As above, there are a few potential causes for this vomiting including anything from and older cat metabolic problem to an infectious gastroenteritis to a poisoning or toxicity causing a reaction in his stomach. In the meantime, please keep an eye on his mucus membranes, capillary refill time and respiratory rate today as follows (do be careful that your boy doesn't try to bite you):
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 appeal 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 blanced 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.
Best of luck with your boy and please keep in touch with his progress. In the meantime, just withhold all food and be sure to offer him plenty of fresh water. If you have any problems in the mean time please feel free to reply, I will be online for the next half hour or so.
Thank you for your question and please now click ACCEPT.
Kind Regards,
Dr M D Edwards
Cat Veterinarian
Veterinarian - BVSc (DVM equivalent) - Webmaster & Head Veterinarian for www. onlinepetdr.com