Objective—To determine the effects of intensive serial plasmapheresis on total plasma protein and total IgG concentrations in donor horses involved in a plasmapheresis program.
Animals—18 horses (13 mares and 5 geldings; 13 Belgians, 3 Percherons, 1 Standardbred, and 1 warmblood) ranging from 7 to 14 years of age (mean ± SD, 10 ± 3 years) and weighing 822 ± 128 kg.
Procedures—Horses from which 22 mL of plasma/kg of donor body weight was harvested at 14-day intervals for a minimum of 8 consecutive plasmapheresis donations were retrospectively selected for use in the evaluation. Automated plasmapheresis procedures were performed by use of 2 modified plasmapheresis instruments/donor horse. Plasma samples were obtained at each donation and used for determination of total protein and total IgG concentrations. Total plasma protein concentrations were determined via refractometry. A commercially available ELISA was used to determine total equine IgG concentrations.
Results—The 18 donor horses were used in 8 to 19 serial donations (mean ± SD, 13 ± 3 donations) during the study. Donor horses had significant decreases in both plasma protein and IgG concentrations over the study period.
Conclusions and Clinical Relevance—Serial plasmapheresis procedures caused significant decreases in both plasma protein and IgG concentrations in donor horses; however, decreases were not physiologically relevant. Performing plasmapheresis in horses in accordance with the evaluated automated plasmapheresis procedures did not result in a critical decrease in total plasma protein or total IgG concentrations.
Objective—To develop a high-speed, continuous-flow, automated plasmapheresis procedure for the high-volume harvest of equine plasma in accordance with current good manufacturing practice.
Animals—143 horses (predominantly draft breeds) between 3 and 10 years of age at the time of purchase.
Procedures—Adaptations were made to automated plasmapheresis instruments and sterile disposable collection sets, which allowed for dual-instrument, continuous-flow operation. Donor horses were connected to the apparatus via 2 catheters (1 inserted in each jugular vein). The instruments removed whole blood from donors, fractionated the blood, diverted plasma to collection bags, and simultaneously returned concentrated cells to the donors. Plasmapheresis was performed on donor horses at 14-day intervals with a maximum of 22 mL of plasma/kg of donor body weight harvested during each plasmapheresis procedure.
Results—During a 5-year period, 3,240 plasmapheresis procedures were performed and > 50,000 L of sterile equine plasma was harvested in accordance with current good manufacturing practice. Donors typically remained calm during the plasmapheresis procedures and tolerated the procedures well. The high-volume and frequent plasma harvest did not result in sustained hypoproteinemia in donor horses. Adverse events associated with the automated plasmapheresis technique were infrequent, and the recurrence of adverse events was minimized by making minor adjustments to the procedure.
Conclusions and Clinical Relevance—The automated plasmapheresis procedure described in this report can be used to safely harvest equine plasma or to perform therapeutic plasmapheresis in horses.
Objective—To evaluate onset of protection induced by modified-live virus (MLV) bovine viral diarrhea virus (BVDV) vaccine administered 7, 5, or 3 days before inoculation with type 1b BVDV (strain NY-1).
Procedures—Calves were assigned to 4 groups: an unvaccinated control group or groups vaccinated with MLV vaccine containing BVDV types 1a and 2 at 7, 5, or 3 days, before inoculation with NY-1 BVDV. Blood samples were collected for leukocyte counts, serum virus neutralization, and virus isolation (VI); nasal swab specimens (NSSs) were obtained for VI, and rectal temperatures were monitored for 14 days after inoculation.
Results—No significant differences in leukocyte counts or rectal temperatures were detected after BVDV inoculation in vaccinated calves. Vaccinated calves had reduced viremia and viral shedding after inoculation, compared with results for unvaccinated calves. On day 5 after inoculation, a higher proportion of calves vaccinated 3 days before inoculation had positive VI from NSSs, compared with NSS VI results for calves vaccinated 5 and 7 days before inoculation. Unvaccinated calves had leukopenia on days 3, 5, and 6 and had higher rectal temperatures on days 7 and 8 after inoculation, compared with temperatures before inoculation. All unvaccinated calves had ≥ 1 positive VI result from NSSs 3 to 11 days after inoculation, and 4 became viremic.
Conclusions and Clinical Relevance—MLV BVDV vaccine prevented fever, viremia, and leukopenia in calves challenge inoculated with NY-1 BVDV. A high proportion of calves vaccinated 3 days before inoculation shed BVDV after inoculation.
Procedures—Weaned calves were or were not vaccinated against BVDV at feedlot arrival (trial 1) or 2 (trial 2) or 3 (trial 3) weeks before feedlot arrival. During trial 1, half of the calves were commingled with PI cattle throughout the feeding period. During trial 2, 63 calves were exposed to PI cattle before weaning and all calves were exposed to PI cattle throughout the feeding period. During trial 3, all study calves were exposed to PI cattle throughout the feeding period. Morbidity and mortality rates and average daily gain (ADG) data were analyzed.
Results—During trial 1, calves maintained with PI cattle had a higher morbidity rate regardless of BVDV vaccination than did calves not exposed to PI cattle; however, for calves maintained with PI cattle, the morbidity rate for those vaccinated against BVDV was less than that for those not vaccinated against BVDV. During trial 2, calves exposed to PI cattle before weaning or vaccinated against BVDV had lower morbidity and mortality rates and increased ADG, compared with those for calves not exposed to PI cattle before weaning or vaccinated against BVDV. During trial 3, health and performance did not vary between calves that were and were not vaccinated against BVDV.
Conclusions and Clinical Relevance—Exposure of cattle to BVDV naturally or through vaccination before or at feedlot arrival mitigated the negative effects of constant exposure to PI cattle.
Objective—To determine whether viral involvement
with platelets obtained from cattle persistently infected
(PI) with bovine viral diarrhea virus (BVDV) is associated
with altered platelet function or decreased
Sample Population—Platelets obtained from 8 cattle
PI with BVDV and 6 age-, sex-, and breed-matched
uninfected control cattle.
Procedure—Manual platelet counts were determined,
and platelet function was assessed through
optical aggregometry by use of the aggregation agonists
ADP and platelet-activating factor. Identification
of BVDV in serum and preparations of purified
platelets was determined by use of virus isolation
Results—No significant difference in platelet counts
was detected between cattle PI with BVDV and control
cattle. In response to the aggregation agonists,
maximum aggregation percentage and slope of the
aggregation curve were not significantly different
between cattle PI with BVDV and control cattle. We
isolated BVDV from serum of all PI cattle and from
purified platelets of 6 of 8 PI cattle, but BVDV was not
isolated from serum or platelets of control cattle.
Conclusions and Clinical Relevance—Isolation of
BVDV from platelets in the peripheral circulation of
cattle immunotolerant to BVDV does not result in
altered platelet function or decreases in platelet
counts. (Am J Vet Res 2005;66:1738–1742)
Objective—To determine the association between
cancer chemotherapy and serum canine distemper
virus (CDV), canine parvovirus (CPV), and rabies virus
antibody titers in tumor-bearing dogs.
Animals—21 client-owned dogs with various malignancies
and 16 client-owned dogs with lymphoma.
Procedure—In study A, serum antibody titers were
measured by use of hemagglutination inhibition (CPV
titers) or serum neutralization (CDV titers) before and
at least 1 month after initiation of chemotherapy.
Baseline values were compared with values obtained
from a control population of 122 healthy dogs seen for
routine revaccination. Titers were considered protective
at ≥ 1:96 for CDV and ≥ 1:80 for CPV.
In study B, serum IgG titers were measured by
use of immunofluorescent assay (CDV and CPV titers)
and rapid fluorescent focus inhibition test (RFFIT,
rabies titers) at baseline and again at weeks 5, 8, and
24 of a standard chemotherapy protocol for treatment
of lymphoma. An IgG titer of ≥ 1:50 was considered
protective for CPV and CDV. An RFFIT titer of ≥ 0.5
U/ml was considered protective for rabies virus.
Results—Significant changes were not detected in
CDV, CPV, and rabies virus titers following chemotherapy
in tumor-bearing dogs.
Conclusions and Clinical Relevance—Results suggest
that established immunity to CDV, CPV, and
rabies virus from previous vaccination is not significantly
compromised by standard chemotherapy used
to treat tumor-bearing dogs. (J Am Vet Med Assoc
Objective—To evaluate persistence of bovine viral
diarrhea virus (BVDV) in semen after inoculation of
Animals—Three 2-year-old bulls and five 6-month-old
Procedure—3 seronegative 2-year-old bulls were
inoculated intranasally with BVDV. Serum and semen
samples were obtained at regular intervals until 7
months after inoculation. Serum samples were tested
for BVDV by use of virus isolation (VI) and reverse
transcription-nested polymerase chain reaction (RTnPCR)
tests. Semen samples were tested for virus by
use of VI and RT-nPCR tests. Testicular biopsy specimens
were obtained 7 months after inoculation and
tested for BVDV by use of immunohistochemical
analysis and VI and RT-nPCR tests. Semen samples
collected from 1 bull immediately before and 5 and 7
months after inoculation were administered IV to
seronegative calves, which were monitored for subsequent
viremia and seroconversion.
Results—Use of VI and RT-nPCR tests detected transient
virus in serum of all bulls. The VI test detected
BVDV in semen of 2 bulls for < 21 days after inoculation,
whereas RT-nPCR assay detected BVDV until 7
months after inoculation. Virus was detected in testicular
biopsy specimens of these 2 bulls by use of
immunohistochemical analysis and RT-nPCR assay
but could only be isolated from the biopsy specimen
of 1 bull. Of the calves administered semen IV to
detect infectious virus, only the recipient of semen
collected 5 months after inoculation of the adult bull
was viremic and seroconverted.
Conclusions and Clinical Relevance—Bovine viral
diarrhea virus can persist in semen of acutely infected
bulls for several months after exposure.
(Am J Vet Res 2003;64:428–434)
Objective—To determine the association between
respiratory tract infection with bovine coronavirus
(BCV), treatment for respiratory tract disease, pulmonary
lesions at slaughter, and average daily gain in
cattle in feedlots.
Animals—837 calves in feedlots in Ohio and Texas.
Procedure—Nasal swab specimens were obtained
from cattle at arrival in a feedlot (day 0) and at various
times during the initial 28 days after arrival.
Specimens were tested for BCV, using an antigencapture
ELISA. Serum samples were obtained at
arrival and again 28 days after arrival and tested for
antibodies to BCV, using an antibody-detection ELISA.
Information was collected regarding treatment for
cattle with respiratory tract disease and average daily
gain during the feeding period. Pulmonary lesions
were evaluated at slaughter.
Results—Cattle shedding BCV from the nasal cavity
and developing an antibody response against BCV
were 1.6 times more likely to require treatment for
respiratory tract disease than cattle that did not shed
the virus or develop an immune response against
BCV. Additionally, cattle that shed BCV from the nasal
cavity were 2.2 times more likely to have pulmonary
lesions at slaughter than cattle that did not shed the
virus. The BCV shedding or seroconversion status did
not affect average daily gain.
Conclusions and Clinical Relevance—Bovine coronavirus
infects feedlot cattle and is associated with an
increased risk for cattle developing respiratory tract
disease and pulmonary lesions. Development of
appropriate control measures could help reduce the
incidence of respiratory tract disease. (Am J Vet Res
Rabies is the deadliest viral infection known, with no reliable treatment, and although it is entirely preventable, rabies continues to kill more than 60,000 people every year, mostly children in countries where dog rabies is endemic. America is only 1 generation away from the time when rabies killed more than 10,000 animals and 50 Americans every year, but 3 to 5 Americans continue to die annually from rabies. Distressingly, > 50,000 Americans undergo rabies prevention therapy every year after exposure to potentially rabid animals. While enormous progress has been made, more must be done to defeat this ancient but persistent, fatal zoonosis.
In the US, lack of public awareness and ambivalence are the greatest dangers imposed by rabies, resulting in unnecessary exposures, anxiety, and risk. Veterinarians have a special role in informing and reassuring the public about prevention and protection from rabies. This summary of current facts and future advances about rabies will assist veterinarians in informing their clients about the disease.