I have just found this old thread here in this forum:
help lice in 2 week old guineas
the interesting post says:
When we bought two of our guinea-pigs (at 6-weeks of age), they had lice. We told the petshop owner and she gave us some Ivermectin and told us to put just a tiny dab on the back of their necks, but it didn't make any difference (presumably because the dose was too low). I looked on Peter Gurney's website and he recommended Neem oil for lice. We treated all our guinea-pigs (including the 6-week-old ones) without any problems and it worked brilliantly. They're still lice-free over 2-months later. You can get organic Neem oil cheaply off eBay (a 100ml bottle which will last ages costs about the same as 3-phials of Ivermectin). Dilute 1 part Neem oil with 3 parts carrier oil (we used extra virgin olive oil as it doesn't have any chemical nasties in it). Wash it off after 2-days, wait 5-days and then repeat the above procedure.
Here's the link:
http://www.oginet.com/pgurney/skinp.htm
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there are other thread similar to this one; search on Google "neem oil guinea pig" and read carefully everything.
About the price of the oil: my bottle is 50ml and I paid 13€. I would pay half price bying it online, but I was in a hurry... my feet were a disaster.
Another advice: vets need customers and a customer with more than one pet is a good investiment for the future. Your vet might be interested in keeping you, offering now a discount (for example I paid one check up although into the pet-carrier I had two piggies... and when I adopted the third one I paid only a check up for a visit, medication of an abscess, prescription, syringes and other stuff...). The receptionist tells you the real price, but then the vet can also visit your pet for free when you are there into the clinic. At least this is what happens here.
I am never able to ask for a discount, but as you know the vet, why don't you try to have a frank conversation?
About the smell of the oil: it is not like a chinese meal...
it is different and very pungent (but actually I even liked it!). I used to put only 2-3 drops on each foot and the smell from the bathroom arrived to the kitchen
. As you have to use it on the whole body and as the piggie is having seizures, I would try only some drops the first time, because seizures sometimes can appear just after strong stimulations of senses.
I hope the oil will help your piggies, I hope the infection is not too serious...
If you like tomorrow morning I can search other info about owners who used this oil and I can send you the links...