Meningothelial hamartoma on the forehead of a young cat.

A 1 year and 2-months-old neutered male cat underwent surgical resection of a cutaneous nodule on the midline of the forehead that had been present since approximately 6 months of age. Histopathologically, the nodule was composed of interlacing collagenous fibres interspersed with varying numbers of spindloid cells with round to oval nuclei and moderate to abundant amounts of pale eosinophilic cytoplasm. Similar to meningothelial cells, the spindloid cells were immunopositive for vimentin, neuron-specific enolase, E-cadherin and somatostatin receptor 2. Based on these findings and the absence of nuclear atypia and mitotic figures, the nodule was diagnosed as meningothelial hamartoma. Although cases of cutaneous meningioma have been reported, this is the first report of meningothelial hamartoma in a domestic animal.

Feline uterine carcinosarcoma infiltrated with osteoclast-like giant cells.

A 12-year-old female Himalayan cat underwent an ovariohysterectomy to remove an intra-abdominal mass. Histologic examination using immunohistochemical staining revealed that the mass was comprised of epithelial and mesenchymal components. Within the lesion, multinucleated giant cells (MGCs) were observed diffusely. MGCs were positive for vimentin and Iba-1 and negative for cytokeratin AE1/AE3 and CD204. In addition, MGCs were negative for Ki-67, indicating nonneoplastic cells. Osteoclast-like MGC (OLMGC) phenotype with tartrate-resistant acid phosphatase positivity was also seen. These findings suggested that the uterine tumor was carcinosarcoma with OLMGCs. Uterine tumors in humans, such as leiomyosarcoma and carcinosarcoma, with OLMGC infiltration, are well-known pathologic entities; however, they are rare in animals and to our knowledge, have not been previously reported in cats.

Benign Mixed Mammary Tumour with Hepatoid Gland Differentiation in a Dog.

A 10-year-old spayed female Shih Tzu underwent surgery to remove a tumour (8 mm diameter) in the right 4th mammary gland. Histopathologically, the tumour consisted of four different components: luminal epithelial cells, myoepithelial cells, cartilage and well-differentiated hepatoid gland-like cells. There were multiple nests composed predominantly of hepatoid gland-like tissue with a small number of tubules formed by luminal epithelial cells at the periphery, in which continuity between the two components was seen. Immunolabelling for cytokeratins (CK14, CK18 and CK19), p63 and α-smooth muscle actin clearly distinguished the neoplastic luminal epithelial, myoepithelial and hepatoid gland-like cells. The immunohistochemical phenotype of the hepatoid gland-like neoplastic cells was identical to that of normal hepatoid gland cells. Based on these findings, a diagnosis of benign mixed tumour of the mammary gland with differentiated hepatoid gland cells was made. To our knowledge, this is the first report of a canine mammary tumour with hepatoid gland differentiation.

Extraskeletal osteosarcoma associated with two different types of synthetic fibers derived from a surgical swab in a dog.

A 10-year-old spayed female Japanese Shiba Inu had an intraperitoneal mass that was excised surgically. The central area of the mass was composed of osteoblast-like neoplastic cells, osteoid, macrophages, and numerous fibers. The neoplastic cells showed nuclear atypia and many mitotic figures. Therefore, the central area of the mass was diagnosed as an extraskeletal osteosarcoma. The peripheral area of the mass was granuloma tissue with numerous fibers. The neoplastic and granuloma area included two types of fibers, which were identified as rayon and polyester by their morphological and staining characteristics. These fibers were consistent with those of commercial surgical swab, suggesting that the fibers may have been derived from retained surgical swabs at the time of ovariohysterectomy. Therefore, this lesion was considered an extraskeletal osteosarcoma associated with a retained surgical swab.

The immunohistochemical detection of peroxiredoxin 1 and 2 in canine spontaneous vascular endothelial tumors.

Peroxiredoxin (PRDX) is an antioxidant enzyme family with six isoforms (PRDX1-6). The main function of PRDXs is to decrease cellular oxidative stress by reducing reactive oxygen species, such as hydrogen peroxide, to H2O. Recently, it has been reported that PRDXs are overexpressed in various malignant tumors in humans, and are involved in the development, proliferation, and metastasis of tumors. However, studies on the expression of PRDXs in tumors of animals are limited. Therefore, in the present study, we immunohistochemically investigated the expression of PRDX1 and 2 in spontaneous canine hemangiosarcoma (HSA) and hemangioma (HA), as well as in selected normal tissue and granulation tissue, including newly formed blood vessels. Although there were some exceptions, immunolocalization of PRDX1 and 2 in normal canine tissues was similar to those in humans, rats, or mice. In granulation tissue, angiogenic endothelial cells were strongly positive for PRDX1 and 2, whereas quiescent endothelial cells in mature vessels were negative. Both PRDX1 and 2 were significantly highly expressed in HSA compared to HA. There were no significant differences in the expression of PRDX1 and 2 among the subtypes and primary sites of HSA. These results suggest that PRDX1 and 2 may be involved in the angiogenic phenotypes of endothelial cells in granulation tissue as well as in the behavior in the malignant endothelial tumors.

Familial adenomatous polyposis in dogs: hereditary gastrointestinal polyposis in Jack Russell Terriers with germline APC mutations.

Many hereditary disorders in dogs have equivalents in humans and thus attract attention as natural animal models. Breed predisposition to certain diseases often provides promising clues to explore novel hereditary disorders in dogs. Recently, cases of gastrointestinal (GI) polyps in Jack Russell Terriers (JRTs) have increased in Japan. In 21 affected JRTs, polyps were found in either or both the stomach and colorectum, with a predilection for the gastric antrum and rectum. Multiple polyps were found in 13 of 21 examined dogs, including 5 dogs with both gastric and colorectal polyps. Some dogs were found to have GI polyps at an early age, with the youngest case being 2.3 years old. Histopathologically, 43 of 46 GI polyps (93.5%) were diagnosed as adenomas or adenocarcinomas. Immunohistochemical analysis revealed cytoplasmic and nuclear accumulation of ß-catenin in the tumor cells. As in the case of human patients with familial adenomatous polyposis, all examined JRTs with GI polyps (n = 21) harbored the identical heterozygous germline APC mutations, represented by a 2-bp substitution (c.[462A>T; 463A>T]). The latter substitution was a non-sense mutation (p.K155X) resulting in a truncated APC protein, thus suggesting a strong association with this cancer-prone disorder. Somatic mutation and loss of the wild-type APC allele were detected in the GI tumors of JRTs, suggesting that biallelic APC inactivation was involved in tumor development. This study demonstrated that despite differences in the disease conditions between human and dog diseases, germline APC mutation confers a predisposition to GI neoplastic polyps in both dogs and humans.

Trimer form of tumor necrosis factor-related apoptosis inducing ligand induces apoptosis in canine cell lines derived from mammary tumors.

We evaluated the cytotoxic effect of isoleucine-zipper tumor necrosis factor-related apoptosis inducing ligand (izTRAIL) against cell lines, B101592, Cha, and C090115, derived from canine mammary gland tumors. These cells were derived from three dogs diagnosed with mammary adenoma or carcinoma. All three cells were positive for vimentin, while B101592 and C090115 were positive for cytokeratin (CK) AE1/AE3 and CK CAM5.2. Treatment with izTRAIL decreased the viability of the three cell lines. The proportion of annexin V+/propidium iodide- cells increased in all three cell lines after treatment with izTRAIL. Additionally, cell cycle analysis revealed that izTRAIL treatment increased the number of cells in sub-G1 phase. Moreover, izTRAIL treatment activated caspase-8 and caspase-3 and enhanced the levels of cleaved poly (ADP-ribose) polymerase. The cytotoxic effect of izTRAIL was mitigated upon co-treatment with caspase-8 or caspase-3 inhibitor. These results indicated that izTRAIL induces apoptosis in cell lines derived from canine mammary tumor, which was also previously reported in canine hemangiosarcoma cell lines. This suggested that canine tumor cells have conserved TRAIL receptors. This study will provide the basis for further studies on TRAIL receptors and TRAIL-related molecules.

Tumour necrosis factor-related apoptosis-inducing ligand induces apoptosis in canine hemangiosarcoma cells in vitro.

Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is an apoptosis-inducing cytokine that shows potential therapeutic value for human neoplasms, and is effective in some canine tumours; however, its potential for killing canine hemangiosarcoma (HSA) cells is unknown. Thus, we evaluated the proapoptotic effect of TRAIL in nine canine HSA cell lines. Cells (JuA1, JuB2, JuB2-1, JuB4, Re11, Re12, Re21, Ud2 and Ud6) were cultured with three recombinant human TRAILs (rhTRAILs): TRAIL-TEC derived from Escherichia coli, TRAIL-TL derived from mammalian cells and isoleucine zipper recombinant human TRAIL (izTRAIL) containing an isoleucine-zippered structure that facilitates trimerization. TRAIL-TEC did not decrease the cell viability in any of the cell lines tested, whereas the other two rhTRAILs effectively decreased the viability of all cell lines as assessed by the WST-1 assay. In canine HSA cells, izTRAIL induced apoptosis more effectively than TRAIL-TL. In JuB4, Re12, and Ud6 cells, izTRAIL increased the activation of caspase-3 and caspase-8 and caused poly (ADP-ribose) polymerase degradation. Moreover, izTRAIL treatment increased the proportion of Annexin V+/ Propidium iodide (PI)- apoptotic cells and nuclear fragmentation in izTRAIL-sensitive cells. These results show that rhTRAIL can induce apoptosis in canine HSA cells, but the sensitivity of TRAIL was different depending on the cell lines. Therefore, TRAIL could be an effective therapeutic agent against canine HSA, but the specific mechanism of resistance should be determined to clarify under what conditions this treatment would be most effective.

Lingual ganglioneuroma in a dog.

A mass was found at the base of the dorsum linguae of a male 11-year-old Labrador retriever. The tumor comprised of ganglion cells and Schwannian cells with Verocay bodies. The ganglion cells were positive for neuron-specific enolase, S-100, nerve growth factor receptor, and beta III tubulin. The Schwannian cells were positive for neuron-specific enolase, S-100, nerve growth factor receptor, and glial fibrillary acidic protein. The lingual mass was diagnosed as a ganglioneuroma. To our knowledge, there has been no previous report of a lingual ganglioneuroma in a dog.

Basal cell adenocarcinoma in the gland of the third eyelid of a brown bear (Ursus arctos).

The right third eyelid of an adult female brown bear (Ursus arctos) was swollen and removed. Histopathology revealed a tumor exhibiting proliferation with mild infiltration, consisting of multi-stratified glandular structures of the innermost laminal neoplastic cells and the basaloid neoplastic cells, and with eosinophilic thick basal lamina material around the glandular structures. Both types of neoplastic cells exhibited moderate anisokaryosis, and mitotic figures were observed in the basaloid neoplastic cells. The laminal neoplastic cells were cytokeratin (CK) 8/18-positive. In contrast, the basaloid neoplastic cells were CK14- and p63-positive, but α-smooth muscle actin- and calponin-negative. The case described herein is the first report of basal cell adenocarcinoma in the gland of the third eyelid of a bear.

Toxigenic Corynebacterium ulcerans isolated from a hunting dog and its diphtheria toxin antibody titer.

Toxigenic Corynebacterium ulcerans is a zoonotic pathogen that produces diphtheria toxin and causes a diphtheria-like illness in humans. The organism is known to infect and circulate among dogs, which can then transmit it to humans. Furthermore, previous studies have found that C. ulcerans is carried by wild animals, including game animals. In the present study, we tested hunting and companion dogs for the presence of toxigenic C. ulcerans and succeeded in isolating the bacterium from a hunting dog. Moreover, several hunting dogs had serum diphtheria antitoxin titers that were higher than the titers required for protection in humans, suggesting a history of exposure to toxigenic Corynebacterium strains. Notably, ribotyping, pulsed-field gel electrophoresis and tox gene sequencing demonstrated that the isolate from the hunting dog clustered with previously characterized C. ulcerans strains isolated from wild animals, as opposed to groups of isolates from humans and companion dogs. Interestingly, the wild animal cluster also contains an isolate from an outdoor breeding dog, which could have formed a bridge between isolates from wild animals and those from companion dogs. The results presented herein provide insight into the mechanism by which the zoonotic pathogen C. ulcerans circulates among wild animals, hunting and companion dogs, and humans.

Distribution patterns of Babesia gibsoni infection in hunting dogs from nine Japanese islands.

Canine babesiosis constitutes a major global veterinary medical problem caused by tick-borne hemoparasites Babesia gibsoni and Babesia canis. Babesia gibsoni induces more severe clinical signs and is mainly transmitted by the ixodid Haemaphysalis longicornis. In Japan, B. gibsoni is primarily found in the western districts, with few records in the eastern parts. The aim of the current investigation was to evaluate distribution patterns of B. gibsoni infection in 9 Japanese islands and peninsulas using direct microscopy and PCR. Therefore, 196 hunting dogs were randomly sampled during the period from March to September 2011. Ages and sexes of dogs were identified. Direct microscopy of Giemsa-stained blood smear revealed pear-shaped piroplasms of B. gibsoni in 3 (1.6%) dogs. PCR was done initially with the universal primer set (B18S-F and B18S-R) amplifying the 1,665-bp portion of the 18S rRNA gene, followed by the specific primer set (Bg18F1 and Bg18R2) amplifying 2,363-bp fragments of the same gene. Accordingly, 84 (42.9%) and 8 (4.1%) dogs were positive, respectively. The current investigation shows that canine babesiosis was recorded in all islands except for Sado Island, Atsumi Peninsula, and Tanegashima Island. The highest infection rate was detected in the main island of Okinawa, while the lowest was on Ishigaki Island. Both sexes were non-significantly infected. However, the diversity of infection in islands was significantly different (P < 0.05). Although B. gibsoni has been previously found in western and eastern Japan, the present work highlights the prevalence of infection in many Japanese districts, including islands and peninsulas, giving realistic data that can facilitate treatment and control.

Pathological and immunohistochemical findings of natural highly pathogenic avian influenza infection in tufted ducks during 2010-2011 outbreaks in Japan.

In the winter of 2010-2011, an outbreak of highly pathogenic avian influenza virus (HPAIV) infection occurred in wild and domestic birds in Japan. Tufted ducks were found dead in an urban area of Toyota City, Koriyama, Fukushima Prefecture. Two tufted ducks were examined histopathologically, immunohistochemically and molecularly. Gross findings included marked dark-red clotted blood in the pectoral muscles and multifocal hemorrhages on the serous membranes. Microscopically, non-suppurative meningoencephalitis, multifocal to coalescing pancreatic necrosis and severe pulmonary congestion were observed. HPAIV antigen was detected in the malacic areas, neuronal, glial and ependymal cells, pulmonary capillary endothelial cells and epithelium of pulmonary bronchioles, necrotic pancreatic acini and degenerated cardiac myocytes. The HPAIV isolate was genetically classified into clade 2.3.2.1 group A. The broad distribution of virus antigen in brain and pulmonary tissues associated with HPAIV spontaneous infection in tufted ducks might be useful in understanding its pathogenesis in nature.

Prevalence and diversity of Hepatozoon canis in naturally infected dogs in Japanese islands and peninsulas.

Canine hepatozoonosis is a worldwide protozoal disease caused by Hepatozoon canis and Hepatozoon americanum and is transmitted by ixodid ticks, Rhipicephalus and Amblyomma spp., respectively. H. canis infection is widespread in Africa, Europe, South America, and Asia, including Japan. The objective of this study was to study the distribution pattern and diversity of H. canis in naturally infected dogs in nine Japanese islands and peninsulas. Therefore, 196 hunting dogs were randomly sampled during the period from March to September 2011 and the ages and sexes were identified. Direct microscopy using Giemsa-stained blood smears revealed H. canis gametocytes in the peripheral blood of 45 (23.6%) dogs. Polymerase chain reaction (PCR) was performed on EDTA-anticoagulated blood, initially with the common primer set (B18S-F and B18S-R) amplifying the 1,665-bp portion of the 18S rRNA gene, and then with the specific primer set (HepF and HepR) amplifying about 660 bp fragments of the same gene. Based on PCR, 84 (42.9%) dogs were positive using the common primer and 81 (41.3%) were positive using the specific primer. The current investigation indicated that all screened areas, except for Sado Island and Atsumi Peninsula, were infected. Yaku Island had the highest infection rate (84.6% in males and 100.0% in females), while Ishigaki Island showed the lowest infection rates (8.3% in males and 17.7% in females). Both sexes were infected with no significant difference. However, diversity of infection among the surveyed islands and peninsulas was significantly different (P < 0.05). Although H. canis has previously been reported in dogs in Japan, the higher infection rate described in the current study and the diversity of infection in a wide range of islands strongly encourage prospective studies dealing with the prevention and treatment of the infection in dogs, as well as control of ticks.