Showing papers in "Veterinary Pathology in 1977"

Cryptosporidium in Snakes with Hypertrophic Gastritis

Abstract: Fourteen captive snakes of three genera and four species had severe chronic hypertrophic gastritis. Persistent postprandial regurgitation and firm midbody swelling were the most common clinical signs. Fecal smears had many roughly spherical organisms confirmed by ultrastructural study to be oocysts of Cryptosporidium. Pathologic changes included hypertrophy of gastric mucosa and atrophy of granular cells. There were cystic changes in gastric glands and focal mucosal necrosis. Many Cryptosporidium lined microvillar surfaces. All developmental forms were identified by ultrastructure. Characteristic oocysts were found in abundance.

Canine Gastrointestinal Neoplasms

Abstract: In a review of 10 270 canine necropsies, 55 neoplasms of the stomach and 64 neoplasms of the small and large intestines were diagnosed. A significant number of these neoplasms were malignant (P < 0.005) and epithelial (P < 0.005). Adenocarcinomas of gastric and intestinal origin were in dogs younger than the average age of 10 years. Average age for dogs with connective tissue neoplasms was higher than that for those with adenocarcinomas, and there was a difference in median ages of the various types of neoplasms. There was a higher percentage (65%) of gastric and intestinal adenocarcinomas in male dogs, whereas leiomyosarcomas of the intestines were more frequent in female dogs. Although no breed predisposition was found in dogs with gastric neoplasms, a significant number of the intestinal neoplasms (P < 0.005), especially the adenocarcinomas, occurred in the Collie (P < 0.05) and German Shepherd (P < 0.05) breeds. Twenty-six percent of the leiomyosarcomas also occurred in the German Shepherds. Half of the gastric adenocarcinomas occurred in the pyloric region (P < 0.005), and the greater curvature was the next most common site. The rectum was the most common site of intestinal adenocarcinomas, then the colon and duodenum. Leiom yosarcomas were more frequent in the intestines and occurred more commonly at sites where adenocarcinomas were less frequent. In contrast to all other types of intestinal neoplasms, primary lymphosarcomas of the intestines usually affected many segments. Four carcinoid tumors of the duodenum and colon were seen. Of the very rare neoplasms, there were two neurilemomas, both of the duodenum and having the same gross and histologic characteristics of this tumor in other locations.

Primary renal neoplasms of the dog.

Abstract: Of 48 canine primary renal neoplasms found in the files of the Armed Forces Institute of Pathology, 36 were of tubular cell origin (five adenomas and 31 carcinomas), six of transitional cell origin (two papillomas and four carcinomas), two were nephroblastomas and four were nonepithelial. With the exception of nephroblastomas, renal neoplasms occurred in dogs older than 5 years and were most common in males. No breed predilection was apparent. Eight of the neoplasms were classified by histologic criteria as benign and 40 as malignant. Seventeen of the malignant neoplasms had metastasized. The neoplasms of tubular cell origin contained solid, tubular and papillary patterns, often mixed within the same tumor.

A review of exertional rhabdomyolysis in wild and domestic animals and man.

Abstract: Exertional rhabdomyolysis is a condition arising in several species of newly captured wild animals after some form of physical exertion and stress. It is characterized by muscle necrosis and myoglobinuria. Death may result from secondary renal failure, acute or chronic heart failure and progressive emaciation.

Spontaneous listeric encephalitis and neuritis in sheep. Light microscopic studies.

Abstract: Sixteen of 17 sheep with spontaneous listeric encephalitis had neuritis characterized by diffuse and focal intrafascicular and perineural accumulations of lymphocytes, plasma cells, macrophages and neutrophils in one or more cranial nerves. Nine sheep had extensive trigeminal neuritis which was usually unilateral. Brain lesions were mainly in the stem and were foci of macrophages or neutrophils or both, malacia, neutrophilic neuronophagia, vascular cuffing, and meningitis. Lesions in the brain and trigeminal ganglia were most severe on the same side as the affected trigeminal nerve. Gram-positive bacilli were in proximal parts of cranial nerves in foci of inflammatory cells and occasionally in morphologically intact nerve fibers. Organisms in the brain were in phagocytes in areas of inflammation and in scattered neurons and axons. The results were consistent with centripetal migration of the infectious agent along one or more branches of the trigeminal nerve to the brain and dissemination in the brain stem occurring, at least partly, along fiber tracts. Intraaxonal movement of bacteria probably is a mechanism involved in the pathogenesis of this disease.

Spontaneous Glomerulonephritis in Dogs: I. Classification and Immunopathology:

Abstract: A morphological study of kidneys of 101 dogs with and without clinical signs of renal disease was done In 90% of the dogs there was morphologic evidence of glomerulopathy Types of glomerulonephritis were: membranous, 26 cases (with spikes, six cases; without spikes, 20 cases); membranoproliferative, 30 cases (with mesangial proliferation, nine cases; with mesangial sclerosis, 21 cases); mesangial-proliferative, 16 cases; and mesangial-sclerosing, 19 cases There was no linear immunofluorescence indicative of autoantibodies to the glomerular basement membrane Membranous glomerulonephritis with spikes was associated with coarse subepithelial deposits of IgG and C3 Membranous glomerulonephritis without spikes often had a linear fluorescence pattern of C3 In membranoproliferative glomerulonephritis, there were subendothelial deposits of IgG and C3, and frequently C3 deposits were within the mesangium Mesangial deposits of C3 were frequently found in kidneys with mesangial-proliferative and mesangial-scl

Chronic Dermatosis and Cutaneous Squamous Cell Carcinoma in the Beagle Dog

Abstract: Chronic dermatosis developed in sparsely-haired, lightly pigmented, ventral body skin in 397 of 1 680 beagle dogs by the time the dogs were 5'12 years old. Twenty-six of 55 other beagles had developed such lesions by 12 years of age. Squamous cell carcinomas developed in the sites of dermatosis in eight of the 397 younger and five of the 26 older beagles. The lesions resembled solar keratosis (solar dermatosis, actinic dermatosis or senile keratosis) in man. They developed under cir- cumstances suggesting that solar radiation is involved in the pathogenesis, as it is in man. Chronic dermatosis and keratosis occur in human skin inadequately protected from prolonged exposure to sunlight. The changes progress to invasive carcinoma often enough to be considered precancerous (7). Chronic inflammatory and prolif- erative lesions also occur in the skin of dogs, but with the exception of nasal solar dermatitis, neither location nor circumstances of development have implicated chronic solar radiation as a cause, and carcinoma is not a sequel (13). This report deals with the development of inflammatory and proliferative lesions in nonpig- mented and sparsely-haired abdominal, inguinal, preputial, and scrota1 skin of beagles. The circumstances suggest that solar radiation is involved in the pathologic processes. Further, invasive squamous cell carcinomas have developed frequently enough in the abdominal, inguinal, and preputial sites of chronic dermatosis to indicate that the preexisting changes are precancerous and that this change may be considered a canine counterpart of human actinic dermatosis and subsequent neoplasia.

Ochratoxin A and Citrinin Induced Nephrosis in Beagle Dogs I. Clinical and Clinicopathological Features

Abstract: Ochratoxin A and citrinin, both mycotoxins, were given separately and combined to young Beagle dogs for 14 days. Ochratoxin A, 0.1 and 0.2 mg/kg, was given by capsule, and citrinin, 5 and 10 mg/kg, was dissolved in ethanol and given by intraperitoneal injection. Clinical signs of toxicosis in dogs given 10 mg/kg citrinin and the higher combined doses included anorexia, retching, tenesmus, weight loss, prostration and death. Severity of the clinical disease and mortality were increased when the mycotoxins were combined, which indicated synergism. The clinicopathological abnormalities reflected renal damage, in that glutamic oxaloacetic transaminase and lactic dehydrogenase increased in the urine of the dogs with clinical signs of poisoning. Serum lactic dehydrogenase was increased in dogs given 10 mg/kg citrinin. Cellular and granular casts, ketones, protein and glucose were in the urine of dogs given large doses of citrinin alone or combined with ochratoxin A. Serum concentrations of sodium, potassium and chloride in the dogs given high doses of each group.

Ischemic Myelopathy Caused by Fibrocartilaginous Emboli in a Horse

Abstract: A horse that suddenly became recumbent had a focal ischemic infarct of the spinal cord between C6 and C7. The infarct was attributed to multiple fibrocartilaginous emboli. Adherence of fibrocartilaginous debris to the outer surface of the dura was interpreted as evidence that intervertebral disc degeneration and displacement of the nucleus pulposus had occurred and that the emboli arose from the disc.

Corynebacterium equi enteritis in foals.

Abstract: Corynebacterium equi is a pathogen associated with respiratory disease in the foal. This paper discusses two cases of Corynebacterium equi infection, one acute and one chronic, in which the major damage was intestinal. Necrosis of Peyer's patches was the only lesion seen in the small intestine of both foals. The foal with acute disease had distinct green-tan focal necrosis and thickened mucosa of the large intestine. In the foal with chronic disease, the mucosa of the large intestine was thickened, rugose, and mottled red-tan. Histologically, the predominant lesions were villous atrophy, mucosal necrosis, mesenteric lymph node necrosis and large numbers of periodic acid Schiff (PAS)-positive macrophages filled with gram-positive pleomorphic bacilli. Electron microscopy of intestinal mucosa showed bacilli undergoing binary fission in macrophages and bacilli free in the lamina propria.

Ochratoxin A and Citrinin Induced Nephrosis in Beagle Dogs II. Pathology

Abstract: Beagle dogs were given ochratoxin A (0.1 and 0.2 mg/kg) and citrinin (5 and 10 mg/kg) alone and in two dose combinations for 14 days. The gross lesions included focal peritonitis and intestinal intussusceptions in dogs given citrinin. Changes in the kidneys of dogs given ochratoxin A were degeneration and necrosis with desquamation of tubular epithelial cells, primarily in the straight segment of the proximal tubules. Dogs given 10 mg/kg citrin had similar changes in the distal tubules and collecting ducts. Dogs given combined doses of citrinin and ochratoxin A had degeneration and necrosis in proximal and distal tubules, and in thin segments and the collecting ducts; there were desquamated cells and granular casts in the lumina. Dogs given ochratoxin A had necrosis of lymphoid tissues in the spleen, tonsil, thymus, peripheral lymph nodes and lymph nodules of the ileum, colon and rectum. There was ulceration of the mucosa of the intestine in dogs given large combined doses of ochratoxin A and citrinin.

Gynecologic Pathology in the Rhesus Monkey (Macaca mulatta): II. Findings in Laboratory and Free-Ranging Monkeys

Abstract: The most prevalent findings in reproductive tracts of 38 laboratory and 17 free-ranging Rhesus female monkeys were vaginitis, cervicitis, metritis, pelvic endometriosis and uterine adenomyosis. Several monkeys had cervical dysplasia and one had a serous cystadenoma. The findings in the two groups were similar although prevalence for several diseases differed. There was a significant relationship between the occurrence of vaginitis, metritis, adenomyosis and endometriosis and gravidity, time since last pregnancy, number of matings, hysterotomies, reproductive ability and reproductive status.

Intestinal Lesions Induced in Gnotobiotic Calves by the Virus of Human Infantile Gastroenteritis

Abstract: Four gnotobiotic calves with intestinal lesions induced by third and fourth calf passages of the virus of human infantile gastroenteritis were studied by light microscopy, scanning and transmission electron microscopy, and by immunofluorescence. Calves, 25-72 hours old, were examined 0.5 hours, 3 hours, 7 hours, and 48 hours after the onset of diarrhea. Intestinal histology of infected calves was compared to that of two noninoculated gnotobiotic calves 48 and 72 hours old. The sequence of events in the small intestine was infection of the absorptive villous epithelial cells, replacement of the tall columnar villous epithelial cells with cuboidal and squamous cells, shortening of the villi, enlargement of reticular cells, lymphocytic infiltration of the villous lamina propria and repair. The association of a reovirus-like agent (also called orbivirus ( 11, orbivirus-like 121, rotavirus (5), duovirus (3) and infantile gastroenteritis virus (El) with acute human infantile gastroenteritis in several countries (2, 6, 8, 9, 161 has stimulated investigations for finding animal models for the disease. These studies have shown that the human agent can induce diarrhea in newborn piglets (15, 191, monkeys (20) and calves (14). Our study evaluated the lesions caused in calves by this virus and compared them with those caused by the antigenically related calf diarrheal reovirus-like agent. Materials and Methods Calves, inocula, and time between onset of diarrhea and death are summarized in table 1. Four gnotobiotic Hereford-Angus crossbred calves were offered 960 milliliters of autoclaved, homogenized cow's milk twice daily. Noninoculated (control) intestines were obtained from two calves (calves 1 and 2) used in reported experiments ( 11, 121; intestines from both calves were examined by light microscopy. The intestine from calf 2 was examined by scanning electron microscopy. Equipment, procedures and isolation units have been described (13).

Paracoccidioidomycosis (South American blastomycosis) in a squirrel monkey (Saimiri sciureus).

Abstract: A female squirrel monkey (Saimiri sciureus) had granulomatous lesions in the liver and colon. There were many fungal organisms in sections of liver and many of these organisms had multiple buds on their surface. Although we did not prepare fungal cultures, the appearance of the organisms was sufficient to identify them as Paracoccidiodes brasiliensis, the cause of paracoccidioidomycosis (South American blastomycosis).

Feline Panleukopenia. I. Pathogenesis in germfree and specific pathogen-free cats.

Abstract: Germfree and specific pathogen-free cats were inoculated panleukopenia vivus. Total leucocyte counts decreased significantly in both germfree and specific pathogen-free cats. Clinical illness was not seen in any germfree cat. Specific pathogen-free cats had anorexia and slight diarrhea 5-6 days after inoculation. None of the cats died. Both germfree and specific pathogen-free cats had thymic involution. No other gross lesions were seen. Tissues for histological virus isolation and immunofluorescence studies were taken daily from days 2 through 6 after inoculation. Virus-infected cells and lesions of panleukopenia were seen in the small intestine of both germfree and specific pathogen-free cats. The incidence of virus-infected cells and lesions was greater in specific pathogen-free cats than in germfree cats.

Spontaneous Glomerulonephritis in Dogs: II. Correlation of Glomerulonephritis with Age, Chronic Interstitial Nephritis and Extrarenal Lesions

Abstract: A morphologic study of 103 dogs, including two with renal amyloidosis, showed that different types of diffuse glomerulonephritis are correlated with different age groups. Membranous and membranoproliferative glomerulonephritis were more common in middle-aged and older animals, whereas mesangial lesions were found predominantly in younger dogs and considered to be early glomerular changes. Glomerulonephritis largely occurred independently of interstitial nephritis. The incidence of interstitial lesions was 71%. Chronic interstitial nephritis was rare in dogs under 1 year old. Glomerulonephritis did not seem to induce interstitial nephritis. Glomerulonephritis occurred not only in kidneys with severe interstitial damage, but also in those with slight damage. The indicated that glomerulonephritis occurred independently of interstitial nephritis. In end-stage kidneys with severe fibrosis, mesangial changes seemed to predominate.

Polioencephalomalacia of Dogs with Thiamine Deficiency

Abstract: A naturally occurring neurological disease occurred in six dogs fed cooked meat. Clinical signs were anorexia, progressive spastic paraparesis, recumbency, convulsions and death. The disease was characterized by bilaterally symmetrical spongy change and necrosis of brainstem nuclei with a lesion distribution pattern similar to that in thiamine deficient foxes and cats. An associated thiamine deficiency was evidenced by decreased thiamine levels in the blood of one dog and in the food of another, and rapid remission of clinical signs in a dog given thiamine hydrochloride. Thermal destruction of thiamine through cooking of the foods probably caused the dietary deficiency.

Classification of epithelial canine mammary tumors in a defined population.

Abstract: Ductal carcinomas accounted for nearly all metastases seen in epithelial canine mammary tumors submitted to the Tulsa Registry of Canine and Feline Neoplasms in a 4-year period from a defined canine population. Lobular and squamous cell carcinomas were the only other metastatic carcinomas seen. Early ductal carcinoma was used to indicate nonmetastatic ductal carcinoma with a favorable post-surgical prognosis. Benign epithelial tumors were categorized as adenoma, ductal papilloma and squamous cell papilloma. Progressive transformation of well defined adenomas and papillomas to carcinoma was not evident in histologic preparations. Squamous metaplasia was seen in many ductal papillomas and ductal carcinomas. Inclusion of pseudocartilage and pseudoosteoid and osteoid, cartilage and bone with ductal carcinomas, adenomas and ductal papillomas seemed related to secretions escaping from neoplastic epithelial cells into stroma or between proliferating tumor cells. There was proliferation and perhaps even neoplastic transforma- tion of myoepithelial cells in some of these tumors. Changes in myoepithelium, however, appeared to be secondary to neoplastic transformation of epithelium. Bone and cartilage in these tumors were consid- ered heterotopic with no neoplastic potential. A classification of canine epithelial mammary tumors was developed in a 4-year period by the Tulsa Registry of Canine and Feline Neoplasms. The Tulsa Registry was established in April, 1972, to survey all canine and feline neoplasms submitted from a defined population through a cooperative agreement with veterinarians in the greater Tulsa, Okla., area. The classification was designed to allow better communication with Tulsa veterinary surgeons and to eliminate the confusion that we and others had experienced in establishing the exact status of these tumors. The proposed classification is adenoma, ductal papilloma, squamous cell papilloma, ductal carcinoma, lobular carcinoma and squamous cell carcinoma. Cases reviewed included all tumors diagnosed histologically in a veterinary hospital population of about 65,000 dogs in each registry year. The human population of this well defined and geographically isolated area is slightly more than 500,000. A registry in California (22) is the only other group attempting to collect all canine tumors from a defined human and canine population. Both registries believe it is important to establish an accurate evaluation of the occurrence of the various types of canine tumors and to establish incidence rates for those tumors. Because of

Ochratoxin A and citrinin induced nephrosis in Beagle dogs. III. Terminal renal ultrastructural alterations.

Abstract: The extent and type of renal ultrastructural changes in Beagle dogs varied with the administration of ochratoxin A and citrinin alone and in the two dosage combinations. The three predominant changes were cytoplasmic vacuolation, myelin figure formation and lesions designated as cytoplasmic disarray. These changes were mainly of the endomembane system of the tubular epithelial cells. Cytoplasmic vacuoles were within proximal and distal tubules and collecting ducts and were most numerous in dogs given 10 mg/kg critrinin. Vacuolation of similar distribution, but less severe, was seen in renal tubular cells of dogs given the higher dose of the combined mycotoxins (0.2 mg/kg ochratoxin A + 10 mg/kg citrinin). This damage was limited to the proximal tubular cells in dogs given only ochratoxin A (0.1 or 0.2 mg/kg). Myelin figures were in proximal epithelial cells of dogs given ochratoxin A alone or combined with citrinin. There was cytoplasmic disarray in dogs of all groups except for dogs given 5 mg/kg citrinin. This lesions was usually limited to the proximal tubules. The lesions, however, was found in cells of the distal tubules of dogs given 10 mg/kg citrinin alone.

Pericardial Mesothelioma in a Horse

Abstract: Primary cardiac neoplasms are considered to be rare in all domestic animals and in man [l-61. Clinical signs in man are lacking or are nonspecific [l]. Little is known about clinical signs of cardiac neoplasia in animals. This report describes a primary pericardial mesothelioma in an aged Quarterhorse mare. A 27-year-old Quarterhorse mare in poor condition was killed because of old age and weight loss. At necropsy all cheek teeth were loose and both upper first molar teeth had marked suppurative alveolar periostitis. Subcutaneous, orbital and perirenal fat deposits were less than normal. The abdominal cavity was normal except for a chronic verminous aneurysm of the cranial mesenteric artery. The pericardial sac was distended with 3 liters of serosanguinous fluid. The epicardial surface of the heart had numerous superficial round, gray-white, firm nodules ranging from 1 millimeter to 5 centimeters in diameter (fig. 1). Largest nodules were near the apex of the heart. Sectioned surfaces of the nodules bulged slightly, were homogenous gray-white and projected into the pericardial space. The percardial sac was lined by numerous other small nodules similar in color and consistency to the larger nodules. Grossly, other areas were only thick (fig. 2). The epicardial or pericardial sac mesothelium was confluent with the folded and branched structures of these nodules. The free surface was covered with mesothelial cells. Numerous nodules were made up of papillary projections with central fibrous core. The projections tended to branch and were lined by squamous to cuboidal to columnar cells with pink cytoplasm and various sizes of well-defined vesiculate nuclei. Mitotic figures were rare. In some of the deeper areas the cells formed tubular structures (fig. 3, 4). In many areas, the cells had various degrees of less of polarity. The nodules were covered by low cuboidal mesothelial cells (fig. 3). Other thick areas of the pericardial sac were sectioned. No nodules were seen grossly. These areas had papillary projections with connective tissue cores covered by cuboidal mesothelial cells (fig. 4). Metastases were not detected. Brain sections included sclerosis of arterial vessel walls mainly in the hypothalamic region. Liver cells and heart muscle cells had lipofuscin deposits in the cytoplasm. Other tissues were normal. Mesotheliomas, rare in domestic animals, may arise from any of the mesothlial coverings such as pleura, peritoneum or pericardial sac. Although the cells are similar in appearance to epithelial cells, they are of mesodermal origin. Based on reported cases, most horses are old when affected with mesothelioma [3-51. Mesotheliomas typically may be multiple and involve both visceral and parietal serosal surfaces [3-51. Either ascites or hydrothorax commonly have been reported

Renal Secondary Hyperparathyroidism in Aged Sprague-Dawley Rats

Abstract: Fourteen aged Sprague-Dawley rats had typical renal secondary hyperparathy- roidism. The renal disease was severe glomerulosclerosis with tubular dilation. The parathy- roid glands were enlarged and had hyperplasia of chief cells. Bone lesions were generalized osteodystrophia fibrosa and osteosclerosis. All rats had osteodystrophia fibrosa and it was severe in 10 rats. Only four rats had osteosclerosis and it was moderate. Metastatic calcification was seen in various soft tissues in 13 rats.

Internal Hydrocephalus and Associated Periventricular Encephalitis in Young Dogs

Abstract: Six dogs that had a sudden onset and rapid progression of neurological signs with enlargement of the cranial vault at 6-8 weeks old were believed to have congenital hydrocephalus. There were severe inflammatory and necrotizing lesions in periventricular sites in the brain. A bacterial infection may have been the cause of this process. Recent studies on hydrocephalus in animals, including the dog, have changed the old and rather simplified concepts on cerebrospinal fluid dynamics and contributed greatly to the understanding of the pathogenesis of hydrocephalus (24, 391. Spon- taneously occurring cases of hydrocephalus, however, remain a clinical and patho- logical challenge. It has been stated that hydrocephalus is the most common congenital malforma- tion of the canine nervous system (23). There is a higher incidence in miniature breeds and brachycephalic types (7, 271. This condition is usually detected soon after birth (lo) and is often associated with malformation of the mesencephalic aqueduct (6, 331. There are few pathological studies on spontaneously acquired hydrocephalus in the dog. One study (7) describes hydrocephalus ex vucuo resulting from senile atrophy of the brain, and others examined five hydrocephalic brains but found histological lesions in only one (34, 35). Our report of clinical and histologic studies on a group of young dogs indicates that these dogs had a type of acquired internal hydrocephalus of probable infec- tious cause not previously reported.

Giant Hypertrophic Gastritis of Basenji Dogs

Abstract: Giant hypertrophic gastritis is a newly recognized disease of adult Basenji dogs similar to Menetrier's disease of man. It is characterized by weight loss, diarrhea, dry coat, pale membranes, anorexia, raised convoluted rugae in the body of the stomach, palpable fluid- and gas-filled intestines, colonic inflammation, and radiographically demonstrable dilated intestinal loops. Laboratory findings include leukocytosis, neutrophilia, low hemoglobin, hypoalbuminemia, hypobetaglobulinemia, hypergammaglobulinemia, decreased serum fatty acids, hypocholesterolemia, indicanuria, low fecal pH, and increased fecal fat and nitrogen. Four dogs studied had gastritis with hypertrophy and diffuse lymphocytosis and plasmacytosis of the small intestine.

Spontaneous Listeric Encephalitis in Sheep Electron Microscopic Studies

Abstract: The brainstems of four sheep with spontaneous listeric encephalitis had scattered small foci of inflammatory cells (neutrophils or macrophages, or both) with scattered fragments of degenerating nerve fibers and glial cells. In extensive areas of malacia in the pons and medulla oblongata, there was loss of parenchyma with massive accumulation of macrophages, a few neutrophils, lymphocytes and plasma cells. In both types of lesions, phagocytes contained debris of myelin and axons, lipid vacuoles and occasionally bacteria. Neutrophils contained bacteria in phagocytic and digestive vacuoles. No bacteria were detected in macrophages but were detected in neurons and in one axon in tissue previously used for paraffin sections. A cardinal feature of listeric encephalitis in sheep is many nodules of macro- phages or neutrophils or both in the parenchyma of the brain stem, especially the pons and medulla oblongata. The proportion of macrophages to neutrophils in these inflammatory foci varies greatly in the same brain. Also, the predominant type of inflammatory cell (macrophage or neutrophil) varies between different brains (4). In light microscopic studies, bacteria occurred more frequently in neutrophils than macrophages (4). No reason was found for this apparent greater phagocytosis by neutrophils. Although the importance of cell mediated immunity in listeric infections is well established (16), there are no reports of the ultrastruc- tural features of the inflammatory response and phagocytosis of bacteria in listeric encephalitis. Experimental studies indicate that some proteins and viruses (herpes simplex virus, infectious bovine rhinotracheitis virus, pseudorabies virus, canine herpes virus) travel to the brain via axons of peripheral nerves (3, 5, 7-11, 17, 181. Viruses also may spread within the brain via neuronal processes (7). A recent study of listeric encephalitis in sheep suggested that bacteria migrated along peripheral nerves to the brain and that migration in the brain occurred, at least partly, along fiber tracts (4). A few neurons and neuronal processes contained organisms which suggested that neuronal cytoplasm is a vehicle for movement of the infectious agent

Mesotheliomas of the tunica vaginalis propria and peritoneum in Fischer rats

Abstract: Nine mesotheliomas were found in a group of 384 mature, male, Fischer-derived rats maintained on various experimental diets in long-term feeding studies The tumors apparently were unrelated to any of the test materials They ranged from solid, raised serosal growths to delicate papillary structures, and occurred primarily on the tunica vaginalis propria of the testis, epididymis and spermatic cord Four of the nine cases were unusual because there was mesotheliomatous involvement of the peritoneal as well as of the genital mesothelium

Ovarian tumors and related lesions in aged chimpanzees.

Abstract: The ovaries of a 48-year-old chimpanzee each contained a large bilateral fibrothecoma. A 39-year-old chimpanzee had two small fibrothecomas in one ovary and a well-differentiated Sertoli-Leydig cell tumor in the other; there also was adenomatous hyperplasia of the endometrium. Both animals had extensive thecal hypertrophy in the ovaries. Thecal hypertrophy might have been a source of excessive estrogen and could have been a partial cause of the ovarian tumors.

Demyelination in Mice After Two or Three Infections with Avirulent Semliki Forest Virus

Abstract: Adult mice given two or three intraperitoneal inoculations with avirulent Semliki Forest Virus showed typical lesions of a viral encephalitis similar to those caused by a virulent strain of the virus. Demyelination also was seen in the medulla and in the folia of the cerebellar white matter. Neuronophagia was seen only in mice that had had three successive infections. The repeated inoculations of avirulent virus exacerbates the encephalitis of a single inoculation and causes demyelination. The mice did not have neurological clinical signs except for a short-lived weakness of the hind legs. No central nervous system lesions were seen by the 7th and 8th week after the initial infection and all mice recovered.

Bacterial adherence in mastitis caused by Escherichia coli.

Abstract: The possible role of bacterial adherence in the pathogenesis of experimental mastitis in the mouse was examined with four strains of Escherichia coli. Two of these strains had a known adhesion antigen (K88) and two did not. The K88 antigen did not play a significant role in the virulence or infectivity of E. coli either in the murine or bovine mammary gland. Two E. coli strains, W1 (K88+) and 52 (K88-) were virulent in the mouse but did not adhere to epithelial cells. Both these strains produced clinical mastitis in the cow. A third strain, D282 (K88-), produced mild disease in the mouse but was avirulent in the cow. The fourth strain, 233/1D (K88+), was avirulent in both the mouse and the cow. Strains D282 and 233/1D were killed rapidly by bovine serum whilst 52 and W1 were more resistant. All strains were more sensitive than the control resistant strain E. coli P4, which is known to be highly virulent for the lactating udder. The selective adhesion of microorganisms to epithelial cells seems to be critical in the pathogenesis of some infections of the trachea (16), small intestine (2, 4, 111, urethra (20) and vagina (12). Adhesion of mastitis-causing organisms to the mammary epithelium may be essential in the establishment of infection. An in vitro study (8) showed that strains of Staphylococcus aureus and Streptococcus agalactiae derived from subclinical mastitis adhered to epithelial cells from lactiferous ducts in greater numbers than did strains of Strep. faecalis, E. coli and Corynebacterium bovis derived from faeces or normal milk. The K88 antigen has been shown to be responsible for the adhesion of enteropathogenic strains of E. coli to the epithelium of the small intestine of the piglet (9, 101. Four strains of E. coli that were known either to have or lack the K88 adhesion-antigen were inoculated into the mammary gland of mice because by using this small animal (6) one can assess virulence and see the organisms in relation to the epithelium. The ability of these strains of E. coli to induce mastitis in the cow was determined by inoculation of lactating quarters. Their susceptibility to killing by bovine serum also was measured because coliform strains that are highly susceptible to the bactericidal activity of bovine serum are avirulent when infused into the udder whilst serum-resistant strains are capable of producing mastitis (5).

Amebiasis in Goldfish

Abstract: Five cases of amebiasis were diagnosed in goldfish (Carassius auratus) from home aquariums and from a laboratory aquarium. Granulomas containing amoebae were in many organs but were most numerous in kidneys. Because there were pseudopods, food vacuoles, vesicular nucleoli and other ultrastructural characteristics of the organisms, we identified the organisms as amoebae. On the basis of mitotic stages it is possible they belong in the family Hartmannellidae.

A study of swine dysentery by immunofluorescence and histology.

Abstract: Twenty-six specific-pathogen-free pigs were fed pure cultures of Treponemu hyodysenteriue. Five untreated pigs were controls. Distribution of this large spirochete in pigs with swine dysentery was shown by the indirect fluorescent antibody technique. Findings by this method were compared with those from dark-field examination of colonic mucosal scrapings and from tissue sections. The cultures caused mucohemorrhagic colitis which by 10 days after inoculation was indistinguishable from the colitis of swine dysentery. Control pigs remained normal. Pigs killed when spirochetes were first seen in their feces had normal colonic mucosa with only a few spirochetes. At the first sign of diarrhea, however, the colonic mucosa was thicker than normal and had many spirochetes. T. hyodysenreriue was confined to regions of hypertrophy and exudation of the large intestine mucosa throughout the course of disease. Culture studies, dark-field microscopy, special staining techniques and electron microscopy have suggested a relationship between T. hyodysenreriue and swine dysentery ( 14-16). Observational limitations, however, have precluded correlation of the findings with the development of the disease. Culture and dark-field obser- vations place the organisms only in the gross vicinity of the lesion; special staining techniques do not identify organisms specifically, and electron microscopy gives a very selective view of the morphologic relationship between the organisms and the disease. We used specific immunofluorescent staining of T. hyodysenreriue in the affected tissues to correlate the presence of the organisms with the development of the lesions. A mucohemorrhagic diarrhea disease of pigs was shown to be distinct from hog cholera and salmonellosis in 1921 and was named swine dysentery (26). A large spirochete was associated with the lesions but feeding a mixed culture containing the organism did not produce the disease. A comma-shaped organism also was seen in swine dysentery at that time and was later isolated and named Vibrio coli. This was considered the cause of the disease (9-111. Although V. coli was generally accepted to be the cause of swine dysentery (4,7, 10, 111, this organism has been commonly found in normal pigs (2, 8, 131, and in