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Group Title: Circular - University of Florida Cooperative Extension Service ; 1023
Title: Common internal parasites of goats in Florida
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
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Permanent Link: http://ufdc.ufl.edu/UF00067070/00001
 Material Information
Title: Common internal parasites of goats in Florida
Series Title: Circular Florida Cooperative Extension Service
Physical Description: 8 p. : ill. ; 28 cm.
Language: English
Creator: Heath, S. E
Harris, Barney
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville Fla
Publication Date: 1991
 Subjects
Subject: Goats -- Parasites -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: S.E. Heath and B. Harris, Jr.
General Note: Cover title.
General Note: "September 1991."
Funding: Circular (Florida Cooperative Extension Service) ;
 Record Information
Bibliographic ID: UF00067070
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 24858633

Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
    Main
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
    Back Cover
        Page 9
    Historic note
        Page 10
Full Text
pt1/


September 1991


CCir cular 123

o10 3 1931
. of F
Iotd


Common Internal Parasites

of Goats in Florida
S. E. Heath and B. Harris, Jr.


L\


Cooperative Extension Service
Institute of Food and Agricultural Sciences
University of Florida
John T. Woeste, Dean

















































































S.E. Heath, former visiting Assistant Professor, rural animal medicine, Department of Large Animal Clinical Sciences. B. Harris Jr.,
Extension Dairy Scientist, Department of Dairy Science.








Introduction
Internal parasites are a problem and hazard to
all classes of livestock because of the inapparent,
unrecognized loss from subclinical parasitism.
They are especially detrimental to young animals
in that they reduce performance and resistance to
other diseases. They may also cause disease and
death in animals.
Parasitism is a herd problem or disease. Mea-
sures to control the problem must be applied to the
total herd as though it was a single animal.
Every parasite has a relatively fixed cycle and
rate of development, despite the abundance of dif-
ferent species. Each species has its own forms,
habits, modes of life, and potentialities for causing
disease and injury. The strongest attack is an ef-
fective prevention program made on the parasite's
stage of development which is most vulnerable.
In a goat herd, young animals under 6 months of
age are by far the most susceptible to parasitic in-
fection. This group of kids is highly susceptible
since they have had very little exposure to para-
sites and thereby have very little resistance of im-
munity.
The second most susceptible animals in the goat
herd are the yearlings and 2-year olds. The grow-
ing animals, with their rapidly expanding blood vol-
umes, are susceptible to blood loss due to the ac-
tions of certain species of the stomach worms. This
age group also is the most likely to suffer malnutri-
tion which will make them more susceptible to
parasitic disease. It is an accepted fact that ani-
mals receiving an adequate, balanced ration are
less susceptible to parasite infection.
The older members of a herd will generally be
resistant to parasitism due to prior exposure to the
various parasites. However, they will harbor
subclinical numbers of the common parasites and
thereby serve as reservoirs of infection for the
younger, susceptible members of the herd.
There are three major internal parasites affect-
ing goats that are a constant threat to good herd
health management. These are the stomach worm
(Haemonchus contortus); a protozoa of the genus
Eimeria, which causes coccidiosis; and the potential
of liver flukes in certain areas. Recognizing infec-
tion with these parasites and knowing how to con-
trol infection by them, is important to any goat
owner wishing to maintain animals under optimal
care. Goat owners need also to be aware of how to
prevent debilitating infection with these parasites
and how to reduce the potential of these parasites
becoming resistant to currently available drugs.


Most information in this publication can also be ap-
plied to sheep since problems with parasites are
similar for both animals.

Major internal parasites

1. Haemonchus contortus
Haemonchus contortus, also known as the
barber's pole worm, stomach worm, blood worm and
"humongous" worm, is the major limiting factor for
the successful survival of small ruminants in the
subtropics. This is because the stomach worm is
very prolific and replicates very rapidly, and has a
vicious ability to suck blood from its host. A single
worm lives for approximately 25 50 days, during
which time it may produce 250,000 eggs. This is
enough to infect and cause debilitating disease in
many other goats.
H. contortus thrives under Florida weather con-
ditions, and is a potential threat all year round
(Figure 1). During the summer months the eggs
hatch readily in the warm, humid and rainy cli-
mate, releasing viable larvae into the environment.
This is the time of greatest exposure and highest
incidence of disease. During the winter months
most of the worms recognize the cooler weather and
have developed the ability to "hibernate". This is
called hypobiosis. During this time the worms are
metabolically very inactive and quite resistent to
treatment. When spring comes the dormant worms
become active again, resulting in a "spring rise" in
the number of eggs excreted, and a seeding of the
environment just before optimal summer conditions
occurs.

Parasitism recognition
The pathogenicity of the stomach worm lies in its
ability to invade the intestines and suck blood. Any
age of animal can be infected and the severity of
clinical signs depends on the parasite burden.
The clinical signs of disease are all secondary ef-
fects of blood loss. In most cases, a relatively small
dose with constant exposure results in chronic
blood loss. These goats do not thrive or grow well,
and milk production is reduced. As the depletion of
blood continues, the goat develops hypoproteinemia
(deficiency of blood proteins) and anemia. The first
sign of serious low blood proteins is edema under
the jaw (bottle jaw) (Figures 2a,b). Anemia is
manifested by pale membranes of the eyes and
gums, exercise intolerance, panting and lethargy. If
the infection is not treated, the goat will continue to
lose blood to the parasite and eventually die.

















Goats Ingest larvae by eating
grass. Larvae develop into
adult worms in goats' intestines.


Eggs passed out in manure.

















Eggs hatch in manure
as first stage larvae (L,).


Infective stage larvae (L3)
on grass.


C


Migration of larvae (L,) from
manure onto grass.


Figure 1. Life cycle of common roundworm Infections In goats.





















V


(a)


hIL I"


I) 9



4 -


Figure 2. Two nubian goats: one normal (a); the other with bottle jaw (b). The goat with bottle jaw (b) has a lot of swelling under the
jaw, often described as "lumps". If the swelling is squeezed gently it will pit, characteristic of edema.


a V6
VA























Figure 3. A severe case of Haemonchus contortus in the stom-
ach abomasumm) of a goat. The dark areas are blood.
Note the spiral arrangement of the worms' intestines,
which are red and white, and give it the name
barber's pole worm. The worm is less than an inch
long.


Heavy, sudden worm infestations will cause disease
in a relatively short time period, and may kill the
goat within days due to massive bleeding into the
intestines (Figure 3). Haemonchus worms cannot be
seen in the manure. A diagnosis is made by finding
worm eggs under the microscope (Figure 4). If
worms are seen in the manure, then they are likely
to be tapeworms, which are not a major cause of
disease.

Control by sanitation
Control of parasites is nearly impossible without
good sanitation. Sanitation is anything that im-
proves the standard of hygiene of the herd. In the
case of parasitism by roundworms and coccidia,
sanitation must concentrate on minimizing the con-
tamination of the feed areas with fecal material, as
these parasites are transmitted through the ma-
nure and by ingestion. Every goat owner must find
the optimal solution to this problem by observing
their goats to identify and control the areas where
the goats feed, which may be contaminated. Com-
mon areas are feed troughs, water troughs and ar-
eas where the goats graze.
To improve hygiene at feeding time the goats
should be fed only as much as they will eat at a
time. Once the feed has been eaten, the goats
should be denied further access to the feeding area
until the next feeding time. If feed troughs are
used they should be turned upside down to prevent
goats from defecating into them. If possible the
feeding area should also be moved periodically, es-
pecially during the wet seasons, so that the goats
are not exposed for long periods to mud that may
harbor parasite eggs.


Another effective way of improving the hygiene
of the kids' environment is to provide climbing ped-
estals for the kids to play on. This will encourage
them to stay off the ground which may be contami-
nated. Movable and washable structures are best;
they should be constructed in such a way that the
kids cannot injure themselves. General recommen-
dations for improved hygiene are to improve drain-
age of the areas where the goats are kept. Im-
proved sanitation will also reduce exposure to other
diseases such as listeriosis, toxoplasma,
salmonellosis and caseous lymphadenitis.

Control of roundworms
Anthelmintics (dewormers) are the most common
method for controlling round worms. To be effec-
tive they must be applied properly. All goats of one
month of age and older must be dewormed regu-
larly, and all animals should be dewormed on the
same day. The most important time to deworm
goats is at the beginning of the year (kidding sea-
son), because the worm is so prolific. A light con-
tamination of the environment at the beginning of
the rainy season (early summer) has the potential
to become a heavy parasite burden later in the
year, when conditions are ideal for the spread of
the worm. Reducing the number of worms in the
environment at the beginning of the summer is,
therefore, a crucial point of control of this parasite.
During the warm season, it is important to de-
worm at intervals of 4 weeks, as the life cycle of the
Haemonchus takes less than 3 weeks to complete.
Most goat owners deworm their goats throughout
the year, but this is not necessary in the northern
part of the state, when average temperatures drop
below 50oF (90C) in the winter months. If these
temperatures persist it is often only necessary to
deworm every three months. The exact months
when to start and stop deworming will vary a little
from year to year and the discerning goat owner
will make adjustments accordingly.
A more sophisticated way of determining the cor-
rect time to deworm is to examine the manure of
several goats for parasite eggs. If one goat of a rep-
resentative sample of the herd (usually 5 10% of
all goats) has more than 500 eggs/gram manure,
then it is time to treat the herd. A veterinarian can
perform such an egg count for goat owners.
New arrivals should always be dewormed and
kept in isolation for at least a week after deworm-
ing before introduction to the herd. It is also advis-
able to deworm all goats being moved onto or into a
new area. This reduces the degree of contamina-
tion of the new pasture. The need to use dewormers
can be reduced if the parasite burden can be kept to







a minimum, and by keeping the goats on dry lots or
uncontaminated pastures. A pasture can be consid-
ered free of Haemonchus in Florida if it has been
free of sheep and goats for longer than 6 months
during the warm season.

Anthelminthics (dewormers)
There are many drugs on the market to treat
worms. Some are more effective than others. Drugs
commonly used are ivermectin, morantel,
levamisole, pyrantel, albendazole, thiabendazole,
fenbendazole, oxbendazole, coumaphos and phe-
nothiazine. The choice of drug depends on personal
preference and experience. The full dose of
dewormer should always be used to ensure maxi-
mum kill, and to prevent resistance from develop-
ing. To provide an accurate dosage individual goats
should be weighed, e. g., using a weigh tape. Some
special comments are necessary: if ivermectin is
given orally the injectable dose must be doubled.
Morantel holds the best hope for the future of treat-


ing lactating goats, as it will probably have no
withdrawal time for milk as a minor use veterinary
drug. Fenbendazole and albendazole are good for
treating tapeworms. Phenothiazine, although li-
censed for use in goats, is an antiquated product
and can no longer be recommended for safe and ef-
fective use.
Only few of the products that are effective
against roundworms are licensed for use in goats.
Therefore, many products must be used extra-label.
This is possible with a veterinarian's prescription.
As for all drugs, special precautions must be taken
to ensure that none of these enter the human food
chain. This is particularly important to the goat
industry, that is growing in importance as a sup-
plier of food (meat and milk) for human consump-
tion.
For drugs used extra-label, the withdrawal times
for meat and milk have to be extrapolated from
other species (usually cattle), in which the drug is
licensed. To be on the safe side, a longer with-


Figure 4. The typical appearance of an Haemonchus contortus egg under the microscope. They can be seen under 10X
magnification.

























I,


i




Figure 5. The typical appearance of Eimeria spp. oocysts under the microscope from a kid with coccidiosis. They are best seen
under 40X magnification, i.e., are much smaller and abundant than round worm eggs.


drawal time than those used in cattle is always rec-
ommended.

Drug resistance
In Florida, roundworms frequently develop resis-
tance to many of the benzimidazoles. These include
thiabendazole, fenbendazole and oxybendazole.
Therefore, these products have to be used judi-
ciously in this State. To ensure the longest effec-
tive use of products currently available, goat own-
ers should aim to keep the potential for resistance
to a minimum. The best way to do that is to use
the same deworming product for an entire year,
rather than using a different product each time the
goats are dewormed. This ensures that each gen-
eration of worms is only exposed to one drug at a
time, so that if a generation of worms has the po-
tential to develop resistance it will only develop re-
sistance to one drug and not several during the
same time period. An example of a good deworm-
ing program would be then to use ivermectin one


year, morantel the next, albenbazole the next; then
to return to using ivermectin again. Drugs to
which worms have developed a resistance should be
eliminated from the deworming program on that
farm for at least two full years. Then it should be
safe to use these products again.

2. Coccidiosis
The other major parasite that is a problem to
goats in many parts of the world including Florida
is a group of protozoa collectively called coccidia.
The most important of these belong to the genera of
Eimeria; there are several species that are conta-
gious. Most of these are specific to the animal they
cause disease in, although some will infect both
sheep and goats.

Clinical signs
Coccidiosis is usually a problem of the young
goat, because this is when it is first exposed and
not immune. Older goats have usually become im-








mune to infections, and therefore do not develop
clinical disease. Disease is usually seen in kids be-
tween 3 weeks and 4 months of age; i.e., after
weaning. The most common signs are soft stool,
decreased appetite and poor weight gains. These
symptoms are usually observed in herds where in-
fection is constant and at a relatively low level.
Heavy exposures to young animals (too high stock-
ing rate), animals not previously exposed, and
those with a deficient immune system (usually due
to poor nutrition) will develop a more serious form
of the disease. Symptoms observed under these
conditions include bloody diarrhea, straining, dehy-
dration and even death.
The disease takes about three weeks after infec-
tion to develop, as the parasite first invades the
cells of the intestinal lining, then reproduces in
these cells and eventually causes the cells of the
intestinal lining to rupture and die. Diarrhea is
seen only when the intestinal cells die. Recovery
sets in as the intestinal cells regrow, which is why
response to treatment is slow once diarrhea has oc-
curred.

Diagnosis
Diagnosis can be made based on clinical signs or
by a veterinarian who will examine the manure un-
der a microscope. Under a microscope many oo-
cysts can be seen in the manure, which confirms
the diagnosis (Figure 5). Once a diagnosis of
coccidiosis has been confirmed the farm can be as-
sumed to be infected forever. This is because the
oocysts (the coccidian equivalent of eggs) persist
and remain infective for a long time after they have
been shed.

Control of coccidiosis
On farms that have or have had problems with
coccidiosis great emphasis must be placed on con-
trolling the spread of disease. It is not possible to
prevent the disease altogether, but it can be con-
trolled, so that suffering of the kids is reduced to a
minimum and economic losses are reduced. There
are two ways to prevent the disease: Sanitation
(the most important, see above) and treatment with
coccidiostatic drugs.
The use of coccidiostats is advisable on any farm
that has had a problem with the disease in the
past, and/or cannot put each generation of kids into
new holding facilities. There are several drugs
available for prophylactic treatment of coccidia.
The only drug licensed in goats is decoquinate
(Decox, Rhone Poulenc, Atlanta, GA 30342).
Other commonly used drugs include amprolium,
monensin, lasalocid and sulfas. None of these


coccidiostats prevent infection but instead reduce
the rate of growth of the parasite in the intestines.
This allows the kids to develop natural immunity to
the coccidia without severe disease.
Most products used for preventing coccidiosis are
safe to add to the drinking water or milk, while oth-
ers can be given directly by mouth or in the feed.
For best results, start the treatment four weeks be-
fore the age at which signs are usually observed
and continue the treatment for about 28 days.

Treatment
The goat kid affected with coccidiosis needs to
be nursed with a great deal of care. Nursing is the
most important aspect of treatment, as, once clini-
cal signs of disease become apparent, the damage to
the intestines has already been done. Recovery can
be prolonged as it can only occur as the intestinal
lining recovers. Special attention must be paid to
the kid to ensure that it continues to eat and drink,
as both of these aid recovery and prevent dehydra-
tion and further deterioration. Even though con-
tinuous feeding contributes to the diarrhea in these
kids, it is very important that they continue eat-
ing, so they may recieve the needed nourishment
for recovery. Pre- venting dehydration is also
very important when the weather is hot. If a
sick kid stops drinking, an electrolyte solution
should be given by stomach tube or nursing
bottle. A cheap alternative to commercial elec-
trolyte solutions is "Gatorade". Kids with di-
arrhea should drink about 15-20% of their body
weight a day. Sulfa drugs are commonly used to
treat animals with coccidiosis. Many people think
that they are curative, but their main effect is to
prevent secondary bacterial diarrhea from de-
veloping.

3. Liver flukes
Liver fluke infection is a potential problem in
goats and cattle located in areas where animals
have access to streams and wet pastures. In
Florida, the area east of St. John's River and most
of the state south of I-4 is of greatest concern even
though other pockets of infestation do exist. While
there is a potential problem in goats, beef and occa-
sionally dairy cattle are more commonly affected by
this parasite. Liver contamination by this parasite
has been reported in slaughter plants. However,
liver contaminations are only a small part of the
economic loss caused by liver flukes. The adverse
effect of liver fluke infection on growth, production
and lowered fertility in the absence of obvious signs
of disease is well documented.








Life cycle of liver flukes
The prevalence of liver flukes is limited by the
distribution of the snail intermediate host. Low ar-
eas such as wet pastures and streams of water
through the eating area promote the growth and
reproduction of snails, which are infected by the
miracidium, a motile larva that hatches from fluke
eggs shed in goat feces. After a 6- to 8-week de-
velopment, motile cercariae are shed by the snail
and encyst as metacercariae on vegetation. These
metacercariae are somewhat resistant to envi-
ronmental extremes and may survive for several
months on pasture. To complete the life cycle,
metacercariae are ingested by goats grazing on
pasture, migrate as young flukes to the liver and
after 8 to 10 weeks of growing to adult flukes
begin depositing eggs that are excreted in feces.


Control of liver flukes
Control of liver flukes includes some sort of
treatment procedure as well as a control of the
snail as the intermediate host. Snails are carriers
of liver flukes, which is why a total parasite control
program should include pasture management.
Snail control means providing good drainage for
low-lying areas or by fencing off the area favorable
for snail habitats.

Treatment
Currently, the only product available for the con-
trol of liver fluke is CURATREM (clorsulon,
Merck and Co., PO Box 200, Rahway, N.J. 07065-
0914). It is highly effective against immature and
adult liver fluke and has a wide safety margin at
the recommended dose.


Mention of a trade name, proprietary product, or specific equipment does not
constitute a guarantee or warranty by the Dairy Science Department, College
of Veterinary Medicine, Institute of Food and Agricultural Sciences or the Uni-
versity of Florida, and does not imply its approval to the exclusion of other
products that may be suitable.
























































































COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES, John T. Woeste,
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