Ivermectin | Horse Racing Free Tips

Potentially Life-Threatening COVID “Cure” Sees Dewormer Sales Surging

Though the U.S. Food and Drug Administration (FDA) and the World Health Organization (WHO) have repeatedly warned the public against using ivermectin as a COVID-19 “cure,” the United States is seeing a massive increase in dewormer purchases from livestock farm and feed stores.

Many stores that sell dewormer have added verbiage to the products that indicate that they are not safe for human consumption and are an unproven cure for COVID-19; other stores have removed ivermectin products from their shelves completely.

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Ivermectin first came on the radar as a possible “cure” for COVID in 2020, when Monash University researchers reported that the drug could kill coronavirus in 48 hours in a lab setting. Though researchers at the Australian institution stressed that further testing was needed to establish the effectiveness and dosage of the drug, the public began seeking out ivermectin.

To date, completed studies on the efficacy of ivermectin are small and not considered of sufficient quality by researchers, though there are several studies currently underway. Reliable evidence doesn't support ivermectin use as a treatment or prophylactically for COVID-19.

Human-grade ivermectin is approved by the FDA for treatment of some parasitic worms and of some external parasites. Animal-grade ivermectin is not approved or dosed for humans and should never be ingested by humans. Side effects of taking livestock-grade ivermectin include nausea, diarrhea, vomiting, skin rash, facial or limb swelling, decreased blood pressure, liver problems and neurologic issues like dizziness and seizures.

Small Strongyles Showing Resistance To Last Effective Class Of Dewormer

Martin Nielsen, DVM, Ph.D., Dipl. ACVM, Schlaikjer professor of equine infectious diseases in the Gluck Equine Research Center, presented his research on small strongyles at the University of Kentucky's Equine Research Showcase in February.

He spoke about current data showing resistance among cyathostomins (small strongyles) to the three main groups of anthelmintic (anti-parasitic) drugs.

“The small strongyle parasite, which is the type of parasite that all horses get, is the primary parasite category, the one that we are always deworming for,” Nielsen said.

The first class of anthelmintic drugs introduced and administered to combat small strongyles was the benzimidazoles in the 1960s. Because this class of drugs has been in use the longest, there is wide-spread resistanceto these drugs.

“It is very rare to find these products still working,” Nielsen said.

Pyrantel salts began experiencing resistance in 1996 and Nielsen said it is also likely to find small strongyles resistant to Pyrantel dewormers today.

Macrocyclic lactones (ivermectin and moxidectin) are our “last resort,” with good efficacy, but there have been some questionable early signs of emerging resistance reported, according to Nielsen. In 2020, routine data collected from a farm in Central Kentucky confirmed resistance to macrocyclic lactones among small strongyles.

Nielsen shared data showing that macrocyclic lactones were 100 percent effective against small strongyles in a group of U.S.-bred yearlings, but the same dewormers administered to a group of imported, Irish-bred yearlings failed to remove small strongyle parasites.

“There's no doubt, looking across this data, that we have clear-cut, proven resistance to ivermectin in these imported parasites,” Nielsen said. “The problem is, if we have resistance to everything, what can we deworm with?” he said.

He described that the efficacy of moxidectin was also evaluated against the resistant parasites. Despite this drug being potentially more potent than ivermectin, it did not overcome the resistance and did not provide better efficacy.

Nielsen closed with a final note that ivermectin and moxidectin resistance is occurring in small strongyles. This case was only discovered due to the meticulous testing procedures in place on this particular farm. Without regular testing of deworming efficacy, drug resistant parasites will go undetected and farms will be left without opportunities to intervene before it is too late. Good parasite control starts and ends with testing the dewormers being used and this must be done every year.

New Study Shows Last Line of Defense Against Equine Parasites Beginning To Fail

New research shows that ivermectin and moxidectin dewormers are losing their efficacy again small strongyles. This is particularly troublesome as these drugs are the last lines of defense against the worms and no new dewormers are in the research pipeline.

The study was the first in the world to confirm small strongyle resistance through repeated testing. Resistance to two of the three deworming drug classes was confirmed years ago and it was predicted that small stronglyes would become resistant to macrocyclic lactones, a class of dewormers of which ivermectin and moxidectin are a part.

The study team included Dr. Martin Nielsen, Professor of Equine Infectious Disease at the M.H. Gluck Equine Research Center, Michael Banahan of Godolphin's Jonabell Farm in Kentucky, and Dr. Ray Kaplan, parasitologist in the Department of Infectious Diseases at the College of Veterinary Medicine at the University of Georgia.

The team found that the efficacy of both ivermectin and moxidectin were reduced in a group of 50 imported Irish Thoroughbreds, though 50 US-bred horses on the same farm had no such resistance. The farm rigorously followed current guidelines for deworming and pulled fecal egg counts on all horses on the farm multiple times.

The horses were dewormed and tested multiple times over an eight-month period. The team concluded that the resistance to ivermectin and moxidectin was imported with the Irish horses. They note that this demonstrates how quickly resistant parasites can spread across the globe. They encourage farm and horse owners to utilize fecal egg count tests and to stringently follow deworming guidelines to attempt to increase the longevity of the efficacy of ivermectin and moxidectin.

Read the study here.