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Abstract

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 calves.

Animals—466 calves.

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 analysis methods.

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)

Full access
in American Journal of Veterinary Research

Abstract

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)

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in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Abstract

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 not abort.

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 caninum.

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; 63:318–325)

Full access
in American Journal of Veterinary Research

Abstract

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.

Design—Crossover study.

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.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare the efficacy of preoperative administration of buprenorphine (via oral transmucosal [OTM] and IV routes) for postoperative analgesia in dogs undergoing ovariohysterectomy.

Design—Prospective, randomized, blinded study.

Animals—18 dogs undergoing routine ovariohysterectomy.

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.

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in Journal of the American Veterinary Medical Association

Abstract

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.

Full access
in American Journal of Veterinary Research