Coccidiosis-Goat Health

18 September, 2015rodster385Comments (0)

1 Coccidiosis is a contagious disease of goats, especially young
kids, throughout the world. The disease is caused by one or more of
approximately 12 different species of protozoa, called Eimeria, which
parasitize and destroy cells lining the intestinal tract of the goat.
Sheep are also very susceptible to coccidiosis, but even though the
sheep forms may share the same names with goat coccidia, many
parasitologists believe that the disease cannot be spread from goats to
sheep or from sheep to goats.

2 An infected goat sheds thousands of microscopic coccidial oocysts
in its feces every day. When first passed, the oocysts are harmless to
another goat. However, under favorable conditions of warmth and
mositure, each oocyst matures (sporulates) in 1 to 3 days to form 8
infective sporozoites. If a young kid swallows the sporulated oocyst,
the sporozoites are released and rapidly penetrate the intestinal
cells. From here on, the life cycle gets very complicated. The coccidia
pass through several periods of multiplication during which large
schizonts are formed. The intestinal cell of the goat is destroyed and
thousands of small forms called merozoites break out and invade other
intestinal cells. Eventually sexual stages are reached and new oocysts
are produced. The entire life cycle from oocyst to new oocyst takes 2-3
weeks.

3 If a young kid is suddenly exposed to many sporulated oocysts, it
may become severely ill 1-2 weeks later. It will be off feed, listless,
and weak. It may show abdominal pain by crying or getting up again as
soon as it lies down. At first, the kid might have a fever, but later
the body temperature is normal or even below normal. Diarrhea begins
pastey, then becomes watery. The kid may dehydrate rapidly. Contrary to
various reports written by people more accustomed to calves than kids,
the diarrhea is only rarely bloody. Neither is straining common. Signs
often show 2-3 weeks after the kids are weaned, because the lactic acid
produced by the digestion of milk helps to inhibit occidia in the
nursing kid.

4 Young kids may be killed quickly by a severe attack of coccidiosis.
Others - those initially stronger or less heavily infected - will
develop a chronic disease characterized by intermittent diarrhea and
poor growth. Tails and hocks are dirty. The kid with chronic
coccidiosis cannot digest its feed properly because the intestines have
been severely damaged. As a consequence, such a kid will be a
potbellied poor-doer for months afterwards. Frequently, such a stunted
kid will be too small to breed it's first winter.

5 Even though coccidiosis is typically a disease of the young growing
kid, most adults are mildly infected and continuously shed oocysts which
serve to infect young kids. Occasionally an adult goat shows temporary
diarrhea when stressed or exposed to a new species of coccidia. This is
especially common after the doe has been boarded on another farm for
breeding.

6 Diagnosis of coccidiosis can be based on clinical signs or
microscopic fecal exams. Coccidiosis is so common that it should be
suspected whenever kids older than about 2 weeks of age are scouring.
Sudden dietary changes can also cause diarrhea, but these make the kid
more susceptible to coccidiosis. Thus diarrhea that begins with the
consumption of too much milk, grain, or lush grass may drag on for days
because of coccidiosis. Older kids and adults with diarrhea may have
worms rather than coccidiosis, or they may have both problems
together. Oocysts can be identified if the feces are mixed with a
concentrated sugar solution. The oocysts float to the top, along with
larger worm eggs. They are collected and examined with a microscope.
Oocysts may be shed in the feces as early as 10 days after a kid is
infected, but often the first attack of diarrhea occurs before oocysts
are available to be identified. In these cases, the trained technician
can do a direct fecal smear to look for smaller merozoites, which do
not float in the sugar solution.

7 If a kid dies of coccidiosis, post-mortem examination will quickly
give the diagnosis. The small intestine will have many irregular raised
white areas, often about 1/8 to 1/4 inch in diameter. A smear taken
from these white spots will show many coccidial forms if examined under
a microscope.

8 Whether or not a goat gets sick with coccidiosis depends on several
factors. One is the number of oocysts swallowed at one time. Small
exposures, frequently repeated, lead to immunity. Large exposures
destroy all the intestinal cells at one time and kill the kid. The age
of the goat is also important. This is partly because the older animal
has usually had time to develop some immunity. Also, very young kids
are more fragile creatures. Good nutrition (including vitamin E-selenium
supplementation in selenium deficient areas) helps the goat to defend
itself against coccidiosis. Immunity to coccidiosis is rarely complete.
This means that the healthy adult goat continues to pass many oocysts
in her fecal pellets. However, most of her intestinal cells are safe
from invading coccidia. As each of the 12 or so coccidia species is
completely independent from the others, with no cross immunity, a goat
that is happily living with one type of coccidia may develop diarrhea
when exposed to a different type.

9 Prevention of coccidiosis is very important in larger herds if
young kids are to thrive. Once diarrhea has developed, most of the
damage to the intestine that leads to stunting has already occurred.
Sick kids are treated to save their lives and to limit contamination of
the pens, but the owner has already lost control of this contagious
disease. Several key facts will help to design a prevention program.
The first is that the adult goats are the original source of infection
for young kids, because they shed oocysts constantly. All old bedding
and manure should be removed from the kidding pens before the new kids
are born. Sporulated oocysts are commonly present on the skin of the
udder; thus the kid may become infected at the same time as it takes
its first drink of colostrum. The doe's udder should be washed and
dried before the kid nurses or else the kid should be removed from its
dam at once and bottle or pan fed the colostrum.

10 If only one doe and her kid are present on a farm, and the pens are
dry and spacious, coccidiosis is not apt to be a problem. The kids may
be safely left with the doe. In larger herds, it is best to raise kids
completely separate from the adults until they are ready to breed. Even
when rushed from the doe to a clean barn, kids still manage to pick up
a few coccidia. As multiplication is rapid, a few can become many very
quickly unless good sanitation is stressed. Fecal contamination of feed
and water must be prevented. This means that feeders and waterers
should be outside the pen whenever possible, and arranged so that fecal
pellets can't fall in. Grain should be put in keyhole creep feeders
rather than the open troughs that kids love to play and sleep in. Hay
racks also must be covered to keep kids out.

11 Because oocysts have to sporulate to become infective, exposure can
be reduced by cleaning the pens daily. Slotted floors are helpful.
However, daily cleaning entails a vast amount of work and give
disappointing results, if used alone. Ordinary disinfectants don't
destroy oocysts. Even 5 20
to concentrate on keeping the pens very dry, as mositure is necessary
for sporulation. Leaking waterers should be fixed at once. Otherwise,
the wet ground or floor around the water source is a perfect
environment for oocyst sporulation. Small grassy ''exercise lots'' are
also very dangerous and should not be used. It is very important to
avoid overcrowding; spreading the kids out decreases the number of
oocysts on any given square inch of pen floor or pasture. If many kids
are present on the same farm, they should be grouped by age. Putting a
2-week-old innocent kid into a pen with kids 2 months old, where
coccidial numbers and immunity have been building up for some time, is
to invite disaster for the newcomer. Oocysts are killed by very cold
temperatures (far below zero) or by hot dry conditions above 104. Thus,
at the end of the kidding season, pens and feeders should be moved out
into the hot sunshine for natural sterilization.

12 A variety of drugs may be given orally to treat the kid sick with
coccidiosis. These include sulfa drugs such as sulfaguanidine and
sulfamethazine, tetracyclines (aureomycin or terramycin), and amprolium
(Corid R). Each of these has associated dangers if overdosed. Sulfas
can cause kidney damage in the kid that is dehydrated. Tetracyclines
will interfere with rumen function in older kids and adults. Very high
levels of amprolium may lead to a fatal nervous disease, called
polioencephalomalacia, because of a thiamin deficiency. Usually
treatment is continued for about 5 days. Labels and veterinary
instructions should be followed. If the diagnosis is not certain, and
the kid may have bacterial enteritis or pneumonia rather than
coccidiosis, sulfamethazine or tetracycline is usually given instead of
amprolium.

13 All of these drugs are coccidiostats, which means that they slow
down rather than kill the coccidia. Thus, if a kid is very heavily
infected when treatment is begun, medication may not help that kid
much. The drugs will greatly reduce the contamination of the
environment, and thereby give other kids time to develop immunity.
After kids have become immune to the disease they still continue to
shed oocysts. Fecal exams may reveal thousands of coccidia per gram of
feces. Medicating these older kids or adults will temporarily reduce
the passage of oocysts but will not improve growth rate. Within 2 or 3
weeks after medication is stopped, coccidial levels will return to
pretreatment values. Thus, except for protection of younger kids, it is
a waste of time and money to treat older apparently healthy animals
that don't show diarrhea. It is far better to separate the young kids
from these older carriers.

14 Medication of apparently healthy animals is necesary for kids on
large farms with previous problems with coccidiosis. The aim is to
prevent damage to the intestines rather than waiting for diarrhea to
occur. For instance, it may help to treat the kids with anticoccidial
drugs on a daily basis for a week or more before stressing them by
weaning or moving onto pasture. In some herds, a drug such as amprolium
may have to be given daily beginning at 2 weeks of age and continuing
until the kids are several months old. Amprolium levels of 25-50 mg/kg
daily should be used. This is approximately 10-20 mg per round, and is
21/2-5 times the treatment level recommended for calves. Amprolium is
not approved for use in goats in this country. It can be given to each
kid individually or it can be mixed with the food or water. As an
example, if there are 50 pounds of small kids in a pen, 500 mg of
amprolium is mixed with the water, milk or feed that they will consume
in one day. The larger kids, by eating more, get more of the drug than
do the smaller kids.

15 Other newer coccidiostats may be mixed with the feed, but most of
them have not yet been adequately tested on goats. Rumensin R (Monensin)
at 15 ppm in the starter grain has eliminated the coccidiosis problem
on at least one large goat farm. This drug is very toxic to horses, so
the medicated feed should not be left where a horse can eat it.
Another potentially useful coccidiostat, now available only for
poultry, is lasalocid. This drug has protected experimental lambs at
2-4 mg/kg/day. The poultry industry has found that the coccidia often
become resistant to a drug after 1 or 2 years. Goat owners may also
need to change drugs if the one in use ceases to be effective in
controlling coccidiosis.

16 In summary, although most goats carry coccidia and will have
positive fecal exams, normally only the young kids become sick with
coccidiosis. Deaths and stunted kids result. Raising kids separately
from adults, keeping pens clean and dry, preventing fecal contamination
of water or feed, and, in some herds, continuous preventative
medication are necessary to prevent the disease. It is neither possible
nor desirable to completely eradicate coccidia from the adult goats. A
low level infection with the parasite serves to keep these goats
immune to the disease.