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Do wormers disrupt the gut microbiome? Yes, and here's what you can do about it.

Updated: May 21

There is a study from January 2023 called:

Species interactions, stability, and resilience of the gut microbiota - Helminth assemblage in horses

You can read it here:

Basically they took 40 ponies with worms. They divided them into high egg shedders and low egg shedders. They treated half the high shedders with a wormer, and half the low shedders with wormer and then studied the gut biomes of all the ponies.

In the discussion, the researchers say:

The gut microbiota displayed quick and robust resilience to disturbance. However, the microbial interacting network remained less stable for six weeks after treatment because of changes in interaction strength and population dynamics, evoking a likely effect of successive larvae emergence into the gut lumen after post-adulticide treatment.

As such, these observations expand past studies focused on the consequences of parasite infection

or anthelmintic treatment on the host gut microbiota composition.

The ecosystem instability following anthelmintic treatment and parasite removal is compatible with the “Anna Karenina principle”, where uneasy communities vary more strongly than non-challenged communities, and environmental changes can more easily tip the balance, especially in aged hosts experiencing recurrent infections and regularly subjected to prophylactic anthelmintic treatments. Therefore, repeated rounds of anthelmintic administration not only increase drug resistance in the cyathostomin population and the emergence of inhibited stages but hamper the buffering of other undergoing stresses and increase the medical comorbidities because of the decreased complexity and stability of the microbial community, or to different indirect host pathways.

So, adult parasites are killed by the wormer, followed by an emergence of larval stage parasites to re-infect the gut into a gut biome that is less diverse than before the treatment. This creates a cycle where the parasites are more resistant to the treatment, and the gut is less able to naturally manage the burden, and a less populated gut has trouble dealing with other gut functions as well.

They go on:

As such, our findings complement past observations on the impact of gut microbiota on treatment outcomes in humans. Combined with good management practices, strategic diet manipulation via pro-, pre- and post-biotics administration could be part of the helminths control program.

Using pre and probiotics alongside wormers to stabilise the gut biome after worming can help as part of your parasite management strategy. This supports a previous study we talked about in the posts below where foals that were given pre and probiotics has less worm burden than foals that weren't.

We have a pre/probiotic bundle which is only 10g each per day, making it low inclusion, well tolerated and cost effective.

Here at Sound Advice we have promoted a holistic approach to parasite management in the past. We have included links to those articles below, but in short, wormers on their own can result in a chronic cycle which exacerbates your parasite problem.

  • Collect and compost manures as much as possible.

  • Harrow manures that you can't collect.

  • Add a small amount of oats to your horse's diet to encourage birds to 'harrow' manures you miss.

  • Rotate your paddocks to break the parasite cycle.

  • Use anthelmintics sparingly.

  • Float manures where possible so that you can pinpoint exactly which parasites are present.

  • Use pre and probiotics to promote a healthy gut.

  • Support your horse's immune function so that they can manage their parasite burden.

More on immune function:

Zinc plays a crucial role in supporting the immune system. Here are some ways how it does so:

Enzyme Activation: Zinc activates enzymes that break down proteins in viruses and bacteria, making them less able to spread.

Immune Cell Activation: Zinc increases the activation of cells responsible for fighting infection.

Cell Growth and Division: Zinc is necessary for the activity of over 300 enzymes that aid in metabolism, digestion, nerve function, and many other processes. It’s critical for the development and function of immune cells.

Wound Healing: Zinc supports skin health and effective wound healing.

DNA Synthesis: Zinc is fundamental to DNA synthesis and protein production.

Thymus Regeneration: Zinc prompts a critical immune organ to regenerate after damage.

It’s important to note that the body cannot produce zinc on its own, so it needs to be obtained through diet or supplements.

Sound Advice Trace Mix includes optimal zinc.

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