Evaluating the Internal Parasite Monitoring Program at the Penn State Horse Farms and Examining the Usefulness of an Additional Test for Tapeworms

Department of Dairy and Animal Science
Penn State
 

     Maintaining a healthy equine population is a primary concern for horse owners because it affects reproduction, growth, performance, and the overall well being of their animals.  When managing a large group of horses like at Penn State, it becomes difficult to keep the internal parasites under control.  In order to keep the parasite burden to a minimum, a program must be organized to monitor the kinds of parasites present and the pasture egg burden to identify successful treatment strategies. To do this, we took fecal samples from each herd at Penn State Horse Barns and determined the egg per gram count using the McMaster technique.  

     Recent research has shown that tapeworms are far more prevalent in the equine gut than previously suspected, and they also may be responsible for some serious health issues in horses.  To validate tapeworm egg detection using the zinc floatation method blood samples were submitted to the University of Tennessee for an ELISA test for the presence of tapeworm antibodies and then compared to the method. 

     This project monitored the parasite burden on the PSU production groups over the course of two years and looked back at the appropriate data to determine whether this strategy has been successful. 
 

Results

As seen in the graph of egg per gram counts, the trend has been for the parasite burden to decrease from 2002 until 2005.
 

The cost per animal unit each month decreased overall as shown in the second graph. The cost per animal unit per month in 2002 was found to be $8.02, while in 2004 it was $3.02: 

 

The floatation test resulted in rare finding of tapeworm eggs on any of the horses that were also tested positive by the ELISA test and were high compared to the positive control.  It is difficult to measure tapeworm infestation based on fecal exams due to the intermittent shedding of eggs.  

Conclusions

     Over the course of the two years that the program has been used, the cost of deworming each horse each month has decreased.  Since the herd size has increased drastically over the past year, especially in the broodmare herd, this program should increase the efficiency of deworming the horses; they are only dewormed when they are found to be over the 125 eggs per gram limit.  This will decrease the cost in anthelmintics, labor, and resistance for the horse barns.  After observing the results found at the Penn State horse farm, it is obvious that the program is feasible if the time is put into monitoring the parasite numbers monthly.

     In reference to the tapeworm tests, more work must be done to determine which method was the most effective in measuring the tapeworm burden in the herds.  The farm should move to using the ELISA test regularly on each herd to gain more knowledge of the tapeworm infestation and to begin a treatment program according to the results.

This study was supported by an undergraduate student research grant from the College of Agricultural Sciences at Penn State.