Y. Akihara

Expression of Monocarboxylate Transporter 1 in Oral and Ocular Canine Melanocytic Tumors

Solid tumors are composed of a heterogeneous population of cells surviving in various concentrations of oxygen. In a hypoxic environment, tumor cells generally up-regulate glycolysis and, therefore, generate more lactate that must be expelled from the cell through proton transporters to prevent intracellular acidosis. Monocarboxylate transporter 1 (MCT1) is a major proton transporter in mammalian cells that transports monocarboxylates, such as lactate and pyruvate, together with a proton across the plasma membrane. Melanocytic neoplasia occurs frequently in dogs, but the prognosis is highly site-dependent. In this study, 50 oral canine melanomas, which were subdivided into 3 histologic subtypes, and 17 ocular canine melanocytic neoplasms (14 melanocytomas and 3 melanomas) were used to examine and compare MCT1 expression. Immunohistochemistry using a polyclonal chicken anti-rat MCT1 antibody showed that most oral melanoma exhibited cell membrane staining, although there were no significant differences observed among the 3 histologic subtypes. In contrast, the majority of ocular melanocytic tumors were not immunoreactive. Additionally, we documented the presence of a 45-kDa band in cell membrane protein Western blots, and sequencing of a reverse transcriptase polymerase chain reaction band of expected size confirmed its identity as a partial canine MCT1 transcript in 3 oral tumors. Increased MCT1 expression in oral melanomas compared with ocular melanocytic tumors may reflect the very different biology between these tumors in dogs. These results are the first to document canine MCT1 expression in canine tumors and suggest that increased MCT1 expression may provide a potential therapeutic target for oral melanoma.

Intussusception of the spiral colon associated with fibroserous granulation in a heifer

MECHANICAL obstruction to the passage of intestinal contents can be caused by a luminal mass, an intrinsic lesion of the bowel wall or extrinsic compression (Kohn 1992). Such obstructions may be induced by factors including intussusception, volvulus, adhesions or hernias (Pearson 1973, Robertson 1979, Van der Velden 1984). Intussusception involves the invagination of the gastrointestinal tract into the lumen of the adjacent segment of the intestine (Pearson 1971). In adult cattle and human beings, the cause of intussusception seems to be intraluminal or intramural lesions such as papillomas, abscesses, parasitic nodules or tumours, since intramural or intraluminal growths or masses have often been observed within intussusceptions (Bosshart 1930, Maldonado and others 2004). However, Pearson (1971) reported that only two of 15 cases of intussusception in cattle were found to have predisposing lesions. However, almost all such cases described in the literature were adult cattle affected in the small intestine. Since this finding has been attributed to the length and mobility of the jejunal mesenteric attachments, Constable and others (1997) suggested the possibility that a remnant of the yolk sac and yolk stalk located near the intussusception might act in a similar way to an intramural mass and facilitate the development of the intussusception. Intussusception of the colon has only rarely been reported in cattle (Hamilton and Tulleners 1980, Strand and others 1993). Hamilton and Tulleners (1980) described a 10-monthold heifer with intussusception of the spiral colon accompanied by signs of colic for 18 hours before presentation. The heifer recovered after the lesion was reduced by gentle traction. Strand and others (1993) reported the apparent lack of either a detectable predisposing lesion or an abnormality of the mesenteric sheet in a three-year-old bull at postmortem examination. The bull had no history of colic, but the intussusception in its colon was highly necrotic and covered with fibrin deposits; these authors considered that the owner had not noticed that his bull had colic. To the authors’ knowledge, there are no reports confirming a predisposing lesion in cases of intussusception of the colon. This short communication describes a secondary intussusception due to a thickened spiral colon, complicated by diarrhoea, in a heifer. On April 21, 2004, a four-month-old Holstein heifer weighing 89 kg presented with signs of hypodynamia, reduced appetite, distention of the hypogastrium and green, mucosanguineous diarrhoea. Its heart rate was 96 bpm, its respiratory rate was 20 breaths/minute, and its rectal temperature was 38·4°C. Haematological and serum biochemical analyses, made on the fourth day after presentation, indicated severe hypoproteinaemia and anaemia (Table 1). The animal’s condition progressed to dysentery with mucus being passed on the fifth day after presentation. Coccidial oocysts and whipworm eggs were detected in the faeces by coprological examination on days 2 and 13. No rotavirus, coronavirus or Salmonella species was detected in the faeces, and bovine viral diarrhoea virus could not be detected in the peripheral blood mononuclear cells on day 14. Three to 6 kg/100 g bodyweight/day of anthelmintic (Daimeton; Daiichi Pharmaceutical) were administered orally for 18 days to treat the parasitic infection and indirect transfusion, using whole blood from three donors, was carried out on days 6, 13 and 15 by intravenous administration, because of the heifer’s severe anaemia. To avoid any possibility of producing an agglutination-haemolysis reaction before the indirect transfusion, matching tests were carried out by mixing a sample of the serum of the recipient with the blood cells of the three donors. The heifer gradually became unable to get to its feet readily on day 18. It produced progressively smaller amounts of faeces, and showed progressive abdominal distension on day 21, and finally dysstasia on day 22. As the heifer failed to improve and because its prognosis was poor, it was euthanased and examined postmortem on day 23. Postmortem examination revealed distension of the proximal colon to the central flexure of the colon, and an adhesion between the dorsal sac of the rumen and the spiral loop of the colon. Examination of the distended region revealed an intussusception impacted into the spiral loop of the colon, beginning 50 cm distal from the proximal loop of the colon. The intussuscipiens occupied approximately 40 cm adjacent to the centripetal gyrus of the spiral loop. Transverse sections of the intussusception revealed that the walls of the intussuscipiens were fully dilated and the serosa of the intussusceptum was severely thickened (Fig 1). The lumen between each mucomembranous aspect was severely stenosed, and the mural lesion of the intussusceptum aspect was severely compromised and covered with a granulating, gangrenous layer. The mural gangrene was more severe at the distal invagination than at the proximal invagination of the intussusception. The intestine cranial to the intussusception was markedly distended with gas, a little fluid and ingesta. After the postmortem examination, tissue specimens from the intestine were fixed in 10 per cent neutral-buffered formalin and embedded in paraffin, and thin sections (4 μm) were stained with haematoxylin and eosin for microscopic examination. Histological examination of the intussusceptum revealed severe fibroserous hyperplasia with granulation tissue in the lamina subserosa (Fig 2a), and effusions of fibrin were sometimes found under the adjacently apposed serous Veterinary Record (2007) 160, 376-378

Mycotic aneurysm in the aortic arch of a horse associated with invasive aspergillosis

AN aneurysm is a localised, abnormal dilation of any vessel. Aneurysms are most important when they affect the aorta in human beings and domestic animals (Robinson and Maxie 1993, Derksen and others 1998). In the horse, various lesions have been described in the aorta, including the formation of a dissecting aortic aneurysm (Holmes and others 1973, Shirai and others 1999), a ruptured aneurysm (Rooney 1979, Roby and others 1986) and a verminous aneurysm (Greatorex 1977), but reports of a mycotic aneurysm in the horse are uncommon. Mycotic aneurysms of the aorta caused by fungi are rare, and are frequently associated with a poor prognosis, as the diagnosis is usually based on an insidious presentation in human beings (Silva and others 2000). This short commu-nication describes a case of a horse with a mycotic aneurysm of the aortic arch caused by

Small intestinal volvulus in a captive Steller sea lion (Eumetopias jubatus)

INTESTINAL obstruction is by far the most common cause of digestive disease in all species (Catherrine 1992). Obstruction can be induced by volvulus, torsion, hernias, strangulation or intussusception (Barker and others 1993). Volvulus has been widely reported in small and large domesticated animals (Andrews 1970, Todd and others 1977, Curtis 1988, Katiyar and others 1988, West and others 1988, Catherrine 1992, Barker and others 1993, Kemble and others 1994, Theyse and others 1998); it has resulted in different clinical presentations, depending on the segments and amounts of bowel involved (Catherrine 1992).Steller (northern) sea lions (

Medullary Sponge Kidney in a 10-Year-Old Shih Tzu Dog:

Medullary sponge kidney was diagnosed in a 10-year-old male Shih Tzu dog with a long history of hyposthenuria, but with no other findings indicating renal failure or hormonal aberration. At the dogs death from heart failure, an autopsy was performed. On gross morphology, bilateral kidneys were normal size and had many cysts ranging from the corticomedullary junction to renal papillae. Histopathologic findings showed that almost all of the cysts were lined by monolayered or multilayered and columnar or cuboidal epithelium with chilium similar to epididymis. immunohistochemically, all of these cells were strongly positive for AE1/AE3 and negative for vimentin. Many of these cells were positive for cytokeratin 7 (CK7), and only a few cells were positive for desmin. The results of staining are the same as those for epithelium of the collecting duct of normal canine kidney. This is the first report of this pathologic entity in the canine kidney.