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Fecal Tests Fail At Tapeworm Detection

Though fecal egg counts are an essential tool in a horse owner's anti-worm arsenal, the test isn't always accurate in detecting the presence of tape worms, a German study has found. The presence of tapeworm eggs can be missed by the tests as tapeworms don't continuously produce eggs like most parasites do; they release packets of eggs only occasionally.

Adding to the issue is that even when the eggs are released, the packets aren't evenly distributed through the manure, meaning they could easily be missed under a microscope. However, there are other methods for detecting the presence of tapeworms in horses, including using manure, saliva or serum.

Drs. Laura Jürgenschellert, Jürgen Krücken, Corrine Austin, Kirsty Lightbody, Eric Bousquet and Georg von Samson-Himmelstjerna used 48 horse farms in Berlin and Brandenburg, Germany, to test different tapeworm analysis methods. They took fecal samples from 484 horses, serum samples from 481 horses and saliva samples from 365 horses. The saliva and serum samples were tested to determine the antibody levels against tapeworms.

The fecal egg count tests detected tapeworm eggs in 0.6 percent of the samples (6.3 percent of the farm). However, antibodies against tapeworms were present in 16.2 percent of serum samples (52.1 percent of farms) and in 29.5 percent of the saliva samples (75.7 percent of farms).

The research team also sent out a questionnaire to horse owners and they determined that pasture access and pasture changes, as well as high strongyle egg counts, were risk factors for positive serum responses to tapeworms.

The scientists determined that treatment with a dewormer targeted to tapeworms is protective. The presence of foals and a large number of horses on the farm also seem to offer protective benefits. Interestingly, daily removal of manure didn't make a difference on whether a horse had tapeworms.

The research team concluded that conventional fecal tests for tapeworms are not accurate; for a true indication of the prevalence of tapeworms, horse owners should consider using antibody detection methods like the saliva test used in the study.

Read the full study here.

Easy-To-Implement Ways To Reduce Parasite Resistance

Currently, equine internal parasites can resist all classes of dewormers on the market. This is especially concerning as internal parasites can cause so much harm—and there are no new dewormers on the horizon. However, there are some things horse owners can do to keep horses healthy naturally, reports The Horse.

Veterinarians originally recommended that horses be dewormed every two months, as that was when parasitologists began seeing worm eggs returning. Now, strategic deworming and an integrated approach to parasite management is preferred. This includes only deworming the horses that need it and not blanket deworming all horses on the farm.

Other ways to prevent worm burdens include:

Quarantining new horses—this includes not turning them out on fields other horses will eventually use. The point is to keep the horse and the worms it os carrying separate long enough for the eggs to pass through his system.
Feeding off the ground to prevent ingestion of larvae
Ensuring feed and water sources are not contaminated with manure
Removing manure piles before eggs hatch
Composting manure at temperatures above 104 degrees F to destroy eggs and larvae
Keeping grass taller than 3 inches to minimize larvae ingestion
Dragging fields on hot days to expose larvae in manure to temperatures they cannot survive
Implementing pasture rotation, which disrupts the parasite life cycle
Stocking pastures with an appropriate number of horses (one horse per acre at minimum) to reduce grazing around manure
Renovating pastures for better forage options
Including other species in the pastures with horses so different plants get eaten

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.