underweight & nervous

Question
Hi,
We recently got a boxer bitch, She is about three years old. Her previous owners just had a baby and as they have also got a labrador they decided that the boxer just was too energetic to cope with.
So my problem is that we brought her straight to the vets for a check up and worming tabs. She is underweight though at 20 kilos. She is not as tall as other fully grown boxer bitches that we have seen... maybe 4 inches shorter. but you can see all her ribs spine and hip bones. She always eats all her food (approx 2 cups red mills premium dry food twice a day). She also is obsessed with food when we are preparing our own! and when she eats her own she seems very jumpy unless we stand over her and then she will eat it up fast, but if i walk away she seems nervous that we are going to leave her while her back is turned when she is eating! she eats very fast too. If she has such an appetite I wonder why she is so underweight, although she defecates between 3 and 5 times a day. Is this normal?
The last thing is her nervousness, she jumps at noises and we cannot get up off a chair without her rushing to follow us around. She is very afraid of my brother in law too even though he has never done anything for her to be nervous about. Yet she loves other dogs... even though they dont all seem to like her! She has not been spayed, we plan to have this done soon, does this affect their behaviour?
Other than this she is a very obedient, energetic, affectionate girl!
Thanks so much for your help.
Kind regards
FA

Answer
Hi,

She does sound a bit skinny - seeing the ribs isn't necessarily a problem, but the spine and hips should not be prominent at an ideal weight.  If her food is heavy on grain, there are more fillers in the food so more waste going out, and you'd need to feed more.  There are some grain-free foods that are generally more appropriate for dogs; I'm not sure where you're located so am not sure about their availability in your area.  A good site for researching foods is www.dogfoodanalysis.com

The nervousness might be in part due to her new situation - you mention you got her recently.  Sometimes it can take a few months even for a dog to settle into new home.  I'd try to provide as much structure and routine for her as possible, and do some basic obedience work with her every day - a 10 minute session would be fine.  This will help her become comfortable with her place in your household, will help her learn to trust you as the one who controls the resources and sets the rules, and will give her something to think about when you're not working with her.  You might also do some obedience work with your brother-in-law present - something simple like 'doggy push-ups' (sit, down, sit, down) - and have him be the "food dispenser" who gives her the treats for correctly responding to the cue - I'd save something super-yummy like liver, braunschweiger, etc. that you only use when he's around; this will help her equate him with "good things" and should help her get past her fear of him.  

In my experience spaying does not really have an effect on behavior, except that behavior which is related to the hormonal changes associated with a heat cycle.

Good luck!