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CONTAINMENT CLASS: archon secret


Foundation Containment Committee Notice

As the anomalies associated with SCP-3787 continue to change over time, its documentation appears here in chronological order. All observed changes to the properties of this anomaly will appear as addenda materials. Only the most recent version of this anomaly's containment procedures is viable.

The original 2021/06/30 documentation is as follows.

Description: SCP-3787 describes a deviance to the natural behaviour of domesticated and free-roaming horse (Equus ferus caballus) populations in the Southern and Southwestern United States.

SCP-3787 refers to the emergence of a gestation period 8–10 times more rapid than the baseline horse-breeding cycle. Among affected horses, the baseline gestation period of 11–12 months is shortened to roughly 30–45 days from conception to birth. As a result, up to 10 times as many foals are born. Growth rates of this size over an extended period are unsustainable and pose a serious risk to the equine industry's ability to maintain it.

Horses involved in this breeding cycle — including both newborn foals and pregnant mares — are not negatively affected. Newborn foals exhibit physiological properties similar in nature to their non-anomalous counterparts. They develop within pregnant mares despite lacking the necessary sustenance over the accelerated developmental period.


SCP-3787-1-affected horses hunting for prey. Image taken remotely (hover to enlarge).

SCP-3787-1 describes an anomalous increase in horse aggression in free-roaming horse populations. Examples of aggression include:

  • Unprovoked hostilities toward horses outside a constituent pack.
  • The active killing of most or all members of a feral horse pack by that pack's dominant stallion.
  • The cannibalization of foals as a show of dominance.

Increase in horse hostility has extended into normal horse feeding patterns as well. Feral horse packs affected by this anomaly carry out organized attacks on other wildlife, escalating to the point of ignoring herbivorous feeding habits. This occurs despite horse jaw structures and digestive systems being biologically unsuited for meat consumption. This manner of aggression has led to the progression of horses to the top of the food chain in many areas.

SCP-3787-1 initially began in newborn foals affected by SCP-3787 but has since transferred to an unknown number of horse populations of varying ages based on a geometric infection model. As well, this anomaly has developed in the same period and area as a second equine anomaly, designated SCP-3787-ε. This anomaly refers to the immediate consequences of a marked increase of total horse population numbers, which has led to the increase of the equine in the human consciousness.

SCP-3787-ε is the designation given to an anomalous memetic form of equinophobia, or the emergence of an intense fear of horses among humans with no previous basis to fear horses. Persons may not be aware that they have been affected by this anomaly until their re-exposure to the concept of horses through forms of media or personal conversations that reference horses.

SCP-3787-ε occurs in suburban areas and urban centres, and among populations far from rural communities. More specifically, SCP-3787-ε occurs among populations with little access to that which is equine in nature.1

An estimated 750,000 persons within the continental United States have contracted this anomaly.

Addendum 3787.1


On June 30, 2021, Foundation efforts to reduce the heightened equine birth rate were deemed successful. The median horse gestation period levelled out to ~1.5 times the baseline. In the two months since detecting the anomaly, ~450,000 new horses were born in the United States alone.

On July 12, Parazoology Division personnel observed what they hypothesized to be an anomalous illness spreading throughout domesticated horse populations. Horses affected by this illness experienced a period of extreme stress, leaving them in a comatose state. In 18% of cases, affected horses later expired. 37% of horses in the Southern and Southwestern United States have been afflicted with this illness.

As of July 29, research efforts into a cure have proven ineffective.

Addendum 3787.2


Since it began, the accelerated spread of this illness has led to the death of ~1.1 million horses in the US. In response, Site-82 — in conjunction with the Scientific Department — published the following reports on Project: DIRE HORSE to the IntSCPFN network.

Addendum 3787.3


On September 3, hostile anomalous entities attempted to force access into Site-41 facility "Aleph" during Procedure MNEMOSYNE. A transcript of the encounter is as follows.

Addendum 3787.4


Foundation personnel specializing in antimemetics training note the emergence of large numbers of antimemetic equine entities (designated 3787-N). These entities appear en masse as a direct result of extended Foundation efforts to control North American horse population numbers.4

A full description of 3787-N is as follows.

Containment analysts at Site-82 have come to understand a complex relationship between the appearance of 3787-N and previous equine anomalies. Analysts conclude that the emergence of increased equine aggression and accelerated birth rates was, in part, a widespread anomalous defence mechanism tailored toward the repulsion of 3787-N. Current reports have shown that this behaviour has almost reversed, in due part of the emergence and influence of 3787-N, which horses now act subservient toward.

Research Director Elliot Alces has approved the reclassification of SCP-3787 to an ARCHON-Class anomaly.5 The Foundation is now undergoing wide-scale internal research efforts focused on the anomalous nature of horses as a species.

Since the appearance of 3787-N, North American horses have deviated from their normal behaviour.6 Almost all observed horse populations display SCP-3787-1 and attack humans, leading to civilian casualties beyond Foundation control. In areas with a high volume of SCP-3787-1, domesticated and feral horses alike have begun a mass transit to a yet undesignated area in the American Southwest, led by groups of 3787-N.

How the two groups communicate is currently under active investigation.

3787-N have directed efforts toward constructing a large equine-centric locale composed of both horses and 3787-N populations. Attempted contact by any non-equine populations has led to confrontational behaviour on the part of 3787-N.

Foundation personnel attempting to hinder the effects of SCP-3787 also face aggression, and in some cases, personnel have undergone transfiguration into horses via inexplicable means.

Addendum 3787.5


Mobile Task Force Pi-5 ("Glue Factory") has formed to repel the attacks of 3787-N. Each member of Pi-5 is trained to deal with antimemetic anomalies and is to remain on a strict Class-W Mnestic prescription. A summary of the task force is as follows:

  • 40 combat operatives using light-based weaponry such as the 1000W N-62A Laser Optics Pistol, the 2000W G1A Tactical Solid-state Laser Rifle, and the prototype 30,000W Basok-Prokhorov RX-7Z Hard-Light Heavy Rifle ("Nulltaker").
  • 4000 lm flashlights and interfaces with night vision and blue-light eye protection lenses.
  • 15 Polaris MV800 ATV medium support vehicles outfitted with Light Reconnaissance Laser Optics (LiLo) gun platforms.
  • 10 Chenoweth RAV light action support vehicles.
  • 4 SL/SX Support Drones fitted with Mariotte-Pashler antimemetic perception filters.

Despite Pi-5's formation, the full containment of 3787-N and any related anomalies is not believed to be possible due to their widespread nature.

Foundation efforts are currently directed toward reducing any public fear of horses.

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