Thank you for your patience. While there could be a range of possible causes for Buddha's vomiting today, the chances are that this is indeed due to him eating the uncooked rice earlier on. Hopefully he just has a little stomach upset here due to the rice expanding a little as it passes through. We wouldn't expect much more in the way of symptoms here from your boy. Do keep an eye out for further vomiting overnight, but hopefully it has settled now. Definitely offer him water and make sure he has plenty available to drink at all times. This won't worsen things here by any means, and he certainly needs water available 24/7. For tonight, with hold his regular food until the morning, then just feed him as per usual.
For now, you may also want to try him with a little pepcid. The typical dose for this type of situation is 0.25mg per pound of body weight up to twice daily. You can read more about the use of Pepcid in dogs online here: http://www.petplace.com/article/drug-library/library/over-the-counter/famotidine-pepcid
Please also keep a close eye on his mucus membranes, capillary refill time and respiratory rate as follows:
Mucus membranes - flip his lip and look at the color of his gums. They should maintain a nice salmon pink color. Get him to the emergency Vet if they appear white or very pale pink, or if they are a dark deep red color.
Capillary Refill time - this measures blood perfusion and test this by putting your thumb on his gum to apply pressure. After you release your thumb you will see the gum blanch. Capillary refill time is the amount of time it takes (in seconds) for the gum to return to a healthy pink color from the blanched white color. If 2 seconds or less don't worry - if it is taking significantly more time, again - off to the emergency Vet.
Respiratory Rate - if he is continuously panting throughout the night, this is a sign of shock and or pain and a signal for a trip to the emergency Vet.
Hopefully that is it for the symptoms now. If there is further vomiting tonight, or if he can't keep water down, then you will need to get him seen tonight. I hope all of the above makes sense? If you have more questions or if I can help in any other way, please do not hesitate to ask! If you would like to accept my answer, please press RATE OUR CONVERSATION (I am not compensated in any other way). Bonuses are always welcome. Thanks! I hope to work with you again soon!
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