Research Accomplishment Reports 2011

Control, Transmission, and Prevalence of Natural Infections of Internal Parasites of Equids and Ruminants

E.T. Lyons
Department of Veterinary Sciences

 

Non-Technical Summary

Effects of internal parasites of domestic animals range from causing no perceivable clinical problems to death of these hosts. Historically, many species of internal parasites have shown resistance to chemical compounds after a period of usage. Research is necessary to continuously monitor the level of activity of the drugs. The purpose is to provide up-to-date information to animal owners and veterinarians about the the most active or inactive compounds for parasite control.

2011 Project Description

The major problem in parasite control of parasites in equids is that over the years, drug resistance of several species has developed. This has occurred for ascarids which can cause a clinical problem in young animals. Also several of the 50 species of small strongyles have become drug resistant. There are no new chemical products forthcoming for parasite control. Our research continues on study of drug resistance.

While all commercially available compounds show some degree of lessened activity on parasites, our goal in more recent years is to show that it is not necessary to "herd" treat horses. That is to be more select in treatment of equids. It has been shown that ivermectin is now inactive on these parasites. Also we have been doing studies to show that small strongyle egg-profiles can be determined for older horses. Once this is done, then this will aid in decision as to whether to treat only those with "high" egg counts.

Also our research has shown that it is advantageous to use compounds like oxibendazole and febendazole for treatment of ascarids in foals.Our results are published and also relayed to horse persons and veterinarians.

2011 Impact

Research has recently been completed on establishing small strongyle egg-profiles in older horses. This study involved 1,300 mares 3 to 32 years old on 26 farms in the Central Kentucky area. It included 1,114 Thoroughbreds, 64 Standardbreds, and 122 mixed light-horses. Results showed for Thoroughbreds that 68% had negative counts and 32%, while positive, had low values. The two other categories of equids had somewhat higher numbers egg-positive.

Most importantly, this study showed the practal value of establishing egg-profiles in a large number of animals. It documented that it would be unnecessary and a waste of money for all older equids in a herd to be dewormed. These types of classical studies on horse parasites are considered important especially because they have diminished the last several years.

2011 Publications

Kuzmina, T.A., Tolliver, S.C., Lyons, E.T. 2011.Three recently recognized species of cyathostomes (Nematoda: Strongylidae) in equids in Kentucky. Parasitology Research.108:1179-1184

Lyons, E.T., Tolliver, S.C., Collins. 2011. Reduced activity of moxidectin and ivermectin on small strongyles in young horses on a farm (BC) in Central Kentucky in two field tests with notes on variable counts of eggs per gram of feces (EPGs). Parasitology Research. 108: 1315-1319

Lyons, E.T., Tolliver, S.C. Kuzmina, T.A., Collins, S.S. 2011. Further evaluation in field tests of the activity of three anthelmintics (fenbendazole, oxibendazole, and pyrantel pamoate) against the ascarid Parascaris equorum in horse foals on eight farms in Central Kentucky (2009-2010). Parasitology Research. 109:1193-1197

Lyons, E.T., Kuzmina, T. A., Tolliver, S.C., Collins, S.S. 2011.Observations on development of natural infection and species composition of small strongyles in young equids in Kentucky Parasitology Research. 109: 1529-1535