First thing is well done finding a vet that has prescribed 3 treatments 2 weeks apart because not all do! How heavy are your piggies - are they very young? There are 2 types of xeno and you have the mini-type so I'm wondering if you have little ones as the prescription is weight dependent. Mine are big chunkers!
The xeno will treat both mites and lice but not fungus. Mites are not usually visible - they can be detected by the vet using a microscope sometimes but if you have symptoms of intense scratching/nibbling and shedding hair - maybe even bald patches - mites are a common candidate and of course they are contagious so all piggies are treated together at the same time. Some mites live in the top layers of skin so when the xeno is applied (by spotting onto the skin) and absorbed throughout the system it kills the mites but they spasm as they die and this can cause very intense itching for a few hours. With low levels of mites you will barely notice anything but heavy infestations can be distressing to see. However it does pass and then piggy is much more comfortable. The second dose deals with eggs which need to hatch out before they can be killed, the third dose is to make sure none have slipped through the net! So they might also scratch a lot after their second dose but the third they shouldn't notice anything.
Xeno is pretty much gone after a few days so there is no need to bath anyone. The only pigs I bathe are perhaps ones which have urinary tract issues and are wet and dirty from dripping urine... these get a 'bum bath' in warm water rather than a full dip as bathing totally freaks them out whether they show it or not. One old girl had to have a full body shampoo for a fungal infection but she was the only one.
Personally I crop my long-haired girl as she hates being groomed but it depends on the type of hair. I'm not convinced that all long-hairs are able to naturally keep themselves clean as looking like a running wig isn't really a 'natural' look for a guinea pig - they've been bred like that! But all healthy pigs will do their best to keep clean and most manage it just fine. Long-hairs often need a trim around the bum and back legs where urine can wick up and start to stink - especially as sows will spray urine to repel piggies pestering them from behind and this can really spread up the bum fur! Louise gets a haircut every couple of months but she needs a bum-trim roughly every 4 weeks... it's pretty obvious when because her buns are usually white so the pee stains are an attractive touch!
Here she is before and after...
View attachment 201967 View attachment 201968
If you are seeing white grit or crust stuck to the outside of the poops it might be from calcium in the urine. Piggies naturally pee out their excess calcium so you might notice their pee is a bit 'milky', but too much can cause issues like bladder sludge and stones. Gritty pee can make them sore and more prone to infections down below too. This is why the forum recommends limiting pellets and filtering drinking water as these are sources of high levels of calcium in the diet. If you have a pellet-monster who is hogging more than her share then you might well see a gritty calcium deposit on her pees/poops. Louise is my culprit here - although she's bottom pig she really loves those pellets and she is fatter than my boar! I make sure to have plenty of water bottles dotted about (4 between 3 pigs) so she can always drink to keep things flushing through.
It is quite natural for one pig to be dominant and first to the food, and this will make her grow faster, but I should just add one more thing. If you've not had the piggies very long and one is being very greedy and increasing in size maybe more than the others - well - is it possible she could be pregnant? Sometimes people have gotten young pigs from a breeder or a shop and one has already had an encounter with a boar - or maybe a young boar was accidently put in the sow group for a while until someone noticed. If you've had them for less than 10 weeks just keep an eye on her - I don't think it becomes obvious until the last couple of weeks. It's probably not this at all - but I'm just being over cautious in case I've missed anything!
I don’t think bathing would be a regular thing maybe once to be honest or not if it’s not recommended… many thanks x
yes your right I did think about pregnancy a few times I will keep a close eye I really hope this is not the case! The white bits I seen were actually in the front of her bum the vet said aww this is probably sawdust I wasn’t very happy they didn’t look at the girls skin or through thier fur they just recommended the Zeno and it’s the mini one yes cause the girls are young I would say between 10-16 weeks maybe 
I will avoid bathing I think as the Zeno has already upset them as it is so wouldn’t want to put more pressure on them ahh that makes sense about the pee as I noticed there was lots of it spread up high in their furplast I have noticed they will chase each other’s back end and run about I hope this is just them figuring out who’s boss as I got 2 girls first then another 2 girls a few weeks later I am very worried about urine infections sludge and bladder stones I will make sure there is plenty water 4 bottles full I’m not sure do I definitely need to filter water as I’m in highlands Scotland the water is pretty soft here thanks so much for your help
