I have a veterinarian character who's examining a cow who died very suddenly and without displaying any previous clinical symptoms. He wants to discover whether she died of grass tetany (hypomagnesemic tetany). As I understand, he will do this by means of a magnesium analysis of the vitreous humour of the eye.
The setting is the equivalent of modern-day central Europe / US.
What I haven't been able to find out is: Would a well-equipped large animal clinic be likely to do this type of analysis itself, or send out the samples to a diagnostic lab? How long would it be until the results were in?
I'm also interested to know the same thing about testing for toxic plants the cow might have ingested. If the veterinarian couldn't find any remains of toxic plants in the rumen but wanted to be entirely sure, would he be likely to send the rumen contents in to a lab to be tested, or could he do these tests himself? How long until *these* results were in?
And lastly: Given the suspicion that the cow might have been intentionally poisoned, I assume there would have to be additional tests performed to check for things like rat poison and other common poisons? Would this have to be performed by an external lab? How long would this take?
My attempts to find this out have included copious amounts of googling with various combinations of the key words "magnesium analysis", "veterinary clinic", "diagnosis", "hypomagnesemic tetany", "vitreous humour" and more. I found a bunch of information and articles on the extraction of the vitreous humour, the time-frame in which it is useful, the question of whether it is actually useful at all, etc - but nothing about who exactly usually can and does perform these tests, and how long they take.
Thank you very much!