First, even if you have had those plants for a while, its worth making sure there are no signs she has been chewing on them. Dogs with nausea as she has do sometimes eat house plants in place of grass to make themselves sick. Now the Malaseb could have irritated her stomach, but that would depend on how much she had. So, it is a consideration but at her age, we do need to also be aware that these signs could be due to a brewing bacterial or viral gastroenteritis, pancreatitis, parasites/protozoa infections, or general dietary indiscretion.
With this all in mind, her appetite loss isn't surprising. IT is going to be trigged by the same nausea that made her vomit. Therefore, to try to address this for her, we an try 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. And I would note that 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.
If she can keep that down and steadies, we can then try her with small meals of an 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. Whichever you choose, start her with a spoonful. If she keeps that down for 30 minutes, then she can have a bit more and so on. The aim of these diets is that they will be better tolerated/absorbed by the compromised gut. Therefore, it should get more nutrients in and result in less GI upset.
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 Lilly. Therefore, we’d want to start supportive care to settle her stomach and keep an eye on her belly tenderness (which is what I suspect caused that breathing change when you pressed). If she cannot keep the above or water down at any point, appears dehydrated already, or doesn’t respond to the above within 12-24 hours; then we'd want to get her vet involved. They can assess her hydration, rule out fever, make sure there is nothing in her stomach that shouldn't be there or any sinister viruses present. Depending on their findings, Lilly's vet can treat her with injectable anti-vomiting medication +/- antibiotics to settle her stomach, and get her back feeling like herself.
All the best,
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