Lyme neuroborreliosis in 2 horses.

Lyme neuroborreliosis--characterized as chronic, necrosuppurative to nonsuppurative, perivascular to diffuse meningoradiculoneuritis--was diagnosed in 2 horses with progressive neurologic disease. In 1 horse, Borrelia burgdorferi sensu stricto was identified by polymerase chain reaction amplification of B burgdorferi sensu stricto-specific gene targets (ospA, ospC, flaB, dbpA, arp). Highest spirochetal burdens were in tissues with inflammation, including spinal cord, muscle, and joint capsule. Sequence analysis of ospA, ospC, and flaB revealed 99.9% sequence identity to the respective genes in B burgdorferi strain 297, an isolate from a human case of neuroborreliosis. In both horses, spirochetes were visualized in affected tissues with Steiner silver impregnation and by immunohistochemistry, predominantly within the dense collagenous tissue of the dura mater and leptomeninges.

Infection of internal umbilical remnant in foals by Clostridium sordellii.

Omphalitis and the resulting septicemia contribute to perinatal mortality in several animal species. In foals, the most important causes of omphalitis are Escherichia coli and Streptococcus zooepidemicus. However to date, no information has been published about the role of Clostridium sordellii in these infections. In this paper, we describe 8 cases of perinatal mortality in foals associated with internal umbilical remnant infection by C. sordellii. The foals studied were between 12 and 21 days old at the time of death, and various breeds were represented in the group. Five of the foals were male and 3 were female. The diagnosis was established on the basis of the detection of C. sordellii by 3 methods (culture, fluorescent antibody test, and immunohistochemistry) and on gross and histopathologic findings. All foals had acute peritonitis, and the internal umbilical remnant was thickened by edema, hemorrhage, and fibrosis. A moderate amount of serosanguinous fluid with fibrin strands was present in the pericardial sac and pleural cavity. Histopathologically, the urachus and umbilical arterial walls were thickened by edema and exhibited hemorrhage, fibrin, and leukocytic infiltration. Gram-positive bacterial rods were observed in subepithelial areas of the urachus, the adventicia of umbilical arteries, and interstitium of the internal umbilical remnant. On the basis of these findings, we suggest that C. sordellii should be considered in the differential diagnosis for infections of the internal umbilical remnant in foals.

Cytokine gene signatures in neural tissue of horses with equine protozoal myeloencephalitis or equine herpes type 1 myeloencephalopathy.

This study was designed to determine the relative levels of gene transcription of selected pathogens and cytokines in the brain and spinal cord of 12 horses with equine protozoal myeloencephalitis (EPM), 11 with equine herpesvirus type 1 (EHV-1) myeloencephalopathy, and 12 healthy control horses by applying a real time pcr to the formalin-fixed and paraffin-embedded tissues. Total rna was extracted from each tissue, transcribed to complementary dna (cDNA) and assayed for Sarcocystis neurona, Neospora hughesi, EHV-1, equine GAPDH (housekeeping gene), tumour necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-8, IL-10 AND IL-12 p40. S neurona cdna was detected in the neural tissue from all 12 horses with EPM, and two of them also had amplifiable cDNA of N hughesi. The relative levels of transcription of protozoal cdna ranged from 1 to 461 times baseline (mean 123). All the horses with ehv-1 myeloencephalopathy had positive viral signals by PCR with relative levels of transcription ranging from 1 to 1618 times baseline (mean 275). All the control horses tested negative for S neurona, N hughesi and EHV-1 cdna. The cytokine profiles of each disease indicated a balance between pro- and anti-inflammatory markers. In the horses with epm the pro-inflammatory Th1 cytokines (IL-8, TNF-alpha and IFN-gamma) were commonly expressed but the anti-inflammatory Th2 cytokines (IL-4, IL-6 AND IL-10) were absent or rare. In the horses with ehv-1 the proinflammatory cytokine IL-8 was commonly expressed, but IL-10 and IFN-gamma were not, and TNF-alpha was rare. Tissue from the control horses expressed only the gene GAPDH.

The influence of crumble and mash feed on oral lesions of white leghorn laying hens.

The effect of crumble and mash feed on oral lesions in laying hens was investigated. Each of two groups of white leghorn hens (group A, n = 120; group B, n = 120) was separated into crumble- and mash-fed treatments. At the start of the trial, group A chickens were free of oral lesions, whereas group B chickens had nearly 100% prevalence of oral lesions. The trials began at 17.4 and 22 wk of age and ended at 32 and 33 wk of age for groups A and B, respectively. Chickens were housed in cages indoors, fed free choice, and serologically monitored. Oral lesions were periodically evaluated by visual scoring. Lesion prevalence peaked in group A chickens at 23-25 wk of age, concurrently with an outbreak of respiratory disease, and decreased to a low level at the end of the trial. For most of the trial, crumble-fed chickens had significantly lower oral lesion prevalence than mash-fed chickens (P < 0.05). Lesion prevalence in group B chickens decreased after treatments began and maintained this trend to the end of the trial. Compared with mash-fed chickens, crumble-fed chickens in group B had significantly lower oral lesion prevalence throughout the trial (P < 0.001). Neither group had significant differences in oral lesion scores between treatments. Most lesions were on the lower palate, pinpoint to 2 mm in diameter, often multiple, and bilaterally symmetrical. Feed analyses for mycotoxins and heavy metals were within normal limits. The inciting etiology of oral lesions was not elucidated in this trial. However, this work demonstrated that once lesions were present, feed type had a strong effect on persistence of oral lesions.

Morphological and molecular characterization of Encephalitozoon hellem in hummingbirds.

Microsporidiosis was identified as a cause of enteritis in wild, migratory hummingbirds (Calypte anna). Electron microscopic examinations of parasites showed microsporidian spores with a double spore coat and a polar filament containing four to six coils, compatible with the genus Encephalitozoon. Molecular analysis of ribosomal RNA genes further identified the parasites from droppings and small intestinal segments as Encephalitozoon hellem, genotype I. Microsporidial spores were identified in 19% of droppings from C. anna, Archilochus alexandri and Selasporus sasin using Gram or modified trichrome staining methods. Since E. hellem is an opportunistic pathogen in immunocompromised humans, the pathogenic potential in avian hosts, the zoonotic potential of this parasite, and the role of birds as reservoirs needs to be further explored.

Pathologic and bacteriologic findings in 27-week-old commercial laying hens experimentally infected with Salmonella enteritidis, phage type 4.

Two strains of 27-wk-old commercial laying chickens (strain A, brown-egg-laying type and strain B, white-egg-laying type) were inoculated either orally (PO) or intravenously (IV) with a field isolate of Salmonella enteritidis phage type 4. Chickens were sequentially necropsied at regular intervals throughout the 17-wk observation period. Gross and microscopic lesions were most evident between 1 and 14 days postinoculation (DPI). Gross lesions consisted of enlarged livers with white foci, enlarged and mottled white spleens, fibrinous exudate in the peritoneum, and atretic, misshapen ovarian follicles. Microscopic lesions included multifocal coagulative necrosis of hepatocytes and inflammation, fibrinous exudation in vascular sinuses of the spleen, and fibrinosuppurative inflammation of the peritoneum and ovarian follicles. The proportion of reproductive organ infections (ovary and oviduct) in the IV group, 83% (20/24, P = 0.007; 50% and 33% for strains A and strain B birds, respectively), was higher than that of the PO group, 46% (11/24; 29% and 17% for strains A and B, respectively), for the first 16 days of observation postinoculation. The proportion of fecal shedding for the IV group of birds was significantly (P = 0.009) lower, 29% (7/24; 33% and 25% respectively for strain A and strain B birds, respectively), than the PO group, 67% (16/24; 75% and 58% for strain A and strain B birds, respectively). Three (2.6%) of 234 egg pools were culture-positive for group D Salmonella from strain A chickens (1 of 119 pools from the IV group and 2 of 115 pools from the PO group of birds). Chickens infected with the field strain of S. enteritidis phage type 4 harbored the organism in tissues only for a brief time, most clearing within 8 DPI and nearly all within 16 DPI. Overall the percentage of culture-positive birds did not differ significantly (P > 0.05) between birds with and without lesions, but isolation of S. enteritidis tended to be more frequent when lesions were evident. This experiment also demonstrated that brown-egg-laying-type chickens were more susceptible than white-egg-laying-type chickens to S. enteritidis phage type 4 isolated from California based on gross and microscopic lesions and bacteriologic findings.

Hoof size, shape, and balance as possible risk factors for catastrophic musculoskeletal injury of Thoroughbred racehorses.

OBJECTIVE: To evaluate hoof size, shape, and balance as risk factors for catastrophic musculoskeletal injuries (CMI), including suspensory apparatus failure (SAF) and cannon bone condylar fracture (CDY) in Thoroughbred racehorses. ANIMALS: 95 Thoroughbred racehorses that died between 1994 and 1996. PROCEDURE: 38 quantitative measures of hoof size, shape, and balance were obtained from orthogonal digital images of the hoof and were compared between case horses with forelimb CMI (70), SAF (43), and CDY (10) injuries and control horses whose death was unrelated to the musculoskeletal system (non-CMI, 25). Comparison of group means between cases and controls was done using ANOVA, and multivariable logistic regression was used to estimate odds ratios. RESULTS: Odds of CMI were 0.62 times lower for a 5mm increase in ground surface width difference and 0.49 times lower for a 100-mm2 increase in sole area difference. Odds of SAF were 6.75 times greater with a 10 degrees increase in toe-heel angle difference and 0.58 times lower with a 100-mm2 increase in sole area difference. Odds of CDY were 0.26 times lower with a 3 degrees increase in toe angle, 0.15 times lower with a 5-mm increase in lateral ground surface width, and 0.35 times lower with a 100-mm2 increase in sole area difference. CLINICAL RELEVANCE: Decreasing the difference between toe and heel angles should decrease risk of SAF for Thoroughbred racehorses and should be considered in addition to increasing toe angle alone to help prevent catastrophic injury. Trimming the hoof to perfect mediolateral symmetry may not be a sound approach to avoiding injury.

Proliferative enterocolitis associated with dual infection with enteropathogenic Escherichia coli and Lawsonia intracellularis in rabbits.

Both enteropathogenic Escherichia coli (EPEC) and an obligate intracellular bacterium, previously referred to as an intracellular Campylobacter-like organism and now designated Lawsonia intracellularis, have been reported as causes of enterocolitis in rabbits. An outbreak of enterocolitis in a group of rabbits, characterized by an unusually high rate of mortality, was found to be associated with dual infection with EPEC and L. intracellularis. The EPEC strain was found to have eaeA gene homology but was negative for afrA homology. The absence of the afrA gene, which encodes the structural subunit for the AF/R1 pilus, indicates that this rabbit EPEC strain is distinct from the prototypic RDEC-1 strain. This finding suggests that rabbit EPEC strains widely reported in Western Europe, which lack AF/R1 pili, are also present in rabbits in the United States. Dual infection with these two pathogens in rabbits has not been previously reported and may have contributed to the unusually high mortality observed in this outbreak.

Isolation of porcine circovirus-like viruses from pigs with a wasting disease in the USA and Europe.

Samples of lung, liver, kidney, pancreas, spleen, and lymph node from pigs with postweaning multisystemic wasting syndrome from California (USA) and samples of mesenteric lymph nodes from similarly diseased pigs from Brittany (France) were examined by light microscopy, in situ hybridization (ISH), and/or virus isolation. Whole genomic probes for porcine circovirus (PCV) and chicken anemia virus (CAV) were used for ISH. Tissue homogenate supernatants were inoculated onto PK/15 cells for virus isolation, and the presence of viral antigen and viral particles was verified by indirect immunofluorescence, ISH, and electron microscopy. Histologic examination of lung from pigs from California revealed interstitial pneumonia, alveolar epithelial hyperplasia, and basophilic nuclear and cytoplasmic inclusions in mononuclear cell infiltrates and various pulmonary epithelial cells. Granulomatous lymphadenitis with syncytial cells typified the lesions seen in the pigs from France. PCV-like nucleic acid was detected by ISH in lung, pancreas, lymph node, kidney, and liver in pigs from California. Positive signal was also obtained in lymph node sections from pigs from France. Probes for CAV were consistently negative. PK/15 cell cultures inoculated with lung preparations from diseased California pigs and mesenteric lymph node preparations from pigs from France had positive fluorescence by indirect staining for PCV using pooled polyclonal pig sera and hyperimmune rabbit serum and had variable staining with a panel of 7 monoclonal antibodies specific for cell culture contaminant PCV. PCV-like nucleic acid was also detected by ISH in cell cultures. Cytopathic effect was not observed. Electron microscopic examination of inoculated cell cultures revealed 17-nm viral particles morphologically consistent with PCV. No other virus particles were observed. Although genomic analysis for the definitive identification of these viral isolates remains to be done, the evidence provided strongly suggests that these tissue isolates are closely related to, although antigenically distinct from, the original PCV cell culture contaminant.

Relationship between race start characteristics and risk of catastrophic injury in thoroughbreds: 78 cases (1992).

OBJECTIVE: To investigate relationships of several racehorse characteristics and race conditions with risk of a catastrophic musculoskeletal injury (CMI) resulting in euthanasia in Thoroughbreds during racing in California in 1992. DESIGN: Retrospective longitudinal study. ANIMALS: Thoroughbreds that incurred CMI during racing and all California race entrants in 1992. PROCEDURE: Necropsy records were reviewed, and race start information was obtained. Incidence risk of CMI/1,000 race entrants was estimated. Relationships between CMI during racing and race-meet, entrant age and sex, race type and length, and racing surface type and condition were evaluated by use of logistic regression. RESULTS: Incidence risk of CMI was 1.7/1,000 entrants. A higher risk of CMI was found at 2 fair race-meets, with incidence risks of 4.9 and 5.5/1,000 entrants. Risk of injury in male horses was 1.7 times greater than that in female horses, and influence of age on risk depended on race type. Risk of injury for horses 2 to 5 years old was two times greater for claiming horses than for maiden horses. Race length or racing surface type (dirt vs turf) or condition (fast, muddy, yielding) were not significantly associated with risk of CMI. CLINICAL IMPLICATIONS: Incidence of CMI was similar among 12 of 14 major and fair race-meets and among various race lengths and racing surface types and conditions, whereas incidence of CMI was influenced by entrant age and sex as well as race type. Investigators should consider controlling for age and sex, race-meet, and race type whenever possible in studies of risk of CMI.

Experimental reproduction of Mycoplasma gallisepticum disease in chukar partridges (Alectoris graeca).

An outbreak of conjunctivitis and severe respiratory disease occurred in an integrated chukar partridge (Alectoris graeca) operation that involved about 8000 birds. The main clinical features were conjunctivitis and sinusitis and frequent mouth breathing, but almost no gasping or coughing. In 1000 breeders, egg production declined from 73% to 20%. Morbidity reached 100%, and losses from mortality and culling approached 60%. At necropsy, a conjunctivitis (often bilateral) and extensive caseated sinusitis were common. There was an occasional slight mucoid tracheitis, but no significant air sac lesions were noted. Mycoplasma gallisepticum, designated strain GM1125, was isolated and identified. Exposure of susceptible chukars to GM1125 reproduced the field disease. GM1125 was reisolated from the conjunctiva of all exposed birds 12 days postinfection, but infrequently from there or the respiratory system 36 days postexposure, even though clinical disease was still present. The experimental disease was confined to the conjunctiva and the upper respiratory tract. An occasional mucoid tracheitis was noted, but generally, the lungs and air sacs were not involved. Infection was followed by an appreciable serological response to M. gallisepticum.

Fatal musculoskeletal injuries incurred during racing and training in thoroughbreds.

OBJECTIVE: To characterize and contrast data from Thoroughbreds that incurred a fatal musculoskeletal injury (FMI; injury resulting in death or euthanasia) during racing or training and data from all California race entrants during a 9-month period in 1991. DESIGN: Case-control study. ANIMALS: Thoroughbreds that incurred a FMI during racing or training at a California race-meet and all California race entrants from January through June and October through December 1991. PROCEDURE: Age and sex were compared with chi 2 and Fisher's exact tests among horses fatally injured while racing and training. A log-linear model was fit to assess the relationship between race-meet and age and sex of California race entrants. Incidence risk of racing FMI was estimated per 1,000 race entrants, and the relationship between the occurrence of FMI during racing with race-meet, age, and sex was evaluated by logistic regression. RESULTS: Injury type and sex-specific age distributions differed among the horses fatally injured during racing and training. Age and sex distributions of the race entrants were not independent and varied among race-meets. Overall incidence risk of racing FMI was estimated at 1.7/1,000 race entrants. Risk of racing FMI in male horses was about twofold that in female horses, and in 4-year-olds was twofold that in 3-year-olds. CLINICAL IMPLICATIONS: Age and sex-related differences in risk of incurring a FMI during racing should be considered when comparing fatal injury rates among race-meets.

Evaluation of abortions in cattle attributable to neosporosis in selected dairy herds in California.

OBJECTIVE: To estimate the minimum rate of abortion attributable to infection with Neospora sp in selected California dairy herds. DESIGN: Prospective study. ANIMALS: Twenty-six dairy herds containing 19,708 cows were studied. Fourteen herds had a history of abortions attributable to neosporosis, and 12 were herds in which neosporosis had not been identified as a cause of abortions. PROCEDURE: During a 1-year period, all available aborted fetuses were submitted to veterinary diagnostic laboratories to determine the cause of abortion. Reproductive records of cows that aborted were reviewed. RESULTS: Neospora sp infection was the major cause of abortion identified (113/266 abortions, 42.5%). The majority (232/266, 87.2%) of the aborted fetuses were submitted from herds with a history of abortions attributable to neosporosis, and Neospora sp infection was identified as the causative agent in 101 of 232 (43.5%) of the abortions from these herds. Fewer aborted fetuses were submitted from the 12 herds that did not have a history of abortion attributable to Neospora sp; however, neosporosis was confirmed as a cause of abortion in 6 of these 12 herds and was identified as the causative agent in 12 of 34 (35.3%) abortions from these herds. The disease was widespread throughout the state (19/26 herds in our study). Available reproductive histories of cows that had abortions attributed to neosporosis were evaluated, and 4 cows were identified that twice aborted Neospora-infected fetuses. CLINICAL IMPLICATIONS: Abortion attributable to Neospora sp infections can be expected to be a continuing major cause of abortion in dairy herds with a history of neosporosis as well as in dairy herds that have a history of sporadic abortions, but for which Neospora sp infections have not been previously identified as a cause of abortion. Subsequent pregnancies in cows that abort a Neospora sp-infected fetus also are at risk of infection, suggesting that the immunity provided by an initial infection is inadequate to prevent repeat infection or that cows can be persistently infected with Neospora sp.

Causes of death in racehorses over a 2 year period.

Necropsies were performed on 496 horses that had a fatal injury or illness at a California racetrack during the period February 20th 1990 to March 1st 1992. The primary cause of death was categorised by breed, activity at time of injury or illness and organ system affected. Most of the submissions were Thoroughbred horses (432) and Quarter Horses (46). Most of the injuries occurred while racing (42%) and in training sessions (39%); with fewer non-exercise (12%) and accident (7%) related injuries or illnesses. Musculoskeletal injuries accounted for 83% of the Thoroughbred and 80% of the Quarter Horse submissions. The Thoroughbred horses incurred 306 fractures with 263 in the limbs and 90% of those in the forelimbs. The proximal sesamoid bone(s), third metacarpal bone and humerus were the most common bones fractured in Thoroughbred horses and Quarter Horses. Other major causes of death included respiratory, digestive and multi-organ system disorders.

A retrospective study of circovirus infection in pigeons: nine cases (1986-1993).

Circovirus infections were diagnosed in 12 pigeons from the United States 4 pigeons from Australia, and 1 pigeon from Canada (1986-1993). Circovirus was identified by electron microscopic examination of basophilic botryoid cytoplasmic inclusions that had a histologic appearance similar to that of psittacine beak and feather disease virus inclusions. Inclusions were seen in splenic, bursal, gut-associated, and bronchus-associated lymphoid tissue macrophages and in bursal epithelial cells. Inclusions were composed of paracrystalline arrays of tightly packed, nonenveloped icosahedral virions 14-17 nm in diameter. Histologic changes in the spleens ranged from lymphofollicular hyperplasia with mild discrete lymphocellular necrosis to lymphoid depletion and diffuse histiocytosis. Lesions in the bursa of Fabricius ranged from mild lymphocellular necrosis to severe cystic bursal atrophy. Remaining histologic findings coincided with concurrent bacterial, viral, fungal, and parasitic infections. Immunoperoxidase staining and DNA in situ hybridization demonstrated that pigeon circovirus is distinct from psittacine beak and feather disease virus; however both viruses apparently share some homologous DNA sequences. Clinical and diagnostic findings indicate that pigeon circovirus may be similar to psittacine beak and feather disease virus with respect to acquired immunodeficiency and subsequent multiple secondary infections.

In vitro isolation and characterization of a Neospora sp. from aborted bovine foetuses.

A Neospora sp. was isolated from the brains of two aborted bovine foetuses and grown continuously in vitro in bovine cell cultures. A comparison of the antigenic reactivity of in vitro cultivated tachyzoites with polyclonal antisera to Neospora caninum, Hammondia hammondi or Toxoplasma gondii revealed that the bovine protozoal isolates were similar to N. caninum and antigenically distinct from T. gondii. Tachyzoites of both bovine isolates had similar ultrastructural features, including an apical polar ring, conoid, electron-dense rhoptries and micronemes. The orientation of the micronemes, presence of micropores and a large number of electron-dense granules in the posterior portion of the bovine isolate tachyzoites differed from previous descriptions of N. caninum in vivo. Tachyzoites of the bovine isolates were ultrastructurally more similar to in vitro cultivated N. caninum tachyzoites than to tachyzoites of T. gondii or H. hammondi. The antigenic and ultrastructural similarities between N. caninum and the protozoal parasites isolated from aborted bovine foetuses in this study support the proposition that these parasites belong to the genus Neospora.

Mycoplasma bovis associated with decubital abscesses in Holstein calves.

Between April of 1990 and March of 1992, calves on a Holstein calf ranch experienced subcutaneous decubital abscesses involving the brisket region, dorsal aspect of the carpus, and lateral aspect of the stifle joints. Fifty out of 2,500 (2%) Holstein calves between the ages of 3 and 12 weeks were affected. Needle aspirates of brisket abscesses from 8 calves and 6 live or dead calves with 1 or more decubital abscesses were submitted for examination. Two of the 6 calves in addition had bronchopneumonia. Mycoplasma bovis was isolated from all abscesses and 1 lung. Formalin fixed tissues taken from the affected areas also revealed M. bovis by immunoperoxidase staining. No evidence of joint involvement was apparent, and no mycoplasma was isolated from the joints adjacent to affected areas. Attempts to isolate mycoplasma from milk and environmental samples were unsuccessful.

Intranuclear inclusions of unknown pathogenic significance from diagnostic cases in three avian species.

Intranuclear inclusions were observed with light microscopy in tissues from necropsy cases from three different species of birds. Because of the nature of these inclusions, the species affected, or their distribution, the inclusions were considered of unknown pathogenic significance. The inclusions were examined ultrastructurally. Parvovirus-like particles were observed in the intranuclear inclusions of pigeon hepatocytes and duodenal stromal cells from a quail. Finely granular eosinophilic intranuclear inclusion bodies from two unrelated pigeon cases were found to be composed of loosely organized filaments. One liver sample from a 16-week-old laying chicken had prominent eosinophilic hepatocellular intranuclear inclusions composed of electron-dense coarsely granular amorphous material.

Tracheal aspergillosis in 6 1/2-week-old chickens caused by Aspergillus flavus.

A case of localized tracheal aspergillosis in 6 1/2-week-old single-comb white leghorn pullets caused by Aspergillus flavus is documented. Yellow caseous plaques adherent to the mucosal surface of the tracheas were observed grossly. In several tracheas, the plaques occluded the lumina, and the surrounding tracheal walls were reddened. Histologically, the mucosa was necrotic and infiltrated with macrophages, and fibroplasia was evident in the subadjacent tracheal wall. The lumen of the trachea was almost completely occluded by a combination of fungal mycelia and pyogranulomatous exudate. Portions of tracheal cartilage were elevated into the lumen of the trachea. Other than a sudden increase in mortality to 0.5% per day, there was no evidence of disease in the flock. Depletion of bursal lymphocytes, with concomitant cryptosporidiosis, was evident on histological examination. Acute infectious bursal disease was diagnosed in the succeeding flock at this ranch based upon serology and typical histology.