Cattle mutilation (also known as bovine excision and unexplained livestock death) is the killing and mutilation of cattle under unusual, usually bloodless and anomalous circumstances. Worldwide, sheep, horses, goats, pigs, rabbits, cats, dogs, bison, deer and elk have been reported mutilated with similar bloodless excisions; often an ear, eyeball, jaw flesh, tongue, lymph nodes, genitals and rectum are removed.

Since the first reports of animal mutilations, various explanations have been offered, ranging from natural decomposition and normal predation to cults and secretive governmental and military agencies, to a range of speculations, including cryptid predators (like the Chupacabra) and extraterrestrials. Mutilations have been the subject of two independent federal investigations in the United States.

The earliest known documented outbreak of unexplained livestock deaths occurred in early 1606 "...about the city of London and some of the shires adjoining. Whole slaughters of sheep have been made, in some places to number 100, in others less, where nothing is taken from the sheep but their tallow and some inward parts, the whole carcasses, and fleece remaining still behind. Of this sundry conjectures, but most agree that it tendeth towards some fireworks." The outbreak was noted in the official records of the Court of James I of England. Charles Fort collected many accounts of cattle mutilations that occurred in England in the late 19th and early 20th centuries. John Keel mentioned investigating animal mutilation cases in 1966 (while with Ivan T. Sanderson) that were being reported in the Upper Ohio River Valley, around Gallipolis, Ohio. The phenomenon remained largely unknown outside cattle-raising communities until 1967, when the Pueblo Chieftain in Pueblo, Colorado, published a story about a horse named Lady near Alamosa, Colorado, that was mysteriously killed and mutilated. The story was republished by the wider press and distributed nationwide; this case was the first to feature speculation that extraterrestrial beings and unidentified flying objects were associated with mutilation.

On September 9, 1967, Agnes King and her son Harry found the dead body of their three-year-old horse, Lady. Lady's head and neck had been skinned and defleshed, and the body displayed cuts that, to King, looked very precise. No blood was at the scene, according to Harry, and a strong medicinal odor was in the air. A subsequent investigation concluded there were "No unearthly causes" of the death. When the Lewis' called Alamosa County Sheriff Ben Phillips he told them that the death was probably due to "a lightning strike," and never bothered to visit the site. Early press coverage of the case misnamed Lady as Snippy. Snippy was Lady's sire and belonged to Nellie's husband, Berle Lewis.

Democratic senator Floyd K. Haskell contacted the FBI asking for help in 1975 due to public concern regarding the issue. He claimed there had been 130 mutilations in Colorado alone, and further reports across nine states. A 1979 FBI report indicated that, according to investigations by the New Mexico State Police, there had been an estimated 8,000 mutilations in Colorado, causing approximately $1,000,000 damage.

In May 2001, 200 goats were mutilated in Panggang District of Gunung Kidul Regency, Yogyakarta, Indonesia.

In most cases, mutilation wounds appear to be clean and carried out surgically. Mutilated animals are sometimes, though not always, reported to have been drained of blood and show no sign of blood in the immediate area or around their wounds.

George E. Onet, a doctor of veterinary microbiology and cattle mutilation investigator, claims that mutilated cattle are avoided by large scavengers "such as coyotes, wolves, foxes, dogs, skunks, badgers, and bobcats" for several days after their death. Similarly, domestic animals are also reported to be "visibly agitated" and "fearful" of the carcasses.

According to a survey taken by the National Institute for Discovery Science (NIDS), mutilation of the eye occurred in 59 percent of cases, mutilation of the tongue in 42 percent of cases, the genitals in 85 percent of cases, and the rectum in 76 percent of cases.

According to Dr. Howard Burgess, nearly 90 percent of mutilated cattle are between four and five years old.

Some mutilations are said to occur in very brief periods. A 2002 NIDS report relates a 1997 case from Utah. Two ranchers tagged a specific calf, then continued tagging other animals in the same pasture. The ranchers were, at the most, about 300 yards (275 m) from the calf. Less than an hour later, the first calf was discovered completely eviscerated—most muscle and all internal organs were missing. There was no blood, entrails, or apparent disturbance at the scene. Independent analysts both uncovered marks on the calf's remains consistent with two different types of tools: a large, machete-type blade, and smaller, more delicate scissors.

The absence of tracks or footprints around the site of the mutilated carcass is often considered a hallmark of cattle mutilation. However, in some cases, strange marks or imprints near the site have been found. In the famous "Snippy" case, there was an absolute absence of tracks in a 100 ft (30 m) radius of the carcass (even the horse's own tracks disappeared within 100 ft (30 m) of the body.) But within this radius, several small holes were found seemingly "punched" in the ground and two bushes were absolutely flattened.[16] In Rio Arriba County, New Mexico, June 1976, a "trail of suction cup-like impressions" was found leading from a mutilated three-year-old cow. The indentations were in a tripod form, 4 inches (10 cm) in diameter, 28 inches (70 cm) apart, and disappeared 500 feet (150 m) from the dead cow. Similar incidents were reported in the area in 1978.

Laboratory reports carried out on some mutilated animals have shown unusually high or low levels of vitamins or minerals in tissue samples, and the presence of chemicals not normally found in animals. However, not all mutilated animals display these anomalies, and those that do have slightly different anomalies from one another. On account of the time between death and necropsy, and a lack of background information on specific cattle, investigators have often found it impossible to determine if these variations are connected to the animals' deaths or not.

In one case documented by New Mexico police and the FBI, an 11-month-old cross Hereford-Charolais bull, belonging to a Mr. Manuel Gomez of Dulce, New Mexico, was found mutilated on March 24, 1978. It displayed "classic" mutilation signs, including the removal of the rectum and sex organs with what appeared to be “a sharp and precise instrument” and its internal organs were found to be inconsistent with a normal case of death followed by predation.

"Both the liver and the heart were white and mushy. Both organs had the texture and consistency of peanut butter"
Gabriel L Veldez, New Mexico Police

The animal's heart as well as bone and muscle samples were sent to the Los Alamos Scientific Laboratory for microscopic and bacteriological studies, while samples from the animal's liver were sent to two separate private laboratories.

Los Alamos detected the presence of naturally occurring Clostridium bacteria in the heart, but was unable to reach any conclusions because of the possibility that the bacteria represented postmortem contamination. They did not directly investigate the heart's unusual color or texture.

Samples from the animal's liver were found to be completely devoid of copper and to contain 4 times the normal level of zinc, potassium and phosphorus. The scientists performing the analysis were unable to explain these anomalies.

Blood samples taken at the scene were reported to be "light pink in color" and “Did not clot after several days” while the animal's hide was found to be unusually brittle for a fresh death (the animal was estimated to have been dead for 5 hours) and the flesh underneath was found to be discolored.

None of the laboratories were able to report any firm conclusions on the cause of the blood or tissue damage. At the time, it was suggested that a burst of radiation may have been used to kill the animal, blowing apart its red blood cells in the process. This hypothesis was later discarded as subsequent reports from the Los Alamos Scientific Laboratory later confirmed the presence of anti-coagulants in samples taken from other cows mutilated in the region.

After coming under increasing public pressure, Federal authorities launched a comprehensive investigation of the mutilation phenomenon.

In May 1979, the case was passed on to the FBI, which granted jurisdiction under Title 18 (codes 1152 and 1153). The investigation was dubbed "Operation Animal Mutilation".

The investigation was funded by a US$44,170 grant from the Law Enforcement Assistance Administration, and was headed by FBI agent Kenneth Rommel. Rommel's final report was 297 pages long and cost approximately US$45,000. It concluded that mutilations were predominantly the result of natural predation, but that some contained anomalies that could not be accounted for by conventional wisdom. The FBI was unable to identify any individuals responsible for the mutilations. Details of the investigation are now available under the Freedom of Information Act. The released material includes correspondence from Rommel where he states that "most credible sources have attributed this damage to normal predator and scavenger activity".

Prior to the involvement of the FBI, the ATF launched their own investigation of the phenomenon.

Both federal investigations were preceded (and followed, to some extent) by a state level investigation carried out by enforcement officials in New Mexico. This investigation reported finding evidence that some mutilated animals had been tranquilized and treated with an anti-coagulant prior to their mutilation. It also contended that alleged surgical techniques performed during mutilations had become "more professional" over time. However, officers in charge were unable to determine responsibility or motive.

The ATF investigation was headed by ATF Agent Donald Flickinger. The New Mexico investigation was headed by Officer Gabriel L Veldez of the New Mexico Police, with the assistance of Cattle Inspector Jim Dyad and Officer Howard Johnston of the New Mexico Department of Game and Fish.

A standard mutilation exhibits one or more of the following characteristics:

* Usually occurs with cattle, horses, or sheep.

* Jaw cut: A precision, surgical-like cut of surrounding flesh to completely expose the jaw bone and teeth. The tongue and surrounding glandular tissue has been removed.

* The sex organs, navel, and nipples have been surgically removed.

* The anus and surrounding glandular tissues have been surgically removed.

* No evidence of any blood, despite the severity of the procedures.

* No footprints of any kind leading to or from the animal.

* The animal is often found in the middle of a perfectly created circle.

* The cuts are made so precisely that a surgeon with a full operating room and a steady hand with the laser would have a difficult time matching these field cuts.

* The precision of the cuts and lack of blood rule out predator kills.

Ten thousand animal mutilations — all of them unexplained.