I think dogs or cats, if connected with a human, can tell if somethings wrong. Years ago before my father was diagnosed with cancer our cat Tiger just sat and starred at him, much to his annoyance , as Tiger was usually so affectionate towards him. this went on for months until eventually my dad was diagnosed with terminal cancer, if only Tiger could have spoke, perhaps we could have caught his cancer earlier, its as if Tiger knew something was wrong.
Then a year after Andrew, my son was diagnosed T1, we got a cat called Fudge, she took to sleeping at the bottom of his bed, and alerted me twice by coming into my room and sitting on my face! and woke him numerous times, when he checked his blood he was always verging on low. Unfortunately she was killed on the road last October. We now have 2 cats but neither have shown any of the sixth sense that previous cats have.
I strongly believe through experience that cats as well as dogs can be alert guardians,
Suzi x