Kevin E. Washburn

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 Walpoles solution for treatment of male goats with urolithiasis. DESIGN Retrospective case series. ANIMALS 25 male goats with urolithiasis treated with Walpoles 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). Walpoles solution was infused once in 18 (72%) animals, twice in 6 (24%) animals, and 3 times in 1 (4%) animal. The amount of Walpoles 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 Walpoles solution may be a useful treatment in male goats with obstructive urolithiasis.

Comparison of three treatment regimens for sheep and goats with caseous lymphadenitis.

OBJECTIVE To compare the effectiveness of 3 treatment regimens for small ruminants with caseous lymphadenitis. DESIGN Randomized clinical trial. ANIMALS 44 client-owned sheep and goats. PROCEDURES Aspirates were obtained from 48 lesions of 44 enrolled animals and submitted for bacterial culture. Animals were randomly assigned to 1 of 3 treatment groups. Treatment for group A (n = 15 lesions) consisted of opening, draining, and flushing the lesions and SC administration of procaine penicillin G. Treatment for group B (n = 15 lesions) consisted of closed-system lavage and intralesional administration of tulathromycin. Treatment for group C (n = 18 lesions) consisted of closed-system lavage and SC administration of tulathromycin. All animals were reexamined approximately 1 month after treatment, unless treatment failure was detected prior to that time. RESULTS 43 animals with lesions had positive results (Corynebacterium pseudotuberculosis) for bacterial culture. Proportions of lesions that had resolution of infection by 1 month after treatment did not differ significantly among the treatment groups (group A, 13/14 [92.9%]; 95% confidence interval [CI], 69.5% to 99.6%; group B, 10/12 [83.3%]; 95% CI, 54.9% to 97.1%; and group C, 14/17 [82.4%]; 95% CI, 59.1% to 95.3%). CONCLUSIONS AND CLINICAL RELEVANCE Acceptable alternatives to opening, draining, and flushing of lesions may exist for treatment of sheep and goats with caseous lymphadenitis. Use of tulathromycin and penicillin in this study constituted extralabel drug use, which would require extended withholding times before milk or meat of treated sheep and goats can be sold for human consumption.

Serologic and bacteriologic culture prevalence of Corynebacterium pseudotuberculosis infection in goats and sheep and use of Bayesian analysis to determine value of assay results for prediction of future infection

OBJECTIVE To determine the serologic and bacteriologic culture prevalence of Corynebacterium pseudotuberculosis infection in sheep and goats and the value of such assays for prediction of future development of caseous lymphadenitis (CL). DESIGN Observational study. ANIMALS 919 goats and sheep in 3 herds in southwest Texas. PROCEDURES During an initial evaluation, serologic and bacteriologic culture status for CL was determined for all animals. Subsequently, animals were evaluated every 6 months for a 13-month period to detect external CL lesions. Affected animals in 2 herds were treated with tulathromycin or a control treatment; affected animals in 1 herd were culled. The value of assays for prediction of future development of CL lesions was determined. RESULTS The serologic prevalence of CL in herds at the start of the study ranged from 7.52% to 69.54%. The bacteriologic culture prevalence of CL ranged from 0% to 6.12% at the start of the study and 0% to 9.56% at the end of the study. Synergistic hemolysin inhibition results were poor predictors of future development of CL lesions in animals during the study period; however, animals with positive bacteriologic culture results for CL were more likely to develop lesions in the future than were animals with negative bacteriologic culture results. CONCLUSIONS AND CLINICAL RELEVANCE Caseous lymphadenitis was detected in animals in this study despite prior management of affected animals in herds via culling. Use of a synergistic hemolysin inhibition test for management of CL may cause unnecessary culling of animals; treatment might allow retention of genetically valuable CL-affected animals in a herd without substantially increasing the prevalence of CL.

Distribution of ceftiofur into Mannheimia haemolytica-infected tissue chambers and lung after subcutaneous administration of ceftiofur crystalline free acid sterile suspension

The objective of this study was to evaluate the penetration of ceftiofur- and desfuroylceftiofur-related metabolites (DCA) into sterile and infected tissue chambers, lung tissue and disposition of DCA in plasma across four different sacrifice days postdosing. Twelve healthy calves were utilized following implantation with tissue chambers in the paralumbar fossa. Tissue chambers in each calf were randomly inoculated with either Mannheimia haemolytica or sterile PBS. All calves were dosed with ceftiofur crystalline free acid sterile suspension (CCFA-SS) subcutaneously in the ear pinna. Calves were randomly assigned to 4 groups of 3 to be sacrificed on days 3, 5, 7 and 9 postdosing. Prior to euthanasia, plasma and tissue chamber fluid were collected, and immediately following euthanasia, lung tissue samples were obtained from four different anatomical sites DCA concentration analysis. Results of our study found that, in general, DCA concentrations followed a rank order of plasma > infected tissue chamber fluid > noninfected tissue chamber fluid > lung tissue. Data also indicated DCA concentrations remained above the therapeutic threshold of 0.2 microg/mL for plasma and chamber fluid and 0.2 microg/g for lung tissue for at least 7 days post-treatment.

Caprine Abscess Model of Tulathromycin Concentrations in Interstitial Fluid from Tissue Chambers Inoculated with Corynebacterium pseudotuberculosis following Subcutaneous or Intrachamber Administration

ABSTRACT Corynebacterium pseudotuberculosis causes chronic, suppurative, abscessing conditions in livestock and humans. We used an in vivo model to evaluate antimicrobial efficacy for focal abscesses caused by C. pseudotuberculosis. Tissue chambers were surgically implanted in the subcutaneous tissues of the right and left paralumbar fossa of 12 goats to serve as a model for isolated, focal abscesses. For each goat, one tissue chamber was inoculated with C. pseudotuberculosis, while the contralateral chamber served as an uninoculated control. Six goats were administered a single dose of tulathromycin at 2.5 mg/kg of body weight subcutaneously, while the other six received the same dose by injection directly into the inoculated chambers. Our objective was to compare the effects and tulathromycin concentrations in interstitial fluid (IF) samples collected from C. pseudotuberculosis-infected and control chambers following subcutaneous or intrachamber injection of tulathromycin. In addition, the effects of tulathromycin on the quantity of C. pseudotuberculosis reisolated from inoculated chambers were assessed over time. Tulathromycin IF concentrations from C. pseudotuberculosis-infected and control tissue chambers were similar to those in plasma following subcutaneous administration. Following intrachamber administration, tulathromycin IF concentrations in infected chambers were continuously above the MIC for the C. pseudotuberculosis isolate for 15 days. There were no significant differences for plasma area under the curve and elimination half-lives between subcutaneous and intrachamber administration. Six of the 12 infected chambers had no growth of C. pseudotuberculosis 15 days postadministration. Results of this study indicate that tulathromycin may be beneficial in the treatment of focal infections such as those caused by C. pseudotuberculosis.

A Practitioners Guide to Diseases and Conditions Leading to Neurologic Dysfunction in the Ruminant

Neurologic signs are often a challenge in our food and fiber animals due to multiple factors. The size and unruly behavior of some of these animals may hinder the performance of a full neurologic examination as well as the ability to practically perform ancillary diagnostic testing. These obstacles may lead to the inability of the diagnostician to achieve a definitive ante-mortem diagnosis. In addition, to add to the anxiety level of these cases, owners are often alarmed at the severity of the symptoms and know something is terribly wrong. Nevertheless, despite this seemingly discouraging and often frustrating scenario, as veterinary clinicians, our charge is to determine whether the signs are of primary (neoplasia) or secondary (metabolic, infectious, toxic, traumatic) in origin in order to address herd ramifications, animal welfare, and zoonotic potential. The determination of origin begins with a thorough history and localization of the lesion(s) by means of a neurologic examination. This regimen should narrow the differential list and determine the course of further diagnostic testing. If it is not physically or economically practical to pursue further diagnostic testing, by this point the diagnostician may well have enough information to achieve a solid working diagnosis. At the least, a working diagnosis allows the clinician to speak to prognosis and potential therapeutic intervention. However, in some scenarios, the diagnostician is left to “treat the treatable” based on the working diagnosis. These articles are laid out by components of the nervous system from head to tail so that various conditions affecting that portion are addressed within. It is hoped that this systematic scheme will serve as a good reference once one has localized the lesion to aid the practitioner in ante-mortem diagnoses. These articles were written by ACVIMboarded food and fiber animal clinicians in addition to one boarded toxicologist. I want

Localization of Neurologic Lesions in Ruminants.

As stated many times throughout this issue, localization of the origin of neurologic deficits in ruminants is paramount to successful diagnosis and prognosis. This article serves as a guide to answer 2 questions that should be asked when presented with a ruminant with neurologic dysfunction: is the lesion rostral or caudal to the foramen magnum, and does the animal have primary neurologic disease? The answers to these 2 broad questions begin the thought processes to more specifically describe the location and nature of the dysfunction. Challenges often facing the diagnostician include economic constraints, size of the animal, and unruly behavior.

Maternal and fetal effects of dexmedetomidine infusion in pregnant ewes anesthetized with sevoflurane

OBJECTIVE To characterize the maternal and fetal cardiopulmonary effects of a low-dose infusion of dexmedetomidine without a loading dose in pregnant ewes anesthetized with sevoflurane. ANIMALS 11 pregnant ewes. PROCEDURES Anesthesia was induced with propofol and maintained with sevoflurane. Ewes and fetuses were instrumented with arterial and venous catheters, and thermodilution-pulmonary arterial catheters were placed in the ewes. Baseline measurements were obtained at an end-tidal sevoflurane concentration of 3.4%, then dexmedetomidine (2 μg/kg/h, IV) was infused for 90 minutes without a loading dose. Cardiovascular and blood gas variables were measured at predetermined time points. RESULTS Dexmedetomidine infusion resulted in approximately 30% decreases in maternal systemic vascular resistance, blood pressure, and heart rate. Maternal cardiac index, oxygenation variables, and acid-base status remained unchanged, whereas pulmonary arterial pressure, pulmonary vascular resistance, and stroke volume increased, compared with baseline values. Uterine blood flow decreased by approximately 30% to 36%. Fetal heart rate and blood pressure remained unchanged, but significant increases in fetal plasma glucose and lactate concentrations were detected. CONCLUSIONS AND CLINICAL RELEVANCE Pregnant ewes receiving a combination of sevoflurane and an infusion of dexmedetomidine without a loading dose had cardiac index in acceptable ranges and maintained normoxia. This balanced anesthesia did not produce significant changes in fetal blood pressure or heart rate. However, the increase in fetal plasma lactate concentration and changes in maternal pulmonary vascular resistance and uterine blood flow require further investigation to better elucidate these effects.

Pharmacokinetics of tulathromycin in nonpregnant adult ewes.

The objectives of this study were to determine plasma concentrations and pharmacokinetic parameters of tulathromycin after a single subcutaneous administration in the cervical region in sheep using the cattle labeled dose of 2.5 mg/kg. Six adult healthy ewes were administered tulathromycin on day 0. Blood samples were collected just prior to dosing and at selected time points for 360 h. Plasma samples were analyzed to determine tulathromycin concentrations, and noncompartmental analysis was performed for pharmacokinetic parameters. The mean maximum plasma concentration was 3598 ng/mL, the mean time to maximum concentration was 1.6 h, and the apparent elimination half-life ranged from 68.1 to 233.1 h (mean 118 h). When comparing our results to goats and cattle, it appears sheep are more similar to cattle in regard to the concentrations observed and pharmacokinetic parameters. In summary, the pharmacokinetics of tulathromycin in sheep appear to be similar enough to those in goats and cattle to recommend similar dosing (2.5 mg/kg SC), assuming that the target pathogens have similar inhibitory concentrations.