Two California horses test positive for EIA in Stanislaus County
Two horses in California have tested positive for equine infectious anemia, or EIA, in Stanislaus County, according to an EDCC Health Watch report carried by The Horse. The report says 25 horses have been exposed. While the article itself is brief, California’s EIA response framework is clear: exposed horses are typically quarantined and retested, and confirmed positive equids must either be euthanized or placed under lifelong quarantine at least 200 yards from EIA-negative horses under USDA program rules. California has used that same approach in recent EIA cases in San Joaquin, San Bernardino, Madera, and Riverside counties. (thehorse.com)
Why it matters: For equine veterinarians and other horse health professionals, this is another reminder that EIA surveillance remains operationally important even when case counts are low. EIA is a viral disease that attacks the horse’s immune system, has no vaccine or cure, and infected horses can become inapparent lifelong carriers. Transmission can occur through blood-feeding insects such as horseflies or through blood-contaminated needles and instruments, so routine testing remains central to movement control and outbreak management. Most states still require proof of a negative Coggins test for interstate travel. The broader U.S. backdrop also matters: EDCC reported that USDA-APHIS had identified 21 linked EIA cases across four states by May 30, 2025, in an investigation that pointed to iatrogenic transmission tied to reused needles or syringes and contaminated heparinized saline at a Texas equine clinic. Separately, Texas recently reported two EIA-positive horses in Harris and Milam counties that were euthanized, with state officials monitoring exposed horses and implementing biosecurity measures. That history keeps attention on both Coggins compliance and basic injection biosecurity. (equinediseasecc.org)
What to watch: Watch for CDFA quarantine updates, 60-day retest results for exposed horses, and any epidemiologic tracing that clarifies whether this was an isolated premises event or part of a broader transmission chain. Clinical signs, when they occur, can include fever, depression, anemia, poor stamina, muscle weakness, and progressive loss of body condition, but some infected horses remain outwardly normal. (cdfa.ca.gov)