Page 1034 - Clinical Small Animal Internal Medicine

972 Section 9 Infectious Disease

anthrax spores are deposited in alveolar spaces and from be on the clothes of a person exposed to an anthrax aero-
VetBooks.ir there are transported by lymphatics to regional lymph sol. Affected clothing should either be destroyed or can
be washed using a 0.5% hypochlorite solution. Wounded
nodes where germination occurs up to 60 days later.
or discharged victims will create a possible vector if they
are not properly decontaminated. Anthrax does not
Signalment readily transfer from one person to another unless the
spores are in the clothing/shoes and there is some
Anthrax occurs throughout the world. B. anthracis exists method of moving the spores to another person. Once a
in the soil as a spore. The question remains unsettled as rescuer walks in the anthrax, then the threat of “move-
to whether its persistence in the soil is due to significant ment” to other areas is very real.
multiplication of the organism in the soil or if it is due Bodies that are not immediately recoverable pose little
solely to cycles of bacterial amplification in infected ani- threat. Anthrax doesn’t “jump up and bite you or me”! As
mals whose carcases then recontaminate the soil. The long as the bodies are not disturbed and/or wind move-
form of the organism in infected animals is the bacillus. ment is low, the anthrax will stay inside the bodies or in
Only when the organism in the carcass is exposed to oxy- the clothing.
gen does sporulation occur.
Anthrax is most common in agricultural regions where
it occurs in animals. It is primarily a disease of herbivores History and Clinical Signs
(Table 107.1); carnivores and humans are incidental
hosts. Animals, domestic or wild, become infected when Anthrax in veterinary species may be peracute, acute or
they ingest spores while grazing on contaminated land or subacute, or chronic. The peracute form most frequently
eating contaminated feed. Environmental conditions affects cattle, sheep, and goats. The acute or subacute
such as drought, which may promote trauma in the oral form is common in cattle, sheep, and horses. Chronic
cavity during grazing, are thought to increase the chances anthrax is most often seen in less susceptible species
of acquiring anthrax. It is spread from animal to animal such as swine but may also be seen in cattle, horses, dogs,
by mechanical means and biting flies. Spread from one and cats. Suspicions of anthrax are raised when livestock
environmental site to another appears to occur via are found dead, bloated, and without rigor mortis. Blood
nonbiting flies, rodents, and carrion‐eating birds. Free is usually evident at body orifices.
anthrax spores can also be spread by water and wind.
Human anthrax victims can also theoretically spread
anthrax spores that landed on their clothing and external Dogs and Cats
body surfaces. Therefore, each victim should be decon- Both the dog and cat appear to be relatively resistant to
taminated and issued new clothes before leaving the anthrax. Dogs are supposedly 500–1000 times more
scene. Estimates have shown that ~90% of anthrax will resistant to anthrax infection than humans. The gastro-

Table 107.1 Anthrax severity in potentially affected species

Other
Dogs Horses Cattle Sheep Goats Pigs Cats Birds animals

D S S S S D D Resistant S
Wild herbivores and carnivores camels,
antelope, guinea pigs

Source: Wingfield et al. (2009). Reproduced with permission of John Wiley & Sons.
D, moderate; S, severe.