Determination of passive mechanical properties of the superficial and deep digital flexor muscle-ligament-tendon complexes in the forelimbs of horses

OBJECTIVE: To determine the relative contributions of the muscles, tendons, and accessory ligaments to the passive force-length properties of the superficial (SDF) and deep digital flexor (DDF) myotendinous complexes. SAMPLE POPULATION: 8 cadaveric forelimbs from 6 adult Thoroughbreds. PROCEDURE: In vitro, limb configurations during slack position and myotendinous lengths during subsequent axial loading of forelimbs were recorded before and after transection of accessory ligaments. Expressions were derived to describe the force-length behavior of each muscle, tendon, and accessory ligament-tendon unit; linear stiffness was computed for these components. The elastic modulus was established for the SDF and DDF tendons. RESULTS; Linear stiffness was 2.80 +/- 0.38 kN/cm for the SDF muscle, 3.47 +/- 0.66 kN/cm for the DDF muscle, 2.73 +/- 0.18 kN/cm for the SDF tendon, 3.22 +/- 0.20 kN/cm for the DDF tendon, 6.46 +/- 0.85 kN/cm for the SDF accessory ligament, 1.93 +/- 0.11 kN/cm for the SDF accessory ligament-tendon unit, and 2.47 +/- 0.11 kN/cm for the DDF accessory ligament-tendon unit. The elastic modulus for the SDF and DDF tendons was 920 +/- 77 and 843 +/- 56 MPa, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Both the muscle-tendon and ligament-tendon portions of SDF and DDF myotendinous complexes had important roles in supporting the forelimb of horses. Although muscle tension can be enhanced by elbow joint flexion and active contraction, the accessory ligaments transmitted more force to the distal tendons than did the muscles under the conditions tested.     

Microbiologic findings in feedlot cattle with acute interstitial pneumonia

OBJECTIVE: To test the hypothesis that feedlot cattle with acute interstitial pneumonia (AIP) have bacterial infection of the lung or liver and concurrent bovine respiratory syncytial virus (BRSV) infection significantly more often than pen mates without AIP ANIMALS: 39 feedlot cattle with signs consistent with AIP and no history of treatment with antimicrobials and 32 healthy control cattle from the same pens. PROCEDURES: Lung and liver specimens were obtained postmortem for bacterial or mycoplasmal culture and histologic examination; lung tissue was assessed for BRSV infection immunohistochemically. RESULTS: Among affected cattle, 26 had AIP confirmed histologically. Lung tissue from 11 cattle with AIP yielded microbial respiratory tract pathogens on culture; tissues from control animals yielded no microbial growth. In 4 cattle with AIP and 2 control animals, liver abscesses were detected; bacteria were isolated from abscessed tissue in 3 and 1 of those animals, respectively. Immunohistochemically, 9 cattle with AIP and no control animals were BRSV-positive. Histologically, 9 AIP-affected cattle had only acute alveolar damage with exudation, and the other 17 had acute exudation with type II pneumocyte hyperplasia. No lesions of AIP were detected in control animals. Only 4 AIP-affected cattle had bacterial infection of the lung with concurrent BRSV infection. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that microbial respiratory tract pathogens are more common in cattle with AIP than in healthy pen mates. Control of bacterial pneumonia late in the feeding period may reduce the incidence of AIP at feedlots where AIP is a problem.     

Outcome and subsequent fertility of sheep and goats undergoing cesarean section because of dystocia: 110 cases (1981-2001)

OBJECTIVE: To determine the outcome and subsequent fertility of sheep and goats undergoing a cesarean section because of dystocia. DESIGN: Retrospective study. ANIMALS: 85 sheep and 25 goats. PROCEDURE: Medical records were reviewed, and information was obtained on signalment, history, physical examination findings, anesthesia protocol, surgical technique, number of lambs or kids delivered, pre- and postoperative treatments, duration of hospitalization, and postoperative complications. Follow-up information was obtained through telephone conversations with owners. RESULTS: The proportion of sheep admitted to the veterinary teaching hospital during the study period that underwent a cesarean section (4.4%) was significantly higher than the proportion of goats that did (2.2%). Pygmy goats were overrepresented, compared with the hospital population. The most common reason for cesarean section was inadequate dilatation of the cervix. The most common surgical approach was via the left paralumbar fossa. Two hundred one lambs and kids were delivered, of which 116 were dead at delivery or died shortly afterward. Forty-two of the 65 dams with 1 or more dead fetuses had been in stage-2 labor for > 6 hours, and fetal death was significantly associated with a prolonged duration of dystocia. The most common complication following surgery was retained placenta (n = 49). Use of antimicrobials was associated with a lower rate of complications. All 16 dams that were rebred became pregnant and had no problems with dystocia. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that cesarean section is an effective method of resolving dystocia in sheep and goats and does not adversely affect subsequent fertility.     

Surgical management of compound odontoma in two horses

Two horses were admitted for evaluation of mandibular swelling (horse 1) or maxillary distortion (horse 2). Both horses had radiographic evidence of tumors of dental origin that had the appearance of a compound odontoma. Extensive surgical resection was performed for treatment. Horse 1 was treated with 1-stage surgical resection, but an iatrogenic fracture occurred during surgery, which was managed successfully with a type I external fixator and extraoral alimentation. Horse 2 was treated in multiple stages to remove all portions of the tumor. To manage an extensive orosinal fistula, a custom-designed dental bridge was constructed to occlude the fistula. For both horses, the histopathologic diagnosis was compound odontoma. Compound odontomas are benign, locally expansive tumors of dental origin. Compound odontomas can be treated successfully; however, multiple surgeries may be necessary.     

Use of a carbon dioxide laser for surgical management of cutaneous masses in horses: 32 cases (1993-2000)

OBJECTIVE: To determine outcome of horses in which cutaneous masses were removed with a carbon dioxide laser. DESIGN: Retrospective study. ANIMALS: 32 horses. PROCEDURE: Medical records of horses with 1 or more cutaneous masses treated with a carbon dioxide laser were examined. Follow-up information was obtained through telephone interviews with owners and referring veterinarians. RESULTS: Cutaneous masses were classified as sarcoids (15 horses), neoplastic masses other than sarcoids (squamous cell carcinoma [91; fibroma [1]; and melanoma [1]), and nonneoplastic masses (6). Minimum follow-up time was 6 months. Five sarcoids and 2 squamous cell carcinomas recurred. Seven (21%) horses had complications associated with dehiscence of wounds that had been closed primarily or failure of wound healing because of recurrence of the mass. Twenty-six (81%) owners were satisfied with the cosmetic appearance following surgery. CONCLUSION AND CLINICAL RELEVANCE: Results suggest that a carbon dioxide laser may be effective for treatment of cutaneous masses in horses.     

Pharmacokinetics of butorphanol tartrate in red-tailed hawks (Buteo jamaicensis) and great horned owls (Bubo virginianus)

OBJECTIVE: To determine the pharmacokinetics of butorphanol tartrate after IV and IM single-dose administration in red-tailed hawks (RTHs) and great horned owls (GHOs). ANIMALS: 6 adult RTHs and 6 adult GHOs. PROCEDURES: Each bird received an injection of butorphanol (0.5 mg/kg) into either the right jugular vein (IVj) or the pectoral muscles in a crossover study (1-week interval between treatments). The GHOs also later received butorphanol (0.5 mg/kg) via injection into a medial metatarsal vein (IVm). During each 24-hour postinjection period, blood samples were collected from each bird; plasma butorphanol concentrations were determined via liquid chromatography-mass spectrometry. RESULTS: 2- and 1-compartment models best fit the IV and IM pharmacokinetic data, respectively, in both species. Terminal half-lives of butorphanol were 0.94 +/- 0.30 hours (IVj) and 0.94 +/- 0.26 hours (IM) for RTHs and 1.79 +/- 1.36 hours (IVj), 1.84 +/- 1.56 hours (IM), and 1.19 +/- 0.34 hours (IVm) for GHOs. In GHOs, area under the curve (0 to infinity) for butorphanol after IVj or IM administration exceeded values in RTHs; GHO values after IM and IVm administration were less than those after IVj administration. Plasma butorphanol clearance was significantly more rapid in the RTHs. Bioavailability of butorphanol administered IM was 97.6 +/- 33.2% (RTHs) and 88.8 +/- 4.8% (GHOs). CONCLUSIONS AND CLINICAL RELEVANCE: In RTHs and GHOs, butorphanol was rapidly absorbed and distributed via all routes of administration; the drug's rapid terminal half-life indicated that published dosing intervals for birds may be inadequate in RTHs and GHOs.     

Training failure among yearling horses

OBJECTIVE: To compare financial returns between pinhooked yearling horses (ie, bought and trained for approximately 5 months with the goal of selling the horse at "2-year-olds in training" sales) that had mild or severe training failure and horses that had planned versus nonplanned training failure. ANIMALS: 40 Thoroughbred pinhooked yearling horses. PROCEDURE: During the period from September 1998 through and April 1999, 20 horses had mild training failure (1 to 11 days lost), and 20 horses had severe training failure (13 to 108 days lost). Horses were assigned to these 2 groups on the basis of frequency distribution (median) of days lost during training. Horses were also categorized on the basis of type of training failure (planned vs nonplanned training failure). The outcome of primary interest was financial return. Median financial returns were compared among groups by use of the Mann-Whitney U test. RESULTS: Median financial returns for horses that had severe training failure ($1,000) were significantly different, compared with horses that had mild training failure ($24,000). Analysis of results also indicated that median returns were significantly different among horses that had planned training failure (-$2,000; eg, horses with radiographic abnormalities detected during routine prepurchase examinations that required surgical treatment, resulting in days lost during training), compared with horses that did not ($10,000). CONCLUSIONS AND CLINICAL RELEVANCE: Training failure has an economic impact on revenues in pinhooked yearling horses. Lameness, planned training failure, respiratory disease, and ringworm were common and important causes of training failure.     

Evaluation of local and systemic immune responses induced by intramuscular injection of a Mycoplasma hyopneumoniae bacterin to pigs

OBJECTIVE: To evaluate immune responses induced by administration of Mycoplasma hyopneumoniae bacterin to pigs. Animals-60 healthy 7- to 10-day-old cross-bred boars. PROCEDURE: Pigs were assigned to 1 of 4 pig groups (15 pigs/group): vaccinated, challenged; vaccinated, nonchallenged; nonvaccinated, challenged; nonvaccinated, nonchallenged. Vaccinated pigs received IM injections of a mycoplasma bacterin on days 0 and 14, whereas nonvaccinated pigs received saline (0.9% NaCl) solution. Pigs in the challenged groups were inoculated intratracheally with M hyopneumoniae on day 42. Pigs were euthanatized and necropsied 41, 44, 48, and 70 days after the first vaccination, and proportion of lung surface with pneumonic lesions was determined. Percentage of lymphocyte subpopulations and number of interferon-gamma (IFN-gamma) secreting lymphocytes in blood and tissues, cytokine and antibody concentrations in bronchoalveolar lavage (BAL) fluid, and serum antibody concentrations were determined. RESULTS: Vaccination against and infection with M hyopneumoniae induced a local mucosal immune response in the respiratory tract of pigs. Proportion of lung surface with pneumonic lesions in vaccinated challenged pigs was reduced on day 70, compared with nonvaccinated challenged pigs. Vaccination stimulated the production of M hyopneumoniae-specific IFN-gamma secreting blood lymphocytes. Tumor necrosis factor-alpha concentration in BAL fluid on day 70 was increased in nonvaccinated challenged pigs, compared with vaccinated challenged pigs. CONCLUSIONS AND CLINICAL RELEVANCE: Vaccination against M hyopneumoniae induced local, mucosal, humoral, and cellular immune responses. Moreover, vaccination reduced the severity of lung lesions in challenged pigs, suggesting that mucosal antibodies, mediation of the inflammatory response, and cell-mediated immune responses are important for control of mycoplasmal pneumonia in pigs.