Thank you for the additional information about Pacha and her family.
As I noted before, your approach here has been spot-on for wee Pacha. Worming is always a first step since parasites notoriously take advantage of the way pregnancy and lactation tap the new mum's resources. As well, you were absolutely correct to increase her nutritional plane with access to the more calorically dense kitten food. So, I do commend you with your approach so far.
Now with those bases covered, it means we have to consider out sources of nutrition loss. Opportunistic bacterial or viral diarrhea issues are a very common reason but if she has been losing weight before then and only had a wee bout, then this isn't likely to be our culprit here. And ruling that out means, that we do have to be suspicious (as you have noted) that the other major output --the kittens-- are the source of her weight loss.
And if that is the case then under the circumstances and the concern for Pacha's health, we do need to consider weaning the kittens now. I am glad to see you have already started to do so and I have to say we are lucky that they are already around that 4 week point since this is a fine age to start getting them onto solid food.
Now you noted that you have been giving Pacha some peace and I think that is a good start. Specifically, I would advise separating them for a few hours at a time from her. Ideally, it should be somewhere where she can see them (so she doesn't fret) and somewhere where they have their resources (ie litterbox, milk, food, water, etc). You noted they weren't keen on the kitten milk, but do make sure it is on offer, ideally in a shallow bowl. This is also a good time to interact with them and you can handfeed the milk to them off your fingers and show them the bowl. Usually with help (and a bit of hunger when mum's not available), they will get an idea of the situation and we can get them lapping milk. As well, you can make them a gruel my mixing the kitten milk into canned kitten food. This can again be hand fed until they get the idea of eating on their own. As they start to pick up eating on their own, we can increase the periods of separation from mum and continue to decrease their tapping her body resources so heavily.
At the same time, you do of course, want to keep her on that higher nutritional plane. That said, I would suggest that you could also supplement her with Hill's A/D (LINK) from your local vet. This is a critical care diet that is comes as a soft, palatable pate. It is calorically dense, so a little goes a long way nutrition-wise and this could just help get some more calories into her even if we can’t get a huge volume of food in. Alternatively, you can use the animal version of Ensure (balanced for animals dietary requirements) called Clinicare Canine/Feline Liquid Diet (LINK)). It is actually by the same people who make Ensure, but is formulated to meet out pet's dietary needs. Your vet should be able to order it for you but it is available without a prescription (some pet stores and even Amazon stock it as well). It would just be another way to get more nutrition into her to try to keep her current weight stable and prevent further loss. As well, I would strongly suggest weighing Pacha and keeping a diary of her weight. If she continues to lose weight despite decreasing her kitten sources output
and further increasing her nutritional inputs, then we'd have to be worried about underlying health issues playing a role (despite the lack of signs, we can see some viral diseases cause issues under these circumstances).
Overall, your approach has been just right but from here we need to increase our initiation of weaning while monitoring Pacha's weight. If you do so and are still seeing her lose, then do consider those critical care diets and potentially having her checked over by her vet to rule out underlying disease. And while we hope it won't be the case, if we cannot get her weight loss under control with the above, then we may even have to consider full removal of the kittens (despite the socialization implications) with initiation of bottle feeding to balance weaning to prevent further harm to mum.
I hope this information is helpful.
If you need any additional information, do not hesitate to ask!
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