Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you with your wee one today.
Now this is quite a common situation for new mums. The reason we can see GI issues (or any health issues) rear its head at this point is because this is a moment in time where she has a very weak immune system. Her body will have been devoting large amounts of her own personal resources to help her kitten develop and make milk to feed them.
Now to approach this opportunistic agent (which would be bacterial, viral, parasitic --especially if she is a stray kitty), there are some things we can do. To start, even though we do like to use light diets for diarrhea cases, we need to instead keep mum on a high nutrient feed since we don't want this to take a toll on her (as it can cause weight loss and weakness for her but could also dry up her milk). So, consider offering her kitten food at this point.
Further to that, we also want to keep an eye on her hydration since it is quite easy for water loss from diarrhea to become too much for her to keep up with. Therefore, it would be a good idea to check her hydration status at this point. To check her hydration status to make sure she is not becoming dehydrated there are a few things we can test. 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. (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 by her vet to avoid this getting serious for her.
If her hydration is good, we still want to support her drinking. Make sure she has fresh water and you can even offer cat milk or low sodium chicken broth. If she isn't drinking well, then you can even syringe feed her pedialyte (which is nice because it replaces electrolytes as well as fluids). A typical maintenance rate for hydration in an animal is 48 milliliters per kilogram of body weight per day. This value will give you the total she needs for the day (though doesn’t take into account diarrhea losses and you'd want to add an equivalent volume in as well) and is a good starting point to give you an idea of her daily requirement. If she vomits you given pedialyte, I would discontinue this as a therapy. (since we don’t want her vomiting more because of our intervention)
As well, to slow her diarrhea, you can consider trying a cat safe GI balancing anti-diarrhea product (ie Protexin Pro-Fiber, Propectalin, etc) or Kaolin/Kaopectate (More Info/Dose @http://www.petplace.com/article/drug-library/library/over-the-counter/kaolin-and-pectin-kapectolin-k-p). These are both OTC and can help slow her diarrhea to avoid further fluid losses and settle her GI. Do make sure to avoid drugs like Loperamide or Pepto Bismol in this situation (as they can cause adverse signs in cats). And canned pumpkin can also be added to her cat food as a fiber source to bulk up this stool. And as she has been a stray and worms are so commonly to blame in these cases, consider starting her on Panacur/Fenbendazole. This is safe to use during lactation, and in young kittens (>2 weeks). And this would just help make sure worms are causing her signs nor posed to infect the kittens.
Overall, your lass is in that period of her motherhood where her immune system and body resources will be the most tapped and therefore vulnerable to opportunistic agents. And it is likely the reason why we are now seeing diarrhea. In this case, we'd want to start the above supportive care to see if we can reduce her signs. If she isn't settling in the next 24-48 hours, then we'd want to consider having a fecal sample evaluated for those common parasitic (worms but protozoa too), viral and bacterial causes of diarrhea in cats +/- have her vet start her on a safe antibiotic to tackle common bacterial gastroenteritis agents. Depending on the findings, you will be able to then address this effectively for her and make sure this agent doesn't get a chance to spread to the kittens.
If you have any other questions, please ask me – I’ll be happy to respond.
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