“No-one seems to know if the poison was a natural substance, like a fungi, or if there is a dog-hating maniac on the loose,” the friend told the publication.
“Obviously, Beatrice is keeping a close eye on her other pets.”
The terriers have been an integral part of Princess Beatrice and Princess Eugenie’s lives, even appearing in British Vogue’s September issue last year.
Revealing a not-so-royal moment from the shoot, interviewer Ellie Pithers said one of the terriers “[relieved] himself on the ruffled hem of Beatrice’s cape.”
Showing the princess support in this tough time is new beau Edoardo Mapelli Mozzi, who rang in the new year with the royal in Kenya.
“She’s loved up with Edo but couldn’t stop thinking about her dog,” the friend revealed.
“It’s very upsetting.”