It appears we replied at the same moment, so I will repost just not but if she is very sore, then we'd want her seen urgently. Otherwise, what I did say above (in case you cannot see it due to posting simultaneously):
First, we can off course see anorexia for a range of issues. Though in Zoe's case, it is the same nausea that caused her vomiting that will be putting her off eating. In regards ***** ***** for both, we can see this with bacterial or viral gastroenteritis, pancreatitis, parasites/protozoa infections, general dietary indiscretions, and ingestion of harmful items (ie toxins, plants, non-edible items). Furthermore, as she is elderly, there is also risk of this being associated with IBD, cancer, and secondary to metabolic disease or organ troubles.
With this all in mind, as long as she can keep water down, we can try some home supportive care to try to settle her stomach. To start, if she hasn’t just vomited (since otherwise we’d need to rest her stomach for a few hours first), then you can consider treating her with an antacid. Common OTC pet safe options would be: Pepcid (More Info/Dose @http://www.petplace.com/article/drug-library/library/over-the-counter/famotidine-pepcid), Zantac (More Info/Dose @ http://www.petplace.com/article/drug-library/library/over-the-counter/ranitidine-hcl-zantac), or Tagamet (More Info/Dose Here @ http://www.petplace.com/article/drug-library/library/over-the-counter/cimetidine-hcl-tagamet). Whichever you choose, we’d give this 20 minutes before food to allow absorption. Of course, do double check with your vet if she has a known health issues or is on any medications you haven't mentioned. Though if you give this and she cannot keep it down due to nausea that is usually a red flag that we need to bypass her mouth with injectable anti-vomiting medication from her vet.
Once that has had time to absorb and she is steadier on her stomach, you can consider starting her on a easily digestible diet like cooked white rice with boiled chicken, boiled white fish, cottage cheese, scrambled eggs, or meat baby food (as long as its garlic/onion free). There are also OTC vet diets that can be used (ie Hill’s I/D or Royal Canin’s sensitivity) too. The aim of these diets is that they will be better tolerated/absorbed by an upset gut.
Since dehydration is a risk here, we need to keep an eye on her hydration. To check that she isn't dehydrated, there are a few things you can test. Further to checking for gum moisture, do make sure she doesn’t have sunken eyes and that she doesn’t have a "skin tent" when you lift the skin. To see how to check these parameters for dehydration, you can find a good video HERE (http://www.ehow.com/video_12232503_dog-dehydrated.html). If you are seeing any signs of dehydration already, then that would be our cue to have her seen before this becomes an additional issue for her (especially as it is often dehydration that makes them feel unwell).
Overall, there are a wide range of agents could trigger this GI upset we are seeing with Zoe. Therefore, we’d want to start supportive care to settle her stomach. If she cannot keep that or water down at any point, appears dehydrated already, or doesn’t respond to the above within 12-24 hours (since she is older and won't have the body reserves she once did); then we'd want to get her vet involved. They can assess her hydration, check bloods to make sure her organs are working as they should, make sure there is nothing in her stomach that shouldn't be there or any sinister viruses present. Depending on their findings, her vet can treat her with injectable anti-nausea medication, appetite stimulants, pain relief if her mouth is found to be sore, +/- antibiotics to settle her stomach, and get her back feeling like herself.
All the best,
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