The metabolic illness in sheep known as pregnancy toxemia has been somewhat more common across Montana this year. Also known as twin lamb sickness, pregnancy toxemia most commonly occurs in the late stages of pregnancy when the ewe is carrying multiple fetuses.
Brent Roeder, Montana State University Extension sheep specialist, says he has been getting several calls from producers across the state reporting the issue in some of their ewes. He says the illness most likely stems from the fact that last year’s harvested hay may be lacking the nutrients required to properly sustain ewes through pregnancy.
“One of the overriding factors we are seeing this year is the quality of hay that was put up last year. While I think it is meeting the requirements for cows, sheep have a higher protein and energy requirement by percentage,” he said.
It turns out, sheep need innately more energy from their feed, especially if they are carrying multiple lambs. Roeder explained that a ewe’s energy requirements are 200 percent of maintenance if she is carrying twins and 250 percent of maintenance if she has triplets.
During breeding season last fall, cooler temperatures created an ideal breeding environment. Because of the favorable conditions, Roeder noticed there are more lambs dropping this lambing season. It is quite common for sheep to have two or more lambs anyways.
Pregnancy toxemia can come about from one of two ways, the first of which is stress. For example, sheep need to be completely dry in order to be shorn. Spring can sometimes bring inclement weather, forcing producers to lock their sheep up the night before the shearers come to ensure the fleece is suitable to be shorn and it can be difficult to get feed to the ewes if they are in a concentrated situation like that. In addition, due to timing and other overarching delays, shearing often ends up butting against lambing. The stress of the whole ordeal could potentially cause pregnancy toxemia.
Older ewes that are in poorer overall body condition are also very prone to pregnancy toxemia. No matter the initial cause, pregnancy toxemia is characterized essentially by hypoglycemia.
Like humans, a sheep’s cells and tissue require insulin to uptake glucose from the blood stream. During late-stage pregnancy, a ewe’s endocrinology needs tend to change, especially since the fetus ends up pulling so much energy away from the ewe. The increased energy demand coupled with low quality hay can be a recipe for disaster.
In the early stages of pregnancy toxemia, ewes will start to appear lethargic. If the illness is not addressed at that point by feeding a higher energy ration or by giving the ewe an electrolyte drench, the ewe will end up laying down on her sternum, too out of energy to stand. Roeder emphasized an aggressive approach to the matter is always best. The metabolic issue happening with the ewes continues on until steps are taken to reverse it.
“Once they go down, hitting them propylene glycol, drenching them with electrolytes or giving them a little better feed tends to help. A lot of those ewes you can get back up,” Roeder said.
Interestingly enough, there is a third potential cause of pregnancy toxemia that is found in severely over-conditioned ewes. The research isn’t totally settled yet, but initial findings indicate ewes that go down and are over-conditioned are dealing with a diabetes like situation that is really difficult to fix, according to Roeder.
“It doesn’t matter how much more concentrate you feed or how much more you drench them, the only way to really resolve the issue is to call a vet and either have them do a C-section or induce labor depending on when that ewe is due to lamb,” he stated.
It is believed this issue is heritable, so it is not recommend to keep replacement ewe lambs out of over-conditioned ewes that end up going down.
In addition to pregnancy toxemia, Roeder reports he has been getting calls from producers who have noticed an increased frequency of abortions. Sexually transmitted diseases (STD), such as chlamydia and vibrio, can cause late-abortions in sheep.
To avoid this issue, it is recommended to vaccinate the breeding stock before bucks are turned out in the fall. There are some treatment options once the abortions occur. For instance, chlamydia is not tetracycline-resistant, so treating ewes with large blasts of a tetracycline can be effective.
Roeder concluded by emphasizing it doesn’t matter if producers are dealing with pregnancy toxemia or an STD within their flock, consulting their herd veterinarian is key. With proactive management approaches and aggressive treatment, these conditions can often be mitigated.