Is Selenium Deficiency in cattle on the increase in Namibia?

Sometimes as vets we are faced with cases that you have no clue what seems to have caused a certain illness in animals.
You have to play detective in real life situations, but sometimes the answer is just in front of you although you just can’t grasp it.
I was recently trying to investigate deaths in calves of a village farmer on the phone.
 We could not understand each other well about what might have caused the deaths of the calves. The farmer mentioned that he thinks that the calves were too pale on post-mortem, but it was a week after the case occurred and there was no longer evidence of it.
If it was in sheep and goats, I would have thought we were dealing with the blood sucking worms (bankrotskapwurm), but in calves I was lost,because I have never seen this condition before. Luckily, what saved me was that the farmer mentioned that the meat of the dead calves looked too whitish for his liking, which I linked to “White Muscle Disease” or selenium deficiency.
What is selenium deficiency?
Selenium (Se in short) is an essential trace element that is required by animals in their diets. Thus, in lay man, it is a nutritional mineral that animals (and people as well) need for proper functioning of the body, just like they need calcium, copper, phosphate and the different vitamins for various body functions. Se is especially linked to Vitamin E, which both helps to protect the body against harmful agents such as toxins (they are both referred to as anti-oxidants). Hence, if the animal does not get enough Se from the diet which may result from inadequate level in the soil, the shortage of it affects the normal functioning of the animal’s body. This is of most importance in cattle and to lesser extent sheep/goats, as compared to other animals.
Normally, the animal need very small amount of Se in its diet, and hence, the shortage of it is not common. But, with the increased overgrazing that is becoming common in our country, especially in the rural areas, we should be seeing more Se deficiency problems mainly in beef cattle than in previous years.  I would also think that the effects of drought and climatic changes arealso contributing to the soil having inadequate concentration of Se.
What does Se deficiency look like in cattle?
The answer is not as simple and predictable, because Se deficiency presents as various disease conditions. The most significant one is White Muscle Disease were muscle looks white instead of red. This is common in young suckling calves in winter, if the dam has low in Vit E/Se blood status. Sometimes a perfectly healthy looking calf may collapse suddenly and die within a short time from heart failureor difficult breathing, if the heart and respiratory muscles are affected. If the affected muscles are of the legs, calves are unable to walk as the muscles become weak and swollen.  The affected calves normally die if not injected with Se supplement.
Clinical signs of low Se (or Vit E) status in adult cows are more difficult to determine.
How do we treat or prevent a case of White Muscle Disease?
Farmers should be aware that Se deficiency is becoming more widespread as a problem in grazing beef cattle. When looking at the disease conditions associated with the shortage of Se in Namibia, it makes me wonder that maybe some of the cases of retained placenta, abortion and infertility that we blame on other conditions such as chlamydia (enzootiseaborsie) and vibriosis without confirming them, might actually be from Se or Vit E deficiency.  This, its important that your veterinarian or animal health technician submit a blood sample to the diagnostic laboratory to quickly and cheaply determine the selenium status of your cattle before it’s too late.
We can see from above that this problem creates additional cost in terms of disease occurrence and treatment cost. Thus prevention is better than cure.