OBJECTIVE To biomechanically compare modified and standard laryngoplasty constructs in monotonic load to failure and cyclic loading. SAMPLES 41 equine cadaveric larynges. PROCEDURES Laryngoplasty constructs were created by use of a standard technique on one side and a modified technique (with a toggle to anchor suture to the arytenoid cartilage) on the other side. For monotonic loading, laryngoplasty constructs were prepared and suture ends attached to a load frame; constructs then were loaded until mechanical failure. Mean load at failure and failure modes were compared between constructs. For cyclic loading, arytenoid cartilages were maximally abducted and constructs were circumferentially loaded for 10,000 cycles. Loss of arytenoid abduction was evaluated every 500 cycles with a subjective grading scale and objective change in rima glottidis cross-sectional area. RESULTS In monotonic loading, modified laryngoplasty constructs failed at a significantly higher mean ± SD load (191 ± 29 N) than did standard laryngoplasty constructs (91 ± 44 N). None of the modified laryngoplasty constructs failed by suture pull-through of the muscular process of the arytenoid cartilage, whereas most of the standard laryngoplasty constructs failed in that manner. In cyclic testing, 11 of 20 standard laryngoplasty constructs failed or achieved Dixon grade 3 abduction, whereas 0 of 20 modified laryngoplasty constructs failed. Modified laryngoplasty constructs lost significantly less rima glottidis cross-sectional area in circumferential testing, compared with loss for standard laryngoplasty constructs. CONCLUSIONS AND CLINICAL RELEVANCE The modified laryngoplasty technique was biomechanically superior to the standard laryngoplasty technique in this ex vivo study.

OBJECTIVE To determine the effect of subchronic oral exposure to zearalenone (ZEA) at a daily dose of 50 μg of ZEA/kg of body weight (an environmentally relevant concentration) on the reproductive system of rabbit bucks. ANIMALS 8 healthy sexually mature New Zealand White rabbits. PROCEDURES During the experimental period (March to June), each rabbit underwent a 7-week control protocol and then a 7-week treatment protocol. Water (0.5 mL) or ZEA solution (50 μg/kg [0.5 mL]) was administered orally once daily during the control and treatment period, respectively; ejaculates were collected weekly. Studied end points included semen quality variables (spermatozoa kinetics, morphology, viability, and DNA fragmentation), serum testosterone concentration, and results of histologic examination of the testes and epididymides following euthanasia at the end of the experimental period. RESULTS Treatment with ZEA solution resulted in significant increases in spermatozoa beat-cross frequency, in the percentages of spermatozoa with head and midpiece abnormalities, and in the percentages of DNA-fragmented spermatozoa, compared with effects of the control treatment. Serum testosterone concentration, other spermatozoa velocity variables, and percentages of progressive and total motility, rapidly or slowly moving spermatozoa, and live spermatozoa did not differ significantly between the 2 periods. Histologic examination revealed no patterns of abnormal findings in the testes and epididymides. CONCLUSIONS AND CLINICAL RELEVANCE Oral treatment with ZEA solution at an environmentally relevant concentration caused minor interference with rabbit bucks' sperm quality. Although mostly considered mild, the sperm quality changes warrant further investigation in terms of fertilizing capacity impairment.

OBJECTIVE To evaluate the effect of lipopolysaccharide (LPS) on apoptosis of equine neutrophils in vitro. SAMPLE Venous blood samples from 40 adult horses. PROCEDURES Neutrophils were isolated from blood samples and cultured with or without LPS from Escherichia coli O55:B5 for 12 or 24 hours. Neutrophil apoptosis was assessed by use of cytologic examination, annexin V and propidium iodide staining quantified with flow cytometry, coincubation with inducers of intrinsic and extrinsic apoptosis or a toll-like receptor (TLR) 4 inhibitor, and measurement of caspase-3, -8, and -9 activities. RESULTS Treatment with LPS resulted in a significant delay in apoptosis after incubation for 12 and 24 hours (neutrophils from blood samples of 40 horses). There was a significant correlation between increases in LPS dose and decreases in apoptosis after incubation for 24 hours (3 experiments, each of which involved neutrophils obtained from the same 3 horses at 3 separate times). Caspase-9 activity, but not caspase-3 or -8 activity, was significantly reduced in LPS-treated neutrophils after incubation for 12 hours (neutrophils from blood samples of 17 horses). Treatment with a TLR4 inhibitor or intrinsic and extrinsic inducers of apoptosis prevented LPS-delayed apoptosis. CONCLUSIONS AND CLINICAL RELEVANCE LPS treatment delayed apoptosis of equine neutrophils in vitro for up to 24 hours in a dose-dependent manner by alteration of the intrinsic pathway of apoptosis and was dependent on TLR4 signaling. Increased neutrophil life span may contribute to the development of a systemic inflammatory response syndrome in endotoxemic horses.

OBJECTIVE To determine the physiochemical properties and pharmacokinetics of 3 midazolam gel formulations following buccal administration to dogs. ANIMALS 5 healthy adult hounds. PROCEDURES In phase 1 of a 2-phase study, 2 gel formulations were developed that contained 1% midazolam in a poloxamer 407 (P1) or hydroxypropyl methylcellulose (H1) base and underwent rheological and in vitro release analyses. Each formulation was buccally administered to 5 dogs such that 0.3 mg of midazolam/kg was delivered. Each dog also received midazolam hydrochloride (0.3 mg/kg, IV). There was a 3-day interval between treatments. Blood samples were collected immediately before and at predetermined times for 8 hours after drug administration for determination of plasma midazolam concentration and pharmacokinetic analysis. During phase 2, a gel containing 2% midazolam in a hydroxypropyl methylcellulose base (H2) was developed on the basis of phase 1 results. That gel was buccally administered such that midazolam doses of 0.3 and 0.6 mg/kg were delivered. Each dog also received midazolam (0.3 mg/kg, IV). All posttreatment procedures were the same as those for phase 1. RESULTS The H1 and H2 formulations had lower viscosity, greater bioavailability, and peak plasma midazolam concentrations that were approximately 2-fold as high, compared with those for the P1 formulation. The mean peak plasma midazolam concentration for the H2 formulation was 187.0 and 106.3 ng/mL when the midazolam dose administered was 0.6 and 0.3 mg/kg, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that buccal administration of gel formulations might be a viable alternative for midazolam administration to dogs.

OBJECTIVE To evaluate cell-mediated and humoral immune responses of calves receiving 2 doses of a dual-adjuvanted vaccine containing inactivated bovine herpesvirus type 1 (BHV1) and bovine viral diarrhea virus types 1 (BVDV1) and 2 (BVDV2) before and after exposure to BHV1. ANIMALS 24 Holstein steers negative for anti-BHV1 antibodies and proliferative cell-mediated immune responses against BHV1 and BVDV. PROCEDURES Calves were randomly assigned to 3 groups. The vaccinated group (n = 10) received 2 doses of vaccine on days 0 and 21. Control (n = 10) and seeder (4) groups remained unvaccinated. Calves were commingled during the study except for the 3-day period (days 53 to 55) when seeders were inoculated with BHV1 (1.04 × 107 TCID50, IV) to serve as a source of virus for challenge (days 56 through 84). Rectal temperature and clinical illness scores were monitored, and blood and nasal specimens were obtained for determination of clinicopathologic and immunologic variables. RESULTS After BHV1 challenge, mean rectal temperature and clinical illness scores were lower for vaccinates than controls. In vaccinates, antibody titers against BHV1 and BVDV2, but not BVDV1, increased after challenge as did extracellular and intracellular interferon-γ expression, indicating a T helper 1 memory response. Additional results of cell marker expression were variable, with no significant increase or decrease associated with treatment. CONCLUSIONS AND CLINICAL RELEVANCE Calves administered 2 doses of a killed-virus vaccine developed cell-mediated and humoral immune responses to BHV1 and BVDV, which were protective against disease when those calves were subsequently exposed to BHV1.

OBJECTIVE To evaluate the thermal antinociceptive effects and pharmacokinetics of hydromorphone hydrochloride after IM administration to cockatiels (Nymphicus hollandicus). ANIMALS 16 healthy adult cockatiels. PROCEDURES During the first of 2 study phases, each cockatiel received each of 4 treatments (hydromorphone at doses of 0.1, 0.3, and 0.6 mg/kg and saline [0.9% NaCl] solution [0.33 mL/kg; control], IM), with a 14-day interval between treatments. For each bird, foot withdrawal to a thermal stimulus was determined following assignment of an agitation-sedation score at predetermined times before and for 6 hours after each treatment. During the second phase, a subset of 12 birds received hydromorphone (0.6 mg/kg, IM), and blood samples were collected at predetermined times for 9 hours after drug administration. Plasma hydromorphone concentration was determined by liquid chromatography–mass spectrometry. Noncompartmental analysis of sparse data was used to calculate pharmacokinetic parameters. RESULTS Thermal withdrawal response did not differ among the 4 treatment groups at any time. Agitation-sedation scores following administration of the 0.3-and 0.6-mg/kg doses of hydromorphone differed significantly from those treated with saline solution and suggested the drug had a sedative effect. Plasma hydromorphone concentrations were > 1 ng/mL for 3 to 6 hours after drug administration in all birds. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that IM administration of hydromorphone at the evaluated doses did not increase the thermal withdrawal threshold of cockatiels despite plasma drug concentrations considered therapeutic for other species. Further research is necessary to evaluate the analgesic effects of hydromorphone in cockatiels.

OBJECTIVE To quantify the effect of time and recumbency on CT measurements of lung volume and attenuation in healthy cats under general anesthesia. ANIMALS 8 healthy research cats. PROCEDURES Anesthetized cats were positioned in sternal recumbency for 20 minutes and then in left, right, and left lateral recumbency (40 minutes/position). Expiratory helical CT scan of the thorax was performed at 0 and 20 minutes in sternal recumbency and at 0, 5, 10, 20, 30, and 40 minutes in each lateral recumbent position. For each lung, CT measurements of lung volume and attenuation and the extent of lung areas that were hyperaerated (−1,000 to −901 Hounsfield units [HU]), normoaerated (−900 to −501 HU), poorly aerated (−500 to −101 HU), or nonaerated (−100 to +100 HU [indicative of atelectasis]) were determined with a semiautomatic threshold-based technique. A restricted maximum likelihood analysis was performed. RESULTS In lateral recumbency, the dependent lung had significantly greater attenuation and a lower volume than the nondependent lung. Within the dependent lung, there was a significantly higher percentage of poorly aerated lung tissue, compared with that in the nondependent lung. These changes were detected immediately after positioning the cats in lateral recumbency and remained static with no further significant time-related change. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that once anesthetized healthy cats were positioned in lateral recumbency, the dependent lung lobes underwent a rapid reduction in lung volume and increase in lung attenuation that did not progress over time, predominantly attributable to an increase in poorly aerated lung tissue.

The purpose of this study was to evaluate the effects of a single intravenous dose of alfaxalone on canine splenic volume. In 6 adult beagle dogs the splenic volume [mean ± standard error (SE)] was determined by computed tomography to be 0.17 ± 0.02 L before alfaxalone administration and 0.24 ± 0.02 L (P = 0.0091) and 0.23 ± 0.02 L (P = 0.0268) 15 and 30 min, respectively, after alfaxalone administration. Hematocrits (mean ± SE) obtained at the same times were, respectively, 46.3% ± 1.3%, 40.6% ± 1.3% (P = 0.0015), and 41.7% ± 1.3% (P = 0.0057). In conclusion, alfaxalone caused relaxation of the canine splenic capsule and an increase in the splenic volume, along with a decrease in the hematocrit in these dogs.

OBJECTIVE To assess and compare 2 injection techniques for conducting ocular anterior segment indocyanine green angiography (ASICGA) and sodium fluorescein (SF) angiography in horses. ANIMALS 3 healthy adult female horses (age range, 19 to 25 years). PROCEDURES Horses were sedated, jugular catheters were placed, and manual restraint was used to ensure proper positioning for the angiography procedure. Two injection techniques (IV and intra-arterial) were performed for each horse 1 week apart. Intravenous injections of 0.25% indocyanine green (ICG; 50 mg) and 10% SF (10 mg/kg) were administered via the jugular catheter. Intra-arterial injections of ICG (1 mg) and SF (1 mg/kg) were administered into the common carotid artery with ultrasound guidance. Angiography was performed by use of an adaptor system comprised of a modified digital single-lens reflex camera, camera adaptor, and lens. Imaging was performed at a rate of 3 images/s for 60 seconds immediately following ICG injection, then at 2, 3, 4, and 5 minutes after injection. The SF was injected 5 minutes thereafter. RESULTS ASICGA allowed visual identification of the arterial, capillary, and venous phases of angiography. Intra-arterial administration provided superior dye fluorescence, sharper contrast, and faster dye passage than IV administration. Visibility of the iris vasculature was limited with SF, and extravasation of SF was noted. No clinically important adverse events were detected. CONCLUSIONS AND CLINICAL RELEVANCE ASICGA images were obtainable with both injection techniques; however, visibility of the iris vasculature was better with intra-arterial administration of ICG. The ASICGA technique may serve as a viable ocular imaging modality for horses.

OBJECTIVE To describe qualitative blinking patterns and determine quantitative kinematic variables of eyelid motion in ophthalmologically normal horses. ANIMALS 10 adult mares. PROCEDURES High-resolution videography was used to film blinking behavior. Videotapes were analyzed for mean blink rate, number of complete versus incomplete blinks, number of unilateral versus bilateral blinks, and subjective descriptions of blinking patterns. One complete blink for each horse was analyzed with image-analysis software to determine the area of corneal coverage as a function of time during the blink and to calculate eyelid velocity and acceleration during the blink. RESULTS Mean ± SD blink rate was 18.9 ± 5.5 blinks/min. Blinks were categorized as minimal incomplete (29.7 ± 15.6%), moderate incomplete (33.5 ± 5.9%), complete (30.8 ± 13.1%), and complete squeeze (6.0 ± 2.8%); 22.6 ± 9.0% of the blinks were unilateral, and 77.3 ± 9.1% were bilateral. Mean area of exposed cornea at blink initiation was 5.89 ± 1.02 cm2. Mean blink duration was 0.478 seconds. Eyelid closure was approximately twice as rapid as eyelid opening (0.162 and 0.316 seconds, respectively). Deduced maximum velocity of eyelid closure and opening was −16.5 and 7.40 cm/s, respectively. Deduced maximum acceleration of eyelid closure and opening was −406.0 and −49.7 cm/s2, respectively. CONCLUSIONS AND CLINICAL RELEVANCE Kinematic variables of ophthalmologically normal horses were similar to values reported for humans. Horses had a greater percentage of complete squeeze blinks, which could increase tear film stability. Blinking kinematics can be assessed as potential causes of idiopathic keratopathies in horses.