Agriculture Reference
In-Depth Information
cally. In endemic herds, it will be necessary to vaccinate
kids annually prior to weaning. Humans are readily
infected by handling the vaccine or lesions on goats.
Goat pox is caused by a pox virus present in countries
from West Africa, North Central Africa, the Middle East,
and South Asia to China. It affects sheep as well as goats
and is transmitted by direct contact to susceptible (usually
young) animals. The skin develops raised red lesions that
turn into scabs. After the scab is removed, a star-shaped
scar remains. In severe cases, lesions also occur in the
lungs. Goat pox can cause severe mortality, but recovered
animals are not carriers and usually have lifelong immu-
nity. In countries where the disease is endemic, vaccina-
tion is an option, but goat pox-free countries opt for
eradication by slaughter to avoid the severe trade implica-
tions of infection.
Foot and Mouth Disease (FMD) affects a wide variety
of cloven-hoofed animals, including goats. It is caused by
a virus that is highly contagious and can quickly spread
over large areas. Its biggest economic impact is on dairies
due to decreases in milk production. Countries that have
FMD face severe trade restrictions on the export of prod-
ucts like milk and meat. Affected goats may develop blis-
ters (vesicles), erosions, and ulcers in their mouths and on
the coronary bands of their hooves. Clinically, animals are
off feed, drool, and are lame. Many infections go unno-
ticed. Control measures are usually a matter for govern-
ment offi cials and can vary from vaccination to quarantine
and eradication.
There are many plant toxins that can cause skin lesions
by photosensitization. Photosensitization can be primary
from ingested plant toxins; St. John's wort and buckwheat
or more commonly secondary to liver disease caused by
caltrops (tribulosis), lantana, senecio, and others. Cases of
photosensitization affect white portions of skin more
severely than pigmented skin.
Goats are affected by neoplasia, most commonly papil-
lomas and squamous cell carcinomas.
which is an obligate parasite of the gastrointestinal tract.
With sudden changes in quantity (overeating) or quality of
carbohydrates ingested,
C. perfringens
proliferates and
produces alpha and epsilon toxins that are absorbed and
cause the actual disease. The epsilon toxin in particular
causes a generalized toxemia with necrosis and neurotoxi-
cosis. This can cause sudden death but sometimes also
nervous signs or diarrhea. All goats should be vaccinated
because the disease is common, often rapid and lethal.
Vaccination is less effective in goats than in sheep and
must be given more frequently. Multivalent vaccines can
cover the other serotypes.
A further group of clostridial organisms causing
sudden death are much less common and include
C. sep-
ticum
(malignant edema)
, C. novyi
(black disease)
,C.
chavoei
(blackleg), and others. Septic wounds are often a
precursor and treatment may save goats if they are identi-
fi ed early enough. Vaccination is far preferable and highly
effective.
Anthrax (
Bacillus anthracis
) is a severe problem in
many countries, partly due to its ability to survive in the
soil for decades. Infection with anthrax is uniformly fatal.
If anthrax is suspected, the carcass must on no account be
opened, and state veterinary authorities must be informed
to ensure proper investigation and carcass disposal. A very
effective vaccine for this disease is available.
Rift Valley fever (a viral disease of Africa) may cause
large outbreaks of disease characterized by sudden death,
hemorrhages, abortions, and liver damage.
Many toxins and plants can cause sudden death, the
main types being urea (used as a protein source or fertil-
izer), nitrates (highly fertilized pastures and nitrate accu-
mulating plants), and cyanide (prussic acid), which is
accumulated by a number of plants.
Whenever sudden death occurs, it is important to estab-
lish an accurate diagnosis. The scene of death should be
carefully examined keeping in mind that trauma and elec-
trocution are major causes of acute death. Asphyxiation by
hanging is a common cause of sudden death in countries
where goats are tethered on mountainsides.
Sudden Death
Sudden death includes animals that die within a period of
minutes to hours (up to 24 hours). Goats are a predator-
prone species and attempt to hide symptoms of disease
until they are moribund. The main infectious cause is a
group of intestinal bacterial organisms called
Clostridium
perfringens
, of which there are four major types designated
A, B, C, and D causing a group of diseases known col-
lectively as enterotoxemia (overeating disease) character-
ized by sudden death, nervous symptoms, or diarrhea. The
main cause of enterotoxemia is
C. perfringens
type D,
Ill Thrift
Ill thrift is the most common problem in goat management.
It is characterized by animals that are slow growing,
thinner than normal, rough-hair coated, and weak. The
most common cause of ill thrift is nutritional and is a result
of inadequate quality or quantity of available food. Caloric
maintenance requirements of goats increase with increas-
ing burdens of parasites and disease. Parasitism and disease
may also cause decreases in feed intake. A common and
