American journal of veterinary research最新文献

Objective: To investigate indicators of mobility, inflammation, and cartilage remodeling in Dunkin-Hartley guinea pigs (Cavia porcellus) treated with manual acupuncture compared to 2 different comparator acupuncture groups.

Methods: 12-month-old male Hartleys were randomly assigned to 1 of 3 in vivo experimental groups that received manual acupuncture, needle sheath taps on corresponding acupoints, or off-point acupuncture. Treatments were performed under isoflurane once weekly for 3 weeks, and open-field enclosure monitoring was performed at the same frequency. After final treatments, all animals were euthanized, blood was collected for inflammatory marker analysis, and tissues were collected for histology, immunohistochemistry, and transcript expression analysis.

Results: 18 animals were involved: 6 per experimental group. Serum concentrations of complement component 3 and prostaglandin E2 were significantly decreased in the acupuncture group (P < .05). Muscle from acupoint stomach-36 had 6 gene transcripts with altered expressions in the manual acupuncture group compared to comparators. From cartilage/menisci, manual acupuncture resulted in the downregulation of 13 gene transcripts. Nerve growth factor (NGF) immunostaining in all 3 layers of articular cartilage of the medial tibial plateau was greater in the manual acupuncture group relative to the comparator groups. There were no differences in enclosure monitoring parameters or histologic grading.

Conclusions: Appreciable changes in voluntary mobility, behavioral or serum biochemical parameters, or stifle histological structure were not seen. Differences in serum inflammatory proteins, the gene expression of cartilage-remodeling transcripts, and NGF protein concentrations in cartilage were elucidated.

Clinical relevance: The short duration of manual acupuncture showed the initiation of beneficial regenerative and remodeling processes.

Objective: To evaluate the utility of routine preanesthetic screening thoracic radiographs in dogs without a specific clinical indication for this test.

Methods: All patients presented for elective tibial plateau leveling osteotomy between January 1, 2022, and December 31, 2022, were enrolled if there were no clinical signs or history of neoplasia or cardiopulmonary or thoracic disease. Three-view thoracic radiographic studies were performed and evaluated by the attending surgeon and a board-certified veterinary radiologist. The incidence of radiographic abnormalities and agreement between the attending clinician and the radiologist were analyzed.

Results: Of the 281 cases evaluated in this study, 10 (3.6%) were found to have radiographic abnormalities that were likely to affect the clinician's decision to proceed with elective surgery. There was no association between patient age and the probability of diagnosing a significant radiographic abnormality. There was poor agreement between the findings of the clinician and radiologist for cardiovascular and pulmonary abnormalities. There was slight agreement between the findings of the clinician and the radiologist for extrathoracic abnormalities.

Conclusions: Our data suggest that the utility of preoperative screening thoracic radiographs in dogs with no specific clinical indications for this test appears to be low. Given the poor agreement between clinician and radiologist findings, clinicians should consider routine evaluation of thoracic radiographs by a radiologist.

Clinical relevance: These findings should be considered by a clinician when deciding whether to recommend thoracic radiographs as a screening tool for a patient without history or physical examination findings suggestive of intrathoracic disease.

Objective: To evaluate plume composition during simulated diode laser equine upper airway surgery.

Methods: A 980-nm diode laser fiber was applied in continuous-wave mode in contact with laryngeal and pharyngeal tissues of 6 equine cadaver heads, and resultant plumes were collected for analysis. Measured parameters included the real-time concentration of particulate matter under the size of 2.5 μm (PM2.5), organic carbon (OC), elemental carbon (EC), and volatile organic compounds (VOCs).

Results: Visible smoke was encountered during surgical laser application and plume collection. Diode laser median activation time was 326 seconds (IQR, 116 to 387 seconds), and median energy was 8,099 J (IQR, 2,721 to 9,110 J). Mean real-time PM2.5 concentrations during laser procedures exceeded 5 mg/m3 throughout. Organic carbon concentrations were much higher than EC concentrations in the surgical plume, with a median OC/EC ratio of 422. Fifty-five individual VOCs were identified. All measured surgical plume components were higher than control samples.

Conclusions: The evaluation of surgical plumes collected during simulated upper airway diode laser surgery revealed high levels of harmful fine particulate matter PM2.5 exceeding Occupational Safety and Health Administration standards. Increased OC and OC/EC ratio were also observed. Surgical plumes contained VOCs, including the known carcinogenic compounds benzene and toluene.

Clinical relevance: These data suggest the need for mitigation strategies, such as specialized masks or local exhaust ventilation, to decrease the exposure of personnel to plumes generated during equine upper airway laser surgery.

Objective: To compare the biomechanical properties of standard-of-care limb salvage stainless steel plates with metal endoprosthesis constructs to constructs without endoprosthesis.

Methods: This was a cadaveric biomechanical study including 5 pairs of normal canine thoracic limbs randomly allocated into 2 groups: limbs with a second-generation, 11.5-mm Veterinary Orthopedic Implants stainless steel plate and a 122-mm stainless steel with endoprosthesis (SS-E) and limbs without endoprostheses or stainless steel with a gap (SS-G). Standard limb-spare surgery was performed and reconstructed with or without endoprostheses (ie, gap). Limbs were tested in axial loading until failure, and load-deformation curves were used to determine the biomechanical properties of the constructs, compared using a Wilcoxon matched-pairs signed-rank test. Failure modes were compared descriptively.

Results: Yield load (644 ± 523 N and 288 ± 153 N), yield energy absorbed (1,126 ± 1,695 N/mm and 239 ± 251 N/mm), and ultimate energy absorbed (39,732 ± 11,679 N/mm and 5,175 ± 878 N/mm) were significantly different between the SS-E and SS-G groups, respectively. Stiffness (360 ± 64 N/mm and 180 ± 50 N/mm) and ultimate load (3,385 ± 512 N and 747 ± 98 N) were not. The mode of failure varied between groups, with 2 SS-E constructs failing by humeral fracture and 3 by plate bending at the most distal radial or radiocarpal screw holes, whereas all SS-G constructs failed by plate bending midgap.

Conclusions: Limbs incorporating endoprosthesis were biomechanically superior to limbs reconstructed with a gap.

Clinical relevance: Limbs reconstructed with locking 11.5-mm Veterinary Orthopedic Implants plates without endoprosthesis may fail at physiological forces during trot or run.

Objective: To develop a protocol for thyroid-stimulating hormone (TSH) stimulation testing in psittacine birds using thyrotropin alfa (Thyrogen; Sanofi).

Methods: Quaker parrots (Myopsitta monachus) were randomized to receive an IM injection of freshly reconstituted high-dose recombinant human TSH (rhTSH; 8 parrots), frozen high-dose rhTSH (8), frozen low-dose rhTSH (8), or saline (8). Total T4 (TT4), free T4 (FT4), T3, and TSH were measured pre- and 4 hours postinjection.

Results: TSH stimulation testing was completed in 31 of the 32 birds. Thyroid-stimulating hormone measurement confirmed proper administration of rhTSH. Median TT4 at baseline in the population was 0.14 μg/dL (range, 0.03 to 0.33 µg/dL). Poststimulation, the median TT4 in rhTSH-treated parrots was 1.31 µg/dL (0.29 to 1.98 µg/dL) versus 0.09 µg/dL (0.04 to 0.14 µg/dL) in control parrots. All parrots administered rhTSH had an increase in TT4 (minimum, 3.5-fold) and FT4 (minimum, 2.2-fold) from baseline but not in T3. Parrots administered saline had no increase in TT4, FT4, or T3. Postinjection concentrations of TT4, but not of FT4 or T3, showed no overlap between controls and rhTSH-treated parrots.

Conclusions: TSH stimulation testing performed with fresh and frozen rhTSH for 3 months is feasible and safe and results in a significant increase in TT4 in Quaker parrots. Total T4 should be the preferred outcome measure for TSH stimulation testing in parrots.

Clinical relevance: Thyrogen can be used at doses as low as 0.01 mL (73 µg/kg) for TSH stimulation tests in Quaker parrots and can be frozen in aliquots to perform more tests per vial.

Objective: To develop and define a model of acute neck pain in an equine cervical articular process joint (APJ) using recombinant equine IL-1β (reIL-1β).

Methods: 12 horses in this experimental study received a randomly assigned, unilateral intra-articular injection of 50 ng (n = 6) or 100 ng (n = 6) of reIL-1β and saline (contralateral side as control) into the C5-to-C6 APJ. Blinded ultrasonographic, clinical, and biomechanical parameters were evaluated between 4 hours and 14 days.

Results: There was a significant increase in APJ effusion on ultrasonographic examination that peaked at 24 hours (P = .0256; effect size, 0.8312; CI, 1.0594 to 0.629). There was a time effect on the clinical examination score (myofascial pain and stiffness) and a significant decrease in stride length and velocity at 24 hours. There was an adverse event (extravasation of injectate) in 1 horse.

Conclusions: Ultrasonographic evidence of the presence and severity of APJ effusion was readily identified and tracked over time. Unilateral injection of the APJ with reIL-1β induced clinical signs of myofascial pain, neck stiffness, and gait adaptations. Using individual control horses, rather than a contralateral saline injection within the same horse, would improve our understanding of the clinical presentation of acute APJ pain using this model.

Clinical relevance: Diagnosing the presence, localization, and clinical effects of neck pain in horses remains challenging and would benefit from the establishment of an experimental model. The induction of acute synovitis using reIL-1β within the C5-to-C6 APJ opens the door for future studies to ultimately better understand equine cervical pain and dysfunction.

Postreactive morphological alterations of enthesal surfaces, often termed historically and collectively as "enthesitis," were thought to reflect typical daily activities. Actually, an important real cause of altered enthesal surfaces is augmentation of the osseous base, a physiological reaction. Further, altered enthesal attachments often reveal partial-to-complete avulsion and dystrophic calcification (ossification) secondary to injury, a pathological process. Descriptively, the suffixes "sis," "osis," and "asis" (as appropriate grammatically) signal a general "affected with" state. The more preferred suffix "opathy" suggests pathology and does not indicate cause. In clinical terms, the suffix "itis" refers specifically to underlying inflammation, whereas suspected noninflammatory disease should be termed "osis" or "asis." From an archeological perspective, the underlying disease usually is not evident, and therefore, enthesopathy would be the more appropriate descriptor. Additionally, when describing apparent physiological responses to normal stressors, "osseous surface augmentation" is appropriate. Importantly, then, the suffix "itis" is associated with defined tissue cellularity, systemic hematology, and clinical signs of heat, swelling, redness, and pain. Where the latter observations are not possible, the "itis" inference is indirect at best. In most of the latter instances, the "itis" suffix should be limited to a properly constructed differential diagnosis list.

Objective: Pituitary pars intermedia dysfunction (PPID) is diagnosed by measuring the ACTH concentrations. Due to the reported instability of ACTH, it is recommended to transfer centrifuged plasma into cryovials; however, in practice, cryovials are infrequently used, and serum (red-top) tubes are used instead. This study investigated whether this procedure affects ACTH concentrations and the diagnosis of PPID.

Methods: This was a cohort study. Blood was collected into EDTA tubes from 9 horses with PPID and 7 controls. After centrifugation, plasma was either aliquoted into a cryovial or into a serum tube. Samples were stored at 4 and 20 °C with ACTH concentrations measured using a chemiluminescent assay at 2, 24, and 48 hours after collection. Data were analyzed using a 2-way repeated measures ANOVA with P < .05 considered significant.

Results: There was a significant effect of time on ACTH concentrations in horses with PPID at 4 and 20 °C and in all horses at 20 °C with decreasing ACTH concentrations over time; however, no significant effect of storing plasma in a serum tube was detected. Three horses diagnosed with PPID would have had a different classification if the samples had been kept at 20 °C for 24 or 48 hours.

Conclusions: Time but not storage of plasma in serum tubes decreases the measured ACTH concentration in horses with PPID.

Clinical relevance: Transferring plasma into serum tubes does not significantly alter the measured ACTH concentrations; however, time between collection and analysis might lead to erroneous diagnoses.

Objective: To describe and compare the pulmonary and plasma pharmacokinetics of different oral formulations of chloramphenicol administered as a single dose to healthy adult horses.

Methods: A single dose of chloramphenicol was administered to 6 healthy, university-owned fasted adult horses IV (25 mg/kg), orally as commercial tablets (50 mg/kg), or orally or intragastrically as compounded suspension (50 mg/kg), according to a randomized crossover protocol. Plasma was collected 5, 10, 15, 20, and 30 minutes and 1, 1.5, 2, 3, 4, 6, 8, 12, and 24 hours after drug administration. Bronchoalveolar lavage (BAL) fluid was collected after 1, 4, and 8 hours and processed to obtain pulmonary epithelial lining fluid (PELF) and the BAL cell pellet (BALc). Chloramphenicol concentrations were determined by means of liquid chromatography-tandem mass spectrometry in plasma, PELF, and BALc. Data were used for plasma noncompartmental analysis and calculation of apparent PELF and BALc concentrations.

Results: Chloramphenicol concentrations were higher in the PELF than in plasma, irrespective of formulation and administration route (IV, orally, or intragastrically). Compounded suspension administered intragastrically yielded higher maximum concentration and drug exposure than administered orally, with a relative bioavailability of 79%. After oral administration, no significant differences were found between compounded suspension and commercial tablets.

Conclusions: Oral administration of chloramphenicol achieved pulmonary concentrations ≥ 2 and 4 µg/mL for at least 4 hours (50% to 75% of a 6- to 8-hour dosing interval) in 4 out of 5 treated horses.

Clinical relevance: Pulmonary pharmacokinetics can be used by practitioners to judiciously select an antimicrobial for the treatment of complex equine pneumonia cases.

RMSF, a tickborne infection caused by Rickettsia rickettsii, produces severe and fatal disease in humans and dogs. Since the beginning of the 21st century, cases have risen dramatically, most notably in Mexico and Brazil, where outbreaks occur in urban centers including cities with populations of > 1,000,000 persons. Reported case fatality rates can exceed 50%. Factors consistent with high case fatality include lack of awareness of disease ecology, limited capacity for diagnosis, and delay in appropriate antimicrobial treatment. The emergence of urban hyperendemic foci has been leveraged by 2 distinct but similar anthropogenic events that create disproportionately high numbers of vertebrate amplifiers of R rickettsii, as well as the tick species that transmit this pathogen in proximity with dense human populations. This often occurs in neighborhoods with a highly marginalized at-risk population that includes persons in poverty and particularly children, and health management systems that are under-resourced. We discuss strategies to reduce host dog populations, particularly in Mexico, and capybaras in Brazil. We review challenges to the control of tick populations in these settings. Robust systems are required to enhance awareness of RMSF among medical practitioners and people at risk of RMSF. Public health campaigns should incorporate innovative behavioral science (eg, diverse learning models, motivational interviews, and gamification) to increase prevention and understanding within communities. While anti-Rickettsia or anti-tick vaccines will be necessary to resolve this One Health crisis, impactful implementation will require data-driven and multiple-target innovations to address challenges with hosts, ticks, medical systems, and public welfare. The companion Currents in One Health by Foley, Backus, and López-Pérez, JAVMA, March 2025, addresses helpful information for the practicing veterinarian.