The effects of Strongylus vulgaris parasitism on eosinophil distribution and accumulation in equine large intestinal mucosa

REASONS FOR PERFORMING STUDY

Eosinophilic granulocytes have been associated with parasite or immune-mediated diseases, but their functions in other disease processes remain unclear. Cause and timing of eosinophil migration into the equine gastrointestinal mucosa are also unknown.

OBJECTIVE

To determine the effects of intestinal parasitism on eosinophils in equine large intestinal mucosa.

METHODS

Large intestinal mucosal samples were collected from horses and ponies (n = 16) from the general veterinary hospital population, ponies (n = 3) raised in a parasite-free environment, ponies experimentally infected with 500 infective Strongylus vulgaris larvae and treated with a proprietary anthelmintic drug (n = 14), and a similar group of ponies (n = 7) that received no anthelmintic treatment. Total eosinophil counts and eosinophil distribution in the mucosa were determined by histological examination. A mixed model analysis was performed and appropriate Bonferroni adjusted P values used for each family of comparisons. P<0.05 was considered significant.

RESULTS

There was no difference in large intestinal mucosal eosinophil counts and eosinophil distribution between ponies infected with S. vulgaris and those raised in a parasite-free environment. Experimental infection with S. vulgaris, with or without subsequent anthelmintic treatment, did not change eosinophil counts, and counts were similar to those for horses from the general population.

CONCLUSIONS

Migration of eosinophils to the equine large intestinal mucosa appears to be independent of exposure to parasites. Large intestinal mucosal eosinophils may have more functions in addition to their role in defence against parasites.

Correlation between anatomic features and low-field magnetic resonance imaging of the equine metacarpophalangeal joint

OBJECTIVE

To expand our current knowledge and to establish limits of correlation between signal intensities of the magnetic resonance (MR) image and actual macroscopic and microscopic anatomic features of the imaged structures of the equine metacarpophalangeal joint (MCPJ).

SAMPLE POPULATION

The right MCPJ was obtained from 4 adult horses that were euthanatized for reasons unrelated to the musculoskeletal system.

PROCEDURE

The distal portion of the right forelimbs was collected from 4 equine cadavers. The bones were drilled to provide fixed reference points and examined by MR imaging. After imaging, the joints were sectioned for gross and histologic inspection. The MR images were aligned and correlated with digitized gross and histologic images to identify tissue types.

RESULTS

Comparison of the images resulted in identification of different bone types, articular cartilage, and soft tissue structures of the equine MCPJ.

CONCLUSION

Results provided relevant information regarding the appearance of the imaged tissues of the equine MCPJ.

CLINICAL RELEVANCE

Although MR imaging does not have current clinical applications for equine practitioners, its wide acceptance as the imaging modality used for most human musculoskeletal derangements may aid in developing more realistic applications in equine medicine.

Radiographic and histologic effects of chondroitinase ABC on normal canine lumbar intervertebral disc

Twelve dogs were divided into two equal groups and given lumbar intradiscal injections of 10, 50, or 100 U/ml of chondroitinase ABC reconstituted in sodium acetate buffer. Radiographs of the lumbar spine were made before and after surgery in both groups. Additional films were made at 5 days after surgery in Group I and at 7, 14, and 21 days after surgery in Group II. All spaces injected with 50 or 100 U/ml chondroitinase ABC demonstrated significant radiographic narrowing in both groups compared with uninjected control and buffer injected discs (P less than 0.001). Discs injected with 10 U/ml of chondroitinase ABC showed increased narrowing over time from 7 to 21 days (P less than 0.05). A zone of safranin O depletion was present in the ventral anulus fibrosus adjacent to the nucleus pulposus in all treated discs, indicating proteoglycan loss. All histologic effects of chondroitinase ABC were confined to intervertebral disc tissues. Chondroitinase ABC appears to be effective for chemonucleolysis in dogs.

Lymphatic drainage of epidural space in rabbits

Epidural lymphatic drainage was examined using epidural catheterization and an infusion of india ink. The india ink was drained quickly through a connecting lymphatic vessel from the nerve root foramen to the anterior lumbar lymphatic vessels. Many kinds of epidurally administered agents may be drained in this manner.

Canine intervertebral disks: correlation of anatomy and MR imaging

Because the structure, maturation, and degeneration of canine intervertebral disks resemble those of humans, the authors developed a model of acute intervertebral disk degeneration in dogs. Herniated disks of 18 dogs were examined with magnetic resonance (MR) imaging and then sectioned with a freezing microtome. On the basis of their morphologic appearance in the freezing microtome sections, most of the lumbar intervertebral disks could be categorized as one of six types. Each type has characteristic features and a distinctive appearance on MR images. Findings of this study--including decreased signal intensity from the intervertebral disk, altered signal intensity in contiguous bone marrow, bulging of the anulus fibrosus, herniation of the nucleus pulposus, and contrast enhancement after intravenous administration of gadolinium diethylenetriaminepentaacetic acid (DTPA)--resemble observations from human clinical studies. Classification of degenerating disks and identification of MR imaging characteristics of each type may improve the interpretation of MR images and recognition of early disk degeneration in humans.

The effect of partial rostral hemimandibulectomy on mandibular mobility and temporomandibular joint morphology in the dog

Partial rostral hemimandibulectomy was performed in 10 adult dogs. The temporomandibular joints (TMJs) were examined radiographically and tomographically before surgery, and mandibular stability was evaluated before and immediately after surgery. Radiographic, tomographic, and hemimandibular mobility assessments were made again at months 3 and 6. The TMJs were examined grossly and histologically in five dogs euthanatized at month 3 and in five dogs euthanatized at month 6. Statistically significant hemimandibular instability (p less than 0.05) persisted in all subjects throughout the study. The radiographic appearance of the joints remained unaltered; however, space asymmetry was identified in postoperative tomograms of three dogs at month 3 and four dogs at month 6. The TMJs were grossly normal at necropsy. Histologically, there were degenerative changes in articular cartilage and subchondral bone in all of the joints. The authors conclude that partial rostral hemimandibulectomy causes TMJ degeneration, as a consequence of hemimandibular instability or abnormal loading, or both.

Canine diffuse idiopathic skeletal hyperostosis

The radiographic and necropsy findings in a case of canine diffuse idiopathic skeletal hyperostosis are reported. Radiographically, the disease was characterized by progressive development of para-articular mineral densities along joint surfaces of the appendicular skeleton; progressive osseous fusion of the ilium, pubis, femur, and ischium; and progressive flowing ossification of the dorsal spinous processes of cervical and thoracic vertebrae. The para-articular lesions were considered to develop as a consequence of fibrocartilaginous proliferation followed by endochondral ossification. Progression of the ossification process led to para-articular joint fusion and almost complete ossification of the metaplastic cartilage. A distinguishing feature was the sparing of intra-articular structures.