Evaluation of the 4-point regional nerve block using 2% lidocaine in sheep

PURPOSE

To determine whether a single 4-point regional nerve block using 2% lidocaine administered distal to the fetlock of sheep with a single distal limb lameness will result in analgesia of the digits.

ANIMALS

Eighteen adult ewes with a single limb lameness originating from distal to the metacarpo/metatarsophalangeal joint were enrolled in the study.

PROCEDURES

Digital lameness was confirmed and scored based on clinical examination. Pain associated with digital lesions was assessed in triplicate using a pressure algometer to quantify mechanical nociceptive threshold. The same procedure was repeated on the contralateral limb as a control, and maximum force and time to response recorded. A 4-point regional nerve block was performed using 8 mL of 2% lidocaine. Mechanical nociception was again applied in triplicate to both limbs as described above, by a blinded investigator. Following appropriate medical treatment, the ewe was released and lameness scoring repeated.Median values for pressure and time to withdrawal were determined for affected and control limbs, and differences between pre- and post-lidocaine block measures were compared using Friedman's ANOVA test. The Wilcoxon Signed-Rank test was used to compare lameness score pre- and post-block. Statistical significance was set at α = 0.05.

MAIN FINDINGS

Application of the 4-point block resulted in a change in pressure required to elicit withdrawal (F-value 17.7; P < 0.0001) as well as time to withdrawal (F-value 20.4; P < 0.0001), for the affected limb as compared to the control limb. Lameness scores decreased following the block (Signed-rank statistic 85.5; P < 0.0001).

PRINCIPAL CONCLUSION

The 4-point nerve block resulted in anesthesia of the distal limb in sheep in this clinical model.

Management of Coxiella burnetii infection in livestock populations and the associated zoonotic risk: A consensus statement

Infections caused by Coxiella burnetii, commonly referred to as coxiellosis when occurring in animals and Query fever when occurring in humans, are an important cause of abortions, decreased reproductive efficiency, and subclinical infections in ruminants. The organism also represents an important zoonotic concern associated with its ability to aerosolize easily and its low infectious dose. Available diagnostic tests have limited sensitivity, which combined with the absence of treatment options in animals and limited approaches to prevention, result in difficulty managing this agent for optimal animal health and zoonotic disease outcomes. The purpose of this consensus statement is to provide veterinarians and public health officials with a summary of the available information regarding management of C. burnetii infection in livestock populations. A discussion of currently available testing options and their interpretation is provided, along with recommendations on management practices that can be implemented on‐farm in the face of an outbreak to mitigate losses. Emphasis is placed on biosecurity measures that can be considered for minimizing the zoonotic transmission risk in both field and veterinary facilities.

Pathogenesis and Treatment of Bovine Foot Rot

Bovine foot rot (BFR) is an infectious disease of the interdigital skin and subcutaneous tissues of beef and dairy cattle that occurs under a variety of management and environmental settings. The anaerobic, gram-negative bacteria Fusobacterium necrophorum, Porphyromonas levii, and Prevotella intermedia are commonly isolated from lesions. A multitude of host, agent, and environmental factors contribute to the development of BFR. Initiation of systemic antimicrobial therapy early in the course of disease commonly leads to resolution. Delays in treatment may result in extension of infection into deeper bone, synovial structures, or ligamentous structures, and the prognosis for recovery is reduced.

Factors affecting use of veterinarians by small-scale food animal operations

OBJECTIVE

To identify factors associated with use of a veterinarian by small-scale food animal operations.

DESIGN

Cross-sectional descriptive survey.

SAMPLE

16,000 small-scale farm or ranch operations in all 50 states.

PROCEDURES

Surveys were conducted via mail or telephone during 2011 for small-scale operations (gross annual agricultural sales between $10,000 and $499,999) in which an animal or animal product comprised the highest percentage of annual sales.

RESULTS

8,186 (51.2%) operations responded to the survey; 7,849 surveys met the inclusion criteria. For 6,511 (83.0%) operations, beef cattle were the primary animal species. An estimated 82.1% of operations (95% confidence interval [CI], 81.1% to 83.0%) had a veterinarian available ≤ 29 miles away; 1.4% (95% CI, 1.2% to 1.7%) did not have a veterinarian available within 100 miles of the operation. Operations for which the nearest veterinarian was ≥ 100 miles away or for which a veterinarian was not available were located in 40 US states. Overall, 61.7% of operations (95% CI, 60.6% to 62.9%) had used a veterinarian during the 12 months prior to the survey. Producers with college degrees were significantly more likely to use a veterinarian (675%) versus those who did not complete high school (52.9%).

CONCLUSIONS AND CLINICAL RELEVANCE

Results of this study indicated most small-scale operations had adequate access to veterinarians during 2011, but there seemed to be localized shortages of veterinarians in many states.

Prediction of serum IgG concentration by indirect techniques with adjustment for age and clinical and laboratory covariates in critically ill newborn calves

The objective of this study was to develop prediction models for the serum IgG concentration in critically ill calves based on indirect assays and to assess if the predictive ability of the models could be improved by inclusion of age, clinical covariates, and/or laboratory covariates. Seventy-eight critically ill calves between 1 and 13 days old were selected from 1 farm. Statistical models to predict IgG concentration from the results of the radial immunodiffusion test, the gold standard, were built as a function of indirect assays of serum and plasma protein concentrations, zinc sulfate (ZnSO4) turbidity and transmittance, and serum γ-glutamyl transferase (GGT) activity. For each assay 4 models were built: without covariates, with age, with age and clinical covariates (infection and dehydration status), and with age and laboratory covariates (fibrinogen concentration and packed cell volume). For the protein models, dehydration status (clinical model) and fibrinogen concentration (laboratory model) were selected for inclusion owing to their statistical significance. These variables increased the coefficient of determination (R (2) ) of the models by ≥ 7% but did not significantly improve the sensitivity or specificity of the models to predict passive transfer with a cutoff IgG concentration of 1000 mg/dL. For the GGT assay, including age as a covariate increased the R (2) of the model by 3%. For the ZnSO4 turbidity test, none of the covariates were statistically significant. Overall, the R (2) of the models ranged from 34% to 62%. This study has provided insight into the importance of adjusting for covariates when using indirect assays to predict IgG concentration in critically ill calves. Results also indicate that ZnSO4 transmittance and turbidity assays could be used advantageously in a field setting.

Salmonella enterica shedding in hospitalized horses and associations with diarrhea occurrence among their stablemates and gastrointestinal-related illness or death following discharge

OBJECTIVE

To evaluate the potential association between Salmonella enterica shedding in hospitalized horses and the risk of diarrhea among stablemates, and to characterize gastrointestinal-related illness and death following discharge among horses that shed S. enterica while hospitalized.

DESIGN

Retrospective cohort study [corrected].

ANIMALS

221 horses (59 that shed S. enterica during hospitalization and 162 that tested negative for S. enterica shedding ≥ 3 times during hospitalization).

PROCEDURES

Information from medical records (signalment, results of microbial culture of fecal samples, clinical status at the time of culture, and treatment history) was combined with data collected through interviews with horse owners regarding formerly hospitalized horses and their stablemates. Data were analyzed to investigate risk factors for death and diarrhea.

RESULTS

Occurrence of diarrhea among stablemates of formerly hospitalized horses was not associated with S. enterica shedding in hospitalized horses but was associated with oral treatment with antimicrobials during hospitalization. Salmonella enterica shedding during hospitalization was not associated with risk of death or gastrointestinal-related illness in study horses ≤ 6 months after discharge, but shedding status and history of gastrointestinal illness were associated with increased risk of death during the preinterview period.

CONCLUSIONS AND CLINICAL RELEVANCE

Stablemates of horses that shed S. enterica during hospitalization did not appear to have an increased risk for diarrhea, but comingling with horses that receive orally administered antimicrobials may affect this risk. Salmonella enterica shedding during hospitalization may be a marker of increased long-term risk of death after discharge. Risks are likely influenced by the S enterica strain involved and biosecurity procedures used.

Factors associated with failure in breeding soundness examination of Western USA rams

Breeding-soundness examination (BSE) and eradication of Brucella ovis infection in rams are critical components of flock-health programs. The aims of this retrospective, cross-sectional study were to describe the results of BSE in a large sample of rams in the Western USA and to determine the association between BSE outcome and the semen collection method (penis manually extended vs. retained in the preputial cavity), ram body-condition score (BCS), the presence of ulcerative posthitis, and the size of the flock of origin. We evaluated the first BSE in a given year for rams from Colorado, Wyoming, and Utah, USA, from 2000 through 2007. Breeding-soundness examination consisted of physical examination, scrotal circumference and BCS measurement, semen collection by electroejaculation, and microscopic examination of semen motility, morphology, and leukocyte concentration. We assigned a reason for failure to each failed BSE and used multivariable logistic and Poisson regressions to measure associations between ram and flock variables and the risk or reason for failure on BSE. A non-random, owner-selected subset of rams was tested for antibodies to B. ovis by serum indirect ELISA (iELISA). The Rogan-Gladen corrected B. ovis seroprevalence was measured. Of the 14,667 BSEs performed on 11,804 rams, 29.0% were classified as "failed;" the most common reason for failure was substandard semen parameters (43.8%). Breeding-soundness examinations were more likely to have been categorized as failure for inflammatory causes when performed on rams from medium-sized flocks (OR 1.6; 95% CI 1.1, 2.3) and large flocks (OR 1.4; 95% CI 1.0, 1.9) (P=0.02), suggesting that larger flocks are at higher risk of contagious diseases. The adjusted seroprevalence of B. ovis antibodies among tested rams in this study was 10.0%. Of 233 rams seropositive to B. ovis, 125 (53.6%) were subclinical, a finding that supports the importance of this test in ram BSE. We found that emaciation in rams was associated with an increased risk of BSE failure from substandard semen parameters (P<0.001), but ulcerative posthitis and the semen collection method were not (P=0.09 and 0.34, respectively). However, collection of semen with the penis retained in the preputial cavity resulted in greater odds of leukospermia relative to semen collection with the penis extended (OR 4.1; 95% CI 2.9, 5.9; P<0.001), presumably from contamination of the semen sample with preputial leukocytes. For ram BSE, therefore, semen collection with the penis manually extended from the sheath is recommended to limit leukocyte contamination of the sample.

Training Methods and Association with Worker Injury on Colorado Dairies

The goals of this study were to define the current methods for training entry-level workers on Colorado dairies, to measure the relationship of training methods to the incidence of work-related injuries on those operations, and to characterize the nature and cause of injuries reported by participating workers. Seventy-two workers from 15 dairies from Weld, Morgan, Larimer and Yuma counties volunteered to be interviewed privately in the language of their choice. Training methods were classified by content (task training versus safety training), method of delivery (on-the-job verbal instruction, on-the-job demonstration, on-the-job supervision, classroom- based, and / or reading materials); and instructor (supervisor and/or co-worker). The majority (84.7%) of interviewed workers were Mexican-born, Spanish-speaking males. Most workers reported the training to be a combination of verbal instruction, demonstration and supervision. Twenty-nine of 72 (40.3%) of all participants suffered at least one work-related injury in the 12 months prior to the interview. Entry-level safety training had no protective effect (P = 0.463) on the reported incidence of injury in dairy workers in the previous year. However, workers that received task-related training were four times less likely to suffer a work-related injury (P = 0.008). Training conducted by a co-worker also had a significant protective effect against work-related injuries (P = 0.028). Dairy workers identified direct contact with livestock or machinery as the main cause for work-related injuries, and most injuries occurred while medicating sick cows and milking.

Characteristics of biosecurity and infection control programs at veterinary teaching hospitals

OBJECTIVE

To characterize biosecurity and infection control practices at veterinary teaching hospitals located at institutions accredited by the AVMA.

DESIGN

Cross-sectional survey.

POPULATION

50 biosecurity experts at 38 veterinary teaching hospitals.

PROCEDURES

Telephone interviews were conducted between July 2006 and July 2007, and questions were asked regarding policies for hygiene, surveillance, patient contact, education, and awareness. Respondents were also asked their opinion regarding the rigor of their programs.

RESULTS

31 of 38 (82%) hospitals reported outbreaks of nosocomial infection during the 5 years prior to the interview, 17 (45%) reported > 1 outbreak, 22 (58%) had restricted patient admissions to aid mitigation, and 12 (32%) had completely closed sections of the facility to control disease spread. Nineteen (50%) hospitals reported that zoonotic infections had occurred during the 2 years prior to the interview. Only 16 (42%) hospitals required personnel to complete a biosecurity training program, but 20 of the 50 (40%) respondents indicated that they believed their hospitals ranked among the top 10% in regard to rigor of infection control efforts.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that differences existed among infection control programs at these institutions. Perceptions of experts regarding program rigor appeared to be skewed, possibly because of a lack of published data characterizing programs at other institutions. Results may provide a stimulus for hospital administrators to better optimize biosecurity and infection control programs at their hospitals and thereby optimize patient care.

Evaluation of the efficacy of a peroxygen disinfectant-filled footmat for reduction of bacterial load on footwear in a large animal hospital setting

OBJECTIVE-To compare the efficacy of a peroxygenbased disinfectant used in footbaths with the efficacy of the same disinfectant used in footmats for reducing bacterial contamination of footwear in a large animal hospital. DESIGN-Prospective study. SAMPLE POPULATION-Bacteria recovered from the soles of rubber boots after experimental microbial contamination and exposure to disinfectant solutions or water (water-treated control boots) or no treatment (untreated control boots). PROCEDURES-Investigators contaminated boots by walking through soiled animal bedding. Swab samples were collected from the sole of 1 untreated boot (right or left); the other boot was treated as investigators stepped through a disinfectant-filled footbath, a disinfectant-filled footmat, or water-filled footmat. Samples were collected 10 minutes after each treatment. Differences in numbers of bacteria recovered from treated and untreated boots were analyzed. RESULTS-Mean bacterial counts from peroxygentreated boots were 1.3 to 1.4 log(10) lower (95.4% to 99.8%) than the counts from untreated boots. Results were similar for footmat- and footbath-treated boots. In contrast, there were no statistically detectable differences in mean bacterial counts in samples collected from water-treated or untreated boots. CONCLUSIONS AND CLINICAL RELEVANCE-Results suggest that footmats and footbaths containing peroxygenbased disinfectant are effective in reducing bacterial contamination on the soles of boots when used in conditions representative of large animal hospitals. Similar results were achieved with use of either footmats or footbaths. The use of footbaths and footmats containing effective disinfectants may help decrease the risk for spread of nosocomial infection but should not be expected to sterilize footwear.

Trichophytobezoar duodenal obstruction in New World camelids

OBJECTIVE

To describe clinical findings, surgical treatment, and outcome associated with trichophytobezoar duodenal obstruction in New World camelids.

STUDY DESIGN

Retrospective study.

ANIMALS

Alpacas (7) and 1 llama.

METHODS

Historical and clinical data were obtained from the medical records of New World camelids with a diagnosis of trichophytobezoar duodenal obstruction confirmed by surgical exploration or necropsy.

RESULTS

Seven camelids were <1 year old. Abnormal clinical findings included anorexia, reduced fecal output, recumbency, colic, abdominal distension, regurgitation, decreased serum chloride concentration, increased serum bicarbonate concentration, and/or elevated first gastric compartment chloride concentration. Survey abdominal radiographs obtained (4 animals) revealed gastric distension (4) and/or visualization of the obstruction (2). Diagnosis was confirmed at necropsy (1) or surgery (7). Right paracostal celiotomy was performed on all animals and duodenotomy (3) or retropulsion of the trichophytobezoar combined with third compartment gastrotomy (4) was used to remove the obstruction. Six animals survived to discharge and 5 were healthy at follow-up, 8-20 months later. The remaining discharged alpaca was healthy at 12 months but subsequently died of unrelated causes.

CONCLUSIONS

Diagnosis of trichophytobezoar duodenal obstruction should be considered in juvenile New World camelids with abdominal distension and hypochloremic metabolic alkalosis. Right paracostal celiotomy can be used for access to the descending duodenum and third gastric compartment for surgical relief of obstruction.

CLINICAL RELEVANCE

Duodenal obstruction from bezoars should be considered in New World camelids <1year of age with abdominal distension and hypochloremic metabolic alkalosis. Surgical relief of the obstruction by right paracostal celiotomy has a good prognosis.

Comparison of the odds of isolation, genotypes, and in vivo production of major toxins by Clostridium perfringens obtained from the gastrointestinal tract of dairy cows with hemorrhagic bowel syndrome or left-displaced abomasum

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 chi2 analysis.

RESULTS

C. 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 RELEVANCE

C. 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.

Evaluation of the efficacy of disinfectant footbaths as used in veterinary hospitals

OBJECTIVE

To evaluate efficacy of 2 disinfectants as used in footbaths in veterinary hospitals for reducing bacterial contamination of footwear.

DESIGN

Prospective study.

SAMPLE POPULATION

Bacteria collected from the soles of rubber boots after experimental contamination and exposure to disinfectant solutions or control conditions.

PROCEDURES

Investigators contaminated boots by walking through soiled straw animal bedding. Swab samples were collected from the sole of 1 boot (right or left) without treatment. The other boot was briefly immersed in a disinfectant solution (either a quaternary ammonium compound [QAC] or a peroxygen compound) or water, and samples were collected after 7 minutes. Differences associated with the experimental treatments were analyzed statistically. Veterinary teaching hospitals (VTHs) in the United States and Canada were contacted to obtain information about the use of footbaths.

RESULTS

Mean bacterial concentrations from peroxygen-treated boots were 67% to 78% lower, compared with samples taken from untreated boots. In contrast, there were no statistically detectable differences in mean bacterial concentrations in samples taken from QAC- or water-treated boots, compared with control boots. Disinfectant footbaths were reportedly used in 30 of 31 VTHs.

CONCLUSIONS AND CLINICAL RELEVANCE

Disinfectant solution containing peroxygen applied in a footbath reduced bacterial concentrations on rubber boots under conditions representative of those found in VTHs. Footbaths are commonly used as a method to control infectious diseases in veterinary hospitals. Disinfectant footbaths should not be expected to sterilize footwear, but they may help in reducing the risk for nosocomial infection when used with effective disinfectants.

Viral diseases of the ruminant nervous system

This article presents the etiology, epidemiology, clinical features,and diagnosis of the primary viral neurologic diseases observed in ruminants. In general, these viral neurologic diseases are uncommon but often fatal. Rabies virus is perhaps the most important cause of encephalitis in cattle because of the public health implications. Other viral encephalitis diseases in ruminants include bovine herpesvirus encephalomyelitis, pseudorabies, malignant catarrhal fever, ovine and caprine lentiviral encephalitis, West Nile virus encephalitis, Borna disease, paramyxoviral sporadic bovine encephalomyelitis,and ovine encephalomyelitis (louping-ill).