Thank you, Cathy.
First, I have to say that her having belly pain here is a major red flag of some of our more urgent issues, so we need to tread with great care. Now to just touch on what you have done so far, I would advise not giving any more Erthyromycin, as this isn't an antibiotic that we really use for gut based issues and is more likely to cause upset then help. Furthermore, we don't routinely use Metacam for gut issues since it can cause diarrhea, GI upset and stomach ulcers and is more likely to do so when they have GI issues. Furthermore, we won't want to reach for the Enrofloxacin either since its not a first line drug for gut infections. Plus it has to be used with great care since it can lead to blindness when used inappropriately in cats. The only treatments you have used so far that we could continue are the electrolytes, probiotics, and the baby food (as long as its garlic/onion free).
Now that aside for the moment, based on the signs we are seeing, we do have a few concerns. Common causes we need to consider include bacterial or viral gastroenteritis, pancreatitis, parasites/protozoa infections, general dietary indiscretions, and ingestion of harmful items (hopefully not an issue since she is indoors). Furthermore, since this has a chronic element to it, we also have to be wary of IBD, organ issues, metabolic disease, and cancer. You didn't list an age, but if she is older then these would be even more a worry.
With this all in mind, as long as she can keep water down, we can try some home supportive care to see if we can 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 pet safe OTC ones we can use include Pepcid (More Info/Dose @http://www.petplace.com/article/drug-library/library/over-the-counter/famotidine-pepcid) 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 offering food to allow absorption. Since she has had Metacam, this should be given ever 12 hours. Of course, do check with her vet before use if she has any known health issues or is on any medications you didn’t mention. As well, if you try this and find her nausea too severe to keep it down, then that is usually a red flag that we need her vet to bypass her mouth with injectable anti-vomiting medication.
Once that has had time to absorb and she is steadier on her stomach, you can consider starting her on a light/easily digestible diet. Baby food is fine but we can also use boiled chicken, boiled white fish, or scrambled eggs. There are also OTC vet diets that can be used (ie Hill’s I/D or Royal Canin’s sensitivity) too. When you offer this start with a spoonful, give her 30 minutes to settle. If she keeps the food down, you can give a bit more and so on. As her stomach stabilizes, you can offer more. 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. As long as improvement is being seen, I usually advise that the diet be continued until her signs are settled, and that they are then slowly weaned back to their normal diet.
Since dehydration is a risk here, we need to keep an eye on her hydration. To check this and ensure he’s not becoming dehydrated, there are a few things you can test. Further to checking for gum moisture, you will want to make sure her eyes are not looking sunken 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).
Finally, as long as you have not seen blood in those stools, you can consider trying a pet safe anti-diarrheal. As I am sure you appreciate, these would not be a cure if the cause were infectious; but it can still be of benefit. It will reduce diarrhea load, allow the body to absorb more water/nutrients, and soothe the upset gut. In regards ***** ***** options for your wee one, the one we most commonly use is Kaolin/Kaopectate (More Info/Dose @ http://www.petplace.com/article/drug-library/library/over-the-counter/kaolin-and-pectin-kapectolin-k-p). This is available OTC at most pharmacies. Otherwise, Propectalin, Canikur, Fast Balance, and Protexin Pro-Fiber (which is available OTC at vets, pet stores, and even Amazon) would be another option. All will slow diarrhea and those last ones have the added bonus of providing support to the delicate good GI bacteria. So, these can be used as a short-term means of soothing this upset GI.
Overall, a wide range of agents could trigger the GI upset we are seeing. Still, her having a painful belly does make me very concerned about blockages, pancreatitis, or issues compromising the gut blood flow (ie twists, tumors, compression from enlarged organs, etc). Therefore, we need to tread with care and if she is very sore, it'd be ideal to have her seen urgently. Otherwise, do make those amendments to your treatment plan and start want to start supportive care to settle her stomach. If she cannot keep that or water down, appears dehydrated already, or doesn’t respond to the above within a few 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, her vet can treat her with injectable anti-vomiting medication +/- gut infection appropriate antibiotics (ie Amoxicillin) if there is actually an infectious cause to settle her stomach, and get her back feeling like herself.
Please take care,
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