| Equine Infectious Anemia is a viral disease for which | | | | show low-grade exercise intolerance, poor appetite |
| there is no vaccine and no cure. Though most horses | | | | and lethargy. Infections ranging from pneumonia to |
| succumb rapidly to EIA a percentage of infected | | | | renal disease can, if prolonged, result in significant |
| horses appear to recover. However they still harbor | | | | anemia. Certain types of cancer may clinically manifest |
| the virus and during times of stress may become ill | | | | as anemia, as may several different viruses, such as |
| again. It is because of these healthy appearing carriers | | | | Equine Infectious Anemia (EIA). Less frequently, |
| that we test horses. It insures that we do not put their | | | | deficiencies of iron, copper, protein and B vitamins can |
| pasture mates at risk.The disease is spread by | | | | impair the body's ability to manufacture red blood cells. |
| horseflies. The large horsefly is the main vector. If they | | | | Anemia resulting from increased red blood cell |
| bite an infected horse and then bite a healthy horse, | | | | destruction is often accompanied by fever and |
| the disease gets transmitted. The virus does not live | | | | yellowish mucous membranes. In more severe cases, |
| for very long on the horsefly, maybe as little as fifteen | | | | the horse's urine will be a dark-reddish brown. This |
| or thirty minutes. So for one horse to infect another | | | | category of anemia has many causes, including red |
| they must be close to each other. This disease occurs | | | | maple leaf toxicity. Parasites, certain types of |
| anywhere horseflies live. | | | | neoplasia, drug toxicity (particularly that which involves |
| The acute horse may be difficult to diagnose because | | | | anti-inflammatory drugs) and neonatal isoerythrolysis |
| the symptoms are very general and he will not be | | | | are other causes. |
| positive on the EIA test for a month and a half. | | | | The diagnosis of equine anemia is based on clinical |
| Approximately one third of infected horses will die of | | | | signs that indicate reduced oxygen transport to tissues |
| the acute form within a month. The chronically infected | | | | and a reduced packed cell volume. The packed cell |
| horse will having recurring acute bouts along with | | | | volume (PCV) measures the percentage of circulating |
| weight loss, ventral edema (swollen belly and legs) and | | | | red blood cells in the bloodstream. Normally a horse |
| anemia. These horses will be positive on a EIA test. | | | | has a PCV of about 40 percent (with some age and |
| These horses may linger for a year or more before | | | | breed variations). A horse with a PCV of less than 30 |
| they die. Anemia in horses may originate from three | | | | percent is considered anemic, and efforts should be |
| major pathways: blood loss; increased red blood cell | | | | made to identify the source of the lack of red cells. To |
| destruction and inadequate red blood cell production. | | | | complicate matters, a significant number--up to 30 |
| Given the variety of pathways involved in developing | | | | percent of the total red blood cells--of red blood cells |
| anemia, horses may present a fairly wide array of | | | | will be sequestered in the spleen of a resting horse, |
| clinical signs. Some of the most common include | | | | even a fit one. |
| decreased capacity for exercise, decreased appetite, | | | | Therefore, initial PCV evaluations on resting horses |
| depression or a trauma that causes acute blood loss. | | | | may be deceiving, because following a period of |
| The horse's heart rate may be elevated--normal is | | | | exercise or excitement, the PCV will be elevated to its |
| about 30 beats per minute--to more than 45 or 50 | | | | normal range. If the PCV drops below 15 percent, a |
| beats per minute. The mucous membranes may | | | | blood transfusion may be necessary. This is often |
| appear very pale or white, and urine may be | | | | performed at a referral center where blood donors |
| discolored or reddish. Anemia resulting from direct | | | | may be kept and cross-matching is performed. |
| blood loss is often the easiest to diagnose, but is still a | | | | While the diagnosis of anemia in horses is |
| challenge to treat. Generally there will be signs of | | | | straightforward, involving a blood sample and |
| shock (weak pulse, elevated heart rate, pale mucous | | | | centrifuge, the challenge is determining the primary |
| membranes). Other signs may include profuse bleeding | | | | cause. If the anemia is due to acute blood loss, the |
| from the nose. | | | | source of the trauma or hemorrhage should be |
| Anemia due to inadequate red blood cell production is | | | | identified and controlled, and your veterinarian should |
| the most common form of anemia in horses; however, | | | | be contacted immediately. |
| it is the most challenging to identify. These horses may | | | | |