Showing is a biosecurity risk
Show ram with abscess
Shearing can introduce diseases
Compost mortality
Don't introduce
anthelmintic-resistant worms
Maintain a closed flock
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Biosecurity on sheep farms
- Biosecurity refers to the management practices taken to prevent
the introduction and spread of diseases. Healthy animals are the
cornerstone of a successful sheep enterprise, regardless of the
reasons for sheep ownership.
These days, there is a heightened awareness of biosecurity
due to the risks of bioterrorism and the fear of introducing
foreign diseases such as foot-and-mouth disease to the United
States. Individual states are also interested in keeping diseases
from within their borders.
Biosecurity is important no matter what size flock or farm you
have. It only takes one sheep to introduce a new disease and
one farm to start a disease epidemic.
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Acquisition of new animals
Introduced sheep (and goats) pose the greatest risk to biosecurity.
While they may appear healthy, they could be carrying a wide
variety of diseases. Anytime a new animal is introduced to the
flock, there is a potential risk of that animal introducing
a new disease. Sheep and goats share most of the same diseases
Before adding new sheep to your farm/flock, it is important
to know the health status of the flock(s) from which you are
buying or receiving animals. Don't be afraid to ask questions
about the farm's health program and disease status of the flock.
Only buy sheep from reputable breeders. Ideally, you should
purchase sheep from a closed flock. A closed flock is a flock
that has not introduced new animals for the past three or more
years. It is best to buy sheep from as few sources as possible.
It is not recommended that breeding stock be purchased from
a sale barn (stockyard, public livestock auction). There's even
a risk when you purchase sheep from a consignment sale or fair,
as you do not have a chance to inspect the farm where the sheep
originate.
You should not purchase animals from flocks or farms in which
you observe lameness, abscesses, soremouth, or other clinical
signs of disease. While healthy-appearing animals may still
be harboring these disease organisms, many diseases can be avoided
by thoroughly observing and inspecting the animals you purchase.
Inspect for soundness
When purchasing mature ewes, be sure to palpate their udders
to make sure they don't have any lumps, scar tissue, or hard
spots, which could be indicative of mastitis. If both halves
of the udder are "hard," the likely cause is ovine
progressive pneumonia (OPP). Examine their teeth to determine
their age and soundness. Palpate the testicles of rams. Do not
purchase rams with reproductive abnormalities or structural
defects.
Ovine progressive pneumonia (OPP)
To prevent the introduction of OPP to your flock, try to purchase
animals from OPP-free flocks. Unfortunately, there aren't many
flocks that have tested and culled for OPP -- despite a study
showing that 26 percent of sheep in the U.S. are infected with
the OPP virus. Cross transmission is possible between OPP and
CAE (caprine arthritic encephalitis) so make sure if there are
goats on the farm that the goat herd is CAE-free.
Scrapie
To prevent the introduction of scrapie to your flock, try to
purchase animals from USDA certified scrapie-free flocks or
enrolled flocks. The purchase of sheep with scrapie-resistant
genotypes (RR or QR) will also help to prevent scrapie from
occurring on your farm. While the prevalence of scrapie in the
U.S. sheep flock is only 1 in 500 sheep, it is 1 in 100 Suffolk
or black-faced sheep.
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Contagious
diseases
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Foreign diseases
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Bluetongue
Campylobacter (vibrio)
Caseous lymphadenitis (CL)
Chlamydia (EAE)
Club lamb fungus (ringworm)
Epididymitis (B. ovis)
Foot rot
Johne's Disease
Ovine progressive pneumonia (OPP)
Pink eye (infectious keratoconjunctivitis)
Scrapie
Soremouth (orf)
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Foot-and-mouth disease
Rift valley fever
Scabies
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Isolate new sheep
Newly purchased sheep should be isolated for at least 2 weeks,
preferably 30 days, before being co-mingled with other animals
on your farm or being turned out to pasture. A period of isolation
provides an opportunity to detect a disease problem before the
rest of your sheep or premises are exposed.
Isolation/quarantine areas should not same the same airspace
with the rest of the flock. A distance of at least 100 feet
is recommended. The farther the isolation pen is from the rest
of the flock, the better it is. The isolation area should be
confinement, ideally another building. If another building is
not an option, you should select a corner of your barn for isolating
new animals. Isolated animals should not have nose-to-nose contact
with the rest of your flock.
While in isolation, new animals should have their hooves trimmed
and inspected for footrot and other hoof problems. Making the
sheep stand in a footbath of zinc sulfate is a good preventative
measure to keep footrot off a farm. Koppertox can be used on
individual animals. Footrot is usually introduced to a farm
through the introduction of infected animals.
To prevent the introduction of drug-resistant worms, new animals
should be dewormed and have their fecals checked. It will probably
take the use of anthelmintics from a least two different chemical
families to prevent the introduction of drug-resistant worms
to your farm. It will be helpful to learn the deworming history
of the farm from which you purchase or receive new animals.
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Buying animals at a sale barn
Purchasing animals at sale barns (or stockyards) greatly increases
the risk of a new disease entering your farm. When you buy animals
at a sale barn, there are no guarantees, written or otherwise,
that the animals are free from contagious diseases.
Since there are no health requirements to sell at a sale barn,
it is possible to take animals infected with soremouth, pinkeye,
caseous lymphadentis, footrot, or other contagious diseases
to a sale barn. These animals can expose healthy animals at
the sale barn. Many producers take their cull animals to sale
barns. An animal that looks okay may actually be harboring a
disease or other problem that will prevent it from being a productive
animal. Buyer beware!
Despite the risks, sale barns can be a viable source of slaughter
and feeder lambs and breeding stock. However, sale barn animals
should only be purchased for breeding by experienced shepherds
who know what they are doing. It is best to purchase ewe lambs
and ram lambs for breeding since there is less chance of them
introducing reproductive problems.
If you purchase animals from a sale barn and bring them to your
farm, make sure you keep them separate from the rest of your
flock. Separate barns and pastures for sale barn animals will
lessen the chances that you will introduce a new disease to
your farm. If you plan to add sale barn animals to your flock,
you should quarantine them for at least 60 days.
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The risk of showing
Taking your animals to shows and other exhibitions increases
the risk that you will introduce a new disease to your farm.
Contact with other animals at a fair can expose your animals
to infectious agents. Try to minimize the nose-to-nose contact
your animals have with other animals at the fair.
While at the fair, try not to share equipment, waterers, or
feeders with other exhibitors. If you loan your equipment to
someone, make sure it is disinfected before you use it on your
animals. When you return from a show, isolate your show animals
from the rest of your flock.
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Shearing
Some diseases can be introduced and spread by shearing. Of particular
concern is caseous lymphadentis, an infectious, contagious disease
that is the third leading cause of carcass condemnation (in
cull ewes). To prevent infections from being introduced and/or
spread, shearers should disinfect their equipment between flocks
and between sheep. Shearing the youngest sheep first will also
prevent the spread of diseases.
Club
lamb fungus (ringworm) has become common among show lambs.
Shearing equipment and close shearing are the primary reasons
for the disease's spread. Good hygiene, careful shearing, and
less frequent grooming may help to limit the spread of the disease
to other sheep and people.
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Limit access
Some diseases can be spread by contaminated footwear and vehicles.
By limiting access to your farm and sheep, you can limit the
risk of introducing and spreading diseases. When people are
given access to your sheep flock, they should not have been
on another sheep operation for several days. They should be
required to wear plastic boots or clean their shoes before entering
your sheep-raising areas. Make sure trucks and trailers are
clean.
Persons who have been in foreign countries within the prior
5 days should probably be denied access to your farm and sheep.
If you travel to a country that has foot-and-mouth disease,
it is best to leave your protective clothing and shoes there.
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Good management
Rodents, cats, and other wildlife can harbor infectious agents.
Some method of rodent control should be employed on the farm.
Usually, this is cats. To prevent ewes from becoming infected
with Toxoplasmosis, one of the leading causes of abortion in
sheep, young cats should be kept away from stored hay and grain.
It is best to neuter and vaccinate any cats on the farm and
maintain a healthy, stable, adult population of cats.
Dead carcasses, and placenta and fetal tissues should be removed
immediately from the sheep-raising areas to prevent the introduction
and/or spread of diseases. The ewe should not be permitted to
eat her placenta, as this can spread diseases, such as scrapie
and abortion. Composting is often the best way to dispose of
waste products.
Under no circumstances should carcasses and other waste products
be left for dogs or wild animals to eat. This attracts predators
and scavengers and can spread diseases. Sheep measles (cysts
in the meat) is perpetuated when dogs and other canines are
allowed to consume sheep carcasses. Dogs which eat infected
placentas can pass the infective organism in their feces, further
infecting the premises and other sheep.
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Preventative health management
A vaccination program provides inexpensive insurance against
common sheep diseases. It is generally recommended that all
sheep and lambs be vaccinated for clostridium perfringins
type C & D (overeating disease) and tetanus. The use of
other vaccines will depend upon the perceived disease risk and
diagnosis of particular diseases in the flock.
Vaccines are available for soremouth, caseous lymphadentis,
footrot, vibrio and chlamydia abortion, epididymitis, and rabies.
Many of these vaccines (e.g. soremouth, caseous lymphadentis)
should not be used unless the disease is already present on
the farm because vaccination will introduce the disease to the
farm. Such vaccines are advocated to reduce the incidence of
disease, not prevent it in its entirely.
Anthelmintic resistance
Gastro-intestinal parasites are the primary health problem affecting
sheep and goats raised in warm, moist climates. An parasite
control program that integrates pasture and grazing management
with selective deworming (using the FAMACHA© system) should
be implemented. Regular deworming of all animals in the the
flock is NOT advocated due to the widespread emergence of drug-resistant
worms.
Fecal testing (fecal egg count reduction test or DrenchRite®)
should be conducted to determine which anthelmintics are effective
on the farm. Natural dewormers should not be trusted to control
parasitism until their effectiveness has been proven under controlled
circumstances.
Abortions
When a ewe experiences an abortion, she should be isolated from
the rest of the flock. The dead fetus(es), placenta, and fetal
tissues should be removed immediately and buried or composted.
The lambing area should be disinfected. Antibiotics should be
given (fed or injected) during an abortion storm to prevent
further losses. Chlorotetracycline is FDA-approved for this
purpose. Including monensin (Rumensin®) or Decoquinate (Deccox®)
in the feed or mineral during the last third of pregancy may
help to prevent abortions caused by toxoplasmosis.
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Maintain a closed flock
The best way to maintain a healthy flock is to maintain a closed
flock. Once the genetics of the ewe flock has been established,
replacement females should be selected from within the flock
and new acquisitions should be limited to rams. Unfortunately,
artificial insemination is not usually a viable option for most
U.S. shepherds, making ram introduction usually necessary.
It may be possible for large flocks to select their own ram
replacements, but for most shepherds, outside ram purchases
are necessary to avoid unacceptable levels of inbreeding. Fortunately,
rams spread considerably fewer diseases than ewes. While rams
can still introduce soremouth, footrot, pinkeye, or caseous
lymphadentits to a flock, they are not likely to introduce vibrio
or chlamydia. They are not believed to transmit scrapie, though
the use of RR rams will ensure the birth of lambs that are scrapie-resistant.
You should not loan your ram(s) to another flock, unless the
health status of the flock is equivalent. You should not allow
other producers to bring ewes (or does) to your farm for breeding,
unless the health status of their flock is equivalent. There
are other ways to help 4-Hers and new shepherds besides making
your farm and animals available to them
<== SHEEP 201 INDEX
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