For Your Info
Eastern Equine Encephalomyelitis Update
Overo Lethal White Syndrome (OLWS)
West Nile Virus (WNV)
Equine Protozoal Myeloencephalitis (EPM)
Beginner's Guide to Horse Health Care
Transport Semen Shipment Data
Cold Weather Tips
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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)
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.