The effects of four, commercial ceruminolytic agents on the middle ear.

Four, commercially available ceruminolytic agents and physiological saline were screened for ototoxic and inflammatory reactions on the middle ear mucosae of guinea pigs (n = 38) and dogs (n = 24). Each solution was injected transtympanically in anesthetized animals. The effects were assessed by brain stem auditory evoked response (BAER) tests to evaluate hearing function and by histological examination of the middle ear structures. Varying degrees of hearing loss and inflammation were observed in some guinea pigs and dogs treated with solutions A, C, and D, whereas no abnormal finding was associated with solution B or saline.

Prolonged gestation, decreased triiodothyronine concentration, and thyroid gland histomorphologic features in newborn foals of mares grazing Acremonion coenophialum-infected fescue.

Newborn foals of mares grazing on Acremonium coenophialum-infected fescue pasture throughout gestation or from gestation day 300 to parturition had increased gestation duration and decreased serum triiodothyronine concentration. Pregnant mares were allotted to 4 treatments: grazing continuously on endophyte-free (E-) fescue, grazing continuously on endophyte-infected (E+) fescue, grazing on E+ fescue from gestation day 300 to parturition, and grazing on E+ fescue from conception to gestation day 300. Morphometric studies indicated that foals born to mares exposed to endophyte late in gestation had large, distended thyroid follicles lined by flat cuboidal epithelial cells. Mean triiodothyronine concentration in foals exposed to endophyte (395.2 ng/dl) was decreased (P < 0.01), compared with mean values in control foals (778.0 ng/dl). Thyroxine and reverse triiodothyronine concentrations were not significantly different among groups. Foal organ weight as a percentage of foal body weight was not significantly different among experimental groups.

Evaluation of the safety and efficacy of vaccination of nursing pigs with living tachyzoites of two strains of Toxoplasma gondii.

The safety of vaccination and persistence and distribution of Toxoplasma gondii stages within tissues following vaccination were examined in 3-day-old nursing pigs vaccinated with living tachyzoites by intravenous and subcutaneous routes of either the TS-4 mutant strain or its parent RH strain of T. gondii. The efficacy of vaccination of nursing pigs with the TS-4 mutant was also examined in pigs challenged orally with oocysts following vaccination. Pigs were vaccinated with 3 x 10(5) living tachyzoites when 3 days old and boosted with 3 x 10(5) living tachyzoites when 17 days old. Group 1 had 2 pigs vaccinated intravenously (i.v.) with Hanks' balanced salt solution (HBSS) and served as a vaccination control. Group 2 and 5 pigs vaccinated i.v. with tachyzoites of the TS-4 mutant; 3 pigs were used to examine the safety, persistence, and distribution of the TS-4 mutant and 2 were used for oocyst challenge. Group 3 had 5 pigs vaccinated i.v. with tachyzoites of the RH strain and all were used to examine the safety, persistence, and distribution of the RH strain within their tissues. Group 4 had 3 pigs vaccinated subcutaneously (s.c.) with tachyzoites of the TS-4 mutant; 1 was used to determine the persistence and distribution of the TS-4 mutant within its tissues and the other 2 pigs were used for GT-1 oocyst challenge studies. Group 5 had 3 pigs vaccinated s.c. with tachyzoites of the RH strain and all were used to examine the safety, persistence, and distribution of the RH strain within their tissues. None of the control pigs or pigs vaccinated with the TS-4 mutant developed clinical signs of disease or died prior to oocyst challenge. The TS-4 mutant was not reisolated from the tissues of vaccinated pigs nor were microscopic lesions present in the tissues of pigs that had been killed and examined at necropsy. Severe disease with clinical signs consisting of dyspnea, inactivity, diarrhea, and ocular lesions was observed in the group 3 pigs vaccinated i.v. with the RH strain. One pig died 7 days after initial vaccination. Microscopic lesions were observed in numerous tissues of all group 3 pigs. Swelling, erythema, and ulcers were observed at the site of inoculation in the group 5 pigs that were vaccinated s.c. with the RH strain. Minimal to no microscopic lesions were observed in these group 5 pigs. The RH strain was reisolated from pigs in both groups vaccinated with this strain.(ABSTRACT TRUNCATED AT 400 WORDS)

Enterocecocolitis associated with Escherichia coli and Campylobacter-like organisms in a hamster (Mesocricetus auratus) colony.

Sporadic diarrhea and weight loss were observed in a breeding colony of Syrian hamsters during a 2-year period. Thirteen adult hamsters with diarrhea, anorexia, and weight loss were examined. Histologic lesions consisted of diffuse nonsuppurative enterocecocolitis and multifocal epithelial proliferation in the cecum and colon. Goblet cell hyperplasia was extensive in the colonic mucosa of many hamsters. The hamsters in this colony had not been treated with antibiotics nor was Clostridium difficile isolated from any of the hamsters. In contrast to typical proliferative ileitis in hamsters, most hamsters involved in this outbreak were mature adults rather than weanlings, and lesions were predominantly inflammatory rather than proliferative and involved small intestine, cecum, and colon rather than ileum. The isolation of beta-hemolytic Escherichia coli and demonstration of Campylobacter-like organisms by transmission electron microscopy and Warthin-Starry staining suggest that these two agents were involved in the pathogenesis of this disease. Further studies, however, are needed to investigate the pathogenesis of this enteric syndrome in hamsters.

Influence of endophyte-infected tall fescue on cyclicity, pregnancy rate and early embryonic loss in the mare.

The effects of grazing endophyte-infected tall fescue on luteal function, pregnancy rates, and embryonic loss rates were compared between treated mares (n=18) and untreated controls (endophyte-free, n=12). Mares grazing endophyte-infected fescue demonstrated significantly (P<0.01) prolonged luteal function (22.9 vs 15.8 d) than those grazing endophyte-free fescue. Continuous grazing of endophyte-infected fescue resulted in a decreased (P=0.30) per cycle 14-d viable pregnancy rate (14/31, 45.2%) compared with that of endophyte-free grazing (12/16, 75.0%). Early embryonic death rates were higher (P=0.20) in the endophyte-infected group (6/20, 30.0%) than the endophyte-free group (1/13, 7.7%). Cumulative pregnancy rates after a 60-d breeding period did not differ between the 2 groups. Embryonic development based on mean vesicle height at 14-d was not significantly different between treatment groups for embryos that maintained viability. Embryos that underwent early embryonic death were smaller (P<0.10) at Day-14 than embryos that maintained viability. Mean plasma progesterone concentrations were significantly (P<0.01) greater at Day-21 postovulation in endophyte-infected mares in which the embryo remained viable (15.8 ng/ml) than in endophyte-free mares that experienced early embryonic death (9.8 ng/ml) or that demonstrated prolongation of luteal function (11.2 ng/ml). The results of this study suggest that grazing endophyte-infected tall fescue can have a detrimental effect on reproductive efficiency in the mare due to an increase in cycles bred per pregnancy rate, increased early embryonic death rate and prolongation of luteal function.

Scanning electron microscopy of intraocular lenses that had been implanted in dogs.

Scanning electron microscopy was used to evaluate changes on the surfaces of polymethylmethacrylate (PMMA), silicone, and polyhydroxyethylmethacrylate (HEMA) intraocular lenses (IOL) that had been implanted in the anterior chambers of the right eyes of 15 dogs. Five dogs received PMMA IOL; 5 dogs received silicone IOL; and 5 dogs received HEMA IOL. Twenty-eight days after surgery, the IOL were removed and processed for scanning electron microscopy. Nonimplanted IOL of each type were processed identically for comparison. Implanted PMMA IOL had significantly more debris and macrophages on their surfaces than did silicone IOL or HEMA IOL. Silicone IOL had significantly less fibrin deposition than did PMMA or HEMA IOL. Silicone IOL had surface defects attributable to handling by surgical instruments. Implanted HEMA IOL had multiple pits that appeared to be caused by biodegradation.

Clinicopathologic findings after experimental implantation of synthetic intraocular lenses in dogs.

Clinical findings indicate that canine eyes tolerate implantation of polymethylmethacrylate (PMMA) intraocular lenses (IOL) well, although inflammation and ocular damage attributable to the implants is not known. The use of silicone or polyhydroxyethylmethacrylate (HEMA) IOL has not been reported in dogs. In this study, 15 conditioned, mixed-breed dogs were allotted to 3 groups: 5 received PMMA IOL; 5 received silicone IOL; and 5 received HEMA IOL. The IOL optic was inserted into the anterior chamber of the right eye and anchored to the cornea. An identical surgical procedure was done on the left eye, except that no lens optic was inserted. Clinical examination and measurement of corneal thickness were done immediately prior to and after surgery. Aqueous humor samples were collected at the time of surgery and 28 days after surgery. Only mild and transient inflammation was observed in IOL-implanted eyes. On several postoperative days, it was found that PMMA IOL induced significantly greater corneal thickness, aqueous flare, anterior uveal irritation, and corneal edema than did other IOL. Significantly more anterior uveal irritation and increased aqueous humor protein concentration was observed with HEMA IOL than with PMMA or silicone IOL. Silicone IOL induced significantly less fibrin deposition than did PMMA or HEMA IOL.

Effects of the fungal endophyte Acremonium coenophialum in fescue on pregnant mares and foal viability.

Effects of the endophyte Acremonium coenophialum in tall fescue on pregnant mares and foal viability were evaluated. Twenty-two mature pregnant mares were randomly chosen to graze either Kentucky-31 tall fescue that was free from A coenophialum (endophyte-free, EF) or tall fescue infected with A coenophialum (endophyte-present, EP) after the first 90 days of pregnancy through parturition. Concentrations of pyrrolizidine and ergopeptine alkaloids were significantly greater in EP grass, compared with EF pasture. Ten of 11 mares grazing EP pasture had obvious dystocia. Mean duration of gestation was significantly greater for the EP group, compared with the EF group. Foal survivability was severely reduced among mares grazing EP fescue with only 1 foal surviving the natal period. Udder development and lactation were low in mares grazing EP grass. The absence of clinical problems in mares grazing EF grass implicated the endophyte as the causative agent of reproductive problems and perinatal foal mortality in pregnant mares grazing endophyte-infected fescue grass. Caution should be exercised in allowing pregnant mares to graze pastures infected with the endophyte A coenophialum.

Mesothelioma in cattle: eight cases (1970-1988)

Over an 8-year period, 8 beef cattle with mesothelioma were admitted to the Auburn University College of Veterinary Medicine and the Louisiana State School of Veterinary Medicine. Diagnosis was confirmed by histologic examination of affected tissues. Five bulls, 1 steer, and 2 cows were affected. Four of the bulls had scrotal swelling; 2 cows and 1 bull had ventral abdominal swelling. The peritoneal cavity was involved in 5 cases, the pleural cavity was affected in 2 cases, and in 2 cases, disease was apparently confined to the vaginal cavity. Of the 8 cattle, 6 died or were euthanatized; only cattle with tumor apparently confined to the vaginal cavity survived.

Experimental Isospora suis infections in miniature swine.

Clinical responses to experimental Isospora suis infections were compared in Sinclair miniature pigs and cross-bred conventional pigs. Pre-patent periods, fecal consistencies, oocyst excretion dynamics, trends in surviving pig weights and lesions were similar in infected miniature and conventional pigs. The results indicate that the susceptibility of miniature pigs to I. suis is similar to that of conventional pigs. These findings should encourage their use as models for the study of neonatal coccidiosis.

Plasmid profiles of six species of Campylobacter from human beings, swine, and sheep.

Twenty-four isolates representing 6 species of Campylobacter were screened for plasmids. A large plasmid with an approximate molecular weight of 38 Mdal was detected in 5 C jejuni isolates originally recovered from diarrheic human beings, in one isolate of C coli recovered from diarrheic pigs, and in 1 isolate of C sputorum ssp mucosalis and 2 isolates of C hyointestinalis recovered from pigs with proliferative enteritis. One isolate of C coli and 1 isolate of C hyointestinalis contained an additional smaller plasmid with an approximate molecular weight of 1.6 Mdal; this plasmid was partially mapped by restriction endonuclease digestion. Fifteen Campylobacter isolates contained no detectable plasmids: 2 C coli, 2 C sputorum ssp mucosalis, 2 C fecalis, 1 C fetus ssp fetus, and 8 C hyointestinalis isolates. In summary, 37.5% of the Campylobacter isolates contained a 38-Mdal plasmid, with 8% having both 38 Mdal and 1.6-Mdal plasmids; 62.5% contained no detectable plasmids.

Postnatal development of the photoreceptor inner segment of the retina in dogs.

In dogs, the retina develops during the postnatal period in a manner similar to that in other animals born with closed eyelids. Photoreceptor inner segments are initially observed as a cytoplasmic bulge protruding sclerad through the external limiting membrane. Outer segment formation begins when a centriole within the inner segment attaches to the distal inner segment cell membrane. A few round mitochondria are observed within the early inner segments. As maturation proceeds, the number of mitochondria within the inner segments increases and the mitochondria elongate, orienting parallel to the long axis of the inner segment.

Pancreatic polypeptide and insulin-secreting tumor in a dog with duodenal ulcers and hypertrophic gastritis.

A 7-year-old spayed female Cocker Spaniel was hospitalized with a history of chronic vomiting, anorexia, and weight loss. Laboratory abnormalities included leukocytosis, metabolic alkalosis, hypoglycemia, hypoproteinemia, and hyperinsulinemia. Gastroscopy and ultrasonography revealed multiple gastric masses and a possible pancreatic mass, respectively. Examination of tissues obtained at necropsy showed a pancreatic adenocarcinoma with hepatic metastasis, gastric hypertrophy, and multiple duodenal ulcers. Immunocytochemical staining of the neoplasia was positive for pancreatic polypeptide (PP) and insulin and negative for gastrin, calcitonin, adrenocorticotropic hormone (ACTH), serotonin, L-enkephalin, chromagranin, glucagon, and somatostatin. Subsequent serum gastrin and PP assays showed a fasting hypergastrinemia with a normal response of gastrin to provocative testing and extremely increased PP values. The high PP values may have resulted in the vomiting and gastrointestinal ulceration. A PP-secreting tumor has not previously been reported in the dog.

The pony as an animal model for vascular implants.

This study evaluated the pony as a potentially suitable model for vascular implant research. Healthy, conditioned ponies were randomly assigned to one of three groups: group I, carotid artery autografts (n = 6); group II, e-PTFE carotid interpositional grafts (n = 5); and group III, e-PTFE carotid interpositional grafts plus aspirin (10 mg/kg) and dipyridamole (3.5 mg/kg) drug administration. It was found that autografts remained patent longest (mean = 396.2 days; grafts were still patent at time of writing) followed by group III grafts (157.5 days), with group II grafts remaining patent for the shortest duration (61.1 days), (p less than 0.01). Patency was determined using two-dimensional real-time ultrasonography with Doppler velocimetry and/or arteriography. It was demonstrated that the pony's response to antithrombotic drugs was consistent and comparable to that in other animal models, both with respect to platelet function and affect on patency rate. The combination of the ease of surgical manipulation, drug administration, and platelet function testing, the comparable size of the pony and its heart and blood vessels to that of an adult human, the long life span of ponies, and the patency results of this study have demonstrated that the pony is a valuable animal model for vascular research.

Granulomatous uveitis in an owl.

Granulomatous lens-induced uveitis was diagnosed in a mature male barred owl. Initial ocular examination revealed a large white mass in the left eye. Differential diagnoses for the mass included intraocular granuloma, neoplasia, foreign body, bacterial or fungal enophthalmitis, and fibrotic hematoma. After enucleation of the left globe, histologic examination revealed the mass to be a granulomatous inflammatory reaction to a posteriorly luxated, traumatized lens. Lens-induced uveitis should be considered whenever a bird has suffered lenticular trauma.

Campylobacter jejuni infections in gnotobiotic pigs.

At 3 days of age, 12 gnotobiotic pigs were inoculated orally with broth cultures of Campylobacter jejuni. One pig was euthanatized and evaluated each day for 12 days. In the cecum and colon, there was diffuse edema, neutrophilic infiltration, and sloughing of epithelial cells from the mucosa on postinoculation days (PID) 2 through 5. Dysplastic colonic crypt epithelial cells were observed in the submucosa of the colon on PID 5 through 12. Curved, rod-shaped bacteria were detected on the surface of ileal, cecal, and colic absorptive and glandular epithelial cells. Bacteria also were found around small submucosal vessels on PID 3 and 4 and were associated with numerous perivascular neutrophils. The gnotobiotic pig appears to provide a simple, well-controlled in vivo model for the study of the pathogenesis of C jejuni infections in human beings, pigs, and other mammals.

Anatrichosoma sp infection in a dog.

Embryonated, double-operculated eggs were observed during routine examination of a fecal specimen from a 5-month-old dog. Similar eggs were found on a skin scraping of a raised, flaking, erythematous nodule on the dorsal midline in the lumbar region. Eggs were identified as being similar to those of Anatrichosoma spp. After surgical excision, histologic examination of the nodule revealed nematodes with morphologic features consistent with those of Anatrichosoma spp.