When the bugs fight the drugs

Each summer DVM students from the Ontario Veterinary College at the University of Guelph delve into hands-on, practical experience at veterinary clinics across Ontario and additional locales during their Externship Veterinary Course. Funded by the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), students must complete an eight-week Externship Course between third and fourth year in a rural veterinary practice that works with food animals and/or equine, as well as companion animals.These Externship blog posts are an opportunity to tag along with students this summer. Here student veterinarian Stephanie looks at anthelmintic resistance in sheep. Check out all the student blogs here.

Veterinary medicine is a constantly evolving field, with new pharmaceutical products being released every year. Drugs can play an important role in preserving the health of individuals and populations as a whole. However, they need to be used in a responsible and appropriate manner. In recent years the issue of drug resistance has become a hot topic. We will explore this complex problem by looking at anthelmintic resistance in sheep.

Sheep kept on pasture can become infected with various types of roundworms that live in the gastrointestinal tract. These parasites can cause a decrease in production and be detrimental to the sheep’s health. One parasite in particular, haemonchus contortus, also known as the ‘barber pole worm’, is highly pathogenic to sheep. It attaches to the inner lining of the stomach and feeds on blood, leading to anemia, edema (bottle jaw) and even death. Therefore, most farmers choose to deworm their flock with anthelmintics. This should lead to healthier sheep and higher production numbers, right? Not always.

The issue is that these gastrointestinal nematodes can evolve over time and no longer be affected by the dewormer, leading to overwhelming worm burdens in sheep. In a recent study on 47 Ontario farms, it was found that most farms had resistance to Ivermectin and fenbendazole, 2 commonly used anthelmintics in sheep. To make matters even more interesting, haemonchus contortus, the barber pole worm, was the main parasite responsible for the resistance. The question becomes: do we treat with a new class of drug that has a different mechanism of action, or do we change our current treatment protocols? The answer: we do both and more!

The Ontario Veterinary College and the Ontario Ministry of Food and Agriculture have come up with the 5 star worm plan that focuses on selective treatments as well as minimizing drug use and pasture contamination.

The goal of programs like this one is to promote proper drug use, maximize animal health and mitigate long term problems like drug resistance, ultimately being of benefit to the industry as a whole. It is evident that long-term, sustainable control of parasites in sheep requires integration of multiple control methods.

Through this brief overview of resistance to anthelmintics in sheep, it is important to be aware that drug resistance is a real issue affecting individual animals, to whole industries, and everything in between. The development of guidelines for prudent drug use in both the human and animal world are key to managing resistance. It is our duty as students, veterinarians, readers, members of the general public to stay educated on the matter of drug resistance. After all, it is the choices we make today that will shape our world of tomorrow.

Dr. Henry Ceelen and I are using the FAMACHA score on a ewe; the system estimates the degree of anemia in sheep through use of a color guided chart that is compared to the mucous membranes around the eye. FAMACHA can be used as an aid to determine which ewes require treatment, acting as part of “star 3” in the 5 star approach. Open communication and education of the producer is imperial to ensure that all 5 stars of the worm plan are covered. We are glad to have helped this farmer on the ongoing, ever-changing road towards a healthy flock.

Follow OVC on Twitter, Facebook, and Instagram @OntVetCollege

Comments are closed for this blog post

Welcome to
Ontario Agriculture

Sign Up
or Sign In

Agriculture Headlines from Farms.com Canada East News - click on title for full story

Guinness World Record attempt to take place in St. Albert on Aug. 22

?ST. ALBERT – If you have ever wanted to witness an attempt at a Guinness World Record, then you will want to be in St. Albert, Ontario on August 22 when an attempt will be made to set a record for the most plow blades pulled simultaneously.

Why Alignment Matters: Domestic Check-Off and the Import Levy

When Canadian beef producers sell cattle, they contribute to the national beef check-off. That investment supports work that benefits the broader Canadian beef industry, including market development, consumer demand, public and stakeholder engagement, and research. When beef or beef cattle are imported into Canada, an import levy is also collected. While the structure is not identical in every detail, the principle behind it is straightforward: beef marketed in Canada should help contribute to the programs that support beef demand in Canada. The national check-off paid by producers and the import levy paid on eligible imports are two parts of a broader investment approach. Together, they help ensure that both domestic beef production and imported beef products are connected to the market development work that strengthens beef’s position with Canadian consumers. For producers, the domestic cattle check-off is collected at the point of sale and includes both national and provincial po

I’ve noticed a lot of wild oat escapes in some of my fields this year; what can I do to prevent it from getting worse next year?

Despite our best efforts, sometimes even the best laid weed control plans go wrong! The first thing to remember is that not all weed escapes are created equal. In some cases, weeds can survive because of application timing issues, challenging weather conditions or late flushes that emerge after spraying. However, when weeds aren’t controlled by herbicide applications, herbicide resistance should also be on your radar. A recent survey in Manitoba found that in fields with uncontrolled wild oats, 100 per cent of populations were resistant to Group 1 products, 82 per cent were resistant to Group 2 products, and 82 per cent were resistant to both Group 1 and 2 herbicides. Those numbers show how important it is to take a closer look at wild oat weed escapes. Identifying why your herbicide failed to control wild oats is the first step toward finding a solution. Start by scouting the field to narrow down the cause. Consider factors such as application timing, weather conditions, late flush

Is fungicide actually effective on Sclerotinia head rot in sunflower?

This is one of the most difficult questions to answer because there are many things to consider. I also don’t want to be outright negative because we do still have options for sclerotinia management in sunflowers. However, management is the operative word. First of all, sclerotinia head rot infections have an interesting pathway. Spores use dead sunflower florets, plus pollen, as the base to infect a sunflower plant. The spores grow into the receptacle, infecting and decaying the entire head after a period of time. Sclerotinia wilt (basal stalk rot) and mid-stalk rot are also infected by the same sclerotinia species, but it will be via the mycelia that grow from the sclerotia bodies in the soil for basal stalk rot. Mid-stalk rot is also infected by ascospores, but this can be earlier in the season than head rot or at the same time. So, management of sclerotinia does not start at flowering. Crop rotation is the most obvious management tool that we are familiar with in sunflowers, but

Using Water More Efficiently in Beef Packing Plants

Packing plants use a time-tested approach to clean their facilities. The first step uses high-pressure hot water to remove fat and meat scraps from equipment, floors and walls. Next, surfaces are cleaned using detergent. Finally, sanitizers are used to further reduce bacterial numbers. Processing companies want to reduce water use as part of their environmental goals and to reduce energy bills. High-pressure water and steam can produce aerosols that capture bacteria and spread them throughout the plant. They can then settle on and cross-contaminate clean surfaces long after the cleaning has been completed, which complicates efforts to effectively clean facilities. Biofilms are another problem. Biofilms are colonies of bacteria surrounded by a protective layer that firmly attaches them to surfaces and shelters the bacteria from hot water, detergents and sanitizers. Biofilms are hard to remove and are commonly found in hard-to-reach places. These researchers investigated potential cro

More…

Badges | Report an Issue | Terms of Service