OBJECTIVE To evaluate a method for identifying intact and degranulated eosinophils in the small intestine of dogs with inflammatory bowel disease (IBD) by use of a monoclonal antibody (mAb) against eosinophil peroxidase (EPX). ANIMALS 11 untreated dogs with IBD, 5 dogs with IBD treated with prednisolone, and 8 control dogs with no clinical evidence of gastrointestinal tract disease and no immunosuppressive treatment. PROCEDURES 4-μm-thick sections of paraffin-embedded tissues from necropsy specimens were immunostained with EPX mAb. Stained intact and degranulated eosinophils in consecutive microscopic fields (400X magnification) of the upper (villus tips) and lower (between the muscularis mucosae and crypts) regions of the lamina propria of the jejunum were manually counted. RESULTS Compared with control and treated IBD dogs, untreated IBD dogs had a significantly higher number of degranulated eosinophils in the lower region of the lamina propria. However, no significant differences were detected in the number of intact eosinophils in this region among groups. In the upper region of the lamina propria, untreated IBD dogs had a significantly higher number of degranulated and intact eosinophils, compared with control and treated IBD dogs. Number of degranulated and intact eosinophils did not differ significantly between control and treated IBD dogs. CONCLUSIONS AND CLINICAL RELEVANCE Immunohistologic analysis with EPX mAb yielded prominent granule staining that allowed reliable morphological identification of degranulated and intact eosinophils, which may provide a strategy for quantitative and selective evaluation of eosinophils in gastrointestinal biopsy specimens and a potential method to diagnose IBD and evaluate treatment outcome.

OBJECTIVE To evaluate the eosinophilic response in intestinal mucosa of horses with intestinal ischemia and reperfusion or with strangulation of the jejunum or colon. SAMPLE Mucosal samples from horses with naturally occurring strangulation (n = 24 horses) or distention (n = 6) of the jejunum or colon (11), with experimentally induced ischemia and reperfusion of the jejunum (6) or colon (15), or that were euthanized for reasons other than gastrointestinal tract disease (13). PROCEDURES Mucosal samples were collected and grouped by type of intestinal injury. Slides were stained with Luna eosinophil stain and histologically examined to determine eosinophil accumulation and distribution. Number of eosinophils per mm2 of mucosa was calculated as a measure of eosinophil accumulation. Additionally, mucosa was categorized into 5 regions; the percentage of eosinophils in each of the 5 regions, relative to the total eosinophil count in all regions, was determined. RESULTS Eosinophil migration toward and onto the luminal surface was evident in tissues after ischemia and reperfusion and after naturally occurring strangulating disease of the jejunum and colon, as indicated by a decrease in the number of eosinophils near the muscularis mucosa and an increase in the number of eosinophils on or near the luminal surface. Ischemia alone did not change eosinophil distribution in the jejunum or colon. CONCLUSIONS AND CLINICAL RELEVANCE Eosinophils responded to mucosal damage evoked by ischemia and reperfusion by migration toward and onto the luminal surface. This migration could represent an important component of the inflammatory response to injury in equine gastrointestinal mucosa.

Objective—To characterize the response of skin of nonallergic horses following ID injection of polyclonal rabbit anti-canine IgE (anti-IgE) and rabbit IgG. Animals—6 healthy horses. Procedures—Skin in the cervical area was injected ID with anti-IgE and IgG. Wheal measurements and skin biopsy specimens were obtained before and 20 minutes and 6, 24, and 48 hours after injection. Tissue sections were evaluated for inflammatory cells at 4 dermal depths. Immunohistochemical analysis for CD3, CD4, and CD8 was performed, and cell counts were evaluated. Results—Anti-IgE wheals were significantly larger than IgG wheals at 20 minutes and 6 and 24 hours after injection. There were significantly more degranulated mast cells after anti-IgE injection than after IgG injection. There were significantly more eosinophils at 6, 24, and 48 hours and neutrophils at 6 hours after anti-IgE injection, compared with cell numbers at those same times after IgG injection. There were significantly more eosinophils in the deeper dermis of anti-IgE samples, compared with results for IgG samples. No significant differences between treatments were detected for CD3+, CD4+, or CD8+ cells. Conclusions and Clinical Relevance—Injection of anti-IgE antibodies was associated with the development of gross and microscopic inflammation characterized by mast cell degranulation and accumulation of inflammatory cells, particularly eosinophils and neutrophils. This pattern appeared to be similar to that of horses with naturally developing allergic skin disease, although lymphocytes were not increased; thus, ID injection of anti-IgE in horses may be of use for evaluating allergic skin diseases of horses.

Fourteen cats were inoculated orally with 1 of 2 infective doses of Toxocara canis to induce eosinophilia. Cats were subsequently challenge exposed twice via intraperitoneal injection with 1 of 2 T canis antigen preparations. Peritoneal lavage was performed 2 days after antigenic challenge exposure, and eosinophils in the peritoneal lavage fluid were quantified. None of the cats developed clinical signs of disease after infection. All cats developed peripheral eosinophilia after infection. Significant (P < 0.05) difference in mean eosinophil count from the lavage fluid was observed between lavage 1 (prechallenge exposure) and lavages 2 and 3 (postchallenge exposure) in both groups of cats. Significant difference in eosinophil count was not found between cats given different doses of eggs. After initial challenge exposure, significantly (P < 0.05) more eosinophils were obtained from cats given antigen preparation 2 (prep-2) than from those given antigen prep-1. This difference was no longer observed after the second challenge exposure with higher doses of either antigen prep-1 or prep-2. In cats given antigen prep-2, significant difference was not found between lavages 2 and 3. However, in cats given antigen prep-1, eosinophil count was significantly (P = 0.005) greater in fluid obtained from lavage 3, compared with eosinophil count from lavage 2. Mean +/- SEM percentage of eosinophils in the fluid from lavage 3 in all cats was 70.8 +/- 2.2%. Other cell types included macrophages, neutrophils, lymphocytes, and mast cells. Gross postmortem findings were mild. One- to 3-mm nodular white foci of inflammation were observed on the serosal surfaces of the liver, spleen, kidneys, and omentum. Microscopic examination of tissues revealed pulmonary artery hypertrophy (n = 4), eosinophilic peribronchitis and perivasculitis (n = 10), mild granulomatous interstitial nephritis (n = 6), interstitial pancreatitis (n = 1), focal lymphocytic myocarditis (n = 1), focal eosinophilic granulomatous hepatitis (n = 1), and eosinophilic hyperplasia of bone marrow (n = 14). Large numbers of eosinophils could be harvested from the peritoneal cavity of cats inoculated orally with 500 embryonated T canis eggs and subsequently challenge-exposed intraperitoneally with preparations of parasite antigens. After the second challenge exposure, at least 108 eosinophils could be harvested from each cat, yielding eosinophils in the quantity required to begin isolation of granule constituents.

Tracheobronchial aspirates obtained from 66 healthy Thoroughbred racehorses in training at the same track were examined. Twenty-seven percent of the horses had > 20% neutrophils in the aspirate. Eosinophils, mast cells, giant cells, and Curschmann's spirals of mucus were observed in 94, 83, 65, and 42% of the horses, respectively. Hemosiderophages were observed in 86% of the horses, half of which had previous confirmation of exercise-induced pulmonary hemorrhage. Although fungal elements were seen in 70% of the horses, bacteria were detected in only 3% of the horses. The authors conclude that inflammatory airway disease is widespread in the racing Thoroughbred population.

Bronchoalveolar lavage (BAL) fluid was analyzed in healthy horses, using different lavage fluid volumes and lung sites. The only significant difference in the cellular composition of BAL fluid between the right and left lungs was the mast cell numbers, which were significantly higher in the left lung. Total cell count ranged from 34 to 330 cells/microliter for the right lung and 43 to 330 cells/microliter for the left lung. Percentage of neutrophils ranged from 1 to 7% in the right lung and 1 to 5% in the left lung. The small-volume (50 ml) lavage had a greater percentage of neutrophils and a lesser percentage of mast cells in the large-volume (350 ml) lavage. Statistical difference in the composition of BAL fluid recovered was not detected between the 3 sequential 100-ml lavages and a single 300-ml lavage, except that macrophages were significantly higher in the 3 sequential 100-ml lavages. Values for BAL fluid analysis in healthy horses have varied considerably and this variation is from a failure to adhere to any standard technique for volume of fluid infused.

Canine granulocytic ehrlichiosis was diagnosed in 37 dogs by finding ehrlichial morulae in 0.1 to 26.2% of their blood neutrophils and eosinophils. All 37 dogs had clinical signs of arthritis or muscular stiffness. Titer to Ehrlichia canis was determined in sera from 31 of the 37 dogs; 25 dogs had titer ranging from 1:20 to 1:5,120. In the other 6 dogs, titer to E canis was < 1:10. The most common hematologic abnormality in these dogs, other than rickettsiemia, was thrombocytopenia. Granulocytes infected with ehrlichial organisms were not found in another 10 dogs that had clinical signs of arthritis or muscular stiffness. Of these 10 dogs, 3 had titer to E canis ranging from 1:40 to 1:320. Titer in the other 7 dogs was < 1:10. Ehrlichial morulae were not found in the granulocytes of 18 healthy dogs. Of these 18 dogs, 9 had titer to E canis ranging from 1:20 to 1:5,120. Titer in the other 9 dogs was < 1:10. Titer to Borrelia burgdorferi was determined in dogs with granulocytic ehrlichiosis, arthritic dogs without detected rickettsiemia, and in healthy dogs. Low titer determined by 2 laboratories was considered to be nonspecific reaction in all 3 groups of dogs and, thus, did not indicate that the arthritic disorders were attributable to canine borreliosis.

Autologous tissue transmission of spontaneously developing feline eosinophilic plaques was attempted in 5 cats. Macerated tissue from the plaque was vigorously rubbed onto 2 scarified skin sites in each cat. The inoculated areas were observed daily for 30 days. During that time, no clinical or histologic evidence of transmission was found.

Functional capabilities of morphologically mature (segmented) and immature granulocytes (neutrophils and eosinophils) from bone marrow from cows were studied and compared with similar activities of segmented granulocytes from blood. Phagocytosis of Escherichia coli and postphagocytic oxidative metabolic stimulation, measured by nitroblue tetrazolium (NBT) reduction, were evaluated simultaneously. Phagocytosis was observed readily in segmented neutrophils, neutrophilic bands, and metamyelocytes and rarely in myelocytes. Phagocytosis was not seen in promyelocytes and myeloblasts. Neutrophilic bands and metamyelocytes were phagocytically less active than were segmented neutrophils. Washed segmented bone marrow neutrophils possessed phagocytic activity similar to that of blood neutrophils, whereas the activity of unwashed segmented bone marrow neutrophils was markedly less than that of blood neutrophils. Reduction of NBT was observed only in blood segmented neutrophils and bone marrow segmented neutrophils; the magnitude of NBT reduction was significantly (P = less than 0.005) less in bone marrow neutrophils than in blood neutrophils. Eosinophils were phagocytically less competent than were neutrophils. The NBT reduction was observed only in eosinophils from blood, but not in eosinophils from bone marrow.