THE largest study1 of its kind ever undertaken suggests that using a non-steroidal anti-inflammatory alongside an antibiotic is a financially viable option for the treatment of even mild clinical cases of mastitis.
A 23% reduction in overall mean quarter somatic cell counts, almost a halving of the culling risk and a potential return on investment of £58 per case, is evidence that the profession still has plenty to learn about the control of this costly disease.
The groundbreaking work, which was published late last year in the Journal of Dairy Science, was carried out at the Animal Health Centre in Waikato, New Zealand.
The results are given added credibility by the unprecedented scale of the trial, which involved 15 farms across New Zealand. A total of 11,163 cows from these farms were screened for inclusion in the trial, and 727 animals that were diagnosed on-farm with mild clinical mastitis during the first 200 days of their lactations were enrolled.
The enrolled animals were split into two equally sized groups. The first received an antibiotic treatment of penethamate hydriodide (Mamyzin, Boehringer Ingelheim) plus the control vehicle for meloxicam, whereas the remainder received the same antibiotic treatment plus a one-off dose of the injectable NSAID, meloxicam (Metacam for Cattle, Boehringer Ingelheim).
Somatic cell counts (SCC)
Measured at 7, 14 and 21 days after treatment, overall post-treatment quarter SCC averaged 711,000 cells/ml for cows receiving antibiotic treatment only (three-day programme of daily intramuscular injections of penethamate hydriodide), compared to just 550,000 cells/ml in cows receiving the Metacam injection plus antibiotic treatment. This represents a 23% reduction in average overall post-treatment SCC, and the difference was statistically significant – see Figure 1.
Culling
The rate of culling during the 45 weeks after mastitis diagnosis was significantly lower where Metacam was added to the mastitis treatment regime: 16.4% in the Metacam group compared to 28.2% in the control group – see Figure 2. There was no impact on the results due to cow age, breed, bacterial species isolated, calving date or days in milk at the time infection was detected.
Although most of the mastitis cases in this study occurred before the breeding cycle began, it is well proven that cows diagnosed with clinical mastitis are more likely to be culled for a wide variety of reasons (not just SCC or mastitis), and typically have lower conception rates, more services per conception and longer calving-toconception intervals. If we are able to modify the negative effects of clinical mastitis, it is likely that we may also be able to modify some of the longer term effects associated with the condition.
The calculated financial benefit of these improvements was £58 for each case of mastitis, based on UK prices.2
According to the authors, the rationale behind this particular study was that maybe there would be benefits from controlling inflammation in the more common, mild clinical mastitis cases that make up the majority of those diagnosed and treated on-farm without direct vet intervention.
Any comparable studies that had been performed previously have not shown any conclusive improvements in the key parameters of somatic cell count or culling rate measured in this study, and most of the available research on the topic was laboratory-based or from small sized trials.
“As vets, we’re typically only called to the most serious mastitis cases, and a routine part of treating these animals is an injection of an NSAID,” explains Dr Scott McDougall, managing director of Cognosco dairy research team and coauthor of the study.
“As well as a basic welfare issue, reducing the pain caused by excessive inflammation in the udder typically
speeds recovery, gets the cow back on its feet quicker and helps both water and feed intakes return to normal.”
The health and financial benefits highlighted by this study have shown that there is a strong argument for recommending a combined antibiotic/Metacam treatment approach to the more commonly seen mild clinical cases of mastitis.
“Clinical mastitis continues to be a major drain on dairy farm profitability across much of the world, and the substantial economic impacts of treatment costs, lost milk production, reduced milk quality and higher culling rates are well recognised. Any advances in mastitis therapy that help reduce these economic losses are therefore going to be of real interest to all dairy farmers,” concludes Dr McDougall.
- McDougall, S., Bryan, M. and Tiddy, R. (2009) J. Dairy Sci. 92: 4,421-4,431.
- Bryan, M. (2009) BCVA presentation, Southport
