Objective—To estimate risk and identify risk factors
for congenital infection with bovine viral diarrhea virus
(BVDV) not resulting in persistent infection and examine
effect of congenital infection on health of dairy
Procedures—Calves from 2 intensively managed drylot
dairies with different vaccination programs and
endemic BVDV infection were sampled before ingesting
colostrum and tested with their dams for BVDV
and BVDV serum-neutralizing antibodies. Records of
treatments and death up to 10 months of age were
obtained from calf ranch or dairy personnel. Risk factors
for congenital infection, including dam parity and
BVDV titer, were examined by use of logistic regression
analysis. Effect of congenital infection on morbidity
and mortality rates was examined by use of survival
Results—Fetal infection was identified in 10.1% of
calves, of which 0.5% had persistent infection and
9.6% had congenital infection. Although dependent
on herd, congenital infection was associated with
high BVDV type 2 titers in dams at calving and with
multiparous dams. Calves with congenital infection
had 2-fold higher risk of a severe illness, compared
with calves without congenital infection.
Conclusions and Clinical Relevance—The unexpectedly
high proportion of apparently healthy calves found
to be congenitally infected provided an estimate of the
amount of fetal infection via exposure of dams and
thus virus transmission in the herds. Findings indicate
that congenital infection with BVDV may have a negative
impact on calf health, with subsequent impact on
herd health. (Am J Vet Res 2003;64:358–365)
Objective—To develop models that could be used to
predict, for dairy calves, the age at which colostrumderived
bovine viral diarrhea virus (BVDV) antibodies
would no longer offer protection against infection or
interfere with vaccination.
Design—Prospective observational field study.
Animals—466 calves in 2 California dairy herds.
Procedure—Serum BVDV neutralizing antibody titers
were measured from birth through 300 days of age.
The age by which colostrum-derived BVDV antibodies
had decayed sufficiently that calves were considered
susceptible to BVDV infection (ie, titer ≤ 1:16) or
calves became seronegative was modeled with survival
analysis methods. Mixed-effects regression
analysis was used to model colostrum-derived BVDV
antibody titer for any given age.
Results—Half the calves in both herds became
seronegative for BVDV type I by 141 days of age and for
BVDV type II by 114 days of age. Rate of antibody decay
was significantly associated with antibody titer at 1 to 3
days of age and with whether calves were congenitally
infected with BVDV. Three-month-old calves were predicted
to have a mean BVDV type-I antibody titer of 1:32
and a mean BVDV type-II antibody titer of 1:16.
Conclusions and Clinical Relevance—Results provide
an improved understanding of the decay of
BVDV-specific colostrum-derived antibodies in dairy
calves raised under typical field conditions.
Knowledge of the age when the calf herd becomes
susceptible can be useful when designing vaccination
programs aimed at minimizing negative effects of
colostrum-derived antibodies on vaccine efficacy
while maximizing overall calf herd immunity. (J Am
Vet Med Assoc 2002;221:678–685)
Objective—To develop a method of probability diagnostic
assignment (PDA) that uses continuous serologic
measures and infection prevalence to estimate
the probability of an animal being infected, using
Neospora caninum as an example.
Animals—196 N caninum-infected beef and dairy cattle
and 553 cattle not infected with N caninum; 50
dairy cows that aborted and 50 herdmates that did
Procedure—Probability density functions corresponding
to distributions of N caninum kinetic ELISA
results from infected and uninfected cattle were estimated
by maximum likelihood methods. Maximum
likelihood methods also were used to estimate N caninum
infection prevalence in a herd that had an excessive
number of abortions. Density functions and the
prevalence estimate were incorporated into Bayes
formula to calculate the conditional probability that a
cow with a particular ELISA value was infected with N
Results—Probability functions identified for infected
and uninfected cattle were Weibull and inverse
gamma functions, respectively. Herd prevalence was
estimated, and probabilities of N caninum infection
were determined for cows with various ELISA values.
Conclusions and Clinical Relevance—Use of PDA
offers an advantage to clinicians and diagnosticians
over traditional seronegative or seropositive classifications
used as a proxy for infection status by providing
an assessment of the actual probability of
infection. The PDA permits use of all diagnostic information
inherent in an assay, thereby eliminating a
need for estimates of sensitivity and specificity. The
PDA also would have general utility in interpreting
results of any diagnostic assay measured on a continuous
or discrete scale. Am J Vet Res (2002;
Objective—To compare the effect of oral administration of tramadol alone and with IV administration of butorphanol or hydromorphone on the minimum alveolar concentration (MAC) of sevoflurane in cats.
Animals—8 healthy 3-year-old cats.
Procedures—Cats were anesthetized with sevoflurane in 100% oxygen. A standard tail clamp method was used to determine the MAC of sevoflurane following administration of tramadol (8.6 to 11.6 mg/kg [3.6 to 5.3 mg/lb], PO, 5 minutes before induction of anesthesia), butorphanol (0.4 mg/kg [0.18 mg/lb], IV, 30 minutes after induction), hydromorphone (0.1 mg/kg [0.04 mg/lb], IV, 30 minutes after induction), saline (0.9% NaCl) solution (0.05 mL/kg [0.023 mL/lb], IV, 30 minutes after induction), or tramadol with butorphanol or with hydromorphone (same doses and routes of administration). Naloxone (0.02 mg/kg [0.009 mg/lb], IV) was used to reverse the effects of treatments, and MACs were redetermined.
Results—Mean ± SEM MACs for sevoflurane after administration of tramadol (1.48 ± 0.20%), butorphanol (1.20 ± 0.16%), hydromorphone (1.76 ± 0.15%), tramadol and butorphanol (1.48 ± 0.20%), and tramadol and hydromorphone (1.85 ± 0.20%) were significantly less than those after administration of saline solution (2.45 ± 0.22%). Naloxone reversed the reductions in MACs.
Conclusions and Clinical Relevance—Administration of tramadol, butorphanol, or hydromorphone reduced the MAC of sevoflurane in cats, compared with that in cats treated with saline solution. The reductions detected were likely mediated by effects of the drugs on opioid receptors. An additional reduction in MAC was not detected when tramadol was administered with butorphanol or hydromorphone.
Procedures—Dogs were allocated to 3 groups (6 dogs/group) and were assigned to receive buprenorphine (20 μg/kg [9.09 μg/lb], IV; a low dose [20 μg/kg] via OTM administration [LOTM]; or a high dose [120 μg/kg [54.54 μg/lb] via OTM administration [HOTM]) immediately before anesthetic induction with propofol and maintenance with isoflurane for ovariohysterectomy. Postoperative pain was assessed by use of a dynamic interactive pain scale. Dogs were provided rescue analgesia when postoperative pain exceeded a predetermined threshold. Blood samples were collected, and liquid chromatography-electrospray ionization-tandem mass spectrometry was used to determine plasma concentrations of buprenorphine and its metabolites. Data were analyzed with an ANOVA.
Results—Body weight, surgical duration, propofol dose, isoflurane concentration, and cardiorespiratory variables did not differ significantly among treatment groups. Number of dogs requiring rescue analgesia did not differ significantly for the HOTM (1/6), IV (3/6), and LOTM (5/6) treatments. Similarly, mean ± SEM duration of analgesia did not differ significantly for the HOTM (20.3 ± 3.7 hours), IV (16.0 ± 3.8 hours), and LOTM (7.3 ± 3.3 hours) treatments. Plasma buprenorphine concentration was ≤ 0.60 ng/mL in 7 of 9 dogs requiring rescue analgesia.
Conclusions and Clinical Relevance—Buprenorphine (HOTM) given immediately before anesthetic induction can be an alternative for postoperative pain management in dogs undergoing ovariohysterectomy.
Objective—To determine the distribution for limbs and bones in horses with fractures of the proximal sesamoid bones and relationships with findings on palmarodorsal radiographic images.
Sample Population—Proximal sesamoid bones obtained from both forelimbs of cadavers of 328 racing Thoroughbreds.
Procedure—Osteophytes; large vascular channels; and fracture location, orientation, configuration, and margin distinctness were categorized by use of high-detail contact palmarodorsal radiographs. Distributions of findings were determined. Relationships between radiographic findings and fracture characteristics were examined by use of χ2 and logistic regression techniques.
Results—Fractures were detected in 136 (41.5%) horses. Biaxial fractures were evident in 109 (80%) horses with a fracture. Osteophytes and large vascular channels were evident in 266 (81%) and 325 (99%) horses, respectively. Medial bones typically had complete transverse or split transverse simple fractures, indistinct fracture margins, > 1 vascular channel that was > 1 mm in width, and osteophytes in abaxial wing and basilar middle or basilar abaxial locations. Lateral bones typically had an oblique fracture and distinct fracture margins. Odds of proximal sesamoid bone fracture were approximately 2 to 5 times higher in bones without radiographic evidence of osteophytes or large vascular channels, respectively.
Conclusions and Clinical Relevance—Biaxial fractures of proximal sesamoid bones were common in cadavers of racing Thoroughbreds. Differences between medial and lateral bones for characteristics associated with fracture may relate to differences in fracture pathogeneses for these bones. Osteophytes and vascular channels were common findings; however, fractures were less likely to occur in bones with these features.