Objective-To investigate the influence of varying morphological parameters on canine stifle joint biomechanics by use of a 3-D rigid-body canine pelvic limb computer model that simulated an intact and cranial cruciate ligament (CrCL)–deficient stifle joint across the stance phase of gait at a walk. Sample-Data from computer simulations. Procedures-Computer model morphological parameters, including patellar ligament insertion location, tibial plateau angle (TPA), and femoral condyle diameter (FCD), were incrementally altered to determine their influence on outcome measures (ligament loads, relative tibial translation, and relative tibial rotation) during simulation of the stance phase of gait at a walk. Outcome measures were assessed for each scenario and compared between an intact and CrCL-deficient stifle joint with the sensitivity index (the percentage change in outcome measure divided by the percentage change in input parameter). Results-In a CrCL-intact stifle joint, ligament loads were most sensitive to TPA. In a CrCL-deficient stifle joint, outcome measures were most sensitive to TPA with the exception of caudal cruciate ligament and lateral collateral ligament loads, which were sensitive to FCD and TPA. Relative tibial translation was sensitive to TPA and patellar ligament insertion location, whereas relative tibial rotation was most sensitive to TPA. Conclusions and Clinical Relevance-The computer model sensitivity analyses predicted that individual parameters, particularly TPA and FCD, influence stifle joint biomechanics. Therefore, tibial and femoral morphological parameters may affect the likelihood, prevention, and management of CrCL deficiency.

Objective- To compare accuracy of a noninvasive single-plane fluoroscopic analysis technique with radiostereometric analysis (RSA) for determining 3-D femorotibial poses in a canine cadaver stifle joint treated by tibial-plateau-leveling osteotomy (TPLO). Sample- Left pelvic limb from a 25-kg adult mixed-breed dog. Procedures- A CT scan of the left pelvic limb was performed. The left cranial cruciate ligament was transected, and a TPLO was performed. Radiopaque beads were implanted into the left femur and tibia, and the CT scan was repeated. Orthogonal fluoroscopic images of the left stifle joint were acquired at 5 stifle joint flexion angles ranging from 110° to 150° to simulate a gait cycle; 5 gait cycles were completed. Joint poses were calculated from the biplanar images by use of a digitally modified RSA and were compared with measurements obtained by use of hybrid implant-bone models matched to lateral-view fluoroscopic images. Single-plane measurements were performed by 2 observers and repeated 3 times by the primary observer. Results- Mean absolute differences between results of the single-plane fluoroscopic analysis and modified RSA were 0.34, 1.05, and 0.48 mm for craniocaudal, proximodistal, and mediolateral translations, respectively, and 0.56°, 0.85°, and 1.08° for flexion-extension, abduction-adduction, and internal-external rotations, respectively. Intraobserver and interobserver mean SDs did not exceed 0.59 mm for all translations and 0.93° for all rotations. Conclusions and Clinical Relevance- Results suggested that single-plane fluoroscopic analysis by use of hybrid implant-bone models may be a valid, noninvasive technique for accurately measuring 3-D femorotibial poses in dogs treated with TPLO.

Objective-To characterize the relationship between plasma dexmedetomidine concentration and the temperature difference between the thermal threshold and skin temperature (ΔT) and between plasma dexmedetomidine concentration and sedation score in healthy cats. Animals-5 healthy adult spayed female cats. Procedures-Cats received IV administrations of saline (0.9% NaCl) solution, dexmedetomidine (5, 20, or 50 μg/kg), or acepromazine (0.1 mg/kg). Blood samples were collected and thermal threshold and sedation score were determined before and at various times up to 8 hours after drug administration. In addition, cats received an IV infusion of dexmedetomidine that targeted a concentration achieving 99% of the maximum effect on ΔT. Results-No change in ΔT over time was found for the saline solution and acepromazine treatments; ΔT increased for 45 minutes when cats received dexmedetomidine at 5 and 20 μg/kg and for 180 minutes when cats received dexmedetomidine at 50 μg/kg. No change in sedation score over time was found for saline solution. Sedation score increased for 120 minutes after cats received acepromazine and for 60, 120, and 180 minutes after cats received dexmedetomidine at 5, 20, and 50 μg/kg, respectively. The plasma dexmedetomidine concentration–effect relationships for the effect on ΔT and sedation score were almost identical. The plasma dexmedetomidine concentration after infusion was lower than targeted, and ΔT was not significantly affected. Conclusions and Clinical Relevance-Dexmedetomidine administration to cats resulted in thermal analgesia and also profound sedation. These data may be useful for predicting the course of thermal analgesia and sedation after dexmedetomidine administration to cats.

Objective-To characterize the pharmacokinetics of dexmedetomidine after IV administration of a bolus to conscious healthy cats. Animals-5 healthy adult spayed female cats. Procedures-Dexmedetomidine was administered IV as a bolus at 3 doses (5, 20, or 50 μg/kg) on separate days in a random order. Blood samples were collected immediately before and at various times for 8 hours after drug administration. Plasma dexmedetomidine concentrations were determined with liquid chromatography–mass spectrometry. Compartment models were fitted to the concentration-time data by means of nonlinear regression. Results-A 2-compartment model best fit the concentration-time data after administration of 5 μg/kg, whereas a 3-compartment model best fit the data after administration of 20 and 50 μg/kg. The median volume of distribution at steady-state and terminal half-life were 371 mL/kg (range, 266 to 435 mL/kg) and 31.8 minutes (range, 30.3 to 39.7 minutes), respectively, after administration of 5 μg/kg; 545 mL/kg (range, 445 to 998 mL/kg) and 56.3 minutes (range, 39.3 to 68.9 minutes), respectively, after administration of 20 μg/kg; and 750 mL/kg (range, 514 to 938 mL/kg) and 75.3 minutes (range, 52.2 to 223.3 minutes), respectively, after administration of 50 μg/kg. Conclusions and Clinical Relevance-The pharmacokinetics of dexmedetomidine was characterized by a small volume of distribution and moderate clearance and had minimal dose dependence within the range of doses evaluated. These data will help clinicians design dosing regimens once effective plasma concentrations are established.

Objective- To determine the pharmacokinetics of hydromorphone hydrochloride after IV and IM administration in American kestrels (Falco sparverius). Animals-12 healthy adult American kestrels. Procedures- A single dose of hydromorphone (0.6 mg/kg) was administered IM (pectoral muscles) and IV (right jugular vein); the time between IM and IV administration experiments was 1 month. Blood samples were collected at 5 minutes, 1 hour, and 3 hours (n = 4 birds); 0.25, 1.5, and 9 hours (4); and 0.5, 2, and 6 hours (4) after drug administration. Results- Plasma hydromorphone concentrations were determined by means of liquid chromatography with mass spectrometry, and pharmacokinetic parameters were calculated with a noncompartmental model. Mean plasma hydromorphone concentration for each time was determined with naïve averaged pharmacokinetic analysis.Plasma hydromorphone concentrations were detectable in 2 and 3 birds at 6 hours after IM and IV administration, respectively, but not at 9 hours after administration. The fraction of the hydromorphone dose absorbed after IM administration was 0.75. The maximum observed plasma concentration was 112.1 ng/mL (5 minutes after administration). The terminal half-life was 1.25 and 1.26 hours after IV and IM administration, respectively. Conclusion and Clinical Relevance- Results indicated hydromorphone hydrochloride had high bioavailability and rapid elimination after IM administration, with a short terminal half-life, rapid plasma clearance, and large volume of distribution in American kestrels. Further studies regarding the effects of other doses, other administration routes, constantrate infusions, and slow release formulations on the pharmacokinetics of hydromorphone hydrochloride and its metabolites in American kestrels may be indicated..

Objective-To compare effects of 2 acetylcholinesterase inhibitors on recovery quality of horses anesthetized with isoflurane. Animals-6 horses in phase 1, 7 horses in phase 2A, and 14 horses in phase 2B. Procedures-The study comprised 3 phases (2 randomized, blinded crossover phases in horses undergoing orthopedic procedures and 1 prospective dose-determining phase). In phase 1, horses were anesthetized with isoflurane and received neostigmine or saline (0.9% NaCl) solution prior to anesthetic recovery. Phase 2A was a physostigmine dose-determining phase. In phase 2B, horses were anesthetized with isoflurane and received neostigmine or physostigmine prior to recovery. Objective recovery events were recorded and subjective visual analogue scale scores of recovery quality were assigned from video recordings. Results-Recovery measures in phase 1 were not different between horses receiving neostigmine or saline solution. In phase 2A, 0.04 mg of physostigmine/kg was the highest cumulative dose that did not cause clinically relevant adverse behavioral or gastrointestinal effects. Horses receiving physostigmine had higher mean +/- SD visual analogue scale recovery scores (70.8 +/- 13.3 mm) than did horses receiving neostigmine (62.4 +/- 12.8 mm) in phase 2B, with fewer attempts until sternal and standing recovery. Incidence of colic behavior did not differ among groups. Conclusions and Clinical Relevance-Inhibition with physostigmine improved anesthetic recovery quality in horses anesthetized with isoflurane, compared with recovery quality for horses receiving neostigmine. Inhibition of central muscarinic receptors by inhalation anesthetics may underlie emergence delirium in horses recovering from anesthesia.

Since there is no registered anthelmintic drug available for use in goats, extra-label use of drugs is a common practice in most countries. The aim of the present study was to compare the pharmacokinetic disposition of levamisole (LVM)-oxyclozanide (OXZ) combination in sheep and goats following per os administration. Goats (n = 8) and sheep (n = 8) 12- to 16-months-old were used for this study. The animals received tablet formulation of LVM and OXZ combination orally at a dose of 7.5 mg/kg and 15 mg/kg body weight, respectively. Blood samples were collected by jugular vein at different times between 5 min and 120 h after drug administrations. The plasma concentrations of LVM and OXZ were analyzed by HPLC following liquid-liquid phase extraction procedures. The plasma concentrations and systemic availabilities of both LVM and OXZ in goats were lower and the plasma persistence of LVM was shorter compared with those observed in sheep. Terminal half-lives (t1/2λz) of both molecules are shorter in goats compared with those in sheep. Goats treated with LVM-OXZ combination at the recommended dose for sheep may result in a reduced efficacy, because of under-dosing, which may increase the risk of drug resistance in parasites. Increased or repeated dose could be a strategy to provide higher plasma concentration and thus to improve the efficacy against the target parasites in goats compared with sheep. However, some adverse reactions may occur since LVM has relatively very narrow therapeutic index due to its nicotine-like structure and effect.

Bacterial biofilms are structured communities of bacterial cells enclosed in a self-produced polymer matrix that is attached to a surface. Biofilms protect and allow bacteria to survive and thrive in hostile environments. Bacteria within biofilms can withstand host immune responses, and are much less susceptible to antibiotics and disinfectants when compared to their planktonic counterparts. The ability to form biofilms is now considered an attribute of many microorganisms. Diseases associated with biofilms require novel methods for their prevention, diagnosis and treatment; this is largely due to the properties of biofilms. Furthermore, the presence of biofilms on surfaces found at farms, slaughterhouses or food processing plants will have an impact on the efficacy of disinfection protocols. Surprisingly, biofilm formation by bacterial pathogens of veterinary or zoonotic importance has received relatively little attention. The objective of this brief Review article is to bring awareness about the importance of biofilms to animal health stakeholders.

The objective of the present work was to determine the effect of Lactobacillus murinus strain LbP2 on canine fecal immunoglobulin A (IgA) levels. Seven dogs were orally treated with a 3-mL suspension of L. murinus LbP2 containing 5 x 109 colony-forming units on alternate days for 2 wk. Six dogs were treated with 3 mL of phosphate-buffered saline as placebo. Fecal samples were taken from the rectal ampulla on days 0 and 16, and the total canine fecal IgA concentration was determined with an immunoperoxidase assay kit. The IgA levels of individual dogs were compared with the nonparametric Wilcoxon test. Differences were considered significant when the P-value was less than 0.05. An increase in the total fecal IgA concentration was observed in the 7 dogs after treatment with L. murinus LbP2 (P = 0.01796). No differences were detected between the initial total fecal IgA values and those obtained at the end of placebo treatment. Thus, after oral administration L. murinus LbP2 showed potential immunomodulatory effects, an important property to assess in a microorganism being considered for use as a probiotic.

The aim of this study was to quantify the longitudinal shrinkage of canine small intestinal specimens after resection and fixation in 10% formalin. Samples were obtained from 12 clinically normal dogs of medium to large breed via ventral midline coeliotomy and enterectomy. The length of each sample was measured before excision, immediately after excision, and after 24 h in 10% formalin. The results were interpreted with the use of single-sample t-tests of the average changes; P-values of less than 0.01 were considered significant. The samples indicated a significant decrease in length after resection and fixation. The mean shrinkage from the pre-excision state was 28.3% immediately after excision (P < 0.0001) and 26.3% after 24 h of fixation (P < 0.0001). There was a small but not significant increase in the length of the specimens between the 2nd and 3rd measurement points. Quantification of the longitudinal shrinkage of resected intestinal specimens may improve interpretation of the distance of surgical margins from abnormal tissue in histopathology reports and allow investigation of the margins required for the clearance of specific tumors.