Sheep and the Resistance!

Eamon Patten, Drystock Advisor, Teagasc Ballinrobe.

The terms AMR (Antimicrobial Resistance) and APR or AR (Anthelmintic Parasite Resistance) are now in common use, but what is there significance at farm level? From the heading it sounds like a type of warfare and in some respects it is with the bugs and parasites now fighting back.

Antimicrobials are drugs used to treat infections in humans and animals, while the term Anthelmintic describes a drug used to treat infections of parasitic worms in animals. In more general terms antimicrobials covers medicines such as antibiotics, antifungals and antivirals, while the anthelmintics refer to drugs that control flukes, roundworms, and tapeworms. There can be some overlap with active ingredients into both groupings.

Resistance occurs when micro-organisms that cause infections adapt, preventing an antimicrobial / anthelmintic from working against it. The product used would normally kill the bug at a certain stage of its life cycle but under new scenario the drug is no longer able to do what it says on the label! This has huge implications for animal and human health. Scientists are alarmed with this problem and have predicted by 2050 there may be more human deaths from AMR than from cancer. Every time antibiotics are used, bacteria have the opportunity to develop resistance. Some drugs are in use across both the animal production and human medicine spheres thus the microbes can be exposed to a drug at any stage. This can happen on the farm, home, hospital or anywhere that a bug can propagate.  Certain drugs are now critically important in the control of some specific microbes, thus explaining the introduction of more stringent controls and proposed greater veterinary supervision at farm level from 2022 onwards.

Why is this resistance (AMR) occurring?

The development of resistance is a natural phenomenon that will inevitably occur when antibiotics are used to treat infection. Some of the reasons it is becoming more of a problem are as follows:

• Overuse of antibiotics
• Under-dosing with antibiotics
• Not finishing the treatment course
• Incorrect disposal of antibiotics
• Use of last resort antibiotics as first line therapy
• Blanket use of antibiotics in an untargeted manner
• Treatment of bacteria that are not susceptible to the particular antibiotic
• Treatment of diseases caused by viruses or other germs not susceptible to antibiotics

Farm Tactics

When it comes to animal health, prevention is better than cure. Inside the farm gate there is a need for better disease prevention strategies such as improved biosecurity measures, better housing strategies and more targeted vaccination / parasite control. The overarching aim on the farm is to achieve good animal health status and minimisation of any stress triggers. Antibiotic use will be required for animal welfare standards but only when necessary. We will need them then, to work effectively on both the veterinary front and in human medicine. A guide for their correct usage is the six R’s.

Sheep Farms

On sheep farms antibiotic usage is not that significant compared to some other enterprises, but there is still room for improvement. The predominate usage areas are for lameness control and around lambing time. There is a need for a more prudent or wiser usage policy everywhere and at all times. Improving farm facilities allowing the greater practice of foot-bathing, more vaccination programmes and ensuring new- born lambs receive adequate colostrum can all have significant effects at reducing the overall antibiotic loading on sheep farms. This is where a discussion with your vet on both the antibiotic and anthelmintic usage comes into play. The outcome can be incorporated into a farm health plan. The consequences of a product administered to a sheep can have repercussions on far more than that single animal.