must be seen by a veterinarian as soon as possible. Make sure to take a fresh stool sample with you when you go.
After his food fast start a bland diet of 1/3 boiled, lean hamburger (or white skinless chicken), all fats and juices drained off, mixed with 2/3 boiled, plain white rice. Feed several small meals a day.
Once he feels better start mixing in his regular dog food very slowly. Less bland more regular with each day. It should take a week or so to convert him back.
If Oscar begins vomiting and feeling poorly though it would be best that he see a veterinarian as anything you give him orally will just come back up making him dehydrated.
Best of luck with your new pup, please let me know if you have any further questions.