[samuria]

let the girls out this morning, all fine bar the old marran.
she walks a few steps then sits. her tail end seems arched.
she did eat and drink a little.
what could be the problem?
thanks

[New shoot]

The arching over of her tail is a sign she really doesn't feel well. 

You mention this hen is elderly.  If she is an oldie who is past laying, you can rule out egg problems, but still check for obvious things like a swollen crop (impacted crop), bad smell to her breath (sour crop) or discharge from her vent (infection).

I would also try bringing her into a cool room and letting her sit in a box or puppy cage for a bit. She may just need a bit of TLC and being away from the flock will give her a chance to recuperate.  I have had oldies respond to this and go on to live a couple more years.

There is a big but with this.  Hens mask illness, so she may be really ill and need a vet, or if you think that she has had her time and you don't want to stress her with a vet visit, she may need culling.

Sorry if that sounds harsh, but I have had many elderly hens over the years and while I will always give them a chance, you can't let them suffer.

I hope she is OK.  My oldest hen is 10 and I do enjoy having old girls around 

[samuria]

i did take old molly to the vet, could not see her suffer...
she was just old!! the vet said she could try a calcium injection, but
it may not help and advised putting her to sleep.
so i agreed. she is now in chicken paradise.......

[New shoot]

RIP Molly 

You did the right thing.  Its the last kindness you can do for an old hen.  I'm sure she had a long and happy life with you, but it was just her time 

[Sassy]

Second what New Shoot said. Its always hard but you gave her a good life. Most hens do not get that!