Everyday on a farm is a learning experience...

Some days you learn some great things, and other days you learn things you would rather not have learn. Like mastitis and prolapse. 

I belong to a number of sheep and livestock groups on Face Book. I learned yesterday from a farmer that when a sheep has mastitis, no matter how mild or severe, it causes scar tissue. That scar tissue can prevent milk from flowing into the teats and feeding the lambs. That might explain why we lost so many lambs last year, even though we never saw/felt mastitis. 
He also said laying in the snow with full bags could cause the same thing... Ours have plenty of hay that they won't eat to lay on, but there are some who prefer the coldness of the snow.  I am not sure of this reason.
This year we've had 2 with massive bags that we had to put down. One who had triplets that we bottle fed for the first 24 hours until she flattened/smothered one, and repeated it with the other two 12 hours later. We were hoping for her milk to let down so she would feed them herself. She had a big enough area, so there really was no reason for her to do this. The following day we put her down as she was going down hill physically and it was the most humane thing to do.
The other one also had a HUGE bag and was prolapsing every time she laid down. Unfortunately a prolapse paddle would not hold it in. She went into labor but was unable to deliver because of the vaginal prolapse. She was put down as well. She broke my heart as she was a favorite. Sweet sheep with great wool. Hubby sheared her for me (he offered) after he put her down.

Mastitis-
 http://beefandlamb.ahdb.org.uk/wp/wp-content/uploads/2016/07/BRP-plus-Understanding-mastitis-in-sheep-180716.pdf

 I never knew mastitis could be contagious. (from the above PDF)
When one ewe has mastitis the flock is at increased risk due to its contagious and transmissible nature.

https://www.canr.msu.edu/news/mastitis-in-sheep-and-goats
 We generally clean the girls area only once, maybe twice, during the winter months. We have found keeping a deep litter pack helps to keep them warmer. Cleaning to the floor allows the cold air to come up through the floor. But, we do put hay that they don't like or straw down to keep the floor clean.


https://www.agric.wa.gov.au/livestock-biosecurity/mastitis-sheep 

https://www.vet.cornell.edu/animal-health-diagnostic-center/programs/nyschap/modules-documents/mastitis-ewes-and-does
https://askavetsheep.wordpress.com/2013/02/03/mastitis/

Prolapse. 
We've had sheep since 1993. We've had a prolapse in a ewe that delivered a 16 pound lamb. We had to have the vet out for that one as it was our first, but not only was it vaginal but also the uterus came out. Her placenta would not detach from her uterus which was causing her to continue pushing. Unfortunately, she also pushed out her intestines causing the vet to euthanize her.
One of the ewes hubby put down yesterday prolapsed her first time pregnant. The prolapse paddle was successful, and she delivered past the paddle as they a supposed to. She went on to deliver 2 more years without an issue, until this year... She was the 3rd prolapse we had this year. The first prolapse her uterus which tore causing internal bleeding. She was the first put down. The second was successfully put in and the paddle and harness(modified sheep coat in our case) put in and on. Two weeks later and she is doing well with the paddle still in. Then we have our 3rd with one of my favorite sheep. The paddle did not work for her.

https://askavetsheep.wordpress.com/2013/02/02/prolapse/

Some of the pictures in the following are quite graphic!
https://www.nadis.org.uk/disease-a-z/sheep/lambing/lambing-part-3-vaginal-and-uterine-prolapse/

Now that you have been thoroughly saddened and grossed out, I will return to my barn to ensure there are no more surprises happening.
As of right now, we've had 5 ewe lambs born to 3 ewes and 1 ram lamb born to another ewe. I have 2 ewes that have normal udders and vulvas that are extremely uncomfortable and may lamb in the next day or two.
I see no signs of huge udders in any of the other sheep, including the one wearing the prolapse paddle.
I am awaiting the arrival of penicillin and LA 200 from https://www.jefferspet.com/ in case of any other treatable cases of mastitis. The Nuflor and the Dexamethasone will have to come from the vet. I am already waiting for Oxytocine from her.