Histochemical and immunohistochemical evidence of a bacterium associated with lesions of epizootic bovine abortion.

Epizootic bovine abortion (EBA), a tick-transmitted disease of pregnant cattle grazing foothill pastures, is a major cause of reproductive failure in California and adjacent states. Affected fetuses develop a chronic disease, resulting in late-term abortion or premature calving. Despite investigations spanning 50 years, to the authors' knowledge, the etiologic agent of EBA has not yet been isolated from affected fetuses or the tick vector. The diagnosis of EBA is based on gross and microscopic lesions. Recently, documentation that the etiologic agent is susceptible to antibiotics and identification of a unique 16S deltaproteobacterial rDNA gene sequence in 90% of thymus tissues from aborted fetuses have supported the role of a bacterial infection as the cause of EBA. To determine whether bacteria could be detected in the tissues, histochemical staining and immunohistochemical procedures were used on formalin-fixed, paraffin-embedded tissues. Use of a modified Steiner silver stain revealed small numbers of intracytoplasmic bacterial rods in 37 of 42 thymic samples from EBA-affected fetuses. Improved detection was achieved by use of immunohistochemical staining with serum from EBA-affected fetuses that resulted in detection of numerous bacterial rods in the cytoplasm of histiocytic cells in the thymus from all 42 EBA-affected fetuses. Immunohistochemical examination of additional tissues from 21 field and experimental EBA cases revealed positively stained intracytoplasmic bacterial rods in many organs with inflammatory lesions. Use of the modified Steiner stain and immunohistochemical staining of tissues from negative-control fetuses failed to reveal organisms. To the authors' knowledge, this is the first report to document morphologic evidence of a bacterium associated with the lesions of EBA.

Bluetongue and equine viral arteritis viruses as models of virus-induced fetal injury and abortion.

A number of viruses have the capacity to cross the placenta and infect the fetus to cause, among other potential outcomes, developmental defects (teratogenesis), fetal death and abortion. Bluetongue virus (BTV) infection of fetal ruminants provides an excellent model for the study of virus-induced teratogenesis. This model has shown that only viruses modified by passage in cell culture, such as modified live virus vaccine strains, readily cross the ruminant placenta, and that the timing of fetal infection determines the outcome. Thus, cerebral malformations only occur after fetal infection at critical stages during development and the precise timing of fetal BTV infection determines the severity of the malformation present at birth. Fetal BTV infection also can result in fetal death, followed by abortion or resorption, growth retardation, or no obvious abnormalities, depending on age of the conceptus at infection. Equine arteritis virus (EAV) infection of the equine fetus causes fetal death and abortion but not teratogenesis. These two fetal viral infections are useful not only for the study of teratogenesis and fetal disease, but also to further characterize and compare the complex process that is responsible for normal induction of parturition in ruminants and horses.

Comparison of results of hormonal analysis of samples obtained from selected venous sites versus cervical ultrasonography for localizing parathyroid masses in dogs.

OBJECTIVE: To compare a technique in which samples obtained from selected venous sites are analyzed for parathyroid hormone (PTH) concentration versus usefulness of cervical ultrasonography for localizing primary hyperparathyroidism (PHP) in dogs. DESIGN: Prospective study. ANIMALS: 12 dogs with PHP. PROCEDURE: For each dog, blood samples were collected from the left and right jugular veins and 1 cephalic vein for determination of serum PTH concentration. Ultrasonography of the neck was performed in each dog. Each dog underwent exploratory surgery of the neck. Abnormal appearing parathyroid tissue was removed. Dogs were included in the study if serum calcium concentration decreased within 12 hours after surgery, hypercalcemia completely resolved within 96 hours after surgery, and serum calcium concentration was maintained within the reference range for at least 6 months after surgery. RESULTS: Serum PTH concentrations from the 3 veins were similar in 11 of 12 dogs with PHP. In 1 dog, the serum PTH concentration from the jugular vein ipsilateral to a parathyroid adenoma was greater than that from the contralateral jugular or cephalic vein. Ultrasonography correctly identified a parathyroid mass and its location in 10 of 11 dogs with a solitary abnormal parathyroid gland and in 1 dog in which both parathyroid glands were enlarged. CLINICAL IMPLICATIONS: Surgeons may benefit from knowing the location of abnormal parathyroid tissue in dogs with PHP before surgical exploration. Ultrasonography has potential value for identifying and localizing abnormal parathyroid tissue, whereas sample collection from selected sites for PTH analysis is not likely to be helpful.

Diagnostic testing for pituitary pars intermedia dysfunction in horses.

Pituitary pars intermedia dysfunction is a slowly progressive disorder that afflicts most breeds of horses. Because it shares features with human Cushing disease, it has been referred to as equine Cushing disease. A variety of tests of pituitary-adrenocortical function were performed on horses with evidence of pituitary pars intermediate dysfunction, and results were compared with those in healthy control horses. Diurnal variations in plasma cortisol concentration were not statistically different between control horses and those with pituitary pars intermedia dysfunction. An ACTH stimulation (1 U of natural ACTH gel/kg of body weight, IM) test or a combined dexamethasone suppression test (10 mg, IM) and ACTH stimulation (100 mg of synthetic ACTH, IV) test also failed to distinguish horses with pituitary pars intermedia dysfunction from control horses. A significant (P < 0.001) dose-related suppression of cortisol concentration in response to increasing doses (5, 10, 20, and 40 micrograms/kg) of dexamethasone was observed in control horses but not in those with pituitary pars intermedia dysfunction. On the basis of plasma cortisol concentration, the dexamethasone suppression test, using 40 micrograms/kg, whether initiated at 5 PM with sample collection at 15 (8 AM) and 19 (12 PM) hours after dexamethasone administration, or initiated at 12 AM with sample collection at 8 (8 AM), 12 (12 PM), 16 (4 PM), 20 (8 PM), and 24 (12 AM) hours after dexamethasone administration, reliably distinguished between control horses and those with pituitary pars intermedia dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)

Primary parathyroid gland hyperplasia in dogs: six cases (1982-1991).

Persistent hypercalcemia attributable to parathyroid gland hyperplasia was identified in 6 dogs with primary hyperparathyroidism. Clinical signs included polydipsia (n = 4), polyuria (n = 4), and signs caused by cystic calculi (n = 3). Abnormal clinical pathologic findings included hypercalcemia (mean, 13.6 mg/dl; range, 12.6 to 14.7 mg/dl; n = 6), hypophosphatemia (mean, 2.2 mg/dl; range, 1.4 to 2.9 mg/dl; n = 6), high serum alkaline phosphatase activity (mean, 222 IU/L; range, 161 to 286 IU/L; n = 3), and isosthenuria (mean, 1.012; range, 1.006 to 1.017; n = 6). Serum parathyroid hormone concentration was within the reference range or high (mean, 23 pmol/L; range, 7 to 119 pmol/L; reference range, 1.5 to 13 pmol/L) in all dogs. At surgery, the number of large parathyroid glands was variable, being limited to 1 gland in 3 dogs, 2 glands in 2 dogs, and 4 glands in 1 dog. All visibly large parathyroid glands were surgically removed from each dog. Serum calcium concentration decreased into or below the reference range within 72 hours of surgery in all dogs, confirming the diagnosis of primary parathyroid disease. Multiple nodules of adenomatous hyperplasia were identified in each dog. All 6 dogs were treated with vitamin D and calcium carbonate following surgery. The dog from which all 4 parathyroid glands were removed has remained eucalcemic for more than 1 year with vitamin D supplementation. Vitamin D and calcium administration was discontinued within 4 to 12 weeks of surgery in the remaining 5 dogs. These dogs remained eucalcemic without vitamin D supplementation.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of two sample collection methods for quantitative bacteriologic culture of canine prostatic fluid.

Ejaculate, urine, urethral swab specimens, and ultrasonography-guided small-needle prostatic cyst aspiration and/or tissue core biopsy specimens were collected for bacteriologic culture from 25 dogs in which prostatic disease was suspected on the basis of history, clinical signs of disease, or results of physical examination. The prostate gland in each dog was examined ultrasonographically, and the tissue core biopsy specimens were examined histologically and bacteriologically. Two methods were used to assess bacterial prostatitis. In 5 dogs (20%), bacteriologic culture results of paired urethral swab and ejaculate specimens differed from culture results of specimens obtained by needle aspiration of prostatic cyst fluid or tissue core biopsy. The prostate gland in 17 dogs had 1 or more cystic, fluid-filled structures (0.5 to 4.0 cm in diameter). Ultrasonographic appearance of the prostate gland did not have obvious correlation with culture results from dogs of the study. Histologic results of prostatic tissue core biopsy specimens correlated well with culture results.

Relationship of upper and lower urinary tract infection and bacterial invasion of uroepithelium to antibody-coated bacteria test results in female dogs.

Urinary tract infection was demonstrated in 12 female dogs via bacteriologic culture of a specimen of bladder urine collected by antepubic cystocentesis. Escherichia coli was isolated in pure culture from the urine of 9 dogs. Urine specimens from 2 dogs contained E coli and alpha-streptococci and from 1 dog contained Streptococcus zymogenes in pure culture. In 6 dogs, urinary tract infection was limited to the urinary bladder, whereas 6 dogs had unilateral or bilateral culture-positive renal pelvic urine as well (specimens collected by percutaneous nephropyelostomy). An antibody-coated bacteria (ACB) test was conducted on a portion of the bladder urine specimen from each dog, and the urinary tissues from these 12 dogs and from 6 healthy, noninfected female dogs were examined at necropsy. Tissues were given a subjective score based on the severity of the lesions seen microscopically. Histologic scores, bacterial cultural results, and ACB test results were examined for significance. A significant difference was found in the histologic scores between infected and noninfected dogs (P less than 0.025), but comparisons among histologic scores, cultural results, and ACB test results were not significant among infected dogs. The ACB test could neither be used to localize bacterial infection within the urinary tract nor could it be used to indicate the presence of bacterial invasion of the uroepithelium in dogs.

Studies on the pathogenesis of epizootic bovine abortion.

Ornithodoros coriaceus Koch ticks were fed on 37 pregnant cows. The fetuses were obtained from the cows at 23 to 126 days after maternal tick exposure. Characteristic lesions of epizootic bovine abortion were observed only in those fetuses recovered 100 days more or after maternal tick exposure. Fetuses collected between 50 and 100 days showed mild-to-moderate lymphoid and mononuclear cell hyperplasia. Reaction in fetuses studied less than 50 days after maternal tick exposure were mild. Lesions could not be seen in 2 of the youngest fetuses. Increases in serum immunoglobulin concentrations were present only in those fetuses examined 80 days or more after their dams had been exposed to ticks. The specificity of the immunoglobulins could not be determined. Sera from 12 fetuses tested failed to fix complement in tests for group-specific chlamydial antibodies. A wide variety of microbiological cultivation attempts were made to recover the causative agent of epizootic bovine abortion from these fetuses; however, no agent was recovered regularly, and chlamydial organisms were not recovered from any. The significance of 2 recovered agents, apparently viral, is still to be determined. Fetal tissues, both frozen and fresh, collected from fetuses of dams exposed to a feeding of ticks were capable of reproducing the disease after inoculation into pregnant cows or directly into fetuses.

Epizootic bovine abortion: histogenesis of the fetal lesions.

The development of the fetal lesions of epizootic bovine abortion (EBA) was studied in a series of experiments and field cases of the disease. Thirty-six experimentally infected fetuses were recovered at periods of 29 to 126 days after their dams had been infected by allowing the vector tick Ornithodorus coriaceus to feed on them. The sequential development of the fetal lesions was studied and the lesions compared with those in both naturally occurring and experimentally induced infections of the dams which either aborted or carried to term. The early changes observed in the fetuses consisted of transformation and proliferation of lymphocytes and mononuclear phagocytes. These changes were marked by 50 days after tick exposure of the dams, but fetal lesions specific enough to permit making the diagnosis of the disease did not develop until 100 days after dams were exposed by tick feeding. In the fetuses which were either aborted or carried to term after prolonged infection, acute necrotizing lesions were superimposed on the chronic proliferative fetuses. Acute necrotizing foci developed in several organs, but most commonly in lymph nodes and spleen. These foci frequently formed pyogranulomas. Acute vasculitis developed at the same time as the acute focal-necrotizing lesions. These lesions were similar to immune-mediated lesions that result from the deposition of toxic complexes in the tissues. Immunofluorescent examination demonstrated that immunoglobulins (Ig)G and IgM were present in the vascular lesions.

Prognostic value of endometrial biopsy in the mare: a retrospective analysis.

A retrospective analysis was made of 79 endometrial biopsy specimens obtained from mares with histories of infertility. The specimens were classified into 3 standard prognostic categories, according to the severity of the histologic changes. The 36 mares that had few endometrial lesions (category I) had a foaling rate of 78%. The 29 mares that had more severe endometrial changes (category II) had a foaling rate of 55%. The 14 mares with the most severe endometrial lesions (category III) had a foaling rate of 35%. The pregnancy losses for each category were 9.7%, 23.8%, and 44.4%, respectively. It was concluded that uterine biopsy can be a useful aid in predicting fecundity in the mare when it is used in conjunction with evaluation of the history, clinical examination, and appropriate diagnostic laboratory tests, but only if satisfactory biopsy specimens are obtained and examined by an individual who has the experience and training to interpret the lesions.

Insulin-secreting islet cell tumors: establishing a diagnosis and the clinical course for 25 dogs.

Twenty-five dogs with insulin-secreting neoplasms of the pancreas were studied. The diagnosis in each case was determined by histologic evaluation of pancreatic tissue obtained at surgery. The breed distribution revealed that German Shepherd Dogs, Irish Setters, and Collies were most commonly represented. Physical examination, complete blood counts, serum biochemical analysis, and urinalysis were of little diagnostic value, aside from the finding of hypoglycemia in 21 of 25 dogs. Radiographs of the thorax and abdomen were noncontributory to the ultimate diagnosis. Prior to surgery, fasting immunoreactive insulin concentrations and blood glucose concentrations were studied. Insulin:glucose ratios, glucose:insulin ratios, and amended insulin:glucose ratios were determined from the insulin and glucose concentrations in a single blood sample in each of 28 trials. In addition, glucagon tolerance tests were performed on 12 dogs. The amended insulin:glucose ratios proved to be the most reliable for diagnosis. Pancreatic masses were evident at surgery in 23 of 25 dogs; the remaining 2 dogs had microscopic evidence of an islet cell tumor. Nineteen of the islet cell tumors were carcinomas and 6 were simply described as "islet cell tumors." The mean life expectancy after surgery was 12.3 months. Treatment for malignant islet cell tumours included frequent feeding glucocorticoids, and diazoxide.

Clinical findings, pathological changes and endocrinological secretory patterns in mares with ovarian tumours.

The clinical, structural and functional characteristics of ovarian tumours were studied in 10 mares. Proliferation of the granulosa cells of large and small follicles and the presence of various numbers of Leydig-like cells in the theca interna were the predominant microscopic findings in 9 of the mares. All 9 of these animals had higher than normal (P less than 0.005) concentrations of testosterone in the peripheral plasma; 2 animals which exhibited male behaviour had testosterone concentrations greater than 100 pg/ml and the largest number of Leydig-like cells in the theca. Mares with lower testosterone concentrations (7/9) exhibited anoestrus or intermittent oestrous behaviour. The predominant microscopic changes in the other mare involved the proliferation of Sertoli-like cells; oestrogen concentrations were highest in this mare. Testosterone values were normal when no Leydig-like cells were observed in the theca. The unaffected ovary of all 10 mares was small and inactive. Eight mares resumed normal cyclic ovarian activity between 115 and 393 days after the removal of the affected ovary.

Gonadal dysgenesis in the mare.

Five phenotypically normal but infertile mares were studied; four had karyotypes of 63XO, and one was a 25,64XX/13,63XO mosaic. The mares exhibited small uteri and has small ovaries that lacked germ cells and consisted primarily of undifferentiated ovarian stroma. These cases demonstrate that chromosome analysis is an important technique for the diagnosis of some forms of equine infertility.

XO-gonadal dysgenesis in the mare (report of two cases).

TWo cases of XO-gonadal dysgenesis in the mare are presented. Case No 1 was a pure 63, XO, while Case No 2 was a mosaic with a preponderance of XX cells. The clinical picture was one of phenotypically normal female mares with small uteri and infantile ovaries. The ovaries lacked germ cells, and consisted of stroma only. This study emphasizes the importance of chromosome analysis in providing information concerning the mechanisms involved is some cases of equine infertility.