Correlations between presence of spontaneous lesions of the pituitary (adenohypophysis) and plasma prolactin concentration in aged Wistar rats.

The predictive value of elevated plasma prolactin concentrations for the presence of spontaneous pituitary lesions was studied in 40 male and 38 female Wistar (Cpb:WU) rats, all 30 months old. The pituitaries were examined light microscopically and stained for prolactin using immunohistochemical methods. Plasma prolactin concentrations were measured by radioimmunoassay. Pituitary lesions were classified on the basis of their morphology in hematoxylin and eosin-stained sections as foci of hypertrophic or hyperplastic cells and hemorrhagic, pleomorphic, or spongiocytic adenomas; no carcinomas were found. There were significantly (P = 0.001) more female than male rats with pituitary adenomas (58% females, 33% males) or without any pituitary lesions (21% females, 5% males); however, there were less female (21%) than male rats (63%) with foci of hyperplastic and/or hypertrophic cells but no adenomas in the pituitary (P = 0.001). Elevation of plasma prolactin concentration above the upper 99th percentile value in age-matched rats without lesions was predictive, but not conclusively, of the presence of pituitary hemorrhagic adenomas in both sexes. It was, however, not predictive of the presence of foci of hypertrophic or hyperplastic cells. Elevation of plasma prolactin concentration above 10 ng/ml in male and 60 ng/ml in female rats was conclusive for the presence of hemorrhagic adenomas. Using multivariate analysis, significant positive correlations (P less than 0.01) were found between plasma prolactin concentration and presence and size of hemorrhagic adenomas and their prolactin staining intensity (correlation coefficients between 0.392 and 0.652). Foci of hyperplastic cells stained positively for prolactin, whereas hypertrophic cell foci and pleomorphic and spongiocytic adenomas did not stain for prolactin. There were no correlations (coefficients of less than +/- 0.189) between plasma prolactin concentration and the presence of hypertrophic or hyperplastic cell foci and pleomorphic or spongiocytic adenomas in the pituitary. The morphologic criteria developed to distinguish spontaneous hypertrophic, hyperplastic, and neoplastic lesions of the rat pituitary corresponded well with their prolactin immunoreactivity and/or ability to elevate plasma prolactin concentration. These criteria constitute a biologically meaningful classification system for these rat pituitary lesions.     

Prevalence of gastric ulcers in endurance horses--a preliminary report

Gastric endoscopy was performed at the end of a 50 or 80 km endurance ride. Gastric ulceration was evident in 67% of the horses with ulcers on the squamous region of the stomach found in 57% of the horses and active bleeding of the glandular mucosa in 27%. Three horses (10%) had lesions only on the glandular mucosa. Values of albumin, creatinine and glucose were higher in horses without gastric lesions. We conclude that horses from endurance competitions have a high prevalence of gastric ulceration that is similar to that observed in performance horses. However the severity of ulceration is less severe than has been reported in Thoroughbred race horses in active training. Owners should be aware of the high prevalence of gastric ulceration in horses that perform in endurance competitions. The high incidence of active bleeding from the glandular mucosa of the stomach in these horses requires further investigation.     

Campylobacter-like organisms isolated from gastric mucosa of ferrets

Campylobacter-like organisms (CLO) were isolated from gastric lesions in 1 ferret and gastric mucosa of 2 healthy ferrets. The organism was not isolated from biopsies of gastric mucosa of 14 other healthy ferrets, 1 of which had small gastric lesions located at the pylorus. Lesions from which CLO were isolated were located in the antrum of 1 ferret and were classified as inflammation with repair. Affected gastric tissue was highly vascularized with fibrous connective tissue surrounding irregularly shaped glands. Necrosis and ulceration of adjacent mucosa also were observed. Using Warthin-Starry stain, Campylobacter-like organisms were seen on and in the glandular epithelium of the ferret with gastric lesions from which CLO were isolated.     

Pathomorphological study on gastroduodenal ulceration in horses: localisation of lesions

Gastroduodenal ulceration is a prevalent disease in foals and adult horses. Decreased performance as well as fatal complications relate to this syndrome. The objective of our study was to determine the prevalence of gastric ulceration in a mixed population of horses by postmortem examination and to evaluate a possible association between equine gastric ulcer syndrome (EGUS) and sex or age of the examined horses, to evaluate the localisation of lesions in the proximal part of the gastrointestinal tract and to determine the occurrence of gastric parasites. Postmortem examinations were performed on 71 horses over a period of 24 months. Gastric ulcers were found in 52 horses (73.2%). There was no significant association between age or sex and occurrence of gastric ulcers. In all horses the squamous mucosa lesions were localised near the margo plicatus (100% of the cases), whereas in 23 horses the lesions were near the margo plicatus and lesser curvature and in 7 horses at the greater curvature. In 18 horses the mucosa was affected in the whole extent of the margo plicatus and in 1 horse diffuse lesions of the squamous mucosa were noted. Lesions of the glandular mucosa were localised in 11 horses at the fundic area, in 1 horse they occurred in the pylorus, and in 10 horses diffuse lesions of the glandular mucosa were recorded. A low prevalence of Gasterophilus intestinalis infection was detected (1 horse, 1.4%). We have confirmed that gastric ulcers are a common problem in horses and duodenal or oesophageal ulceration is rare (not a single case of the latter was found in this study). Lesions in the glandular mucosa of the stomach are more frequent in suckling foals than in older animals. Lesions of the glandular mucosa are also common in adult horses, and a complete gastroscopic examination including examination of the pylorus is advisable to evaluate this syndrome.     

Validation of a transendoscopic glandular and nonglandular gastric biopsy technique in horses

Reasons for performing study: In order to study the evolution of histopathological and immunohistochemical changes in the gastric mucosa of horses with EGUS (equine gastric ulcer syndrome), a feasible, useful, valid and safe in vivo gastric biopsy technique is required. Objectives: To determine the average gastric mucosal healing time following endoscopic gastric biopsy sampling, and evaluate the feasibility, safety and usefulness of samples obtained by this method for histopathological analysis. Methods: Six mature mares from the Faculté de Médecine Vétérinaire research herd were used. Transendoscopic gastric biopsy was performed on Days 0 and 9 using a flexible forceps with oval and fenestrated jaws to obtain gastric mucosal samples from 4 different sites: cardia (C), fundus (F), margo plicatus (MP) and glandular mucosa (GL). A maximum of 4 samples per site was taken and processed routinely for histopathology, evaluated by a pathologist. On Days 1–4 and 9–11 the lesions created by the biopsies were evaluated by gastroscopy. Lesions were evaluated over time based on a score from 0–4, where 4 was the most severe. Results: Biopsy samples could be obtained from all targeted sites except C. No abnormal clinical signs were observed up to 7 days post biopsy. The average biopsy lesion scores decreased significantly with time for all sites. The average lesion score was significantly higher for the MP compared to the other sites at Days 1 and 2. Samples taken from the nonglandular portion of the stomach were considered inadequate for histopathology, while those taken from the glandular mucosa were adequate. Conclusion: The transendoscopic gastric biopsy technique described here is a feasible, safe and useful technique for obtaining samples from the equine gastric glandular mucosa. Although biopsy samples could be obtained from several areas in the nonglandular mucosa, these were very small, took longer to heal and were not considered adequate for histopathological evaluation, and another technique should therefore be validated.     

Endoscopic findings of the gastric antrum and pylorus in horses: 162 cases (1996-2000)

Medical records and endoscopy images were examined for 209 horses that had gastroscopic examinations performed with a 2.5- or 3-m-long endoscope by one of the authors (MJM) during a 4-year period (1996-2000). The antrum and pylorus were viewed in 162 horses, and the duodenum was viewed in 94 horses. Of these 162 horses, the gastric squamous mucosa was seen in 157 horses and 50% or more of the glandular mucosa of the body of the stomach was seen in 156 horses. Erosions or ulcers were seen in the gastric squamous mucosa in 91 (58%) horses. Erosions or ulcers were seen in the glandular mucosa of the body of the stomach in only 8% of the horses. Lesions consisting of erosion or ulceration were seen in the antrum or pylorus in 94 (58%) horses. Lesions consisting of hyperemia and a rough or "bumpy" appearance were seen in the mucosa of the duodenum of 16 horses. An association between the presence of lesions in the squamous mucosa and the presence of lesions in the mucosa of the antrum/pylorus was examined by Fisher's exact test, and the linear association of lesion severity scores between the squamous mucosa and the mucosa of the antrum/pylorus was tested using a Monte Carlo estimate for linear-by-linear association. There was no association (P = .88) between these sites for presence of lesions or lesion severity scores. Similarly, there was no association between scores for the glandular mucosa in the gastric body and those in the antrum/pylorus. Because of the high prevalence of lesions in the antrum and pylorus of the stomachs of adult horses examined in a hospital setting, the entire stomach should be viewed during a gastroscopic examination.     

Study on the role of gastric Helicobacter infection in gross pathological and histological lesions of the stomach in finishing pigs

The prevalence of gastric Helicobacter infection in finishing pigs and the influence of this infection on gastric lesions was studied. Stomachs of 89 finishing pigs from 27 randomly selected herds were sampled at the slaughterhouse. Forty cases (Group A) were selected based upon the presence of gross pathological lesions in the pars oesophagea, and further 49 cases were obtained at random (Group B). Three samples of gastric tissue (junction of pars oesophagea and pars cardiaca, fundic area, and pyloric area) were collected from each stomach for histological and immunohistochemical examination. Helicobacter antigen was detected in 76 cases (85.4%). No association was found between the presence of Helicobacter in the stomach and the occurrence of gross pathological lesions in the pars oesophagea or gastritis detected on histological examination. However, a significant association was found between the occurrence of Helicobacter in the pyloric area and the presence of erosions/ulcers in the pars oesophagea (OR: 7.01, p = 0.022) in Group B. A significant association was also evident between the presence of Helicobacter and glandular lesions (dilatation of the glands + glandular abscess + degeneration of glandular epithelial cells). In conclusion, Helicobacter infection seems to be a contributing factor to pathological changes in the stomach of finishing pigs.     

Giant hypertrophic gastritis (Menetrier's-like disease) in an Old English sheepdog

An 11-year-old, male Old English sheepdog was admitted for weight loss and intermittent vomiting of 1 month's duration. A cranioventral abdominal mass, anemia, hypoproteinemia, and hypoalbuminemia were the prominent abnormal findings. Imaging studies identified a remarkably thickened gastric wall with multilobulated folds protruding into the gastric lumen. Gastrotomy revealed the presence of giant cerebriform rugal folds arising from the fundus and body of the stomach. Pronounced gastric glandular hyperplasia and lack of evidence of cellular atypia were suggestive of giant hypertrophic gastritis. The dog was treated with prednisolone, cimetidine, and hyoscine butylbromide, only to experience a short-term remission.     

Morphological,morphometric and histochemical characterization of the gastric mucosa of the camel (Camelus dromedarius)

Mucosal morphology, morphometry and mucin histochemistry of the stomach were studied in the one-humped camel. The lining of the stomach was divided into eight grossly identifiable regions. The first region was non-glandular, occupied the body of the first compartment of the stomach and constituted 53.2% of the gastric mucosa. The other seven regions were lined by a glandular mucosa. Histological, histochemical and morphometric investigations have shown that glandular mucosa comprises pseudo-cardiac, cardiac, fundic and pyloric regions. The pseudo-cardiac region was characterized by widely separated short tubular serous glands. It constituted 36.2% of the gastric mucosa; it extended over the entire lining of the second compartment and parts of the first and third compartments. The cardiac region was confined to the initial zone of the third compartment amidst the psuedo-cardiac region but contiguous with the distal end of the gastric groove. It constituted 3.4% of the gastric mucosa and was characterized by neutral and acid mucin positive glands. The fundic and pyloric regions occupied the distal distended part of the third compartment. The fundic region constituted 4.3% of the gastric mucosa. It was packed with typical fundic glands characterized by chief cells, parietal cells and acid mucin positive neck cells. The pyloric region constituted 2.9% of the gastric mucosa. Its glands were positive to acid mucins except for their bases that were positive to neutral mucins. Differences in volume densities of the mucosal components and reactivity of the surface epithelium and gastric pits to mucin stains were noted in the different regions of the stomach.     

Gastric zygomycosis in a pig affected with postweaning multisystemic wasting syndrome--case report

A postweaning pig died in spite of antibiotic therapy showing wasting in a small herd. Postweaning multisystemic wasting syndrome (PMWS) was diagnosed on the basis of gross pathological and histological lesions and the presence of moderate amounts of porcine circovirus 2 (PCV2) antigen in tissue samples. Mycotic gastritis caused by Zygomycetes spp. was found on round areas with a diameter of 1 to 3 cm in the glandular mucosa of the stomach. Moderate amount of PCV2 viral antigen was detected almost evenly in the stomach and mostly in the macrophages. In addition, acute uraemia, revealed by an ammonia-like stink of the gastric mucosa and the presence of acute erosions on the glandular mucosa of the stomach, was observed as a consequence of PCV2-induced interstitial nephritis. Only PCV2 infection could be identified as a cause of secondary mycotic gastritis. The results further support the immunosuppressive ability of PCV2 infection in PMWS-affected pigs.     

Chronic flunixin meglumine therapy in foals

Effects of a therapeutic dose of flunixin meglumine on gastric mucosa of horse foals were determined by endoscopy, double-contrast radiography, and gross and histologic examinations. Foals were administered 1.1 mg of flunixin meglumine/kg of body weight, PO/day for 30 days in an encapsulated form that was divided into 2 doses/day (group 1; n = 3) or by IM injection once a day (group 2; n = 7). Three control foals (group 3; n = 3) were administered capsules (n = 1) containing dextrose powder or IM injections (n = 2) of vehicle solution without flunixin meglumine. All 3 groups-1 foals given flunixin meglumine PO developed oral ulcers. Group-2 foals given flunixin meglumine IM did not develop oral ulcers. One control foal (group 3) developed 1 oral ulcer that healed during the study. Endoscopic examination revealed linear crease-like mucosal lesions in the glandular portion of the stomach in 2 group-2 foals. Radiographic evidence of gastric ulcers was observed in only 1 gastrogram of a group-1 foal. Foals were euthanatized, and necropsy revealed erosions and/or ulcers of the glandular portion of the stomach. Oral ulcers were observed in all 3 group-1 foals. Erosions of the glandular portion of the stomach developed in all 10 foals given flunixin meglumine, but did not develop in group-3 foals. Ulceration of the glandular portion of the stomach was present in 1 group-2 foal.     

Ultrastructural Study on the Stomach of Tilapia spp (Teleostei)

An ultrastructural study has been made of gastric mucosa of a teleostean fish, Tilapia spp. The cytological features of the surface mucous cells, mucous neck cells, glandular cells and endocrine cells are described. The surface mucous cells, identified by their superficial localization, are characterized by apical granules. The mucous neck cells are distinguished by the appearance of their mucous granules and their localization between surface mucous cells and glandular cells. The gastric glands contain only one form of cell whose fine structure is similar to cells that secrete hydrochloric acid. Physiological implications of some ultrastructural features are also discussed.     

Changing cytokeratin expression patterns in diethylstilbestrol dipropionate-induced metaplastic lesions of the goat prostate.

Five-month-old male goats were treated with 25 mg diethylstilbestrol dipropionate (DES-DP) by a single intramuscular injection, causing characteristic histological alterations in the peripheral glandular epithelium of the prostate, resulting in squamous metaplasia. Using a panel of monoclonal and polyclonal cytokeratin antibodies on frozen tissue sections of control prostates, we were able to immunohistochemically distinguish between the normal secretory cells, which are positive for cytokeratin 18 as detected with the antibody RGE 53, and the scattered basal cells, which could be specifically stained by the antibody RCK 103. Cytokeratins indicating squamous differentiation, i.e., nos 4 and 13, recognised by the antibodies 6B10 and 1C7, respectively, were found in sporadic cells throughout the normal goat prostate. Profound changes in cytokeratin expression were observed in the metaplastic lesions as compared to control peripheral glandular tissue. In this respect three monoclonal antibodies are of special interest. RCK 103 is immunoreactive with resting and all stages of differentiating basal cells. Antibodies 1C7 and 6B10 strongly stain the squamous cells in the metaplastic lesions, with 1C7 staining all the squamous cells in the lesions except the basal cell layer, and 6B10 being immunoreactive with the same suprabasal cells or the more differentiated cells in the upper strata. As a result the number of cytokeratin 18-positive cells is drastically reduced upon metaplasia. The results indicate that the goat system can be used as a suitable model system to further test the applicability of immunohistochemical methods in meat inspection and toxicological pathology.     

Appearance of granulated cells in blood films stained by automated aqueous versus methanolic Romanowsky methods

Background: Romanowsky stains are used routinely by veterinary clinical pathology laboratories for cytologic and blood film evaluations. Automated stainers are available for both aqueous and methanolic Romanowsky stains. Mast cell granules and canine distemper virus inclusions are known to stain differently by these 2 methods, but we have noticed differences in the staining characteristics of other granulated cells. Objective: The aim of this study was to investigate and document the variable appearance of basophils and large granular lymphocytes in blood films stained using aqueous and methanolic Romanowsky methods. Methods: Cytologic preparations from 1 canine mast cell tumor and blood films from 8 dogs, 1 cat, 1 rabbit, and 1 ostrich were stained using an automated aqueous stain (Aerospray 7120, with and without a predip fixative) and an automated methanolic stain (Hematek). Staining quality and intensity of the cytoplasmic granules in mast cells, basophils, and large granular lymphocytes was evaluated subjectively. Results: Cytoplasmic granules of mast cells, basophils, and large granular lymphocytes stained poorly or not at all with the automated aqueous stain but stained prominently and were readily identified with the automated methanolic stain. Use of the predip fixative with the Aerospray method improved the visibility of basophil granules but not mast cell granules, and had a variable affect on the visibility of granules in large granular lymphocytes. Conclusion: Clinical pathologists should be aware of the staining methodology used on the slides they evaluate to avoid incorrect interpretation of granulated cell populations.     

Chronic gastroenterocolitis in nine cats.

Lesions of a chronic gastroenterocolitis were found in 9 cats of the Persian breed that were euthanized after a prolonged period of bloody diarrhea. Gross lesions consisted of gastrointestinal edema with prominent Payer's patches, multiple grayish nodules, and a few irregular erosions within the colonic mucosa. Microscopically, the changes were composed of degeneration, necrosis, and proliferation of gastric glandular epithelium, dilated intestinal crypts with lymphoplasmacytic cell infiltration of the lamina propria, and in 1 cat, severe transmural necrosis of the colon. With the Giemsa stain, spiral-shaped organisms in the gastrointestinal lumen and intracellularly in the gastric and the colonic epithelium were observed. These organisms could not be cultured. Although the role of these spiral-shaped organisms was not determined, other agents that could explain the disorder were not found.     

The effect of a pectin-lecithin complex on prevention of gastric mucosal lesions induced by feed deprivation in ponies

This study examined whether a product containing a pectinlecithin complex (Pronutrin) (1) could prevent gastric lesions induced in the equine gastric squamous epithelial mucosa using a protocol of intermittent feed deprivation that resulted in prolonged increased gastric acidity (Murray and Eichorn 1996). Eight ponies were used and served as their own controls in 2 trials in which there were 72 h cumulative deprivation (alternating 24 h with no feed, then 24 h free choice hay), with a 4-week interval between trials. Ponies were assigned randomly to receive either 250 g Pronutrin plus 200 g pelleted feed, or 450 g pelleted feed only. Ponies were conditioned to each treatment for 7 days and received Pronutrin and pellets or only pellets once daily during the feed deprivation protocol. Gastroscopy was performed at the beginning and conclusion of the feed deprivation protocol. The endoscopist (MJ.M.) was blinded as to treatments, and lesion severity was scored on a scale of 0-5. Gastroscopy revealed normal-appearing gastric mucosa at the beginning of feed deprivation, with the exception of 2 ponies which had focal squamous mucosal erosion and 1 pony with focal glandular mucosal erosion. After 72 h cumulative feed deprivation, each pony, except 1 pony in one of the trials, developed erosions or ulcers in the gastric squamous mucosa. There was no difference (P = 0.6) in the presence or severity of gastric lesions between treatments. Lesions did not develop in the gastric glandular mucosa as a result of the intermittent feed deprivation with either treatment. In this study, the pectin-lecithin complex in Pronutrin failed to prevent lesions in the gastric squamous mucosa induced by intermittent feed deprivation.     

Endoscopic appearance of gastric lesions in foals: 94 cases (1987-1988)

Of 183 foals examined by use of gastroendoscopy during 1987 and 1988, 94 had gastric lesions. Sixty-eight of 120 foals in the 1- to 85-day-old age range had endoscopically confirmed gastric lesions, and 26 of 63 foals in the 90- to 310-day-old age range had gastric lesions. Lesions were observed most frequently in the stratified squamous mucosal epithelium, particularly adjacent to the margo plicatus. Lesions were observed in the gastric glandular mucosa in 26 of the 94 foals with gastric lesions, and with a greater frequency in foals with a clinical disorder than in foals with no disorder (27% vs 3%). In young foals, lesions were consistently observed in the stratified squamous mucosal epithelium adjacent to the margo plicatus along the greater curvature of the stomach at 2 specific sites. These lesions were frequently associated with desquamation of the stratified squamous mucosal epithelium, which was observed in 69 of the 82 foals less than or equal to 30 days old and in 13 of the 101 foals greater than 30 days old. Lesions in the stratified squamous mucosal epithelium adjacent to the margo plicatus were associated with concurrent clinical disorders in foals greater than 90 days old, but developed with identical frequency in foals less than 90 days old with or without a clinical disorder. Lesions in the stratified squamous mucosal epithelium along the lesser curvature of the stomach were observed only in foals with concurrent clinical disorder, and with a higher frequency in foals greater than 90 days old than in younger foals (24% vs 3%).     

Small intestine large granular lymphoma in a horse

A 12-year-old Appaloosa gelding was referred to the Texas Veterinary Medical Center with a history of chronic diarrhea and weight loss. At necropsy, numerous oval, craterlike ulcers were observed throughout the small intestine. Histologically, these lesions were composed of a neoplastic proliferation of round cells with intracytoplasmic phosphotungstic acid-hematoxylin-positive granules. The tumor cells stained positively for the CD3 antigen and negatively for a B-cell marker. A diagnosis of large granular lymphoma was based on the morphologic and immunohistochemical characteristics of the neoplasm. The postmortem presentation of this case depicted unusual multifocal, ulcerative lymphomatous lesions throughout the small intestine without involvement of the regional lymph nodes. The histologic and ultrastructural morphology of the neoplastic lymphocytes was similar to that in previously reported cases of abdominal equine large granular lymphomas, but in this case the neoplasm was restricted to the small intestine.     

Pathological and immunohistochemical study of gastrointestinal lesions in dolphins stranded in the Canary Islands

This paper describes the gross, histopathological and immunohistochemical characteristics of gastrointestinal lesions and regional lymph nodes of six common dolphins (Delphinus delphis), 11 striped dolphins (Stenella coeruleoalba) and six Atlantic spotted dolphins (Stenella frontalis) found stranded along the coasts of the Canary Islands. The most common lesion was chronic granulomatous gastritis of the glandular stomach, associated with the parasite Pholeter gastrophilus, and characterised by the parasites, their eggs, or parasite debris in the mucosa, submucosa or tunica muscularis, surrounded by numerous lysozyme-positive macrophages and neutrophils, and more peripherally by abundant fibrous tissue containing variable numbers of immunoglobulin (Ig) G+ plasma cells, and small numbers of CD3+ T lymphocytes and IgM+ and IgA+ plasma cells. Anisakis simplex nematodes were found in two dolphins that were also parasitised by P gastrophilus and had parasitic granulomatous gastritis and multiple small chronic gastric ulcers. Lymphoplasmacytic enteritis was found in eight cases, three of them parasitised by Diphyllobothrium species; the lesion was characterised by moderate to severe infiltrations of CD3+ T lymphocytes and IgG+ plasma cells, with small numbers of IgM+ and IgA+ plasma cells in the lamina propria and submucosa, mainly of the small intestine. One dolphin had severe fibrinopurulent peritonitis, which may have been secondary to gastric perforation caused by the large mural granulomatous gastritis associated with P gastrophilus parasitism.     

Adenosquamous carcinoma of the oesophagus in a dog

A six‐year‐old mixed‐breed male dog weighing 7.0 kg was presented with chronic vomiting and regurgitation. Endoscopic examination revealed prominent oesophageal dilation in the thoracic region, multiple small greyish‐white nodules over the oesophageal lumen and cauliflower‐like masses in the caudal oesophagus. Histopathological studies revealed a characteristic pattern of coexisting elements of infiltrating adenocarcinoma and squamous cell carcinoma. Immunohistochemical staining with anti‐cytokeratin AE1 + AE3 was positive in both types of neoplastic cells. Neoplastic glandular cells stained positively for cytokeratin 8 while neoplastic squamous cells stained positively for cytokeratin 5/6. On the basis of these findings, the dog was diagnosed with oesophageal adenosquamous carcinoma. The case history and findings suggest that the malignancy might have developed from Barrett's oesophagus following irritation of the oesophageal mucosa due to chronic vomiting and regurgitation.