In this section, you can find links and information about current issues in equine health. We have also provided a few forms and bulletins that are available for download.

Word of warning: Please keep in mind that not everything you read on the internet is true. Critical reading, careful thought and common sense are essential for deciphering the large amount of information you can find on the internet. At Greystone Vet we try our best to provide you with current information from reliable sources that are trusted by veterinarians nationwide. But we are by no means infallible, nor are our sources, so as a reader you should do your best to confirm information found here or anywhere else on the internet with your local veterinarian.

Eastern Equine Encephalomyelitis (EEE): A report from the NCDA&CA Equine Disease Committe meeting on June 25, 2003 indicated that 4 cases of EEE have been confirmed so far this year, about a month ahead of the traditional "start of the season." It is felt this early start is probably due to the rains and bumper crop of mosquitoes. Please remember that:

  • It is a reportable disease to the NCDA&CA
  • It is important to confirm acute neurological disease, whether Rabies, EEE, or WNV. Where there is one case of EEE, there is the potential for other human and/or horse exposure
  • Proper initial vaccination is important - 2 does 3-6 weeks apart. Vaccination needs to be 6 months apart. Annually vaccinated horses may not be protected sufficiently towards the end of their vaccination interval.

Neonatal Isoerythrolysis (NI): A genetic condition affecting foals within the first week of life, where the mare generates an antibody response against the foal's red blood cells. The mare's antibodies enter the foal's circulation via colostrum ingestion. If the foal has the target antigen on its red cells, the antibodies attach to the red cells and cause their destruction.

Clinical signs of NI appear in the first 2 to 24 hours, but may occur as late as 7-8 days of age. They include weak, depressed, 'floppy' foals with evidence of tachycardia, tachypnea and pallor.

One way to prevent NI is to avoid incompatible matings and the other is to prevent the offending antibodies from entering the foal. This involves muzzling the foal until a colostrum titer shows a sufficiently low antibody level, usually 24-72 hours.

(Adapted from "Neonatal Isoerythrolysis" by Jill Johnson McClure in Current Therapy in Equine Medicine ed. N. Edward Robinson)

UC Davis Veterinary Medical Teaching Hospital now offers equine blood typing and antibody screens. Equine antibody screens should be performed on mares 2-3 weeks prior to foaling to detect anti-erythrocyte antibodies. This will establish if the foal is at risk of developing neonatal isoerythrolysis (NI). For more information, please call Joy at 530-752-1303.

Overo Lethal White Syndrome (OLWS) is a condition that occurs in newborn foals. The condition is genetic, and both parents carry the defective gene. Horses that carry this gene are most commonly overo white patterned horses (frame overos), but there are exceptions. OLWS foals have blue eyes and are completely or almost completely white at birth. These foals initially appear normal except for their unusual coloring. After a varying period of time, troubling signs of colic emerge due to the foal's inability to pass feces. The OLWS foal has an underdeveloped, contracted intestine caused by a failure of the embryonic cells that form nerves in the gastrointestinal system. Oddly enough, these cells also play a role in determining skin color. There is no treatment for OLWS, and surgery to bypass the intestinal damage has never been successful due to the extensive nature of this type of lesion. Veterinarians advise euthanasia for all OLWS foals because death will inevitably occur from colic caused by fatal constipation. See full article

West Nile Virus (WNV):On August 1, 2001, the USDA and Fort Dodge Animal Health announced approval of a conditional license for an inactivated vaccine against West Nile Viral Encephalitis (WNV) for use in horses. Also, keep in mind that it is important to confirm acute neurological disease, whether Rabies, EEE, or WNV. Where there is one case of WNV, there is the potential for other human and/or horse exposure.

Signs and symptoms of encephalitis in horses:

  • Ataxia, characterized by stumbling, staggering, or wobbly gait more often affecting the rear limbs
  • Weakness
  • Lying down with difficulty and inability to rise
  • Depression and listlessness
  • Facial paralysis or twitching
  • Teeth grinding
  • Blindess
  • Fever in 1/3 of affected horses

For the most current information on West Nile Virus and your horse, please check this webpage:


Cold Weather Tips:

Eight Steps to Effective Cold Weather Management:

Adapted from the NCSU Cooperative Extension Service Newsletter

The latest Equine Protozoal Myeloencephalitis (EPM) update can be found in this bulletin from Michigan State.

Click here for quick guide to Equine Healthcare, prepared for a beginner's clinic on basic horse care.
Also available in Word format for download.

This is the Foaling Assessment form we use for each foal delivered at Greystone. We probably adapted it from some other source, so please feel free to use it for your babies if you find it helpful.

Our transported semen shipment data form is also available for download. It is in Excel format.

Have a question for Dr. Newell?
Please send us an email at