Meddleton Equine Hospital

Blister beetle toxicosis can cause serious disease in horses that can lead to death. The causative agent, cantharidin, is a potent irritant found in the blister beetle. Alfalfa flowers attract the beetles and at harvest they may be incorporated into hay.

Equine Herpesvirus (EHV-1 or Rhinopneumonitis) infection in horses can cause respiratory disease, abortion in mares, neonatal foal death, and/or neurologic disease. The neurologic form of EHV-1 is called Equine Herpesvirus Myeloencephalopathy (EHM) and is a sporadic paralytic disease (myeloencephalopathy) secondary to vasculitis of the spinal cord and brain.

A Horse was diagnosed with Rabies this past week from Eddy County in Hope, New Mexico, between Roswell and Carlsbad. There have been several rabid skunks in the area. We strongly recommend vaccinating your horses for Rabies this fall.

While very rare, cases of Thelazia lacrymalis commonly known as the Eye Worm do occur, most often in the summer months. They are often noticed while a horse is being examined for another issue as many horses infected with Thelazia show no clinical symptoms whatsoever, other than the presence of these tiny worms in their eyes.

The New Mexico Livestock Board, Office of the State Veterinarian has posted an update on the EHV-1 outbreak on 5-25-2011. Most local horse shows have been cancelled including the NM Dressage Association Show and the Sandia Classic.

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There has been an outbreak of Equine Herpes Virus-1 (EHV-1) also known as the neurological form of Rhinopneumonitis causing paralysis. The outbreak stems from the National Cutting Horse Association's (NCHA) Western National Championships in Odgen, UT on April 30 - May 8, 2011. All individuals from New Mexico attending that show have been contacted and are isolating their horses.

Threadworms are generally found to cause problems in horse foals, donkeys and zebras. Threadworm infection is the first patent parasitic infection often observed in foals from dams who have not been dewormed. Transmammary Transmission most common – larvae are actually transmitted from mammary tissue of dam via mare's milk to foal where they then undergo mucosal migration in foal's small intestine and mature into adult worms by the time the foal is 8 – 14 days of age. This is why mares should be de-wormed in the month prior to their due date.

Roundworms (aka Ascarids) are a common parasite of even well-managed young horses.  These large, white worms in their adult form are sometimes passed in horse’s manure (often just after deworming) and are noticed because of their size and stark color.   Adult Roundworms are the largest parasite that infects horses.  Weanlings, yearlings and 2 year olds are commonly affected, although Roundworms are sometimes present in horses older than 2 years of age and geriatric horses are susceptible as immunity wanes with age.

Small Strongyles (aka Cyathostomes) are currently recognized as the most common equine parasite. Horses can harbor Small Strongyle worm loads in their gastrointestinal tract and show no outward symptoms whatsoever. The larval stages of these parasites are known to burrow into the walls of the small intestine, only emerging into the intestinal lumen at certain times of the year to molt into adult worms and produce eggs that would be recognized on fecal examination! Therefore, horses infected with Small Strongyles may or may not exhibit eggs on fecal exam when, in fact, they may actually be carrying a significant parasite population. Small Strongyles even have the ability to remain encysted in their larval stage for up to 3 years before emergence.

Infectious disease control (IDC) is an important issue in any equine operation or facility. Many factors are involved in the spread and control of disease. There are common viral, bacterial and parasitic agents that are likely to be found in all areas with a high concentration of horses, but some simple prevention and control measures and having a plan for quickly acting to control potential outbreaks can minimize the impact of these issues on your barn.