Review/Oorsig Volume 22, Issue 05 - Page 21

Volume 22 • Issue 05 • 2018 AvZ - 16 Sep 2013 I have seen a few confirmed cases of leucosis in sheep, but none up to now in cattle. I will definitely look a bit harder now. I think if we could get more info from local Abattoirs it will help a lot. The specific case you are referring to was actually an incidental finding at an abattoir while we were looking for something else. The communication between veterinarians and abattoirs needs urgent attention. Maybe somebody can comment on this. TC - 26 Sep 2013 One of the many frustrating things in our business is that we are dealing with an inexact science! EBL seems to be one of the most “inexact” and hence, we gathered, our colleagues in the States threw in the towel for a while, in trying to control let alone eradicate the disease. There might be some immune-suppressive gremlins at work, because in herds with a high sero-prevalence there can be minimal clinical cases for years, then all of a sudden we begin picking up the mega-nodules on rectal palpations and also autopsy cows that have died. (That’s “vrot taal”, we don’t autopsy cows that haven’t died.) Then again, those herds go quiescent and other things like subclinical hypocalcaemia and late embryonic deaths take centre stage again. We must admit, we haven’t done any large-scale investigations of EBL levels for a long time; probably because we really don’t know what the heck to do if/when we find high sero-prevalence, and secondly, as Rob pointed out, there are other disease conditions that are equally, or more, damaging to dairy economics, and that we CAN do something about. This is an argument we use when farmers have read about EBL in the lay press and become excited. Perhaps, for a start as with BVD we should encourage buyers, sellers and agents to insist on only EBL sero-negative animals exchanging hands. Having rectally palpated nearly 2000 dairy cows last week (and in herds that are certainly EBL positive) I shudder to think of using a new glove for each one! When the world/farm is Stomoxys free, then maybe we can start talking …..? TESTING, CERTIFICATION AND EXPORT LS - 23 Oct 2006 My opinion is, that the current certificate is in general quite good and serves its general purpose for breeding soundness of bulls for self-use. However, when it comes to sale bulls (option B), I feel a bit uncomfortable to say that a bull is breeding sound without a negative result for Bovine Leucosis, Brucellosis, BVD PI, Trichomoniasis and Campylobacteriosis. These tests should be compulsory and not optional. AvZ - 15 Sep 2013 We had to test 250 heifers in Heidelberg, Southern Cape, recently for export purposes. 20% of them were sero-positive for EBL, yet I don’t see regular symptoms or outbreaks of the disease. Maybe I missed some of the cases, but we did not have major outbreaks with lot of deaths. PI - 16 Sep 2013 Albert. I wonder if any of these were false positives ie. low specificity of the test. The reason I suspect this is that as far as I know most animals only seroconvert at 4 years of age when using the AGID test. The ELISA, while it is more sensitive, could possibly pick it up a bit earlier, it also takes some considerable skill in interpretation. ... lab personnel are like rugby refs; they can sometimes be overzealous in their interpretation. CN - 10 Nov 2014 I need some advice from the dairy vets. Have a group of 36 pregnant heifers intended for export to Zim. Tested BM, avian and bovine TB. Then blood samples for EBL. Just received results from the lab... 26 of the 36 tested positive for EBL. There is no history of clinical EBL cases on this farm and it's a group of heifers. Problem is that an EBL-positive means NO export. Advice required: 1. What now? 2. What information regarding EBL can anyone share... the questions the owner will ask. 3. What is the implications regarding future of these heifers? I was only able to speak to the technician, there's no vet available at lab to give advice. JG - 10 Nov 2014 Which test was used for the EBL result? From what I understand animals of any age can be infected and the disease may be subclinical which means that although the farmer may not have noticed anything going on in his herd it’s possible that it is there. Of course, re-testing may be worth it but with such a high rate of positives from your first sampling I think that false positive results are highly unlikely, so farmer shouldn’t count on this… Here is a good article on EBL http://bit.ly/EBLarticle Unfortunately, if EBL negative animals (on serology) are the requirement for export to Zim then your farmer should reconsider exports, but if he/she is looking to maintain an export route to that country then eradication would be the 21