Possible causal association of idiopathic inflammatory bowel disease with thrombocytopenia in the dog

Extraintestinal manifestations of inflammatory bowel disease (IBD) are commonly observed in humans but are poorly documented in companion animals. Thrombocytopenia is an uncommon but well-documented extraintestinal hematological abnormality in humans; however, there are no previous reports of IBD and concurrent thrombocytopenia in the veterinary literature. Seven dogs having idiopathic IBD and concurrent thrombocytopenia were identified and evaluated retrospectively (this represents an incidence of 2.5% in the authors' IBD population). Obvious known causes for thrombocytopenia were eliminated by diagnostic testing as deemed appropriate by the clinician of record. Thrombocytopenia resolved with treatment for the IBD in some but not all patients. This is similar to reports in humans. Thrombocytopenia typically appears to be subclinical, and the severity does not correlate with the degree of intestinal inflammation defined histopathologically. However, quantitative platelet counts should be monitored during IBD therapy, as additional immunosuppression may be required to treat thrombocytopenia, despite resolution of gastrointestinal signs. It is speculated that thrombocytopenia may be causally associated with canine IBD, possibly secondary to immune stimulation from lumenal bacterial antigens, altered immunological regulation, or both.

Flow cytometric analysis of colonic and small intestinal mucosal lymphocytes obtained by endoscopic biopsy in the healthy dog

Flow cytometric analysis of the lymphocyte population of the gut could provide useful information on the immune cells present in the gut that would not be easily obtained in tissue sections. However, little is known of the normal lymphocyte population in the canine gut as determined by flow cytometry, which allows for simultaneous staining of multiple cell surface antigens and identification of specific lymphocytic subsets. Therefore, intraepithelial lymphocytes were obtained from biopsies of the healthy canine proximal small intestine and colon taken with an endoscope, and flow cytometric analysis was used to characterize the lymphocyte subsets present. Endoscopic biopsy of the intestine is a minimally invasive technique commonly used for diagnostic purposes. Although CD3+ lymphocytes were the most abundant subset in both colon and small intestine, CD3+/CD8- lymphocytes predominated in the proximal small intestine, whereas CD3+/CD8+ lymphocytes did in the colon. Canine CD8+ intraepithelial lymphocytes were predominantly CD8alphabeta+ in both small intestine and colon. CD4+ intraepithelial lymphocytes were always much less numerous than CD8+ intraepithelial lymphocytes. As in man, a majority of intraepithelial lymphocytes expressed the T-cell receptor, TCRalphabeta, but TCRgammadelta was expressed by a third of intraepithelial T-cells in the proximal small intestine, and approximately 15% of those in the colon. Very few CD21+ lymphocytes were detected in samples of healthy canine colon and small intestinal intraepithelial cells. We have showed that canine intraepithelial lymphocytes are regionally specialized, and that those from the small intestine are unique in comparison to those of other species such as man and rodents due to the large numbers of CD3+/CD8- intraepithelial lymphocytes. This study provides a baseline for comparison with intraepithelial lymphocytes obtained from canine patients with intestinal disease.

Colonic lymphocyte and plasma cell populations in dogs with lymphocytic-plasmacytic colitis

OBJECTIVES

To quantitate immunoglobulin-containing cells (IgA, IgG, and IgM) and CD3+ T cells in colonic biopsy specimens obtained from dogs with lymphocytic-plasmacytic colitis (LPC), and to compare lymphocyte and plasma cell populations in dogs with LPC with those in healthy dogs.

ANIMALS

10 healthy dogs and 11 dogs with LPC.

PROCEDURE

Colonic mucosal specimens obtained from healthy dogs and dogs with LPC were stained specifically for IgA-, IgG-, and IgM-containing cells and CD3+ T cells by use of immunoperoxidase techniques. Morphometric analyses were done to quantitate lymphocytes and plasma cells in standardized areas of colonic mucosa. Data analyses allowed determination of mean cell numbers in each dog group, and comparison of mean numbers of lymphocytes and plasma cells between dog groups.

RESULTS

CD3+ T cells predominated in healthy dogs, whereas CD3+ T cells and IgA-containing cells were most numerous in dogs with LPC. In both dog groups, the IgG- and IgM-containing cells were considerably less numerous than the other 2 cell types. Comparison of cell populations between dog groups indicated that IgA- and IgG-containing cells and CD3+ T cells were significantly more numerous in the colonic mucosa of dogs with LPC.

CONCLUSIONS

Dogs with LPC have significantly increased numbers of IgA- and IgG-containing cells and CD3+ T cells. These lymphocyte and plasma cell distributions indicate similarities to and differences from such distributions in human beings with inflammatory bowel disease. Results provide a basis for future correlation between histologic stage of disease activity and immunologic findings in dogs with LPC.

Immunohistochemical characterization of immunoglobulin-containing cells and T cells in the colonic mucosa of healthy dogs

OBJECTIVES

To quantitate numbers of immunoglobulin (Ig)-containing cells (IgA, IgG, and IgM) and T cells (CD3+, CD4+, and CD8+) in the colonic mucosa of healthy dogs, and to determine whether mean cell numbers differ among colonic regions.

ANIMALS

10 clinically normal young adult mixed-breed dogs.

PROCEDURE

Endoscopically obtained specimens of ascending, transverse, and descending colonic mucosa were stained specifically for IgA, IgG, and IgM heavy chains and T-cell antigens, CD3+, CD4+, and CD8+, using immunoperoxidase techniques. Morphometric analysis, performed by light microscopy, was used to quantitate numbers in these standardized areas of colonic mucosa. Data analysis allowed determination of mean cell numbers in each colonic region, as well as comparison of mean cell numbers among colonic regions.

RESULTS

The CD3+ and CD8+ T cells were the predominant immune cell types in all colonic regions. In the mucosa, CD3+ T cells were significantly (P < 0.05) more numerous than CD8+ T cells, and CD8+ T cells were significantly (P < 0.05) more numerous than CD4+ T cells. The IgA-containing cells were significantly (P < 0.05) more numerous than IgG-containing cells, whereas IgM-containing cells were least numerous (P < 0.05). Differences in mean cell counts among colonic regions were not significant for Ig-containing cells or T cells.

CONCLUSIONS

Mean numbers of immune cells did not differ significantly among colonic regions in healthy dogs, although differences existed in mean populations of T cells and Ig-containing cells. The CD3+ and CD8+ T cells were the most numerous immune cell types in colonic mucosa.

CLINICAL RELEVANCE

These quantitative data provide a basis for study of alterations in populations of mucosal immune cells and their possible contribution to the pathogenesis of gastrointestinal tract disease.

Field isolates of Mycoplasma ovipneumoniae exhibit distinct cytopathic effects in ovine tracheal organ cultures

Ovine tracheal ring explants were infected with four different Mycoplasma ovipneumoniae and one M. arginini field isolate and their ability to induce cytopathic effects was tested by measuring ciliary activity and intracellular calmodulin release. Infected tracheal rings showed significantly decreased ciliary activity as compared to the non-infected control rings. There were, however, marked differences between isolates in the onset and severity of the effects which correlated with their ability to produce hydrogen peroxide. Infected tracheal rings released more calmodulin than the non-infected controls. The amount of calmodulin released also varied between isolates, and somewhat reflected the degree of loss of ciliary activity in the corresponding rings induced by the different isolates. Light and electron microscopic examinations of infected tracheal rings revealed disorganisation and sloughing of the epithelium, and association of mycoplasmas only with the cilia. Following repeated in vitro passages, the organisms had reduced ability to inhibit ciliary activity which correlated with decreased hydrogen peroxide production. Addition of catalase to the organ cultures delayed loss of ciliary activity. These results suggest that M. ovipneumoniae induced ciliostasis in ovine tracheal ring explants which correlated with hydrogen peroxide production. Furthermore, these M. ovipneumoniae-induced injuries to respiratory epithelial cells could contribute to the role that this organism may play in sheep respiratory disease.

Colonic nitrite and immunoglobulin G concentrations in dogs with inflammatory bowel disease

OBJECTIVE

To evaluate lavage analytes as markers of mucosal inflammation in healthy dogs and dogs with inflammatory bowel disease (IBD).

DESIGN

Case control study.

ANIMALS

9 healthy dogs and 10 dogs with IBD.

PROCEDURE

A polyethylene glycol electrolyte solution was administered into the dogs colons via a rectal balloon catheter prior to colonoscopy. Lavage solution was allowed to remain intraluminally for 30 minutes and then was withdrawn. Lavage supernatant samples were immediately analyzed for total protein, IgG, and nitrite concentrations and myeloperoxidase activity. Mucosal biopsy specimens were obtained from the descending colon and histologically reviewed.

RESULTS

All dogs with IBD had mild to severe lymphocytic-plasmacytic colitis, whereas 8 of 9 healthy dogs did not have substantial mucosal inflammation. Myeloperoxidase activity was not detected in lavage samples from healthy dogs or dogs with IBD. Total protein concentration was not significantly different between groups. Mean nitrite and IgG concentrations were significantly higher in samples from dogs with IBD (1.83 nmol/ml and 46 mg/dl, respectively), compared with samples from healthy dogs (0.245 nmol/ml and undetectable concentrations, respectively). Severity of lesions was not correlated with nitrite or IgG concentration.

CLINICAL IMPLICATIONS

Assay of nitrite and IgG concentrations in colonic lavage fluid is a simple, objective means of evaluating mucosal inflammation in dogs with IBD. Potential uses include monitoring response to treatment and evaluation of complex cases of chronic intestinal inflammation.

Aspergillus fumigatus keratitis with intraocular invasion in 15-day-old chicks

Eye infections were initially observed in single-comb white leghorn breeder chicks at 5 days of age, and morbidity increased from 0.05% to 1.5% after debeaking at 7 days of age. All chicks necropsied at 15 days of age had cheesy yellow exudate within the conjunctival sac of one eye and small (1 mm diameter) white nodular lesions in lungs and on thoracic air-sac membranes. Histopathologic examination of the eyes revealed septate fungal hyphae and inflammatory cells in the anterior chamber, cornea, and conjunctival sac. Similar fungal hyphae were present within lung granulomas. Aspergillus fumigatus was isolated from the eyes. Eye infections were the only health problem reported for several consecutive flocks on this farm. Elimination of moldy feed from the diet and environment and proper management of sawdust litter have prevented fungal ophthalmitis in subsequent flocks.

Histomorphologic features of the nasal cavity of pigs exposed to Pasteurella multocida type-D dermonecrotic toxin

Microscopic examination of the nasal mucosa of clinically normal specific-pathogen-free pigs and of toxicogenic type-D Pasteurella multocida toxin challenge-exposed specific-pathogen-free pigs indicated that the surface epithelium in pigs of both groups was microscopically normal; erosions or appreciable inflammatory changes were not evident. In pigs of both groups and in all 3 regions of the nasal cavity, the endothelial lining of all blood vessels appeared normal without detectable changes to the walls at postinoculation day 10. Vascular injury in the cartilage or the bone was not discernible in control or challenge-exposed pigs. There were marked differences in the osseous structures of the conchae when the 2 groups were compared. In control pigs, active bone formation and remodeling were observed, and the septal cartilage was normal. In toxin challenge-exposed pigs, there likewise was normal bone formation and remodeling in the vestibular region, and the septal cartilage was normal. In marked contrast, conspicuous changes were observed in the osseous core of the conchae of the respiratory and, sometimes, the olfactory regions. These changes consisted of bone necrosis and resorption by large numbers of osteoclasts with variable replacement by dense mesenchymal stroma, which resulted in conchal atrophy. In the absence of any discernible damage or injury (angiopathy) to the nasal vessels, it appears that the action of the dermonecrotoxin of P multocida serotype D is on the most active osteoblasts and the associated organic matrix of the bone, with subsequent disruption of normal bone formation and remodeling of the nasal conchae.

Growth hormone concentrations in plasma of healthy pigs and pigs with atrophic rhinitis

Plasma concentrations of porcine growth hormone (PGH) were similar in healthy pigs and those with atrophic rhinitis (AR), therefore, observed reduced growth rates and feed efficiency in naturally infected pigs with AR were not attributed to low concentrations of plasma PGH. Also, pituitary glands in both groups of pigs were responsive to growth hormone-releasing hormone (GHRH) challenge by increasing PGH secretion. Administration of clonidine hydrochloride to pigs naturally infected with AR failed to elicit any significant change (5.3 +/- 1.4 ng/ml) in the plasma concentration of PGH within a 45-minute bleeding interval. The pretreatment concentrations of PGH were similar in specific-pathogen-free toxin-treated and specific-pathogen-free control groups, but they increased significantly in toxin-treated pigs (20.7 +/- 8.2 ng/ml) within 15 minutes after GHRH injection. Porcine growth hormone release in toxin-treated pigs was variable; however, all pigs did not respond to GHRH administration: 3 responded with an increase in PGH release (35.6 +/- 10.6 ng/ml), 2 did not respond (6.7 +/- 0.5 ng/ml), and 1 had a decrease in PGH release (3.9 ng/ml). Therefore, the observed reduced growth rates reported in the literature may be attributed to factors at the target level of PGH action, such as insufficient or down-regulation of PGH receptors, changes or impaired ability in the PGH receptor-binding characteristics, and inability of PGH receptor complex to transduce signal. Toxins are known to modulate signal transduction pathways. It has been speculated that serotype-D Pasteurella multocida toxin may influence growth by its effect on signal transduction from PGH receptor complex on the cell membrane to the interior of the cell.(ABSTRACT TRUNCATED AT 250 WORDS)

Ocular manifestations of a metastatic pulmonary adenocarcinoma in a cat

A primary pulmonary bronchogenic adenocarcinoma originating from an intramediastinal accessory lung was diagnosed in a 14.5-year-old cat. The cat had been admitted because of a cloudy right eye. Physical examination revealed a thin cat with severe iritis, aqueous flare, and a fibrin clot in the anterior chamber of the right eye. Right fundic examination revealed bullous retinal detachment superior to the optic disc. Euthanasia and necropsy were requested when FeLV test results were positive. Metastatic neoplastic cells similar to those of the primary tumor were detected in the choroid, ciliary body, and ciliary processes of the right eye. Ciliary and iridic stromal necrosis attributable to neoplastic embolization of uveal vessels had led to severe uveitis. Foci of metastasis were also in the heart, kidney, and cerebral meninges.

Intracardiac rhabdomyosarcoma in a dog

Intracardiac rhabdomyosarcoma was diagnosed in a 14-month-old Golden Retriever referred for evaluation of syncope. The dog was weak, with irregular heart rate, pulse deficit, heart murmur, and hepatomegaly. Thoracic radiography revealed generalized cardiomegaly, and electrocardiography revealed sinus rhythm with multiform ventricular premature complexes and intermittent ventricular tachycardia. Two-dimensional echocardiography revealed extensive soft-tissue density masses in both ventricles. An intracardiac neoplasm seen at postmortem examination was identified histologically as rhabdomyosarcoma, an uncommon intracardiac tumor in dogs.

Pathologic, hematologic, and serologic changes in rabbits given T-2 mycotoxin orally and exposed to aerosols of Aspergillus fumigatus conidia

The influence of immunosuppression by T-2 mycotoxin on the fungal disease aspergillosis was investigated in rabbits. Four groups of rabbits (groups 1A, 1B, 3A, and 3B) were given 0.5 mg of T-2 toxin/kg of body weight/day, PO; in addition, rabbits of groups 3A and 3B were exposed to aerosols of Aspergillus fumigatus conidia from days 7 through 16. Rabbits of groups 2A and 2B were exposed to A fumigatus aerosols, but were not given T-2 toxin, and rabbits of group 0 served as controls. Two rabbits of group 1A, 1 rabbit of group 1B, and 1 rabbit of group 3A died before scheduled necropsy. Rabbits of groups 1A, 2A, and 3A were killed and necropsied on day 17, and the remaining rabbits (groups 0, 1B, 2B, and 3B) were killed and necropsied on day 28. Changes caused by T-2 toxin included leukopenia, marginal anemia, and increased number of and morphologic changes in nucleated erythrocytes by day 21, followed by a regenerative hematologic response. Serum alkaline phosphatase and sorbitol dehydrogenase activities and antibody response to A fumigatus (as measured by an indirect hemagglutination test) were decreased by T-2 toxin ingestion. Rabbits with aspergillosis had leukocytosis, increased PCV, and increased antibody response to A fumigatus. Histologic lesions consisting of centrilobular hepatocellular swelling, portal and periportal fibrosis, and lymphocyte necrosis and/or depletion within secondary lymphoid tissue were observed in most rabbits treated with T-2 toxin. Normal defense mechanisms against A fumigatus infection were compromised by T-2 treatment, as evidenced by the severity and extent of lung lesions, greater number of hyphal elements observed, and greater number of colonies of A fumigatus isolated from rabbits of groups 3A and 3B. There were no significant changes in group-0 rabbits.

Effects of T-2 mycotoxin ingestion on phagocytosis of Aspergillus fumigatus conidia by rabbit alveolar macrophages and on hematologic, serum biochemical, and pathologic changes in rabbits

Rabbits were given T-2 mycotoxin orally at 0, 0.25, 0.5, and 0.75 mg/kg of body weight/day for 21 days. Only rabbits in the 0.75 mg/kg/day group (4 of 5 rabbits) died. Alveolar macrophages were harvested on day 22 and used for in vitro phagocytosis of killed Aspergillus fumigatus conidia. Cultures included sera from untreated rabbits or rabbits treated with T-2. Phagocytosis was significantly (P less than 0.01) reduced in cultures that used serum from rabbits treated with 0.5 mg of T-2/kg/day and alveolar macrophages from untreated rabbits or rabbits treated with T-2. There was little reduction in phagocytosis when alveolar macrophages from rabbits treated with T-2 and normal serum were used. Ingestion of 0.5 mg of T-2 toxin/kg/day significantly (P less than 0.05) reduced weight gain, serum alkaline phosphatase activity, serum sorbitol dehydrogenase activity, and serum bacteriostasis. Similar changes were found in the 0.75 mg/kg/day group, as well as a significant (P less than 0.05) reduction in PCV, total WBC, and differential leukocyte counts. Neutrophil counts decreased, but not significantly (0.05 less than P less than 0.10). Significant changes were not detected in alanine transaminase activity, aspartate transaminase activity, blood urea nitrogen concentration, or complement hemolytic activity. Histopathologic changes consisting of centrilobular hepatocellular swelling, mild portal and periportal fibrosis and lymphocyte necrosis within secondary lymphoid tissues developed in most rabbits treated with T-2. Thymic atrophy, bile duct reduplication, and lymphocyte depletion of secondary lymphoid tissues developed in the group given 0.75 mg/kg/day.(ABSTRACT TRUNCATED AT 250 WORDS)

Blindness in a dog with IgA-forming myeloma

A 9-year-old dog with a 2-month history of weight loss and a 1-week history of blindness had an IgA-forming myeloma. Seemingly, the blindness was a result of bilaterally detached retinas. The dog also had leukopenia, anemia, hypoalbuminemia, hyperglobulinemia, and proteinuria as well as lytic lesions in the cervical portion of the spine and high IgA concentrations in serum and urine. Evaluation of aspirates from the subretinal spaces revealed lymphocytes in a proteinaceous fluid. Histologically, retinal lesions consisted of vascular endothelial cell damage and intraretinal cysts and hemorrhages.

Effects of intramuscular injections of selenium and vitamin E on selenium-vitamin E deficiency in young pigs

Effects of intramuscular injections of selenium and vitamin E on lesions in pigs with selenium-vitamin E deficiency syndrome were determined in 2 factorial experiments, using a total 69 pigs. The pigs were fed a selenium-vitamin E deficient, 22.3% protein ration, supplemented with methionine, minerals, and vitamins. Weekly intramuscular injections of isotonic saline solution, vitamin E, selenium, or vitamin E and selenium were given to the respective treatment groups. Selenium-vitamin E deficiency lesions occurred only in pigs that were given saline injections. Weekly intramuscular injections of either selenium (as selenous acid buffered to pH (7.3) at the rate of 0.05 mg/kg of body weight or vitamin E at the rate of 20 IU/kg of body weight or the combination of selenium and vitamin E prevented cardiac and skeletal myodegeneration, hepatic necrosis, and death. Significant increases of serum aspartate aminotransferase activity values were noted in pigs with liver, heart, or skeletal muscle lesions, but these increases were not correlated with the extent of the lesions. Vascular lesions, epicardial and endocardial hemorrhages, and yellow discoloration of body fat were not features of this experimentally induced disease. These lesions may be related to factors other than the deficiency of selenium, vitamin E, or selenium and vitamin E in rations previously used in reported studies.