Review/Oorsig Volume 22, Issue 05 - Page 23

Volume 22 • Issue 05 • 2018 on production. 4. However, the disease leads to increased mortalities, and should not be regarded unimportant. We as veterinarians should NOT put our own heads also under the sand about BLV infection in our dairies. If the importing country requires BLV free status, we cannot export from infected herds. Period. Perhaps some others can chip in here, but my opinion is that the only way you can certify animals free of BLV infection from your herd would be to put sero-negative animals under strict quarantine far away from the positive herd, and re-test them 4-monthly after that: once ALL quarantined animals tested sero-negative for 2 years that quarantined herd is probably free from the infection. MJ - 3 May 2017 We have recently discovered EBL in a client’s herd. The farmer is wanting to eradicate the disease and has sold most of the positive cows, with the remaining being marked and separated from the rest of the herd. Are there any labs in SA that test for Bovine Leucosis from milk samples? What would be the best interval between testing in order to eradicate the disease? WG - 4 May 2017 Testing frequency is a trade-off between the cost and the benefit of identifying and removing/ separating positive animals sooner. Three to six monthly intervals were used in most of the EU countries where the disease was eradicated. It is important to remember that as you reduce the prevalence in the herd the number of animals that need to be tested increases (i.e. your costs increase as you move towards achieving your goal!). The blood test is done by a number of labs in SA and it is worth shopping around for the best price if you are doing large numbers of samples at once. There is currently no milk test commercially available in the UK. Sello and I used one supplied by Zoetis for our research and there are others on the market internationally, so perhaps one of the labs will introduce it if there is sufficient demand from vets? In order to eradicate the disease successfully it is important to have a robust programme in place to minimise disease spread alongside the test and cull/separate policy. You will need to consider the following: 1. Preventing heifers from becoming infected from their dam (calving management and colostrum). 2. Preventing spread between heifers (dehorning and other procedures) 3. Reducing transmission in the milking herd (needles, rectal gloves etc.) ERADICATION AND CONTROL RM - 26 Jun 2009 I have a herd with a high incidence of Clinical cases. We bled the herd, and pooled samples(10/ tube), to save on tests. All groups of ten tested positive. It appears that this is almost futile. With such a high incidence, it is prob not worthwhile eradicating. This is a dairy herd of 600 Holstein cows in milk. We have already instituted seperate gloves for rectals, new needle every Rx, etc. GB - 1 Jun 2011 I am partly responsible for the health of the dairy cows at the University of Pretoria proefplaas. At some stage in the past, a cow or cows infected with Bovine Leukosis was/were introduced into the herd. I bled all animals, including very small calves, and submitted samples for ELISA. Now, 11 animals (out of 112) are marginally BLV positive on ELISA. They show titres of 35-39 (where greater than 40 is considered positive and 30-40 is considered suspicious.) The remainder of animals are negative on ELISA. On occasion, clinical cases are presented to the Production Animal Clinic here at Onderstepoort with a raging lymphocytosis/lymphoblastosis and spinal abscesses, discrete tumours etc. The cardiac form has also been diagnosed. I intend to retest the ELISA positives using AGID (primarily for my own edification) as well as a control sample of ELISA negatives to see what the correlation is. Once I've done this, all positive animals will be removed from the herd. We are also implementing biosecurity measures against transmission (fresh rectal glove per cow, separation of positive and negative animals, new needle per animal, etc) These animals are used in various trials, so they need to be BLV negative to remove potential confounding factors, so trying to live with the disease is not an option. Do any of you have any thoughts or personal experiences with BLV that you would mind sharing with me? TS – 1 Jun 2011 Your situation obviously differs from most situations in the field where one has to live with the disease. If memory serves, leucosis is also transmitted to 20% of calves born from positive mothers, so take this into consideration in your attempt to eradicate the disease from the herd. WG - 13 Sep 2013 There is not currently much known about the 23