Thank you for the further information about wee Shady, Karen.
Now as I am sure you can appreciate, just like people, cats can have diarrhea for a range of reasons. In Shady's case, I would be concerned that this may have more of an underlying issue than a GI disturbance from the treats if it was settled and then recurred again so soon.
In regards to common causes for diarrhea in cats, we'd have to consider bacteria viral agent, parasites (worms but also protozoa like Giardia, Coccidia, Tritrichomonas), toxins (less likely here hopefully), cancer (ie GI lymphoma), nutritional issues, and general dietary indiscretions. As well, we can see loose stools precipitated by ingestion of toxins or non-edible items, btu at her age this hopefully is not an issue. Of course some will be more prevalent in certain cat age groups. It can be daunting to get to the bottom of which differential is to blame, but since it sounds like she is otherwise normal and the diarrhea is not profuse, there are a few things you can try at home try and get it to settle.
Now I am glad to see that she is wormed and these creepy crawlies can be ruled out. Though I would warn that if she is a keen hunter, then it is possible for her to have picked worms again since the last treatment. If she is and this is thus a risk, then you can consider covering her again now to ensure there have been no worms missed.
From there, the next step one would try with settling feline diarrhea is to offer a light/easily digestible diet. Examples of this would be boiled chicken, boiled white fish, scrambled eggs (made with water and not milk), meat baby food (do avoid the ones with garlic powder in the ingredients) or there are also veterinary prescription diets that can be used in cases of gastroenteritis (ie Hill’s I/D or Royal Canin’s sensitivity). These diets aim for provide nutrition to the stressed gut without making it work hard to digest the food. I would advise frequent small meals to minimize strain on the already stressed gut, and to help lower the volume of diarrhea.
As well, do keep a close eye on her water intake and her hydration. Since she is an older lass she will not have the body reserves she used to have. This means that if the diarrhea continues, she can quickly become dehydrated. To check her hydration status to make sure she is not becoming dehydrated there are a few things we can test at home. One is whether the eyes appear sunken, if the gums are tacky instead of wet/moist, and whether she has a "skin tent" when you lift the skin. To see how to check these parameters for dehydration, you can find a wee video on this HERE. (They use a big dog but it makes it easier to see and the principles are exactly the same) If you are seeing any signs of dehydration already, then you do want to have your kitty seen by her vet before this gets out of control.
If you are concerned that she is becoming dehydrated from the fluid loss via diarrhea, you can try and encourage her to drink but offering fresh water or even low-sodium chicken broth. If she isn’t amenable to these, you can syringe feed pedialyte. Pedialyte is good here (though aim for a flavourless one since cats don’t love fruit) because it will get both fluids and lost electrolytes back into your kitty. A typical maintenance rate for hydration in an animal is 48mls per kilogram of weight a day. If you do give syringe pedialyte, this should obviously be divided up into multiple offerings through the day rather then all at once. This value will give you the total she needs for the day and is a good starting point to give you an idea of the feline daily requirement. (we aren’t calculating losses, so you can add an equivalent volume to match how much diarrhea is being producing). If she vomits when you have given pedialyte, then therapy should be discontinued (since we don’t want vomiting because of our intervention).
Finally, to help firm up her stools and limit fluid/nutrient loss via diarrhea, there are a few feline safe anti-diarrheals and GI supports that we can use to restore balance to the GI. In regards to safe options for her, the one we most commonly use in cats is
Protexin Pro-Fiber (which is available OTC at vet practices; example). As well, we can use Kaolin (More Info/Dose) available from your local pharmacy (do avoid using any PeptoBismol or similar products with aspirin in them since those can he harmful to our kitties) Both will slow diarrhea safely for a cat and the Pro-Fiber has the bonus of providing support to the delicate good bacteria of the GI. Furthermore, when we face GI upset, we do find supplementation with a probiotic to be beneficial. One preparation we often use is FortiFlora for Cats (LINK). This product is quite good for kitties with diarrhea from GI disturbance and will also give her a wee immune system boost. Some vets and pet stores carry it or you can get it online (Amazon even carries it).
Overall, diarrhea can be caused by a wide range of agents. If she is otherwise well in herself, properly hydrated, eating/drinking, and only having mild diarrhea; then you can try supportive care and the above anti-diarrheal medications to see if you can settle the signs at home. If you try the above and the diarrhea isn’t settling within a few days, then we'd have to consider more sinister causes for her diarrhea. In that case, that would be a good point to consider following up with her vet. Ideally, you could submit a fresh fecal sample to the vet for testing. Depending on the fecal test findings and your vet's exam, your vet will be able to pinpoint which agent is to blame and guide you on effectively targeting treatment against the causative agent to settle this diarrhea for Shady.
I hope this information is helpful.
If you need any additional information, do not hesitate to ask!
All the best & happy holidays,
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