i wouldn't be concerned about the metacam long term to be honest. mollie has been on 0.5ml twice a day since last may and she is staying on this dose. bladder inflammation is one of the hardest to control and can take months and months to control or bring down (which is why two lots of cover are usually given) - our vets don't consider mollie to be on a high dose, but an adequate one for this type of illness. it's highly unlikely that metacam causes any damage at all long term due to the fast metabolism and even if it did, it would take longer than they would probably be around for, for it to happen anyway. the vet was saying that even in already damaged kidneys, it has to be used more cautiously but can still be given. mollie can only have the metacam reduced if she can come off the cerenia first. i know people worry about metacam but i really think it's so important to have an adequate dose of it, even if that means long term. i hope that helps
mollie doesn't technically have IC as such, because although she has bladder inflammation, it's thought to be mainly caused by the excess calcium salts. but she does have generalised swelling aswell which was originally though to be just bladder, but turned out to be both bladder and reproductive area (the two are often linked and this is why the spay was needed)
so we don't follow the IC diet as such, although it's still low calcium. the vet said the best fresh foods for mollie are lettuces. she has these as the bulk of her fresh food and then smaller amounts of other low calcium veggies. but the vet said she would also be fine on just lettuces. she started off with no pellets whilst we tried to get symptoms under control, but now she is able to have very very small amounts of vitakraft pellets which seem to suit her well. alongside this she has a variety of hays and fresh grass when possible aswell. she does very well on this diet and has kept a fairly stable weight. this is alongside her diuretic aswell for the excess calcium salts. her body cannot deal with the calcium so she needs the diuretic for good.
mollie originally had blood in her urine however this completely stopped after her initial course of treatment (she was on even higher metacam then to bring the inflammation down as quickly as possible, and also marbocyl which is our vets preferred choice for treatment of uti's)
i would certainly ask about the cerenia as i think it's been excellent for mollie.
it does sound like emma has IC but you could also look into possible inflammation in the reproductive area aswell. sometimes ovarian cysts cause issues and act as an immunosuppressant which is why the piggy cannot deal with or clear bladder issues. it happened to be the case with both maisie and with mollie so definitely something to consider. depending on the piggy and particular circumstances, treatment could be the hcg injections or a spay. maisie had the injections and mollie the spay was needed.
you could perhaps look at higher metacam at least initially aswell just to really settle down any inflammation. i know our vets start higher to get the majority under control and then taper as required.
i hope this helps a bit. best of luck with emma x