Our BVD Story
by Lucy and Charles Farrar
Please read this through to the end! It contains information you need to know.
BVD in Alpacas
On
Dec.1, 2005 we received a phone call telling us that we might
possibly be the Colorado
farm mentioned in Steve McCarthy’s Alpacasite BVD posts. Another
breeder in Colorado
brought the female in question to us for stud service in October
& November of 2004, subsequently sold the bred female to a person
in NY and the result was a PI cria born at Steve’s farm in NY.
Both the selling farm and ours immediately had
blood drawn on a large sampling of our herds. Theirs came back
first and was negative except for one female that had been
here for breeding at the same time as the one they sold....so
it looked like we were the ones with the exposure.
After getting that fateful phone call, we spent the weekend reading everything
we could find on the web via googling “BVD in alpacas” including
Nancy Carr’s excellent “Detective Story”. Our stud service
records showed that there were only 5 females breeding at
our farm in October & November of 2004: 2 of ours, 2 from the
other farm that had sold the female to NY, and a female with cria from
another front range farm, here only for about 10 days. A phone
call revealed that this particular cria had become unthrifty and
died at about 7 months old. The other "outside" female did not
get pregnant, but tested positive for BVD antibodies and later
produced a healthy non-PI cria. Our two females both had premature
crias on Aug.27 (Sandman) and Sept.5 (Snowman) that were low birth
weight, with intermittent runny noses and eyes, strange suri-like
fleece for huacaya out of well-crimped parents, and in general
were "just not right". Sandman had an incompetent immune
system and fit Nancy
’s description of her PI exactly. We had already been told he
would not live much longer, so we had him put down on Dec. 5 and
our vet, Dr. Kim Gardner-Graff, sent tissue samples from major
organs, skin and blood to Dr. Dubovi at Cornell. Snowman
was healthier and gaining weight, so we waited for his results.
Meanwhile we continued reading everything available
on BVD and contacting knowledgeable persons like Nancy
Carr, Steve McCarthy and researchers like Dr. Dubovi at Cornell, while
preparing ourselves for the worst. On Dec. 14, reports came
back on Sandman as positively a PI [Persistently infected] and
14 of the 15 of our herd sample tested positive for antibodies
on the serum neutralization [SN] test. Our herd and other females
here for breeding had been exposed to Sandman over a 100 day period.
Subsequent tests were positive on most of our herd and Snowman
was determined to be a PI also. We began the very heart-rending
task of calling all our 2005 breeding clients, informing them
of their alpaca’s exposure, offering to pay for tests on their
alpacas that were at our farm and replace their breeding. We also
called those farms to which we had sold alpacas or sent alpacas
for breeding, offering the same testing for those alpacas even
though little risk was involved since we could pinpoint the initial
exposure to a 10-day period in 2004 in the female pasture and
the active disease is very short-lived. Lest you think
this is just a Colorado problem, the "outside" female that had
the presumed PI cria at her side in 2004 was bought as a bred
female from a ranch in Oregon and if you look on the ARF website
at their census, nine PI's were listed on there as of today
[last update 11/15/05] not including Steve's 2 and our 2. Subsequent
tests at the farm that brought the presumed PI and dam for breeding
have revealed another PI from a dam purchased from the same farm
in Oregon .
A female bred at our farm was sold to NY and another PI at Steve's
farm originated in Maine
. Alpacas are moved around much more than cattle! Charles
began making graphs of all our 21 females that are pregnant, determining
their vulnerability for producing a PI cria in 2006. We began
making bio-security changes at our farm, pushing construction
on an already planned doubling of our barn size to make stalls
for our herdsires nearer the breeding females. This leaves our
auxiliary barn, which is over 100 feet from the main barn,
as an isolation barn for our near-term females that are at risk
of producing PIs. We'll have foot baths for helpers going into
that area, lots of hand sanitization gel pumps, and will not allow
visitors in that area. We have offered to bring back "outside"
bred females for birthing if their owners do not have isolation
capability. Blood will be drawn on all crias at birth before they
nurse, so the dam's antibodies will not contaminate the sample.
CSU will perform the PCR tests at their lab and get the results
back to us ASAP. Any PI cria will be put down immediately. A month
has passed since Sandman was put down and our farm is now free
from active infection and by the end of 2006 will be PI-free as
well, probably one of the safest farms around with a herd testing
positive to antibodies. Meanwhile, we'll require any cria accompanying
a dam for breeding to be tested as PCR negative to prove it is
not PI prior to coming on our farm. We'll have to make some difficult
decisions, but will get through this somehow. Why
are we going public on this? It is imperative that breeders take
BVD seriously. It probably has been around for a long time [think
of all those stillbirths, abortions, crias that died from failure
to thrive, etc.] and we were just not testing for it or performing
the correct tests because most vets felt that alpacas were
not vulnerable to BVD. [See www.claacanada.com
and www.alpacaresearchfoundation.org
for testing protocol.] We have found that most cases of BVD infection
in alpacas are sub-clinical and do not involve diarrhea or any
other symptom. There was no diarrhea on our farm, no evidence
of other sickness or being “off feed” and Sandman was producing
normal pellets even on the day we put him down.
Five weeks ago all we knew about BVD was from
posts on Alpacasite and the first question from most of our customers
was “What’s BVD?” In September we had BVD tests
performed at CSU on a stillborn as part of the necropsy. That
case just happened to be BVD negative and we thought we didn't
have a BVD problem. Wrong! That dam was absent during our 2004
exposure. Please educate yourselves, get samples from your herd
tested to see if you have an exposure, and consider some strict
bio-security measures if you have alpacas coming to your farm
to breed. The biggest threat of exposure is from a PI cria and
PI crias can look entirely normal and possibly grow to adulthood.
[Ours just happened to look different from our usual healthy crias.] In
cattle, 93% of all BVD infections originate with PI calves because
they continue to shed billions of viruses every day as long as
they live. PI crias have to be eliminated. That is the secret
to controlling this disease before it becomes a national epidemic.
And please, please report any cases of PIs to ARF for their census. I understand that there are a lot of known cases that are not on the census because owners would not allow them to be posted even anonymously by region! [Are we that market-driven in this industry???] ARF has two BVD projects going: one at Iowa and the other at Nebraska . They need to find out everything they can about this disease and honest disclosure on the part of breeders is the only way they will ever develop a body of knowledge about BVD in camelids.
Snowman is being kept alive in isolation and we have offered
to donate him to a research projects. If ARF doesn’t need him,
CSU may take Snowman and another PI from this area if funding
can be found to take advantage of this research opportunity like
Tufts is having with Copper Penny and Tag from Steve's farm.
In addition to the articles in the 2 most recent Alpacas Magazines and articles published in 2005 in Camelid Quarterly, we found the following links valuable in learning about BVD:
www.diaglab.vet.cornell.edu/issues/alpacas.asp
www.claacanada.com [Articles]
www.alpacaresearchfoundation.org
Our entire herd has been tested, some more than once. The costs of tests range from $10-$12 for a Serum Neutralization [SN] looking for antibodies to Type 1 & 2 strains of BVD, to $30 - $35 for a PCR test looking for the active virus. Vet charges may vary to draw, prepare and ship the vials, and ours is averaging about $15 for this service, plus overnight shipping. Regardless of the costs, we need to know the herd status and plan accordingly to isolate late-term females who might produce PI crias this year. If there is a “silver cloud” in all of this, our herd is now all positive for antibodies, has no active infection that can be spread, and all the females should be invulnerable to producing PI crias after this year…and we are able to tell potential purchasers the BVD status of every alpaca in our herd so that they will not have to go through the same agonizing learning and testing process.
The following was prepared by Dr. Rob Callan at CSU for distribution regarding BVD testing and control:
BVDV Testing and Control Practices for Alpaca Herds
Goals:
1. To identify exposed herds.
2. To identify and eliminate any persistently infected animals from the herd.
3. To identify non-PI animals and certify them as safe for travel to breeding farms, shows, and sale.
4. To minimize introduction and spread of BVDV in a herd.
Screening For Exposed Herds
· Identify Seropositive Animals
o Select animals with a greater likelihood of exposure to BVDV
§ Females that have gone to another farm for breeding
§ Animals that attend shows
§ Animals exposed to visiting animals (i.e. exposed to breeding animals and their crias from other farms)
§ Recommend screening at least 10% of your animals or a minimum of 15 animals.
o Collect Blood Samples (serum, red top tubes)
o Submit for BVDV Serum Neutralization Test
§ Detects antibodies to BVDV
§ Any positive tests indicate exposure to BVDV
§ Test costs about $5.00 per sample
§ Currently, testing for BVDV Type 1 is sufficient
· If you have any animals with a measurable BVDV titer (i.e. any titer ≥8) then you have evidence of BVDV exposure in your herd.
o This indicates that you MAY have a PERSISTENTLY INFECTED (PI) animal in your herd.
o Alternatively, the positive animals may have been exposed at another herd or a show.
o If any of these positive animals are pregnant, they may now be carrying crias that will be born persistently infected.
Identifying PI Animals
· Available Tests:
|
Test
|
Advantages |
Disadvantages |
|
Whole Blood PCR
($30, 1-2 weeks) |
High Sensitiviy, No maternal antibody interference |
May pick up acutely infected animals. Cost |
|
Whole Blood Virus Isolation ($25, 3 weeks) |
Sensitive, No maternal antibody interference |
May pick up acutely infected animals. Cost. Time |
|
Skin Immunohistochemistry (IHC, $2-20 per sample, 1 week, Kansas State or Nebraska ) |
Sensitive, simple to collect sample, inexpensive for multiple numbers, rarely detects acute infections |
Leaves a skin defect (ear notch, axila), samples stored and sent in formalin, send within 1 week of collection |
|
Antigen Capture ELISA–Skin
($5-10, 1 week) |
Simple to collect sample, inexpensive, rarely detects acute infections. |
Lower sensitivity, some false negatives. Leaves a skin defect (ear notch) |
|
Antigen Capture ELISA–Serum ($5-10) |
Inexpensive, rarely detects acute infections. |
Lower sensitivity, some false negatives, not suitable for crias <6 months due to maternal antibody interference |
· Recommend Whole Blood (EDTA) PCR Test
o High Sensitivity, very few false negatives
o No interference in crias from maternal antibody
o Immediately send sample refrigerated on ice
o Positive Test Result Interpretation
§ Persistently Infected or Acutely Infected
§ Retest after 3 weeks, acutely infected animals should be PCR negative at that time and persistently infected animals will continue to be positive.
· Testing Strategy
o PI Test all animals under 12 months of age independent of individual animal serology
o In herds with known exposure (i.e. at least 1 seropositive animal), test any adult animals with unknown titers or BVDV titers <32.
§ Currently the oldest known PI alpaca is 30 months. You may consider restricting PI testing to animals born AFTER JANUARY 1, 2003. Animals born before this date are perhaps less likely to be PI.
o Continue testing ALL crias at birth by PCR
§ Isolate crias and dams from other pregnant animals until test results are know.
§ A negative cria means the cria, her dam, and all previous maternal ancestors are non-PI.
§ A positive cria is likely a PI
· The cria should either be euthanized (to prevent transmission to other animals) or isolated and retested in >3 weeks as indicated above.
· The dam may be a PI and should also be tested by PCR if BVDV titer is unknown or <32.
Testing Stillborn or Aborted Fetuses
· Stillborn or aborted fetuses can be tested by several methods. Two recommended methods are:
o Skin Immunohistochemistry – Obtain a skin sample (about 1x1cm, ear notch or axila) and place in 10% buffered formalin. Submit within 7 days to a diagnostic lab that will perform BVDV IHC ( Nebraska or Kansas State Diagnostic Labs)
o Skin PCR – Obtain a skin sample (about 1x1 cm) and place in a clean container (i.e. red top blood tube). Ship immediately on ice to a lab that will perform BVDV PCR.
· After collecting the skin sample, the fetus can be frozen and used for neonatal classes if desired.
Biosecurity and Biocontainment
· Do not allow animals into your herd without confirmation of non-PI status.
· Isolate new animals from remaining herd for at least 3 weeks.
o Isolation area should be at least 10 meters from any pregnant females.
· Utilize breeding farms with an active BVDV control program that only accept confirmed non-PI dams and crias from herds with an active BVDV control program.
· Utilize shippers that are willing to ship only animals with confirmed non-PI BVDV status.
· Restrict as best as possible contact with other animals of undetermined BVDV status at shows and other events.
o Direct contact is the primary means of transmission.
o BVDV can spread by aerosol at distances of at least 10 feet.
o BVDV can be spread by items in contact with infected animals such as feeders, waterers, equipment, clothing, shoes, etc.
o BVDV is susceptible to many disinfectants including regular detergents (soap and water), bleach, povidone iodine, chlorhexidine, etc.
ADDRESSES:
Colorado Veterinary Diagnostic Laboratory
300 West Drake
Fort Collins, CO 80523
Phone: (970) 297-1281
Fax: (970) 297-0320
www.dlab.colostate.edu/ for forms to accompany samples
For Skin Immunihistochemistry (IHC) Tests
Kansas State Veterinary Diagnostic Laboratory
1800 Denison
Kansas State University
Manhattan , KS 66506
Phone: (785)532-5650
FAX: (785)532-4481
http://www.vet.k-state.edu/depts/dmp/service/index.htm
Veterinary Diagnostic Center
University of Nebraska
Fair St. and East Campus Loop
P.O. Box 82646
Lincoln , NE 68583-2646
Phone: 402 472-1434
Fax: 402 472-3094
E mail: vdc2@unl.edu
http://vbms.unl.edu/nvdlssbvd.shtml
Charles & Lucy Farrar, owners
P.O. Box 9
Monument, CO
80132
ph. 719-488-0986
fax 719-481-2153 |
Maple Tree Alpaca Farm | Alpaca Library Information | 
