What is the ethical justification for lacto-vegetarianism or ovo-vegetarianism?

I understand the reasoning behind vegetarianism and veganism, but could someone kindly explain the reasoning behind abstaining from only eggs and not dairy or only dairy and not eggs (the ethical reasons, not health).
Thanks =)

yeah I'm sorta confused about that too.

lacto-vegetarianism or ovo-vegetarianism isn鈥檛 just refraining from eggs or just from dairy.
It鈥檚 refraining from meat plus eggs or meat plus dairy.
Basically with every animal or animal byproduct food there is different suffering involved. With dairy there is the suffering that happens to dairy cows and it is also directly connected to the veil industry.
With eggs there is the suffering of the chickens cooped up in cages.
When you decide to become vegetarian you make the decision to take a stand against the cruelty to animals.
Some people just refrain from meat. Some take it a step further and stop eating eggs and dairy. Some choose to do one or the other. For some people it鈥檚 really hard to refrain from all animal products so they do what they can live with comfortably.
I was vegan for 3 years and then after a while it was just too hard to keep up with it as far as eating out and going to family events and parties. So I decided to allow myself a limited amount of eggs and dairy. My vegetarian life style is now easier for me to keep up.

I agree with JV the Greatest, I am a lacto-ovo vegetarain, and for those who say an egg is an unborn chicken they should have there heads read???, I chose to become a vegtarian for health reasons, I was a chef for over 20+ year around the world, ate anything and everything that moved, but as a diabetic and having a celiac condition I have had to seek out a veggie lifestyle for both health and comfort reasons.

As JV said some people can adapt to the vegan lifestyle and not have issues, it is matter of body preference, I see no ethical issues with a lacto or ovo veg person, it is a choice to not eat them and any animal products, but it can make getting your protein levels in the diet you choose to be enough, especially if your a convert like me. I have no problem as I eat tofu, beans/legumes, all veg, a modicum of dairy in the form of yougart mostly, and only egg whites in cooking no whole eggs.

For some it is an ethical reason, they are unaware of things beleive all the retoric about unborn chicks and puss in the milk, trust me I have seen the processing of these foods and in the U.S and Canada there are very strict regulations as to the content of our food now, so the blind issues are not there anymore, and those who would say the are have mental issues.

In favour of lacto vegetarianism:

-regarding the egg as an unborn animal, and therefore analogous to eating meat

In favour of ovo vegetarianism:

-the necessity for a cow to reproduce to give milk, thereby supporting the killing of unwanted calves, as opposed to hens being able to lay eggs for human consumption without having babies as "by-products"