I am sorry it has been so long since any updates. It is now 11 months since Betsy left and Ophelia steadily maintained the low weight Betsy had left her at. We have been monitoring her closely for any signs that the low weight is the result of something sinister, but she remained her lively, friendly self. There was no point repeatedly taking her to our vet to pay around £50 to be told that they couldn't find anything wrong and that we needed to pay up to £300 for scans. However, a new vet has opened nearby, recommended to us... So, two weeks ago, when Ophelia's weight dropped (coinciding with a heatwave), we took her to a lovely vet who happened to have an interest in guinea-pigs.
Besides the fact that this vet would have charged £100 for those scans (without the need for sedation), her careful prodding resulted in her finding a lump in Ophelia's neck. The hypothesis, without doing a biopsy, is that Ophelia has hyperthyroidism and this would explain the fact that she has always seemed so well and lively and yet won't put on weight despite the quantities she clearly eats. They had recently had two other piggies in with the same condition and the off-licence prescription worked.
We are concerned, however, that sometimes Ophelia's movements are no longer as fluid as they once were but the vet said that she would expect to see some arthritis in a piggy this age (she will turn 7 in less than a week) but that she had done well to show so little sign of it. Because Ophelia hasn't yet put on much weight in the first two weeks of the new medication, however, I have asked for her also to have painkiller as a just-in-case, which I will pick up tomorrow.
We can see that she is a 'senior piggy' now. My aim is to make sure that she is comfortable and happy.