Sharon ~ Louie's mom posted this information in response to our request.

I'm so sorry to hear about your friend's kitty. Chylothorax is just a terrible condition and if it's not treated right away, the chances of recovery are so slim. It's just so so sad. Some animals can overcome it by different types of medications and with time while others cannot. They really don't know what the condition is caused by more times than not and it can easily disappear as quickly as it came on. When I was speaking with Louie's regular doctor, she told me that a practitioner might see it maybe 3 times in their career. Little is known about it and treatment options are far and few.

In Louie's case, it was idiopathic. They ruled out every single possible cause that they could test for prior to surgery. That's why I was trying to wait to see if he could recover on his own or if the condition would resolve itself but the fluid just kept coming back. Then it got to a point where scar tissue was building up and he only had a week or so to have the surgery before they wouldn't perform it any longer due to the conditions of his lungs. So Louie ended up having a thoracic duct ligation, pericardectomy and ablation of the cisterna chyli. Having all 3 things completed at once raises the success rate up to 80%. (Rather than doing the more standard and typical surgery for this condition of completing just the thoracic duct ligation which is around a 20% success rate, from what I've been told.)
In addition, she recommends this website https://www.acvs.org/small-animal/chylothorax