It pays to read up on these things!
Read about this just the other day, Bonnie became slightly lame last night, took her to the vet today and low and behold she had a grass seed. Not like the ones on the pictures, about 6cm long, slightly fatter on one end and really hard like a needle. The vet said that if I had waited another day the grass seed would probably have gone right up and she would have needed an op.
She's had a painkiller, is on antibiotics, had her paw bathed in salt water and I've just cut masses of fur off her paws.
So thank you Michele I think you promoted me to act more zealously.
Bonnie sends licks.