Thank you for your patience. While there are a number of things that could be going on here, given both dogs seem to be affected here, it is more than likely this is due to the sudden diet change, however we also have to consider an infectious gastroenteritis due to something else they have come in to contact with, intestinal worms, or even a toxicity. You will need to continue to keep a close eye on both dogs, but especially Stella given her age and symptoms. Encourage both dogs to drink and hopefully they are drinking with no issue. If Stella can't keep water down, then there is the concern she could quickly become dehydrated, so if this is the case, play it safe and get her seen tonight. For now, with hold both dog's food until the morning. You may be best to put them on a very bland food for a few days. Cooked boneless, skinless chicken breast and boiled white rice is ideal for this, and very gentle on the stomach. After 2 - 3 days on that, you can slowly transition them on to the wet food again (over a 7 day period if you can).
For Stella - given her vomiting you may also want to try her 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 keep an eye on Stella's mucus membranes, capillary refill time and respiratory rate tonight as follows (do be careful that your girl doesn't try to bite you):
Mucus membranes - flip her lip and look at the color of her gums. They should maintain a nice salmon pink color. Get her 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 her 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 she seems to be panting or breathing rapidly 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 both dogs, but definitely pay closer attention to Stella right now as it sounds like she is quite lethargic. If the parameters above aren't right in either dog - play it safe and get them checked over by your local ER vet 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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