Failure of subtotal arytenoidectomy to improve upper airway flow mechanics in exercising standardbreds with induced laryngeal hemiplegia

Upper airway flow mechanics and arterial blood gas measurements were used to assess the efficacy of subtotal arytenoidectomy for treatment of induced left laryngeal hemiplegia in horses. Measurements were collected with the horses at rest, and trotting or pacing on a treadmill (6.38 degrees incline) at speeds of 4.2 and 7.0 m/s. Experimental protocols were performed after right common carotid artery exteriorization (baseline), after left recurrent laryngeal neurectomy (LRLN), and after left subtotal arytenoidectomy. At baseline, increasing treadmill speed progressively increased peak inspiratory and expiratory flow (VImax and VEmax, respectively), peak inspiratory and expiratory transupper airway pressure (PuI and PuE, respectively), respiratory frequency (f), tidal volume (VT), minute volume (VE), and heart rate. Inspiratory and expiratory times (TI and TE, respectively) and arterial oxygen tension (PaO2) decreased with increased treadmill speed; inspiratory and expiratory impedance (ZI and ZE, respectively) did not change. After LRLN, VImax, f, and PaO2 significantly (P less than 0.05) decreased at exercise, whereas PuI, TI, and ZI significantly increased. Minute volume decreased at exercise after LRLN, but the changes were not significant; LRLN had no effect on VEmax, PuE, ZE, heart rate, arterial carbon dioxide tension (PaCO2), or VT. Subtotal arytenoidectomy did not improve upper airway flow mechanics or blood gas measurements impaired by laryngeal hemiplegia.     

The effect of compacted cancellous bone grafting on the healing of subchondral bone defects of the medial femoral condyle in horses

Objective— To compare the quality of second-intention healing and that of compacting sternally harvested cancellous bone into subchondral bone defects of the medial femoral condyle in horses.
Study Design— A controlled experiment using a surgical technique that minimizes soft tissue trauma, customized for consistency among horses.
Animals or Sample Population— Ten horses, aged 2 to 5 years, free of hindlimb lameness and with radiographically normal stifles.
Methods— After a 12.7-mm-diameter × 19-mm-deep defect was created into randomly selected medial femoral condyles, bone and cartilage healing was evaluated over a 6-month period in control horses (  n = 5  ) and horses receiving a compacted cancellous bone graft (  n = 5  ). Healing was evaluated using lameness assessment, radiographic and microradiographic interpretation, arthroscopic appearance, percent bone fill, proteoglycan content, and histology.
Results— Six months after surgery, there was no significant difference between grafted and ungrafted defects with respect to lameness, radiographic score, or percent bone fill. Histologically, grafted defects were characterized by the presence of dead graft and secondary cyst formation in four defects. Ungrafted defects filled with fibrous tissue and no cyst formation were identified.
Conclusions— Grafted defects do not heal better than ungrafted defects, and lameness was not affected by surgical technique.
Clinical Significance— Cartilage healing is similar in grafted and ungrafted defects in the equine medial femoral condyle at 6 months, suggesting that surgical debridement alone of cystic structures remains the treatment of choice.     

Abscessation following intralesional formalin treatment of congenital parotid salivary duct atresia

A 5-month-old colt with a history of nonpainful left-sided facial swelling present since birth was presented for evaluation and treatment. A diagnosis of congenital parotid salivary duct atresia was made, and surgical correction was attempted but was unsuccessful. Follow-up treatments consisted of repeat intralesional injection of 10% neutral-buffered formalin. The horse developed ventral mandibular abscessation with multiple draining tracts secondary to this treatment; however, no other significant complications occurred and a cosmetic outcome was achieved.     

Cytology of diffuse mesothelioma in the thorax of a horse.

Examination of effusions from body cavities must include a search for neoplastic as well as inflammatory cells. Neoplastic cells found in the thorax are generally derived from adenocarcinomas or mesotheliomas. Mesotheliomas are relatively uncommon and the neoplastic cells found in effusions are difficult to differentiate from activated cells in inflammatory effusions. An ante-mortem diagnosis of mesothelioma was made in a mare on the basis of the large volume of fluid produced, the pleomorphic mesothelial cells, the polyp formation and the absence of PAS staining material after digestion of the cell impression with maltase diastase.     

Determination of 2,3,7,8-tetrachlorodibenzo-1,4-dioxin in 2,4,5-trichlorophenoxyacetic acid and 2,4,5-T alkyl ester herbicides

A gas chromatographic method for the determination of 2,3,7,8-tetrachloro-dibenzo-1,4-dioxin in 2,4,5-trichlorophenoxyacetic acid and 2,4,5-T alkyl ester herbicides is described. Of 80 samples of 100% 2,4,5-trichlorophenoxyacetic acid alkyl ester herbicides 25 contained less than 0.05 part/million and 75 less than 0.5 part/million 2,3,7,8-tetrachlDrodiben2o-1,4-dioxin. Of 32 samples of 50% formulations of 2,4,5-T alkyl esters in mineral oil, 8 contained less than 0.05 part/million and 18 less than 0.5 part/million tetrachlorodioxin. The maximum found was 28.3 part/ million.     

A one-stage repair of third-degree perineal lacerations and rectovestibular fistulae in 17 mares.

Third-degree perineal lacerations or rectovestibular fistulae in 17 mares were repaired surgically by a one-stage method. Primary healing occurred in 14 mares; there were one complete dehiscence and two partial dehiscences with fistula formation. Twelve of 13 mares that were bred became pregnant; nine carried foals to term and two are still pregnant. Two mares have each produced one unthrifty foal. One mare repeatedly aborts in the first trimester. Four mares have produced several healthy foals with no further problems. One mare suffered further perineal trauma while foaling.     

Cystic lymphangioma in a colt.

A 6-month-old Morgan colt was examined because of preputial edema and multiple nodular masses in the left inguinal region. A tentative diagnosis of lymphatic hamartoma was made on the basis of initial biopsy findings. The prognosis for surgical excision was poor due to the progressive expansile growth of the tumor. Secondary infectious complications developed, and the colt was euthanatized at the owner's request. An abdominal and retroperitoneal mass was seen at postmortem examination. The mass was adherent to the left lumbar musculature, the craniodorsal aspect of the pelvic inlet, the midjejunum, the left testicle, and the left kidney. The mass extended through the left inguinal and femoral canals into the deep intermuscular fascia of the hindlimb. Histologic examination of the mass indicated that it was a cystic lymphangioma.     

ULTRASONOGRAPHIC DIAGNOSIS OF A DEEP MUSCLE ABSCESS IN A HORSE

A deep muscle abscess was diagnosed in a horse with a clinical history of a painful swelling in the left gluteal region. The thick walled hypoechoic structure seen on presentation and the multiloculated hyperechoic mass seen on reevaluation are common Ultrasonographic appearances of abscesses. Ultrasonographic evaluation allowed characterization of a chronic mass with subsequent successful surgery and treatment.