Spontaneous and bilateral necrosis of the femoral head in a young experimental beagle dog

This report describes the pathological characterizations of a rare case of necrosis of the femoral head that was spontaneous, bilateral, avascular and nontraumatic. A 14-month-old beagle dog was presented with pain in the hind limbs. At necropsy, the articular surface in the bilateral femoral head was markedly irregular. There were no gross abnormalities other than in the hip joints. Microscopically, a wide range of trabecular bone necrosis localized in the subchondral area was observed in both femoral heads. In the right femoral head, fibrosis and proliferative vessels were noted in the subchondral area. The articular cartilage was thickened irregularly, but there was no evidence of cartilage necrosis. The bone marrow adjacent to the affected area showed severe depression. In the metaphysis, atrophic bone marrow, but not bone necrosis, was observed. This was a rare case of spontaneous necrosis of the femoral head in an experimental beagle dog.     

Eosinophilic substance is "not amyloid" in the mouse nasal septum

An eosinophilic substance (ES) is usually observed in the mouse nasal septum and increases in volume with aging. It has been described as amyloid in textbooks and one report. However, it has been described as "not amyloid" in other reports because there was a negative reaction to Congo red. In this study, the ES was investigated histopathologically and electron microscopically to determine whether it was amyloid or not. The ES was only observed at the interstitium of clear HE-stained nasal glands in the septum, in which 2 kinds of glands were present (dark and clear stained by HE). The volume of the ES was small in young mice and large in older ones. Neither nasal gland degeneration nor inflammation resulted, even if a large amount of the ES was observed. The ES reacted negatively to Congo red but was strongly positive to periodic acid-Schiff reaction with prior diastase treatment. In the electron microscope observation, the ES consisted of amorphous material and collagen, but no nonbranching fibrils. Similar amorphous material was also observed in the nasal gland epithelial cells and was connected to the material in the rough endoplasmic reticulum. The above-mentioned findings indicated that the ES was not amyloid and suggested the ES might consist of not only collagen but also complex carbohydrate, which was produced by the nasal gland epithelial cells.     

Effect of isoflurane anesthesia on hemodynamics following the administration of an angiotensin-converting enzyme inhibitor in cats

The objective of this study was to evaluate the hemodynamics of the anesthetic isoflurane in healthy cats given angiotensin-converting enzyme inhibitor (ACEI). The 7 healthy young cats and 3 old cats were received placebo or enalapril 0.5 mg/kg orally. The change in systolic arterial pressure from the baseline to 30 min postanesthesia in the ACEI group was significantly higher than in the placebo group (mean +/- SD: -39 +/- 13% vs. -17 +/- 12%, respectively). The present study indicated that general anesthesia may induce hypotension after the administration of an ACEI.     

High incidence of the gullet worm, Gongylonema pulchrum, in a squirrel monkey colony in a zoological garden in Japan

Histological examination revealed the gullet worm (Gongylonema pulchrum) embedded in the lingual mucosa of two of four dead Bolivian squirrel monkeys (Saimiri boliviensis) from a zoological garden in Kyushu, Japan. The zoo had kept the monkeys as a colony of approximately 80-100 individuals in a moated, open ground since 1981. To assess the incidence of G. pulchrum infection in this colony, lingual scraping with disposable plastic sticks was conducted in February during 2 consecutive years (2003 and 2004). The oval, thick-shelled egg containing a larva was found in 15 of 27 arbitrarily-chosen adult monkeys (55.5%) in 2003, and 27 of 106 monkeys (25.5%) in 2004. Infection of other zoo-kept mammals with G. pulchrum was not assessed. Since the gullet worm infects a variety of mammals including primates as natural definitive hosts, and dung beetles and cockroaches as intermediate hosts, the zoological garden may provide an ideal environment for the parasite. Zoo veterinarians should be aware of this disease in kept mammals, and should consider in the case of primates, monthly or bimonthly prophylactic anthelmintic treatment.     

Carcinogenicity of biphenyl in mice by two years feeding

Carcinogenicity and chronic toxicity of biphenyl was examined in the male and female BDF1 mice fed a diet containing biphenyl at 667, 2,000 or 6,000 ppm for 2 years. There was no difference in survival rate between any biphenyl-containing diet-fed group of either sex and the respective control. Body weights of the males and females fed 6,000 ppm diet were significantly lower than the respective control. Incidences of hepatocellular carcinomas and hepatocellular adenomas in the females fed diets containing biphenyl were significantly increased in a dose-related manner, and exceeded a range of the historical control data in the Japan Bioassay Research Center. Incidences of basophilic cell foci in the liver were increased in the females fed 2,000 and 6,000 ppm diets. There was no increase in tumor or tumor-related lesion in the males fed diets containing biphenyl. Chronic toxicity of biphenyl was characterized by increased incidences of urothelial desquamation in the renal pelvis in males and females and mineralization in the inner stripe of renal outer medulla in females, as well as changes in serum levels of BUN, ALP and some electrolytes in males and females. In conclusion, the 2-year oral administration of biphenyl-containing diets induced pre-neoplastic and neoplastic lesions in the liver of females and non-neoplastic lesions in the kidney of males and females. Causative factors for the biphenyl-induced hepatocarcinogenicity were discussed in light of our published finding of peroxisome proliferation.     

Perirenal pyelocaliceal diverticulum in an infant cat

A 3-month-old female tortoise-shell cat showing azotemia died with a marked swollen abdomen. Necropsy revealed a huge perirenal cyst (8.5 x 6.0 x 4.5 cm) on the ventral aspect of the right kidney. The cyst was filled with the pellucid yellow fluid with a smell of urine. The lumen was connected with irregularly dilated renal pelvis by a narrow channel passing through the renal parenchyma. The cyst was lined by epithelial cells and its wall was consisted of collagen fibers and smooth muscle cells as that of the renal pelvis and ureter. Renal parenchyma adjacent to the channel showed interstitial infiltration of the lymphoid cells. The cyst was a diverticulum of the renal pelvis due to an impaired development.     

A novel immunohistochemical marker of normal and neoplastic melanocytes in formalin-fixed, paraffin-embedded tissues of albino rats

In albino rats, spontaneous occurrence of melanocytic tumors is rare, with diagnosis difficult. This study evaluated immunoreactivity for PNL2 in normal and neoplastic melanocytes in formalin-fixed and paraffin-embedded tissues of albino rats. The samples consisted of 11 (1.57%) amelanotic melanomas in 700 rats (2 studies), 23 non-melanocytic tumors, and a wide variety of normal tissues. In normal albino rats, PNL2 stained the melanocytes in the iris and choroid of the eyeball and the hair bulb and basal cell layers of the epidermis of the whole body. In amelanotic melanoma, the tumor cells consisted of spindle cells with eosinophilic cytoplasm without melanin granules. PNL2 consistently stained cytoplasm in all amelanotic melanoma cells. In contrast, the nonmelanocytic tumor cells were not labeled. Electron microscopically, neoplastic, and normal melanocytes showed numerous cytoplasmic premelanosomes (stage II melanosome). In conclusion, PNL2 is direct against a fixative- and decalcific-resistant melanocyte-associated antigen, and has high specificity against normal and neoplastic melanocytes of albino rats.     

Virulence characteristics of Yersinia pseudotuberculosis isolated from breeding monkeys in Japan

Between April 2001 and 2007, 18 Yersinia pseudotuberculosis outbreaks occurred in breeding monkeys at 12 zoological gardens in Japan, and 28 monkeys of 8 species died. A total of 18 Y. pseudotuberculosis strains from the dead monkeys, comprising one strain per outbreak, were examined for serotype and the presence of the virulence genes virF, inv, ypm (ypmA, ypmB and ypmC) and irp2. Of the 18 Y. pseudotuberculosis strains, 7 (38.9%) were serotype 4b, 7 (38.9%) were serotype 1b, and there was one each of serotypes 2b, 3, 6 and 7. All the 18 strains examined harbored virF and inv. Sixteen (88.9%) strains, including the strain of serotype 7, harbored ypmA. However, no strain harbored ypmB, ypmC and irp2.

This study demonstrated that among other pathogenic factors, almost all the Y. pseudotuberculosis isolated from the outbreaks had the ypm gene encoding the superantigenic toxin, YPM. As most of the monkeys who died in those outbreaks originated from South America and other regions, where the presence of the ypm gene have not been reported, YPM might be the cause, or at least the most important factor for, the high mortality of the breeding monkeys infected by Y. pseudotuberculosis in Japan. This is also the first report of a fatal case due to Y. pseudotuberculosis serotype 7 infection in the world.     

Intracranial meningioma with polygonal granular cell appearance in a Chihuahua

A menigioma with polygonal granular cell proliferation in an 11-year and 8-month-old male Chihuahua is described. The tumor was observed under the dura matter of the right cerebrum. Microscopically, the tumor consisted of solid growth foci of small- or large- sized polygonal cells, with pale-stained nuclei, prominent nucleoli, and fine granular to foamy eosinophilic cytoplasm. Some of the proliferating cells contained variable amounts of cytoplasmic PAS-positive granules. Immunohistochemical analysis revealed that neoplastic cells were positive for vimentin and S-100 protein. Ultrastructurally, the neoplastic cells contained vesicular structures with a few small round-shaped bodies in the cytoplasm. We diagnosed the case as canine meningioma with granular cell appearance.     

Multi-voxel magnetic resonance spectroscopy of cerebral metabolites in healthy dogs at 1.5 Tesla

This study was conducted to measure the difference in levels of cerebral metabolites in the right and left hemispheres, gray (GM) and white matter (WM), imaging planes, and anatomical regions of healthy dogs to establish normal variations. Eight male Beagle dogs (1 to 4 years of age; mean age, 2 years) with no evidence of neurologic disease were studied. Using the multi-voxel technique on a 1.5 Tesla magnetic resonance imaging scanner, metabolite values (N-acetyl aspartate [NAA], choline [Cho], creatine [Cr]) were obtained from the frontoparietal WM, parietal GM, temporal GM, occipital GM, thalamus, cerebellum, mid-brain, and pons. There was no significant difference in levels of these metabolites between the right and left in any locations or between the GM and WM in the cerebral hemispheres. However, there were significant differences in metabolite ratios within imaging planes. The NAA/Cr was lower in the cerebellum than other regions and the thalamus had a higher Cho/Cr and lower NAA/Cho ratio than in other regions. The spectral and metabolic values will provide a useful internal reference for clinical practice and research involving multi-voxel magnetic resonance spectroscopy. Measurement of metabolite values in the transverse plane is recommended for comparing levels of regional metabolites.