Adverse reactions in horses that underwent general anesthesia and cervical myelography.

BACKGROUND: The study was prompted by a perceived high prevalence of myelographic complications varying in severity and type, and attributed to the contrast material or the procedure. HYPOTHESES: 1. Any adverse reaction (AAR) is associated with a change in CSF volume induced either by removal of CSF or addition of contrast material. 2. AAR occurs more frequently in horses with higher premyelography neurologic grade. 3. Nonspecific hyperthermia is attenuated by anti-inflammatory and osmotic agents. ANIMALS: Horses (n = 278) that underwent myelography between 2000 and 2012 at 5 institutions: A (87), B (68), C (65), D (46), and E (12). METHODS: Multi-institutional, retrospective, observational cross-sectional study. RESULTS: AAR were observed in 95/278 (34%) horses, were associated with longer general anesthesia time (P = .04) and higher contrast-medium volume (P = .04); euthanasia because of AAR was performed in 5/278 (2%) horses. Adverse neurologic reactions were the most common type of complication observed occurring in 15/278 (5%) and 42/235 (18%) of horses in the intra- and postmyelography periods. A relationship between AAR and premyelography neurologic grade was not identified (P = .31). Nonspecific hyperthermia was observed in 25/235 (11%) horses; no relationship was observed with administration of anti-inflammatory drugs and osmotic agents (P = .30). CONCLUSIONS AND CLINICAL IMPORTANCE: The category of AAR occurred in one-third of the horses generally was mild and self-limiting. These reactions were associated with increased contrast-medium volume and longer anesthesia time; but, no specific procedural recommendations could be made because of small odds ratios (OR) of <2 for each 1 mL increase in contrast material and for each 1 minute of additional anesthesia time.

Immunohistochemical identification of collagen in the equine lung.

Recurrent airway obstruction (RAO) in the horse is a disease characterized by reversible bronchoconstriction and by mucus and neutrophil accumulation in the airways. It has been hypothesized that in horses with RAO, remodeling changes occur that are similar to those described in humans with asthma. Although collagen fibrils are present surrounding normal airways, they are a prominent feature of airway remodeling in human asthma with evidence of enhanced collagen III and I fibril deposition. An immunolabeling method was developed to identify collagen I and III in equine lung and to describe the collagen fiber type and distribution within the walls of the noncartilagenous bronchioles. The health status of 14 horses was characterized by clinical respiratory exam, bronchoalveolar lavage cytology, and pulmonary function tests. Following postmortem examination and histological assessment, horses were divided into RAO-affected (n = 4) and nonaffected (n = 10) groups. Eight sections per horse from all lung regions were evaluated histologically. Results of the study showed that collagens I and III were present in the lamina propria and adventitial area of the noncartilaginous bronchioles. There was clear staining differentiation between collagen I or III, airway smooth muscle, and the airway epithelium. Collagen I and III were present in the lamina propria and adventitial areas of the noncartilaginous bronchioles of horses, and there was no significant difference in the relative amount of collagen I and III between this group of RAO-affected and nonaffected horses.