Complications associated with surgical dehorning in goats: A retrospective study of 239 cases.

OBJECTIVE: This article describes complications following surgical dehorning of goats. STUDY DESIGN: Retrospective. Medical records of goats that underwent surgical dehorning were reviewed. ANIMALS: Two hundred thirty-nine goats. METHODS: The medical records of 239 goats, not previously dehorned by other methods, that were cosmetically dehorned between January 2006 and April 2016, were reviewed. Data retrieved from the medical records included breed, weight, the surgeon performing the procedure, intraoperative complications, and the occurrence of return visits to the teaching hospital because of complications related to the dehorning procedure. The owner of record then completed a standard questionnaire during a telephone interview. RESULTS: One or more complications following the surgical dehorning procedure were reported in 93/239 (38.91%) of goats. Complications were divided into major and minor categories. Eighty-four of 239 goats (35.14%) had minor complications, 3/239 goats (1.26%) experienced major complications, and 6/239 (2.51%) had both major and minor complications. The mean weight of goats with complications was 29.73 kg compared to 24.91 kg for goats without complications. This difference was statistically significant (P = .015). CONCLUSION: Surgical dehorning of goats results in a high rate of complications; however, the majority of these complications are minor and do not affect health and performance of the goats. Goats experiencing complications weighed significantly more than goats without complications. CLINICAL SIGNIFICANCE: Surgical dehorning of goats requires minimal aftercare and results in a low rate of serious complications.

Fluid therapy in mature cattle.

Fluid therapy for mature cattle differs from that for calves because the common conditions that result in dehydration and the metabolic derangements that accompany these conditions are different. The veterinarian needs to know which problem exists, what to administer to correct the problem, in what quantity, by what route, and at what rate. Mature cattle more frequently suffer from alkalosis; therefore, acidifying solutions containing K(+) and Cl(-) in concentrations greater than that of plasma are frequently indicated. The rumen provides a large-capacity reservoir into which oral rehydration solutions may be administered, which can save time and money.

Perceptions of veterinarians and producers concerning Johne's disease prevalence and control in US beef cow-calf operations.

BACKGROUND: Efforts to educate producers and veterinarians in the United States regarding the management, prevention and control of Mycobacterium avium subspecies paratuberculosis (MAP) infection have increased over recent years. While nationwide awareness about MAP infection is improving, current level of awareness among beef producers and veterinarians is largely unknown. This study compares the perceptions of beef producers and veterinarians on the burden of MAP infection in cow-calf herds and on measures to control new infections. Questionnaires were mailed to 989 US beef producers through state Designated Johne's Coordinators and to 1080 bovine veterinarians belonging to a US nationwide professional association. RESULTS: Twenty-two percent (34/155) of producers reported having infected animals in their herds. The mean (minimum, median, maximum) prevalence reported by producers was 0.8% (0, 0, 10). Twenty-seven percent (27/100) of producers had at least one clinical animal during the previous year. Compared to the small herds (<50 head), the mean test-positive percentages and estimated prevalences were higher in medium (50-149) and highest in large (≥150) herds. Seedstock herds had a lower prevalence and these producers were more likely to enroll in Johne's disease (JD) control programs and test their herds. Veterinarians reported a mean overall animal level prevalence in their client herds of 5% (0, 2, 60). Similarly, 26% (0, 10, 100) of client herds had at least one infected animal. Mean percentage of infected cows within infected herds was 9% (0.01, 5, 80). Producers generally performed activities to control MAP transmission more frequently than perceived by veterinarians. Compared to veterinarians' opinions, producers were less likely to cull cows with signs consistent with JD (P < 0.01), but more likely to test purchased additions (P < 0.01). Testing recommendations by veterinarians (n = 277) for beef cow-calf herds were bacterial culture of feces (3%), PCR (14%), ELISA (35%) and a combination of these tests (47%). Seventy-nine percent of veterinarians recommended a 12-month interval between testing. CONCLUSIONS: Seedstock producers who had had JD risk assessments performed on their farms were more supportive of JD control programs and had a correspondingly lower prevalence. It is important to increase educational activities to provide relevant information to veterinarians and producers for better management and control of JD. Educational programs should target larger herds to maximize the impact.

Comparison of calf weaning weight and associated economic variables between beef cows with and without serum antibodies against or isolation from feces of Mycobacterium avium subsp paratuberculosis.

OBJECTIVE: To compare calf weaning weight and associated economic variables for beef cows with serum antibodies against Mycobacterium avium subsp paratuberculosis (MAP) or from which MAP was isolated from feces with those for cows that were seronegative for antibodies against or culture negative for MAP. DESIGN: Retrospective study. ANIMALS: 4,842 beef cows from 3 herds enrolled in the USDA National Johne's Disease Demonstration Herd Project. PROCEDURES: Individual cow ELISA and culture results were obtained from the project database. During each parity evaluated for each cow, the 205-day adjusted weaning weight (AWW) of its calf was calculated. The AWW was compared between test-positive and test-negative cows by use of multilevel mixed-effect models. The median value for feeder calves from 2007 to 2011 was used to estimate the economic losses associated with MAP test-positive cows. RESULTS: The AWW of calves from cows with strongly positive ELISA results was 21.48 kg (47.26 lb) less than that of calves from cows with negative ELISA results. The AWW of calves from cows classified as heavy or moderate MAP shedders was 58.51 kg (128.72 lb) and 40.81 kg (89.78 lb) less, respectively, than that of calves from MAP culture-negative cows. Associated economic losses were estimated as $57.49/calf for cows with strongly positive ELISA results and $156.60/calf and $109.23/calf for cows classified as heavy and moderate MAP shedders, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Calves from cows with MAP-positive test results had significantly lower AWWs than did calves from cows with MAP-negative test results, which translated into economic losses for MAP-infected beef herds.

Perceptions of veterinarians in bovine practice and producers with beef cow-calf operations enrolled in the US Voluntary Bovine Johne's Disease Control Program concerning economic losses associated with Johne's disease.

This study compares the perceptions of producers and veterinarians on the economic impacts of Mycobacterium avium subspecies paratuberculosis (MAP) infection in cow-calf herds. Questionnaires were mailed to beef producers through the Designated Johne's Coordinators and to veterinarians belonging to a nationwide professional organization. Important components of losses associated with MAP infected cows were used to estimate total loss per infected cow-year using an iterative approach based on collected survey data. Veterinarians were more likely to perceive a lower calving percentage in MAP infected cows compared to producers (P=0.02). Income lost due to the presence of Johne's disease (JD) in an infected cattle herd was perceived to be higher by veterinarians (P<0.01). Compared to veterinarians without JD certification, seedstock producers were more likely to perceive genetic losses due to culling cows positive for MAP (P<0.01). There were mixed opinions regarding the magnitude of lowered weaning weight in calves from infected cows and perceived differences in risk of other diseases or conditions in infected cows. An annual loss of $235 (95% CR: $89-$457) for each infected animal was estimated based on information from the producer survey. The analogous estimate using information inputs from veterinarians was $250 ($82-$486). Mean annual loss due to JD in a 100 cow herd with a 7% true prevalence was $1644 ($625-$3250) based on information provided by producers. Similarly, mean annual loss based on information collected from veterinarians was $1747 ($575-$3375).

Evaluation of an alternative method of herd classification for infection with paratuberculosis in cattle herds in the United States.

OBJECTIVE: To develop a better system for classification of herd infection status for paratuberculosis (Johne's disease [JD]) in US cattle herds on the basis of the risk of potential transmission of Mycobacterium avium subsp paratubeculosis. SAMPLE: Simulated data for herd size and within-herd prevalence; sensitivity and specificity for test methods obtained from consensus-based estimates. PROCEDURES: Interrelationships among variables influencing interpretation and classification of herd infection status for JD were evaluated by use of simulated data for various herd sizes, true within-herd prevalences, and sampling and testing methods. The probability of finding ≥ 1 infected animal in herds was estimated for various testing methods and sample sizes by use of hypergeometric random sampling. RESULTS: 2 main components were required for the new herd JD classification system: the probability of detection of infection determined on the basis of test results from a sample of animals and the maximum detected number of animals with positive test results. Tables were constructed of the estimated probability of detection of infection, and the maximum number of cattle with positive test results or fecal pools with positive culture results with 95% confidence for classification of herd JD infection status were plotted. Herd risk for JD was categorized on the basis of 95% confidence that the true within-herd prevalence was ≤ 15%, ≤ 10%, ≤ 5%, or ≤ 2%. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of the findings indicated that a scientifically rigorous and transparent herd classification system for JD in cattle is feasible.

Control of paratuberculosis in beef cattle.

As with any susceptible livestock species, the key to control of paratuberculosis in beef cattle is to reduce exposure of the susceptible calves to Mycobacterium avium subsp. paratuberculosis (MAP)­contaminated feces. Because beef calves remain with mature, potentially shedding cattle until weaning, control strategies are aimed at providing an environment with the least possible fecal burden and removing MAP shedders as soon as possible. Testing and culling or separation may be more important in beef cattle than in dairy cattle. Seedstock owners have greater potential for economic loss from paratuberculosis, making control program more financially attractive to them than to commercial beef cattle producers.

A two-component nonlinear mixed effects model for longitudinal data, with application to gastric emptying studies.

Gastric emptying studies are of great interest in human and veterinary medical research to evaluate effects of medications or diets for promoting gastrointestinal motility and to examine unintended side-effects of new or existing medications, diets, or procedures. Summarizing gastric emptying data is important to allow easier comparison between treatments or groups of subjects and comparisons of results among studies. The standard method for assessing gastric emptying is by using scintigraphy and summarizing the nonlinear emptying of the radioisotope. A popular model for fitting gastric emptying data is the power exponential model. This model can only describes a globally decreasing pattern and thus has the limitation of poorly describing localized intragastric events that can occur during emptying. Hence, we develop a new model for gastric emptying studies to improve population and individual inferences using a mixture of nonlinear mixed effects models. One mixture component is based on a power exponential model which captures globally decreasing patterns. The other is based on a locally extended power exponential model which captures both local bumping and rapid decay. We refer to this mixture model as a two-component nonlinear mixed effects model. The parameters in our model have clear graphical interpretations that provide a more accurate representation and summary of the curves of gastric emptying pattern. Two methods are developed to fit our proposed model: one is the mixture of an Expectation Maximization algorithm and a global two-stage method and the other is the mixture of an Expectation Maximization algorithm and the Monte Carlo Expectation Maximization algorithm. We compare our methods using simulation, showing that the two approaches are comparable to one another. For estimating the variance and covariance matrix, the second approach appears approximately more efficient and is also numerically more stable in some cases. Our new model and approaches are applicable for assessing gastric emptying in human and veterinary medical research and in many other biomedical fields such as pharmacokinetics, toxicokinetics, and physiological research. An example of gastric emptying data from equine medicine is used to demonstrate the advantage of our approaches.

Preliminary investigation of a humoral and cell-mediated immunity ratio for diagnosis of paratuberculosis in beef cattle.

One thousand three hundred and twenty-four adult beef cattle were tested for paratuberculosis using 2 antibody enzyme-linked immunosorbent assays (ELISA), an interferon-gamma (INF-gamma) ELISA, and radiometric bacterial culture of feces from 5 populations. Two populations of cattle (n=226) had data available to calculate a ratio of humoral to cell-mediated immunity based on results from one antibody test and the INF-gamma ELISA. Latent class analysis was used to estimate accuracy of the 4 paratuberculosis assays within a Bayesian framework. Determination of test accuracy and paratuberculosis prevalence in the latent class analysis allowed for estimation of predictive value positive (PVP) functions. The estimated PVP functions were used to iteratively assign paratuberculosis status to sampled cattle. Accuracy of the immunity ratio, an antibody ELISA, and the INF-gamma ELISA were determined for multiple cutoffs based on probabilistically assigned paratuberculosis status. Area under the receiver-operating characteristic (ROC) curves (95% probability interval) were estimated as 0.78 (0.66, 0.89), 0.81 (0.68, 0.92), and 0.59 (0.47, 0.71) for the immunity ratio, antibody ELISA, and INF-gamma ELISA, respectively. The Youden index (sensitivity+specificity-1) peaked at immunity ratios of 0.5 (J=0.48) and 1.0 (J=0.46). Sensitivity and specificity (95% probability interval) at an immunity ratio cutoff of 0.5 were 0.65 (0.44, 0.85) and 0.83 (0.78, 0.88), respectively. Sensitivity and specificity (95% probability interval) at the 1.0 cutoff were 0.55 (0.33, 0.77) and 0.91 (0.87, 0.95), respectively. An immunity ratio could be used to diagnosis paratuberculosis in beef cattle but requires further investigation.

Use of Walpole's solution for treatment of goats with urolithiasis: 25 cases (2001-2006).

OBJECTIVE: To determine results of ultrasound-guided cystocentesis and percutaneous infusion of Walpole's solution for treatment of male goats with urolithiasis. DESIGN: Retrospective case series. ANIMALS: 25 male goats with urolithiasis treated with Walpole's solution. PROCEDURES: Information obtained from the medical records included signalment, degree of urethral obstruction (partial vs complete), pertinent examination findings, concurrent illnesses, diet, other treatments administered, duration of hospitalization, whether the obstruction resolved, and outcome (ie, discharged vs euthanized). RESULTS: 14 (58%) animals had complete urethral obstruction, and 10 (42%) had partial obstruction (degree of urethral patency was not recorded in 1 animal). Walpole's solution was infused once in 18 (72%) animals, twice in 6 (24%) animals, and 3 times in 1 (4%) animal. The amount of Walpole's solution required to achieve the target urine pH of 4 to 5 ranged from 50 to 250 mL. In 20 (80%) goats, the urethral obstruction resolved, and the goat was discharged. The remaining 5 (20%) goats were euthanized because of unresolved urethral obstruction. Six of the 20 (30%) goats that were discharged were reexamined because of recurrence of urethral obstruction. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that ultrasound-guided cystocentesis in combination with percutaneous infusion of Walpole's solution may be a useful treatment in male goats with obstructive urolithiasis.

Assessment of clinical reasoning skills in veterinary students prior to and after the clinical year of training.

OBJECTIVE: To examine the effect of various clinical tracks within the veterinary medical clinical curriculum at Texas A&M University on clinical diagnostic proficiency as determined by pre- and post-training assessment. We expected that the clinical track chosen by the student would impact their measured outcome with bias toward higher scores in their chosen field. DESIGN: Prospective cohort study. STUDY POPULATION: 32 students from the College of Veterinary Medicine and Biomedical Sciences at Texas A&M University. PROCEDURES: By use of standardized, written case scenarios, clinical reasoning was assessed twice: once prior to the clinical (fourth) year of the curriculum and again at completion of the clinical year. Students demonstrated their abilities to collect and organize appropriate clinical data (history, physical examination, and laboratory findings), determine clinical diagnoses, and formulate and implement acceptable treatment modalities. Data from clinical assessments were compared for a given cohort and correlated with other measures (eg, grades, standardized test scores, and species-specific curricular track). RESULTS: Differences were detected in clinical diagnostic proficiency among students in different clinical tracks and for different species groups in the case scenarios. Tracking by species group in the clinical veterinary curriculum appeared to affect development of clinical reasoning and resulted in differential proficiency among cases for differing species groups. CONCLUSIONS AND CLINICAL RELEVANCE: Differences in clinical experiences between small animal tracks and all other track opportunities (large animal, mixed animal, and alternative) influenced the development of clinical proficiency in fourth-year veterinary students during their clinical training period.

Comparison of three methods of surveillance with application to the detection of Johne's disease seropositivity in Texas cattle.

Surveillance and monitoring are important for measuring the level of disease in a population, documenting changes in prevalence over time, determining high-risk areas for implementation of control measures, eradicating disease, and documenting freedom from disease. The documentation of freedom from disease has importance for international trade and the resumption of production after an outbreak. Johne's disease (JD) is an example of an endemic disease of cattle that has variable prevalence related to environmental and animal-level factors. Three methods of sample collection were used to describe the prevalence and distribution of JD seropositivity in Texas. Sampled cattle were: (1) extensively managed herds, (2) market cattle, and (3) clinically ill cattle examined by practicing veterinarians throughout Texas. Samples were evaluated for JD using a commercially available serum ELISA. Proportion of seropositive samples was compared and spatial distributions were evaluated for clustering. Difference of JD seropositivity was observed among the three sample populations suggesting that estimation of disease prevalence is dependant upon the source of samples.

Assessing familial aggregation of paratuberculosis in beef cattle of unknown pedigree.

The objective of this study was to assess genetic similarity of beef cattle using microsatellite markers and to use this information to describe familial aggregation of paratuberculosis test results in Texas beef cattle. Paratuberculosis testing was performed on 2622 adult beef cattle using two commercially available serum ELISAs and radiometric fecal culture. Pedigree records were collected for registered purebred herds and herds with sufficiently detailed production records to identify parent-offspring pairs. Cases were defined as cattle with at least one positive paratuberculosis test result. Three controls were matched by herd of residence for each case. All parent-offspring pairs, cases, and controls were genotyped for 12 microsatellites. Bayesian analysis of allele frequency data was used to describe population substructure and assign individual cattle into groups of genetically similar cattle. The proportion of known parent-offspring pairs assigned to the same cluster was used to assess the validity of the approach to identify familial structure. Conditional logistic regression was used to describe the association between cluster assignment and paratuberculosis test-status matched by herd. Nine clusters of genetically similar individuals were identified and were supported by the proportion of parent-offspring pairs assigned to the same clusters. Increased odds of having at least one positive paratuberculosis test result were identified for two clusters compared to the cluster with the lowest proportion of positive paratuberculosis test results after conditioning on herd. The results of this study demonstrate that population substructure can be used to describe familial aggregation of paratuberculosis test results in beef cattle of unknown pedigree.

Familial associations with paratuberculosis ELISA results in Texas Longhorn cattle.

The objective of this cross-sectional study was to estimate familial associations with paratuberculosis ELISA status in beef cattle. Texas Longhorn cattle (n=715) greater than 2years of age were sampled for paratuberculosis testing using ELISA and fecal culture. Diagnostic test results were indicative of substantial numbers of false-positive serological reactions consistent with environmental exposure to non-MAP Mycobacterium spp. Associations between ancestors and paratuberculosis ELISA status of offspring were assessed using conditional logistic regression. The association between ELISA status of the dam and her offspring was assessed using linear mixed-effect models. Significant associations were identified between some ancestors and offspring ELISA status. The odds of being classified as "suspect" or greater based on ELISA results were 4.6 times greater for offspring of dams with similarly increased S:P ratios. A significant positive linear association was also observed between dam and offspring log-transformed S:P ratios. Results indicate that there is familial aggregation of paratuberculosis ELISA results in beef cattle and suggest that genetic selection based on paratuberculosis ELISA status may decrease seroprevalence. However, genetic selection may have minimal effect on paratuberculosis control in herds with exposure to non-MAP Mycobacterium spp.

Evaluation of the ruminant serum chemistry profile.

In general, laboratory tests provide useful information about a patient and aid in making a diagnosis, determining a prognosis, formulating a treatment plan, and monitoring response. The serum chemistry profile, composed of a battery of tests, is readily available to clinicians through in-house testing or veterinary reference and diagnostic laboratories. A chemistry profile allows for evaluation of several body systems and assessment of metabolic, acid-base, or electrolyte disturbances. The first sections of this article introduce concepts important to all laboratory tests, such as sample collection and handling, reference intervals, and quality control. The remainder of the article discusses each of the analytes found on a typical clinical chemistry profile and the interpretation of abnormal results.

Environmental mycobacteria in soil and water on beef ranches: association between presence of cultivable mycobacteria and soil and water physicochemical characteristics.

Exposure to environmental mycobacteria has been reported to be a factor contributing to false-positive results on bovine serological tests detecting antibodies to Mycobacterium avium subsp. paratuberculosis (Mptb). This study was conducted to investigate the association between recovery of mycobacteria from the environment of cattle and both (i) historically high or low seroprevalence to Mptb, and (ii) soil and water physicochemical characteristics. Eighty-two samples (soil and water) from nine beef cattle ranches in South-central and South Texas were assessed for the presence of mycobacteria. Twelve mycobacterial species were cultured from soil and water from four herds; no Mptb were detected in environmental samples. A positive culture of environmental mycobacteria from soil was significantly associated with lower pH and calcium as well as higher iron, zinc and manganese contents. Beef cattle are likely to be exposed to environmental mycobacteria that may contribute to false-positive results on ELISAs for Mptb infection. Exposure rates to these mycobacteria likely vary across small geographical areas and may be related to soil and/or water physicochemistry.

Association of fecal shedding of mycobacteria with high ELISA-determined seroprevalence for paratuberculosis in beef herds.

OBJECTIVE: To evaluate the seroprevalence of paratuberculosis by use of 2 commercial ELISAs in association with prevalence of fecal shedding of mycobacteria within beef cattle herds. DESIGN: Cross-sectional field study. ANIMALS: Six beef herds (affected herds; 522 cattle) with and 3 geographically matched herds (181 cattle) without high seroprevalence of paratuberculosis. PROCEDURES: Blood and fecal samples were collected from adult cattle and assessed for serum anti-Mycobacterium avium subsp paratuberculosis (MAP) antibodies with 2 commercial ELISA kits and submitted for bacterial culture for MAP and environmental bacteria (termed environmental mycobacteria) via a radiometric method, respectively. Species of mycobacterial isolates were identified, and sensitivities and specificities of the 2 ELISAs were compared. RESULTS: Compared with comparison cattle, cattle from affected herds were 9.4 times as likely to have environmental mycobacteria isolated from feces. Among the 6 affected and 3 comparison herds, the proportions of cattle shedding environmental mycobacteria were 0.225 (range, 0.1 to 0.72) and 0.04 (range, 0 to 0.06), respectively. Although relative MAP- detection specificities (compared with bacterial culture of feces) were different between the 2 ELISAs, sensitivities were not. Nine environmental mycobacterial species were identified from participating herds. All affected herds apparently had > or = 1 bovid infected with MAP, although MAP was not isolated from any cattle in comparison herds. CONCLUSIONS AND CLINICAL RELEVANCE: In beef herds with persistently high rates of false- positive ELISA results, which may be associated with recovery of environmental myco- bacteria from feces, organism detection via bacterial culture of feces or PCR assay should direct paratuberculosis control measures.