I have an old illustration in my archives of a brown otter almost completely covered in white spots. It is in the Irish Naturalist vol.18 but I am not clear of the page numbers - quite near 1907 I think. The story accompanying the photo is as follows:
'The National Museum of Ireland recently acquired from Mr. W. J. Williams, of Dublin, a full-grown Otter, which differs from ordinary otters, in that its rich brown fur is dotted all over with white spots, as shown in the accompanying illustration. It was trapped in Lough Sheelin, which lies partly in the County Cavan and partly in Westmeath.
The fur, as a rule, is of a rich chestnut brown in Irish Otters. …Mr Williams informs me that,occasionally, amounting to about 1 per cent of the skins prepared by him for the fur trade, the skins are speckled in this manner. The whiteness, however, in these cases, is still hidden to some extent, in the unprepared skin, by the brown colour of the long hairs. It is only after removal of the hairs by the furrier that the white spots become plainly visible.
In the specimen here figured, not only has the under-fur white patches of variable size, but the whiteness extends even to the long hairs, giving the Otter a most peculiar specked appearance. Mr Williams tells me that, among several thousands of skins that have passed through his hands, this is the only specimen of that kind he has seen.
From the Royal Irish Academy Fauna and Flora Committee`s records, I find that perfectly white Otters have been observed in the River Shannon, being, presumably, true albinos,, and recorded in the Field (vol. xci., 1898,pp 141-142). We know that an albino Otter from Scotland is preserved in the Belfast Museum…In connection with this very abnormal skin of the Otter, I re-examined the ordinary ones with a view to verifying Mr Ogilby`s statement that Irish Otters differ so much from English ones as to deserve a special name. He proposed to call the Irish Otter Lutra roensis instead of Lutra vulgaris (1)
1.Anon Irish Naturalist vol 18 pp?