The World Health Organisation warns that the increasing emergence of antimicrobial resistance (AMR) will be the number one cause of human death in the next 30 years, if judicious and strategic use of antibiotics/antivirals in human and animal medicine is not put into daily practice. As reported last month, increased pressure will be applied to farmers and veterinarians to revisit the use of antibiotics, in particular the choice of which antibiotics are used under particular circumstances.
The World Health Organisation warns that the increasing emergence of antimicrobial resistance (AMR) will be the number one cause of human death in the next 30 years, if judicious and strategic use of antibiotics/antivirals in human and animal medicine is not put into daily practice. As reported last month, increased pressure will be applied to farmers and veterinarians to revisit the use of antibiotics, in particular the choice of which antibiotics are used under particular circumstances.
In dairy production, mastitis infection is still the main reason for use of antibiotic treatments. The selection of which mastitis treatment to use, is generally based on the treatment that has historically caused good therapeutic outcomes. Reasons for initial treatment not clearing the mastitis from the udder include:
1 Defences of the mastitis bugs
- The mastitis bugs are not susceptible to the antibiotics available
- The bugs involved in the infection are resistant to the treatment selected
2 Issues around treatment used
- The treatment selected has not penetrated the udder
- The duration of the treatment has been too short to clear infection. Research has shown that therapeutic success is improved with extending duration of treatment ─ caution this will affect withhold periods ─ seek veterinary advice
3 Cow factors
- The cow may have already cleared the infection and clinical signs of mastitis (e.g. flecks in the milk) are just the aftermath of the cow’s immune system responding to infection with inflammation, swelling and redness
- The age of the cow, duration of the mastitis infection, days in milk and the number of quarters infected influence the ability of the treatment to effect a cure.
The key to successfully dealing with a mastitis problem is to understand the enemy ─ what is the bug causing infection in the cow/herd? Whilst it is not practical to wait for milk culture results before initiating treatment, collecting a milk sample and freezing it before treatment, allows for a culture to be done later. If normal mastitis treatment fails to clear the udder infection, responsible antibiotic use requires a milk culture to identify the bug involved.
Judicious use of mastitis treatments requires an understanding of the likely cause of infection, sensitivity of the infection to treatment and the way the treatment penetrates the udder. Culturing milk samples can give useful information for appropriate herd treatment in future lactation.
Strategic management of mastitis requires veterinarians and farmers working to understand the specific reason(s) for the problem on a given farm and developing a plan that will effectively reduce risk factors contributing to mastitis infections. This prudent approach may reduce reliance on antibiotic treatment, decrease discarded milk and reduce emergence of antibiotic resistant bugs that threaten the health of animal and human populations.
