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BOTULISM, CANINE - USA: (FLORIDA) SUSPECTED
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A ProMED-mail post
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International Society for Infectious Diseases
<http://www.isid.org>
Date: 5 Feb 2010
Source: The Miami Herald [edited]
<http://www.miamiherald.com/news/breaking-news/story/1464427.html>
A month after frigid temperatures killed reptiles all over South
Florida, veterinarians are still treating dogs that may have
contracted botulism by gnawing iguana carcasses. The result:
paralysis so severe that a few had to be euthanized.
Like other cold-blooded creatures, thousands of iguanas froze to
death during the freeze. Some dogs mistaking them for chew toys have
shown classic symptoms of a disease so rare that most vets don't see
a case for a decade. "I think it's botulism, although it's nearly
impossible to prove definitively,'' said Dr. James Dugan, a Pinecrest
vet. His clinic has treated several dogs suffering varying degrees of
paralysis since the cold snap. All had munched on iguanas. "Why they
want to eat a rotten reptile that smells horrible and could kill you,
I don't know," Dugan said.
Paralysis begins in the back end, then progresses to the front legs,
and in some cases disables the diaphragm. At that point, dogs must be
intubated so they can breathe, an expensive step that many owners
can't afford. In at least 2 such South Florida cases, dogs that
couldn't breathe were euthanized. Serious problems like pneumonia
also arise when paralysis affects the esophagus.
Broward County veterinary neurologist Dr. Brian Roberts first raised
the alarm about the possible botulism link in a mass e-mail to South
Florida colleagues in late January 2010. He said that several dogs
had come to Veterinary Specialists of South Florida in Cooper City
with paralyzed hindquarters. The common denominator: dead iguanas.
"We didn't have a clue what it was for days or weeks," said Roberts,
who has sent tissue samples to the state's animal diagnostic
laboratory in Kissimmee. He diagnosed botulism after ruling out other
possible conditions. There's not much a vet can do beyond "supportive
care and range-of-motion" exercises, he added.
Typically, paralysis sets in a day or so after the iguana encounter,
and the worst symptoms last at least a week. The dogs can eat but
can't stand or walk. However, they're not in pain, vets say.
That's the case with Baby Miller, a 68-pound, 8-year-old Pompano
Beach pit bull whose human family rushed her to Dr. Kevin
McAllister's clinic on 26 Jan 2010. "She picked up a dead iguana in
the yard and by the next day was showing signs of weakness in the
back leg that progressed to the front, and she could no longer
stand," McAllister said. "She was in a little distress: high heart
rate, anxious and totally down." The family "had no idea what it was,
and I didn't either," said McAllister, in practice for 10 years. "We
were thinking maybe a stroke or [human] drugs. In hindsight, she had
the classic signs of botulism. I'd never seen it."
Baby's [owner] said that Baby had "gotten hold of an iguana" 2 days
before she showed symptoms. "My brother found her on the floor, and
she couldn't move," said the owner. Blood tests ruled out painkillers
and roofing sealer, 2 possible culprits. The normally playful Baby is
slowly recovering. "She is more irritated than anything. She's very
aware of what's going on. She can lift her head and wag her tail and
is trying to sit up. She has "refused to go to the bathroom in the
house," and must be carried outside. The tab so far: USD 300 at the
vet; USD 6 a day for Pedialyte to keep Baby hydrated. "She's been
stable and didn't get any worse, and that's what we look for," McAllister said.
Dr. Jonathan Kreissler of Miami Veterinary Specialists said his
hospital has seen "5 similar cases in 3 weeks. Three are not walking;
one was euthanized," and one didn't return for follow-up care. Its
owners can't be reached, and Kreissler suspects the dog has died. Two
remain at his clinic getting "recumbent care to make sure they don't
get bed sores" or secondary infections. One is a Cane Corso, a huge
dog in the mastiff family. Kreissler said the dog weighed 110 pounds
in September 2009 and weighs 70 now due to muscle wasting. The dog
had complications and spent a day on a ventilator. Care so far is in
5 figures, he said.
Still, Kreissler isn't sure he's dealing with botulism or that
reptiles are the culprit. "It would be really convenient to blame the
iguanas, but it might be premature," he said. With botulism, he'd
expect to see problems with the autonomic nervous system that
controls involuntary functions like pupil dilation and heart rate,
"and I'm not seeing any of that. These dogs are alert and can wag
their tails." Still, in analyzing the cases, vets have to take into
consideration recent, abnormal environmental changes, such as a
prolonged freeze that kills cold-blooded reptiles, he said.
--
Communicated by:
ProMED-mail <promed@promedmail.org>
[There is a useful video attached to the above article in which
Sherry L. Schlueter, Executive Director of the Wildlife Care Center
in Ft. Lauderdale, explains how to handle a frozen iguana. With
temperatures dipping near freezing, these non-native reptiles can't
handle the cold, and their scaly bodies shut down until they are able
to warm up again.
_Clostridium botulinum_ grows in an anaerobic environment, and some
of these iguanas will be quite large; during the cold snap there were
various national TV news reports of chilled immobile iguanas falling
out of the trees. Botulism, especially in animals, is a rare but
serious paralytic condition caused by a nerve toxin produced by the
bacterium _Cl. 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 deficits. If this is
botulism, the animals would go down, and would normally die over a
few hours as the muscles of respiration become paralyzed.
Fortunately, for people and companion animals, there is an antitoxin.
If there was a record of a successful canine recovery following the
use of the antitoxin, it would add weight to this working diagnosis
of botulism.
Anyone with direct information on these canine cases is asked to
share it. If it is botulism, it would be nice to have laboratory
confirmation of some sort.
More extensive information on botulism can be found at:
<http://emedicine.medscape.com/article/829125-overview>. - Mod.MHJ]
[see also:
2009
----
Botulism, avian - USA: (NV) 20090808.2814
Botulism, equine - USA: (WY) 20090502.1651
2008
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Botulism, avian - USA (02): Great Lakes 20080817.2556
Botulism, avian - USA: Great Lakes 20080116.0210
2007
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Botulism, avian - USA (02): (MI), susp. 20071111.3665
Botulism, avian - USA: (MI), susp 20071103.3572
Botulism, avian - USA (NY): susp 20070812.2624
Botulism, avian - USA (NY) 20070714.2259]
..............................mhj/msp/mpp
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