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Abstract

Objective—To determine signalment, history, and clinical, necropsy, and microbiologic findings in dairy cows with hemorrhagic bowel syndrome.

Design—Retrospective study.

Animals—22 adult dairy cows from a single farm in Colorado.

Procedure—Medical records were reviewed for information on signalment, medical and reproductive history, the owner's chief complaints, results of physical examinations and ancillary diagnostic tests, treatment and response to treatment, results of microbiologic testing, and, if applicable, postmortem findings.

Results—Common clinical signs were acute signs of profound depression, decreased milk production, tachycardia, ruminal stasis, abdominal distention, and dark clotted blood in the feces. Rectal examination revealed distended loops of small intestine in 7 of 14 cows. Transabdominal ultrasonography revealed small intestinal ileus and distention in 12 of 12 cows and homogeneous echogenic intraluminal material compatible with intraluminal hemorrhage and clot formation in 4. Seven of 8 cows treated medically died; 9 of 13 cows that underwent surgery died or were euthanatized. Clostridium perfringens was isolated from fecal samples from 17 of 20 cows. The most common morphologic diagnosis at necropsy was severe necrohemorrhagic enteritis or jejunitis with intraluminal hemorrhage or blood clots. The most prominent histologic finding was severe, segmental submucosal hemorrhage and edema of the small intestine.

Conclusions and Clinical Relevance—Results confirm that in adult cattle, hemorrhagic bowel syndrome is a sporadic acute intestinal disorder characterized by intraluminal hemorrhage and obstruction of the small intestine. Clostridium perfringens was consistently isolated from the feces of affected cows. The prognosis for affected cows was grave. (J Am Vet Med Assoc 2002;221:686–689)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare the frequency of isolation, genotypes, and in vivo production of major lethal toxins of Clostridium perfringens in adult dairy cows affected with hemorrhagic bowel syndrome (HBS) versus left-displaced abomasum (LDA).

Design—Case-control study.

Animals—10 adult dairy cattle with HBS (cases) and 10 adult dairy cattle with LDA matched with cases by herd of origin (controls).

Procedure—Samples of gastrointestinal contents were obtained from multiple sites during surgery or necropsy examination. Each sample underwent testing for anaerobic bacteria by use of 3 culture methods. The genotype of isolates of C perfringens was determined via multiplex polymerase chain reaction assay. Major lethal toxins were detected by use of an ELISA. Data were analyzed with multivariable logistic regression and X2 analysis.

ResultsC perfringens type A and type A with the beta2 gene (A + beta2) were the only genotypes isolated. Isolation of C perfringens type A and type A + beta2 was 6.56 and 3.3 times as likely, respectively, to occur in samples from cattle with HBS than in cattle with LDA. Alpha toxin was detected in 7 of 36 samples from cases and in 0 of 32 samples from controls. Beta2 toxin was detected in 9 of 36 samples from cases and 0 of 36 samples from controls.

Conclusions and Clinical RelevanceC perfringens type A and type A + beta2 can be isolated from the gastrointestinal tract with significantly greater odds in cattle with HBS than in herdmates with LDA. Alpha and beta2 toxins were detected in samples from cows with HBS but not from cows with LDA. (J Am Vet Med Assoc 2005;227:132–138)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To monitor ovine herpesvirus type 2 (OvHV-2) infection status and the association between OvHV-2 infection and development of clinical signs of malignant catarrhal fever (MCF) in cattle.

Design—Longitudinal study.

Animals—30 mature adult cows and 18 cattle submitted for necropsy.

Procedure—Blood and milk samples were collected at monthly intervals from 30 adult cows for 20 consecutive months. Nasal and ocular swab specimens were also collected during months 9 through 20. Polymerase chain reaction (PCR) assay for detection of OvHV-2 was performed on blood, milk, nasal swab, and ocular swab specimens. Competitive inhibition ELISA (CI-ELISA) for detection of antibodies against MCF viruses was performed on serum samples obtained prior to study initiation and monthly during the last 12 months. Tissues obtained from herdmates without clinical signs of MCF that were submitted for necropsy were analyzed for OvHV-2 DNA via PCR assay for possible sites of latency.

Results—Initially, 8 of 30 cows had positive CI-ELISA results. Seroconversion was detected in 4 cows. Ovine herpesvirus type 2 DNA was intermittently detected in blood, milk, nasal secretions, or ocular secretions from 17 of 30 cows. Twenty-one cows had positive CI-ELISA or PCR assay results. No cattle in the study developed clinical signs of MCF. Results of PCR assays performed on tissue samples from 2 of 18 animals submitted for necropsy were positive for OvHV-2.

Conclusions and Clinical Relevance—OvHV-2 infection can occur in cattle without concurrent development of clinical MCF. Ovine herpesvirus type 2 DNA was detected intermittently, suggesting fluctuating viral DNA loads or reinfection in subclinical cattle. A definitive site of latency was not identified from tissues obtained during necropsy. (J Am Vet Med Assoc 2005;227:606–611)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the incidence of bacteremia in dairy cows with naturally occurring acute coliform mastitis (ACM) with a wide range of disease severity.

Design—Cohort study.

Animals—144 dairy cows with ACM from 6 herds.

Procedure—Cows were examined at time of identification of ACM (time 0) and classified as having mild, moderate, or severe mastitis on the basis of rectal temperature, hydration status, rumen contraction rate, and attitude. Cows were reexamined at 24 or 48 hours. Bacteriologic culturing of milk and blood (30 ml), CBC, and serum biochemical analysis were performed at each time point. Appropriate samples were obtained at a single point from herdmates without mastitis (controls) that were closely matched for lactation number and days since parturition. Blood culture results were compared among severity groups and controls by use of χ2 tests, as was outcome of an ACM episode for cows grouped by blood bacterial isolates.

Results—Bacteria were isolated from 52 blood samples from 46 of 144 (32%) cows with ACM, which was significantly more than control cows (11/156; 7.1%). Group-1 isolates (Escherichia coli, Pasteurella multocida, Mannheimia haemolytica, Klebsiella pneumoniae, Enterobacter agglomerans, and Salmonella enterica serotype Typhimurium) were identified in 20 of 144 (14%) cows with ACM and 0 of 156 control cows. Group-1 isolates were identified in 4.3, 9.1, and 42% of cows classified as having mild, moderate, and severe ACM, respectively. Escherichia coli and K pneumoniae milk and blood isolates obtained from the same cow were of the same genotype. Bacillus spp were identified in 21 of 144 (15%) cows with ACM, which was significantly more than control cows (3/156; 1.9%). Thirty-five percent of cows with a group-1 isolate died during the mastitis episode.

Conclusions and Clinical Relevance—Results suggest that bacteremia develops in a substantial proportion of cows with ACM. Classification of severity of disease is important for establishment of effective treatment protocols; parenteral antimicrobial treatment may be indicated in cows with ACM. (J Am Vet Med Assoc 2001;219:976–981)

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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE

To assess signalment, clinical findings, and treatments for New World camelids (NWCs) hospitalized for evaluation and treatment of neonatal disorders and investigate associations between these factors and death during and after hospitalization.

ANIMALS

267 NWCs ≤ 30 days of age.

PROCEDURES

Medical records of a veterinary teaching hospital were retrospectively reviewed to identify NWCs admitted for evaluation and treatment of neonatal disorders between 2000 and 2010. Signalment, physical examination data, diagnostic findings, treatments, and outcomes were recorded. Factors were examined for association with death during hospitalization and the overall hazard of death by use of multivariable logistic regression and Cox proportional hazards analysis, respectively.

RESULTS

The sample comprised alpacas (n = 255) and llamas (12). Median age at admission was 3 days, and median hospitalization time was 2 days; 208 of the 267 (77.9%) neonatal NWCs survived to hospital discharge. Factors associated with increased odds of death during hospitalization included prematurity or dysmaturity, hypothermia, sepsis, toxic changes in neutrophils, and undergoing surgery. The odds of death during hospitalization also increased as anion gap increased. After discharge, 151 of 176 (85.8%) animals had follow-up information available (median follow-up time, 2,932 days); 126 (83%) were alive and 25 (17%) had died. Prematurity or dysmaturity, congenital defects, sepsis, oxygen administration, and undergoing surgery as a neonate were associated with an increased hazard of death; the hazard of death also increased as serum chloride concentration at the time of hospitalization increased.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested the prognosis for survival during and after hospitalization is good for most NWCs hospitalized because of neonatal disorders.

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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE

To evaluate IM injection of oxytetracycline as an experimental model to induce pain and assess the analgesic efficacy of flunixin meglumine (FM) in dairy cows.

ANIMALS

15 healthy nonlactating Jersey (n = 10) and Holstein (5) cows.

PROCEDURES

In the first of 2 experiments, 5 Jerseys were administered oxytetracycline (10 mg/kg, IM), divided between the right side of the neck and left hind limb. The left side of the neck and right hind limb received sham injections. Cows were also randomly assigned to receive FM (2.2 mg/kg, IV; n = 3) or an equal volume of saline (0.9% NaCl) solution (0.044 mL/kg, IV; control; 2) once daily for 5 days. The mechanical nociceptive threshold (MNT) was measured before oxytetracycline administration and at predetermined times after each injection of the assigned treatment. Experiment 2 was similar to experiment 1 except it involved 5 Jerseys and 5 Holsteins, oxytetracycline was injected only in a hind limb, and the assigned treatment was administered for 10 days.

RESULTS

For both experiments, mean MNT for the oxytetracycline injection site was consistently less than that for the sham injection site in the hind limbs, and mean MNT at the hind limb oxytetracycline injection site for FM-treated cows was greater than that for control cows beginning on day 3.

CONCLUSIONS AND CLINICAL RELEVANCE

IM injection of oxytetracycline in a hind limb reliably induced signs of pain in dairy cows and, with validation, might be useful as an experimental model for assessing pain mitigation strategies in cattle.

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in American Journal of Veterinary Research

Abstract

Objective—To compare neutralizing antibody response between horses vaccinated against West Nile virus (WNV) and horses that survived naturally occurring infection.

Design—Cross-sectional observational study.

Animals—187 horses vaccinated with a killed WNV vaccine and 37 horses with confirmed clinical WNV infection.

Procedure—Serum was collected from vaccinated horses prior to and 4 to 6 weeks after completion of an initial vaccination series (2 doses) and 5 to 7 months later. Serum was collected from affected horses 4 to 6 weeks after laboratory diagnosis of infection and 5 to 7 months after the first sample was obtained. The IgM capture ELISA, plaque reduction neutralization test (PRNT), and microtiter virus neutralization test were used.

Results—All affected horses had PRNT titers ≥ 1:100 at 4 to 6 weeks after onset of disease, and 90% (18/20) maintained this titer for 5 to 7 months. After the second vaccination, 67% of vaccinated horses had PRNT titers ≥ 1:100 and 14% had titers < 1:10. Five to 7 months later, 33% (28/84) of vaccinated horses had PRNT titers ≥ 1:100, whereas 29% (24/84) had titers < 1:10. Vaccinated and clinically affected horses' end point titers had decreased by 5 to 7 months after vaccination.

Conclusions and Clinical Relevance—A portion of horses vaccinated against WNV may respond poorly. Vaccination every 6 months may be indicated in certain horses and in areas of high vector activity. Other preventative methods such as mosquito control are warranted to prevent WNV infection in horses. (J Am Vet Med Assoc 2005;226:240–245)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the prevalence of bovine viral diarrhea virus (BVDV)–infected alpaca herds in the United States and investigate factors associated with seropositive herd status and, subsequently, determine the proportion of animals within seropositive alpaca herds that are persistently infected (PI) carriers for BVDV, obtain information regarding previous herd exposure to BVDV, determine titers of anti-BVDV antibodies of dams, and ascertain whether individual seropositive crias had received supplemental colostrum at birth.

Design—Prevalence study.

Animals—63 alpaca herds with ≥ 12 registered female alpacas.

Procedures—250 alpaca breeders were randomly selected from 562 eligible herds listed in the Alpaca Owner and Breeders Association membership directory and mailed a voluntary participation request. Sixty-three alpaca breeders participated in the study. From each herd, blood samples from ≥ 4 crias were tested for BVDV, BVDV RNA, and serum neutralizing antibodies against BVDV. A region of the genome of BVDV recovered from PI crias was sequenced to determine genetic homology.

Results—Among the 63 herds, 16 (25.4%) had seropositive crias and 4 (6.3%) had PI crias. Infections in 3 of the 4 herds with PI crias were linked as evidence by the genetic homologies of viruses. In addition to PI crias, feeding supplemental colostrum was associated with herd seropositivity.

Conclusions and Clinical Relevance—Results confirmed the importance of BVDV infections in alpacas in the United States and highlighted the importance of determining the BVDV infection status of animals before they are commingled to limit exposure of herds to BVDV infection.

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in Journal of the American Veterinary Medical Association