you can refer  medicine and surgery of camelids by fowler 

i hope that its not acommon disorder in camels but south american camelids get it commonly

deficiency and overweight may be areason

I'm thinking about the hump of dromedary camel which compensate negative energy balance... 

In camelid, the serum NEFA is increased in lower rates during starvation and this family also have higher serum glucose compared to bovine and ovine. This means, ketone bodies prevent to elevate during starvation (DOI: http://dx.doi.org/10.7557/2.21.1.1527 ).

The buffering effect of hump as well as low glucose outlet and higher gluconeogenic precursors are the main reason of lower incidence of ketosis in camelids.

Dear Amir Ahmadpour,

Thanks for your concrete and scientific reply. Your reply is great answer to this complicated question. 

Here is the link of my blog regarding the Ketosis in camel.

https://camel4milk.wordpress.com/2016/03/01/is-ketosis-possible-in-naqa-dairy-camel/comment-page-1/#comment-127