Answer

Egg peritonitis is a possible complication of egg laying birds. In some birds the ova end up in the body cavity. There is no chance of success of this egg and it cannot re-enter the oviduct. There are many reasons this happens to begin with, but the most important thing you have done and the most responsible was to get the bird to a vet.

As you've found out, when you notice symptoms that may appear to be egg binding, any discharge from the vent that looks unusual or is happening without the bird making a dropping, any lethargy or depression in a bird that has been known to lay eggs, enlargement of the abdominal area – you can’t waste any time with a ‘wait and see’ stance. The misplaced egg will generally cause peritonitis (inflammation in the body cavity) and as the yolk is absorbed by the peritoneum it will likely cause a reaction in the bloodstream that can be fatal rather quickly.

You've done a caring, very good job in having her treated.

A study published by (and in journals) with the Dept. of Nutrition, Zootechnics & Zoohygiene and the University of Veterinary and Pharmaceutical Sciences as recently as last year indicates that Silvbum marianum (milk thistle) had non-significant effects on the overall health of the livers in the birds used for the study. However, it did reduce the levels of lipids (fats) in the liver and increased levels of glycogen.

It does seem to help in ‘fattening them up’ (adding weight).

The milk thistle made up approximately 3% of a well balanced feed mix that included seed and pellets appropriate for the particular type of bird.

It's certainly worth the try. Good luck and keep up the good work.