JULY 2021

In recent years, a novel equine virus, Equine Parvovirus-Hepatitis (EqPV-H) has been implicated as causing Equine Serum Hepatitis, formerly referred to as Theiler’s Disease.  This virus is implicated to cause disease only in equines.  It has been associated with administration of biologic products of equine serum origin, but also from unknown sources.  Currently this virus has not been isolated or laboratory grown, and only can be detected by a qPCR test, which only measures the presence of genetic material, not live virus.

USDA/APHIS/CVB, our federal regulatory agency, has currently mandated that all serials of products of equine serum origin, and all donor animals, be tested for absence of EqPV-H genetic material by the Cornell University Diagnostic Laboratory qPCR test prior to release for marketing.  Products that are not to be used in horses still need to have donor animals tested.

Colorado Serum Company, as well as CVB and Cornell, has been working for several years to develop a test which can detect the presence of live virus, but with no success so far.  Unfortunately, in our opinion, the CVB limit of detection requirement makes the Cornell test overly sensitive and has resulted in, and will continue to result in, the elimination of donor horses and final product that would otherwise be considered acceptable.  Based on the qPCR testing there is a high prevalence of EqPV-H genetic material in the healthy horse population which will make finding negative donor horses very difficult going forward.

The imposition of this testing requirement will have an adverse effect on product availability.  At this point there will be no further production of Tetanus Antitoxin – Concentrated/Purified, and West Nile Virus Antiserum.  All finished serials of these products must be tested and the economic risk of doing so with this particular test is simply not viable.

Additionally, our regular Tetanus Antitoxin is required to be labeled “Do not use in equine species.”   Please advise your customers of this.  We will continue production of this product, as well as our Cl. Perf. C&D Antitoxin, for use in other species, but there may be very limited availability of both products due to the testing requirements for our donor herds.

We will continue to diligently pursue all avenues of cooperation with CVB for reasonable test developments to ensure that these safe and effective products will continue to be available.


Tetanus Antitoxin

Tetanus Antitoxin – Concentrated, Purified

Clostridium Perfringens Types C&D Antitoxin

Normal Equine Serum

West Nile Virus Antiserum

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