Saturday, May 2, 2009


A ProMED-mail post

ProMED-mail is a program of the
International Society for Infectious Diseases

Date: 30 Apr 2009
Source: Star Tribune [edited]

Metro investigates 10 sudden horse deaths
Metro Animal Control is investigating the sudden
deaths of 10 horses on a property west of Casper,
Wyoming, in April 2009, its manager said Thursday
[30 Apr 2009]. Metro learned of the deaths on 11
April 2009 from the veterinarian of the horses'
owner, Rick Sulzen said. A total of 6 horses were
already dead by that date and the other 4, which
were lethargic and unable to stand, died within
the next 24 hours, he said.

The causes and manners of their deaths are
unknown, Sulzen said. "We didn't see anything out
of the ordinary." The horses appeared well cared
for, investigators did not find any apparent
environmental problems, and there was no evidence
of foul play, he said.

The horses drank from Casper Creek, which has
selenium in the water, Sulzen said. But other
animals drink from the stream and don't have
problems, he said. The owner kept the horses in
an area near 7 Mile Road and U.S. Highway 20-26.
The owner, Sulzen said, did not want to talk to
the press about the deaths.

Metro officials sent specimens of the horses to
the state veterinary laboratory in Laramie, and
to a lab at Colorado State University in Fort
Collins, Colo., he said. Metro is still waiting
for the results of the necropsies from the labs,
Sulzen said.

State Veterinarian Dr. Walter Cook learned of the
deaths by e-mails sent from local veterinarians.
Although the tests on the specimens are not
finished, a tentative cause of the deaths may
have been botulism, Cook said. Botulism is a form
of food poisoning caused by the bacterium
botulinum, which secrets a virulent nerve toxin
called botulin. It is not infectious, Cook said.
Spoiled food often is the culprit for animals and
humans, he said.

Botulism grows in an anaerobic -- oxygen-free --
environment such as canned goods consumed by
humans, Cook said. With livestock, botulism can
occur when a dead animal is trapped in a hay bale
and the bacteria grow because of the lack of
oxygen in the compressed feed, he said. When
consumed, the contaminated food causes paralysis
and almost always death, Cook said. He urged
animal caretakers to contact a veterinarian if an
animal becomes ill, and urged them to constantly
monitor the food sources.

Because the horse deaths apparently were not
caused by an infectious disease, the state
veterinarian's office rarely hears or deaths from
botulism and in his experience those occur every
4 to years, he said. In this case, the
near-sudden deaths of 10 horses is probably
unique, Cook said.

Likewise, Sulzen said he's never seen this number
of such deaths during his time as manager of
Metro, which is overseen by a joint powers board
of representatives from Bar Nunn, Mills,
Evansville, Natrona County and the city of
Casper. Metro has not notified local
veterinarians or horse owners because they don't
know the reasons for the deaths, he said. "We
haven't sent memos," Sulzen said. "We don't know
what to look for."

[Byline: Tom Morton

Communicated by:
ProMED-mail Rapporteur Susan Baekeland

[Botulism, especially in animals, is a rare but
serious paralytic condition caused by a nerve
toxin produced by the bacterium _Clostridium
botulinum_. This organism produces a pre-formed
toxin responsible for the nerve paralysis. The
toxin binds to receptors on presynaptic terminals
of cholinergic synapses, is internalized into
vesicles, and then is translocated to the
cytosol. In the cytosol, the toxin mediates the
proteolysis of components of the calcium-induced
exocytosis apparatus (the SNARE proteins) to
interfere with acetylcholine release. Blockade of
neurotransmitter release at the terminal is
permanent, and recovery only occurs when the axon
sprouts a new terminal to replace the
toxin-damaged one. The classic syndrome of
botulism is a symmetrical, descending motor
paralysis in an alert patient, with no sensory

If this is a case of botulism, the animals would
go down, and would die over a few hours as the
muscles of respiration become paralyzed. This
article does not provide much of a clinical
picture of what is happening with the animals. We
know that 10 animals are dead, and 6 were dead
before the authorizes began an investigation. Of
the brief description, 4 more with lethargy that
died within 24 hours is suspicious of botulism.

Unfortunate animals that have been baled into hay
sets up the situation for botulism to form in the
hay, which allows for the toxin to form in the
hay and then be consumed by animals.

Fortunately, for people and companion animals
there is an antitoxin, but it becomes rather
expensive for large animals.

Portions of this comment were extracted from:
- Mod.TG

The state of Wyoming can be located in the
HealthMap/ProMED-mail interactive map at:

- CopyED.EJP]

[see also:
Undiagnosed deaths, equine - USA: (FL) 20081010.3217
Botulism, bovine - UK (England) 20060925.2743
Botulism, bovine - Australia 20060524.1464
Botulism, cattle - Israel 20020618.4531
Botulism, bovine - USA (California) (04) 19990605.0935
Botulism, bovine - USA (California) (03) 19990528.0901
Botulism, bovine - USA (California) (02) 19990526.0883
Botulism, bovine - USA (California) 19990524.0871
Botulism, bovine - USA (California) (05) 19980501.0854
Botulism, bovine - USA (California) (04) 19980428.0813
Botulism, bovine - USA (California) (03) 19980424.0765
Botulism, bovine - USA (California) (02) 19980424.0763
Botulism, bovine - USA (California) 19980421.0748]

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