Serum cortisol concentrations in dogs with pituitary-dependent hyperadrenocorticism and atypical hyperadrenocorticism

Background

Atypical hyperadrenocorticism (AHAC) is considered when dogs have clinical signs of hypercortisolemia with normal hyperadrenocorticism screening tests.

Hypothesis/Objectives

To compare cortisol concentrations and adrenal gland size among dogs with pituitary‐dependent hyperadrenocorticism (PDH), atypical hyperadrenocorticism (AHAC), and healthy controls.

Animals

Ten healthy dogs, 7 dogs with PDH, and 8 dogs with AHAC.

Method

Dogs were prospectively enrolled between November 2011 and January 2013. Dogs were diagnosed with PDH or AHAC based on clinical signs and positive screening test results (PDH) or abnormal extended adrenal hormone panel results (AHAC). Transverse adrenal gland measurements were obtained by abdominal ultrasound. Hourly mean cortisol (9 samplings), sum of hourly cortisol measurements and adrenal gland sizes were compared among the 3 groups.

Results

Hourly (control, 1.4 ± 0.6 μg/dL; AHAC, 2.9 ± 1.3; PDH, 4.3 ± 1.5) (mean, SD) and sum (control, 11.3 ± 3.3; AHAC, 23.2 ± 7.7; PDH, 34.7 ± 9.9) cortisol concentrations differed significantly between the controls and AHAC (P < .01) and PDH (P < .01) groups. Hourly (P < .01) but not sum (P = .27) cortisol concentrations differed between AHAC and PDH dogs. Average transverse adrenal gland diameter of control dogs (5.3 ± 1.2 mm) was significantly less than dogs with PDH (6.4 ± 1.4; P = .02) and AHAC (7.2 ± 1.5; P < .01); adrenal gland diameter did not differ (P = .18) between dogs with AHAC and PDH.

Conclusions and Clinical Importance

Serum cortisol concentrations in dogs with AHAC were increased compared to controls but less than dogs with PDH, while adrenal gland diameter was similar between dogs with AHAC and PDH. These findings suggest cortisol excess could contribute to the pathophysiology of AHAC.

Effects of diagnostic test accuracy and treatment efficacy on the occurrence of suspected failure of heartworm prophylaxis in dogs

BACKGROUND

Food and Drug Administration Center for Veterinary Medicine (FDA/CVM) cited concern regarding failure of heartworm prophylaxis. The positive and negative predictive value of the heartworm antigen test is an estimate of the probability of adult heartworm infection.

HYPOTHESIS/OBJECTIVES

Assess the sensitivity, specificity, and predictive value of heartworm antigen tests. Explore the role of heartworm test accuracy and treatment with immiticide to generate reports of suspected failure of heartworm prophylaxis.

METHODS

Literature searches for published information on the accuracy of heartworm antigen tests and efficacy of immiticide for treatment of the adult heartworm.

RESULTS

Weighted averages for heartworm antigen test sensitivity and specificity were 78.2 and 97.3%, respectively. Efficacy of immiticide by 2-injection or alternate dose protocols were 88.3 and 89.1%, respectively. Depending on prevalence, the positive predictive value of the heartworm antigen test ranged from 15 to 54% and negative predictive value from 99 to 99.9%. For a hospital testing 1,000 dogs per year, false-positive test results may vary from 24 to 27 dogs. If these dogs were on heartworm preventive, they may undergo treatment and be classified as prophylaxis failures. Ten percent of dogs who were treated and continued or placed on prophylaxis at the time of treatment may have adult heartworms when tested 1 year later and be presumed to represent failure of prophylaxis.

CONCLUSIONS

When interpreting heartworm antigen test results, clinical signs, history, and regional prevalence of heartworm disease should be considered in estimating the predictive value of the test result. Limitations of test and treatment should be discussed with clients as part of the decision-making process.

Serial evaluation of neutrophil function in tumour-bearing dogs undergoing chemotherapy

We hypothesized that neutrophil function in tumour-bearing dogs is negatively impacted by chemotherapy. Flow cytometric techniques were used to assess neutrophil oxidative burst and phagocytic activities at baseline, 7 and 21 days after induction chemotherapy in 20 dogs with lymphoma. Dogs had a lower percentage of neutrophils exhibiting oxidative burst activity after stimulation with Escherichia coli (day 7; P = 0.009) and phorbol 12-myristate 13-acetate (PMA) (days 7 and 21; P = 0.0003 and P = 0.01, respectively), compared with healthy controls. From day 0 to 7, the percentage of neutrophils exhibiting oxidative burst activity decreased after stimulation with E. coli (P = 0.016) and PMA (P = 0.0006). Induction chemotherapy suppresses the percentage of neutrophils capable of oxidative burst in dogs with lymphoma, with improvement in phagocytic activity over time (P = 0.03). The impact of neutrophil dysfunction on incidence and severity of sepsis in dogs receiving chemotherapy should be investigated.

C-kit Expression in Canine Mucosal Melanomas

The c-kit receptor is responsible for transmission of promigration signals to melanocytes; its downregulation may be involved in malignant progression of human melanocytic neoplasms. Expression of this receptor has not been examined in normal or neoplastic melanocytes from dogs. In this study, 14 benign dermal and 61 malignant mucosal melanocytic tumors were examined for c-kit (KIT) expression. Sites of the mucosal melanomas were gingiva (not further specified; n = 30), buccal gingiva ( n = 6), soft palate ( n = 4), hard palate ( n = 5), tongue ( n = 7), lip ( n = 6), and conjunctiva ( n = 3). Melan A was expressed in all 14 dermal melanocytomas and in 59 of 61 (96.7%) tumors from oral or conjunctival mucosa, confirming melanocytic origin. C-kit receptor expression was strong and diffuse throughout the cytoplasm in all 14 dermal melanocytomas and was identified in basilar mucosal melanocytes over submucosal neoplasms (27 of 61, 44.3%), junctional (neoplastic) melanocytes (17 of 61, 27.9%), and, less commonly, neoplastic melanocytes of the subepithelial tumors (6 of 61, 9.8%). KIT expression anywhere within the resected melanomas correlated with significantly longer survival. These results suggest that c-kit receptor expression may be altered in canine melanomas and may have potential as a prognostic indicator for mucosal melanomas.

The role of mecA and blaZ regulatory elements in mecA expression by regional clones of methicillin-resistant Staphylococcus pseudintermedius

Two major regional clones of methicillin-resistant Staphylococcus pseudintermedius (MRSP) have been identified in Europe and North America. They are designated multilocus sequence types (ST) 71 and 68 and contain staphylococcal chromosome cassette (SCCmec) types II-III and V(T), respectively. One notable difference between the two clones is a deletion in the mecI/mecR1 regulatory apparatus of ST 68 SCCmec V(T). This deletion in analogous methicillin-resistant Staphylococcus aureus (MRSA) results in more responsive and greater expression of the mecA encoded penicillin-binding protein 2a, and is associated with SCCmec types occurring in community-acquired MRSA lineages. The aim of this study was to characterize mec and bla regulatory apparatuses in MRSP and determine their effects on expression of mecA. Seventeen S. pseudintermedius isolates representing nine methicillin-resistant ST lineages were screened for the presence of the repressors blaI and mecI and sensors blaR1 and mecR1. The bla and mec operons for each isolate were sequenced and compared for homology between the repressor open-reading frames (ORF), sensor ORFs, and mecA promoter regions. A real-time reverse transcriptase PCR expression assay was developed, validated and applied to nine isolates determining the effect of oxacillin induction on mecA transcription. Significant differences were found in mecA expression between isolates with a full regulatory complement (mecI/mecR1 and blaI/blaR1) and those with truncated and/or absent regulatory elements. Isolates representative of European and North American MRSP ST regional clones have dissimilar mecA responses to oxacillin.

Renal Lesions of Nondomestic Felids

To comprehensively evaluate the occurrence of renal lesions in a variety of nondomestic felids, necropsy cases from 1978 to 2008 were reviewed from a municipal zoo and a large cat sanctuary for those in which the kidneys were examined histologically. Seventy exotic felids were identified (25 tigers, 18 lions, 6 cougars, 5 leopards, 3 snow leopards, 3 clouded leopards, 3 Canadian lynx, 2 ocelots, 2 bobcats, 2 cheetahs, 1 jaguar), and their histologic renal lesions were evaluated and compared. The most common lesion was tubulointerstitial nephritis (TIN); 36 of 70 (51%) cats were affected to some degree. Lymphocytic interstitial nephritis was the most common lesion in the tigers (9 of 25, 36%) and was rarely seen in other species. Although the renal pelvis was not available for all cats, 28 of 47 (60%) had some degree of lymphocytic pyelitis. There was no significant association between the presence of pyelitis and that of TIN. Only 1 cat had pyelonephritis. Renal papillary necrosis was present in 13 of 70 (19%) cats and was significantly associated with historical nonsteroidal anti-inflammatory drug treatment (odds ratio, 7.1; 95% confidence interval, 1.9 to 26.8). Only 1 cat (lion) had amyloid accumulation, and it was restricted to the corticomedullary junction. Primary glomerular lesions were absent in all cats. Intraepithelial pigment was identified in many of the cats but was not correlated with severity of TIN. Despite several previous reports describing primary glomerular disease or renal amyloidosis in exotic felids, these lesions were rare to absent in this population.

Uterine Lesions in 32 Female Miniature Pet Pigs

Thirty-two 4-month-old to 19-year-old female miniature pet pigs were spayed. Uterine lesions were present in all except 8 pigs. The 24 remaining pigs had diffuse cystic endometrial hyperplasia, of which 14 had smooth muscle tumors, including leiomyomas and leiomyosarcomas, in the uterus or broad ligament. Nodular endometrial lesions—including adenocarcinomas, adenomas, and/or adenomyosis—were present in 10 pigs, 3 of which had concurrent smooth muscle tumors. Pyometra was present in 3 pigs. In uterine sections with cystic endometrial hyperplasia, adenomyosis, or adenomas, approximately 70% of epithelial nuclei expressed estrogen receptor and progesterone receptor immunohistochemically; in adenocarcinomas, expression was 20%. Regardless of malignancy, more than 50% of nuclei in smooth muscle tumors expressed estrogen receptor and progesterone receptor. Aging was associated with the development of uterine lesions in miniature pet pigs.

Leukocyte and platelet changes following low-dose lipopolysaccharide administration in five dogs

Effects of low-dose LPS (0.1 μg/kg i.v.) on leukocyte and platelet parameters measured using an Advia 120 hematology analyzer were investigated. Five dogs received a saline sham treatment prior to LPS, and blood was collected before and 3, 6, and 24 h post-treatment. LPS-treated dogs had mild neutrophil toxic change and increased neutrophil bands at 3 and 6 h. Compared to saline-treated controls, total leukocyte, neutrophil, and monocyte counts of LPS-treated dogs were significantly decreased at 3 h and increased at 24 h. Compared to baseline, total leukocyte counts of LPS-treated dogs were significantly decreased at 3 h and increased at 24 h. Mean platelet volume was significantly increased and mean platelet component concentration was decreased at 3 h compared to baseline. Platelet count was significantly decreased at 3 and 6 h; plateletcrit did not change significantly. High dosage is not required in order to detect LPS-mediated hematologic effects in dogs. Low-dose LPS administration causes significant changes in leukocyte and platelet indices in dogs without causing severe clinical signs or death.

A Retrospective Study of Eyelid Tumors from 43 Cats

Submissions to the University of Tennessee pathology service from June 1999 to June 2008 were searched for feline cases of tumors involving the eyelids or nictitans. Forty-three tumors were identified. The average age at diagnosis was 10.4 years. Significantly more males than females had eyelid tumors. There were 12 squamous cell carcinomas (SCCs), 11 mast cell tumors (MCTs), 6 hemangiosarcomas (HSAs), 4 adenocarcinomas (ACAs), 3 peripheral nerve sheath tumors (PNSTs), 3 lymphomas, 3 apocrine hidrocystomas (AHCs), and 2 hemangiomas. Cats with MCTs were significantly younger than cats with all other tumor types combined. In contrast, cats with SCCs were significantly older than cats with other tumor types. The HSAs and SCCs were significantly more likely than other tumors to occur in nonpigmented areas. The MCTs, HSAs, AHCs, and hemangiomas did not recur after surgical excision. In contrast, the lymphomas, ACAs, SCCs, and PNSTs frequently recurred and/or resulted in death or euthanasia of the cat. The SCCs were significantly more likely to recur than the MCTs. The average survival time for cats with SCCs was 7.4 months. Although eyelid MCTs have been reported in cats, the prevalence in this study is much higher than previously described.

Feline Gastrointestinal Eosinophilic Sclerosing Fibroplasia

A retrospective study of cases of a unique intramural inflammatory mass within the feline gastrointestinal tract was performed in order to describe and characterize the lesion. Twenty-five cases were identified from archival surgical and postmortem tissues. The lesion most often occurred as an ulcerated intramural mass at the pyloric sphincter (n = 12) or the ileocecocolic junction or colon (n = 9); the remaining cases were in the small intestine. Seven cases also had lymph node involvement. The lesions were characterized by eosinophilic inflammation, large reactive fibroblasts, and trabeculae of dense collagen. Intralesional bacteria were identified in 56% of the cases overall and all of the ileocecocolic junction and colon lesions. Fifty-eight percent of cats tested had peripheral eosinophilia. Cats treated with prednisone had a significantly longer survival time than those receiving other treatments. We propose that this is a unique fibroblastic response of the feline gastrointestinal tract to eosinophilic inflammation that in some cases is associated with bacteria. The lesion is often grossly and sometimes histologically mistaken for neoplasia.

Evaluation of a modified surgical technique to correct urine pooling in cows

Various surgical techniques to correct urovagina in cows describe creating a mucosal extension from the urethral orifice to the labia; however, a fistula often forms in the mucosal extension. The objective of the present study was to determine if the incidence of fistula formation could be decreased by covering transposed submucosal tissue on the dorsal aspect of the urethral extension with a mucosal graft. Cows in both the control group (19) and the experimental group (19) received a modified McKinnon technique of urethral extension; cows in the experimental group also had a sheet of mucosa, obtained from the dorsal aspect of the vestibule, grafted to submucosa exposed during creation of the urethral extension. During histological examination of the biopsy of the graft and its recipient site (harvested 1 week after surgery), neither inosculation nor revascularization of the graft was evident in any sample. Fourteen of 19 (74%) cows in the control group and 10 of 19 (53%) cows in the experimental group developed a fistula in the extension (P=0.18). We concluded that application of a mucosal graft to the subcutaneous tissue exposed to the vestibule using the McKinnon technique of creating a urethral extension was of little or no benefit in preventing the formation of a fistula in the extension. Furthermore, during evaluation of the extensions, digital palpation alone was often insufficient for detection of a fistula.

Canine subcutaneous mast cell tumour: diagnosis and prognosis

The aim of this study was to characterize the pathology and clinical outcome of the subcutaneous variant of canine mast cell tumour. Fifty-three cases satisfying the inclusion criteria were selected from the pathology archive of the College of Veterinary Medicine, University of Tennessee. Referring veterinarians provided information on outcome. These dogs had a median age of 9 years (range 3-17 years). After characterizing tumours histologically, nuclear expression of proliferating cell nuclear antigen (PCNA) and Ki67 (MIB-1 clone) was determined immunohistochemically and mast cell origin was confirmed with c-Kit staining. Counts of argyrophilic nucleolar organizer regions (AgNOR) were determined by silver staining. Nuclear labelling was counted in 100 tumour cells. Margins were recorded as incomplete in 66% of dogs, and metastases occurred in 6% of dogs. The estimated minimum mean survival time from date of diagnosis was 1199 days, ranging from 55 to >1780 days. The median scores from immunohistochemical labelling were PCNA 0.05 and Ki67 0.03 per 100 tumour cells. The median score for AgNOR staining was 1.25 per 100 tumour cells. The patterns of c-Kit expression included membranous labelling in 20 tumours, stippled cytoplasmic labelling in 23 tumours and diffuse cytoplasmic labelling in 10 tumours. Age (r=-0.61, P=0.14) and AgNOR score (r=-0.58, P=0.17) had moderate, but non-significant, negative associations with survival. PCNA (r=-0.32, P=0.47), Ki67 (r=-0.22, P=0.64) and c-Kit immunolabelling was not associated with survival. The subcutaneous variant of canine mast cell tumour is distinct in having features of intermediate histological grade and extended mean survival times, suggesting a slightly better long-term prognosis than for higher grade dermal variants. Expression of nuclear proliferation markers is not associated with outcome.

Effects of lipopolysaccharide and phenylbutazone on gastric contents in the horse

REASONS FOR PERFORMING STUDY

Endotoxaemia causes a disruption of gastrointestinal motility in the horse but there is no information on its effects on gastric secretion. Lipopolysaccharide (LPS) administration is known to affect gastric secretion in other species.

HYPOTHESIS

That LPS, a toxic component of Gram-negative bacteria, would reduce gastric acid secretion and that pretreatment with phenylbutazone (PBZ) would block the effects of LPS.

METHODS

The effects of LPS and PBZ on gastric contents were investigated in fasted, mature horses, with permanent gastric cannulae. Horses were pretreated with either saline or PBZ 15 mins before a 60 min infusion of either LPS or saline. Gastric contents were collected at 15 min intervals for 3 h, beginning 15 mins after the start of the LPS or saline infusion.

RESULTS

Lipopolysaccharide significantly decreased gastric acid output, [K+] and potassium output and increased [Na+] and sodium output. Phenylbutazone did not affect basal gastric acid secretion but decreased LPS-induced changes in the secreted volume, [Na+] and sodium output.

CONCLUSIONS

This study provides evidence that LPS affects gastric acid secretion in the horse and that these LPS-induced changes are mediated, in part, by prostaglandins.

POTENTIAL RELEVANCE

Lipopolysaccharide administration can induce changes in the composition of gastric contents in the horse but further work is needed to determine the source of these changes.

Steroid hormone concentration profiles in healthy intact and neutered dogs before and after cosyntropin administration

The purpose of this study was to determine steroid hormone concentration profiles in healthy intact and neutered male and female dogs. Seventeen intact female dogs, 20 intact male dogs, 30 spayed female dogs, and 30 castrated male dogs were used in this study. Serum samples were collected before and 1h after cosyntropin administration, and serum concentrations were determined for cortisol, progesterone, 17-OH progesterone (17-OHP), dehydroepiandrosterone sulfate (DHEAS), androstenedione, testosterone, and estradiol. Intact male dogs had greater concentrations of DHEAS, androstenedione, and testosterone. Intact female dogs had greater concentrations of progesterone. There was no significant difference in estradiol concentration among the four groups. Intact male dogs had lower concentrations of cortisol post-stimulation. DHEAS and testosterone did not increase in response to ACTH in intact males, and estradiol concentrations did not increase in response to ACTH in any group. Results from this study will enhance interpretation of suspected adrenal and/or gonadal disorders of dogs. Because estradiol concentrations were similar in all groups of dogs, measuring estradiol may not be a useful diagnostic test. Cortisol concentrations for intact male dogs with hyperadrenocorticism may be lower than those of female or neutered dogs.

Serum and vitreous humor antibody titers in and isolation of Leptospira interrogans from horses with recurrent uveitis

OBJECTIVE

To measure antibody titers against Leptospira interrogans in serum and vitreous humor and determine the prevalence of L interrogans in vitreous humor of horses with recurrent uveitis.

DESIGN

Cross-sectional study.

ANIMALS

242 horses (270 eyes) with recurrent uveitis undergoing vitrectomy and 39 control horses (54 eyes) without any history or clinical signs of recurrent uveitis undergoing euthanasia or enucleation for unrelated reasons.

PROCEDURE

Serum and vitreous humor were tested for antibodies against 13 serovars of L interrogans. Vitreous humor was submitted for leptospiral culture; isolates were typed to the serogroup level.

RESULTS

Leptospira interrogans was isolated from vitreous humor from 120/229 (52%) horses (126/252 [50%] eyes) with recurrent uveitis but was not isolated from vitreous humor from 36 eyes of 21 control horses. Duration of recurrent uveitis was > or = 1 year for 45 of the 120 (38%) horses from which the organism was isolated. Geometric mean antibody titers against L interrogans in the vitreous humor and serum of horses with recurrent uveitis were 1:1,332 and 1:186, respectively. Only 91 of 120 (76%) horses from which the organism was isolated had a 4-fold or greater difference between serum and vitreous humor antibody titers.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that persistent ocular infection with L interrogans is common in horses with recurrent uveitis. A 4-fold increase in vitreous humor versus serum antibody titers may not be a sensitive test for the diagnosis of L interrogans-induced recurrent uveitis. We hypothesize that the immune component of recurrent uveitis can be directly induced and maintained by persistent infection of the eye with L interrogans.

Epidemiology of feline infectious peritonitis among cats examined at veterinary medical teaching hospitals

OBJECTIVE

To determine proportions of cats in which feline infectious peritonitis (FIP) was diagnosed on an annual, monthly, and regional basis and identify unique characteristics of cats with FIP.

DESIGN

Case-control study.

SAMPLE POPULATION

Records of all feline accessions to veterinary medical teaching hospitals (VMTH) recorded in the Veterinary Medical Data Base between January 1986 and December 1995 and of all feline accessions for necropsy or histologic examination at 4 veterinary diagnostic laboratories.

PROCEDURE

Proportions of total and new feline accessions for which a diagnosis of FIP was recorded were calculated. To identify characteristics of cats with FIP, cats with FIP were compared with the next cat examined at the same institution (control cats).

RESULTS

Approximately 1 of every 200 new feline and 1 of every 300 total feline accessions at VMTH in North America and approximately 1 of every 100 accessions at the diagnostic laboratories represented cats with FIP. Cats with FIP were significantly more likely to be young, purebred, and sexually intact males and significantly less likely to be spayed females and discharged alive than were control cats. The proportion of new accessions for which a diagnosis of FIP was recorded did not vary significantly among years, months, or regions of the country.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that FIP continues to be a clinically important disease in North America and that sexually intact male cats may be at increased risk, and spayed females at reduced risk, for FIP. The high prevalence of FIP and lack of effective treatment emphasizes the importance of preventive programs, especially in catteries.

Fatal Clostridium botulinum toxicosis in eleven Holstein cattle fed round bale barley haylage

Twenty-two lactating Holstein cattle in Tennessee had clinical signs of intoxication with preformed Clostridium botulinum toxin. These signs included weakness, paralysis of the tongue and chest muscles, abdominal breathing, and, in 11 of the 22 cows, death. Differential diagnoses included hypocalcemia, hypomagnesemia, carbohydrate overload, and several toxicoses including mycotoxin, lead, nitrate, organophosphate, atropine or atropine-like alkaloid, and botulism. A diagnosis of botulism by the ingestion of preformed C. botulinum type B toxin was made by eliminating these other diseases, by finding C. botulinum type B spores in 3 bales of round bale barley haylage fed to these cattle, and by isolating preformed type B toxin from 1 of the 3 bales. Confirmation of the toxin type was made by demonstrating mouse lethality by intraperitoneal injection of specimen extracts with neutralization by C. botulinum type B antitoxin. The haylage, harvested green and encased in black plastic bags to facilitate fermentation, was presumably contaminated by the botulinum toxin when fermentation failed to produce enough acid to lower the pH to 4.5, the pH below which C. botulinum growth is inhibited. Farmers and ranchers who use round hay balers to produce haylage should be alert to this potential problem.

Risk factor analysis for breast cellulitis complicating breast conservation therapy

Women who undergo breast conservation therapy for early-stage breast cancer can develop breast cellulitis, a complication for which risk factors are undefined. A matched case-control investigation was conducted to identify risk factors for the development of breast cellulitis among patients who have undergone breast conservation therapy. Patients comprised 17 patients with cases of breast cellulitis diagnosed after partial mastectomies that had been performed from 1992 through 1997 and 34 control patients who were matched to case-patients by date of breast lumpectomy and by primary surgeon. Statistical analyses indicated the following factors were associated with breast cellulitis: drainage of a hematoma (P=.010); postoperative ecchymosis (P=.021); lymphedema (odds ratio [OR], 10. 154; 95% confidence interval [CI], 1.348-208.860); resected breast tissue volume (OR, 1.456; 95% CI, 1.035-2.168); and previous number of breast seroma aspirations (OR, 3.445; 95% CI, 1.036-19.771). This is the first matched case-control study to identify risk factors for the development of breast cellulitis after breast conservation therapy.

Alterations in hemograms and serum biochemical analytes of steers after prolonged consumption of endophyte-infected tall fescue

The objective of the current study was to delineate changes that occur in serum analytes and blood cellular elements in cattle that graze endophyte-infested (Neotyphodium coenophialum) tall fescue. Tall fescue is grown on more than 35 million acres (14.2 million ha) of pasture in the United States, and three-fourths of the pastures are infected with the endophyte at a 60% or greater level. Tall fescue toxicosis caused by endophyte-produced ergot alkaloids continues to be the most important grass-related disease in the United States, in terms of economic loss to animal producers. However, the agronomic attributes of tall fescue make it an attractive forage species because of its ability to withstand cool temperatures, drought, poor soil conditions, and intensive defoliation from herbivore species, including insects. Tall fescue toxicosis is a complex disease and the need exists to understand the mechanisms of the toxic effects in order to institute effective, prophylactic control measures. Our group previously reported changes that occur in serum biochemical analytes of cattle that graze endophyte-infected tall fescue. An additional year's worth of data have been added, strengthening and corroborating these data. Consistent and significant changes associated with tall fescue toxicosis during the 3-yr study included decreased serum concentrations of cholesterol, globulin (increased albumin/globulin ratio), prolactin, total protein, and copper. The activity of alanine aminotransferase was decreased in serum, whereas an increase in serum concentrations of creatinine and total bilirubin occurred. The present report also documents comparative hemograms of cattle that grazed endophyte-infected or endophyte-free tall fescue over a prolonged period. The mean erythrocyte counts were increased in cattle that grazed endophyte-infected tall fescue, whereas mean corpuscular hemoglobin and mean corpuscular volume were decreased, as were mean eosinophil counts. Thus, repeatable changes have been identified that occur in serum biochemical and blood cellular values of cattle grazing endophyte-infected tall fescue that will aid in understanding the pathogenesis of the disease. In addition, these consistently altered parameters can be used to assess the effectiveness of potential prophylactic treatments.

Tissue strength and wound morphology of the equine linea alba after ventral median celiotomy

OBJECTIVE

To evaluate the tensile strength and wound morphology of the equine linea alba at intervals over 6 months after ventral median celiotomy.

STUDY DESIGN

Linea alba tensile strength and wound morphology were determined at 2, 4, 8, 16, and 24 weeks postoperatively. Linea alba samples from 3 unoperated horses were used as controls.

ANIMALS

Eighteen adult horses, weighing 400 to 500 kg, 4 to 15 years old.

METHODS

Tensile strength and thickness of incised linea alba samples collected at 2, 4, 8, 16, and 24 weeks after ventral median celiotomy were compared with control linea alba samples. Additional samples were subjectively evaluated for wound morphology, notably collagen morphology.

RESULTS

Control linea alba had a mean (+/-SEM) tensile strength of 484.9 +/- 58.3 N and was significantly (P < or = .05) stronger than at 2 weeks (87.7 +/- 61.4 N) after surgery. The tensile strength of 4-week (305.8 +/- 61.7 N), 8-week (465.4 +/- 56.5 N), and 16-week (477.8 +/- 57.2 N) samples were not significantly different from control linea alba. At 24 weeks, the tensile strength (721.0 +/- 57.9 N) was significantly stronger than control. The 2-, 4-, and 8-week samples were significantly thicker than controls, whereas the 16- and 24-week samples were not different from controls. On microscopy, control samples were characterized by dense mature collagen bundles. At 2 weeks, samples consisted primarily of granulation tissue, whereas at 4 weeks, samples had immature collagen fibers that were not formed into bundles, and at 8, 16, and 24 weeks, all samples had abundant mature collagen fibers formed into bundles.

CONCLUSIONS

At 8 weeks, incised and sutured equine linea alba had a tensile strength comparable with non-incised linea alba and was characterized by mature collagen.

CLINICAL RELEVANCE

Based on tensile strength and wound morphology, horses that have had an uncomplicated recovery after ventral median celiotomy should be able to return to controlled exercise as early as 60 days after surgery.

Intrathoracic and concurrent orthopedic injury associated with traumatic rib fracture in cats: 75 cases (1980-1998)

OBJECTIVE

To characterize rib, intrathoracic, and concurrent orthopedic injuries, and prognosis associated with traumatic rib fracture in cats.

DESIGN

Retrospective study.

ANIMALS

75 cats.

PROCEDURE

Medical records from January 1980 to August 1998 were examined for cats with traumatic rib fracture. Signalment, cause of trauma, interval from trauma to evaluation at a veterinary teaching hospital, referral status and date, method of diagnosis, duration of hospitalization, number and location of rib fractures, presence of flail chest, costal cartilage involvement, intrathoracic and concurrent orthopedic injury, and clinical outcome were reviewed.

RESULTS

Median age was 3 years. Twenty-five (58%) cats with reported cause of trauma were injured by interaction with another animal. Forty-seven (78%) cats that were treated survived. Cats that died had a median duration of hospitalization of < 1 day. Ten (13%) cats had flail chest. Sixty-five (87%) cats had intrathoracic injury (median, 2 injuries). Nine (100%) cats without detected intrathoracic injury that were treated survived. Thirty-five (47%) cats had concurrent orthopedic injury. Cats with flail chest, pleural effusion, or diaphragmatic hernia were significantly more likely to die than cats without each injury.

CONCLUSIONS AND CLINICAL RELEVANCE

Traumatic rib fracture in cats is associated with intrathoracic and concurrent orthopedic injury. Aggressive treatment of cats with traumatic rib fracture is warranted, because the prognosis is generally favorable. Diagnosis and treatment of intrathoracic injury associated with traumatic rib fracture in cats should precede management of concurrent orthopedic injury.

Risk factors for abomasal displacement in dairy cows

OBJECTIVE

To determine whether various periparturient events or 305-day milk production during the previous lactation period were associated with abomasal displacement in dairy cows.

DESIGN

Retrospective, case-control study.

ANIMALS

75 pairs of case and control cows from 3 university-owned and 3 commercial dairy herds.

PROCEDURE

Cows with abomasal displacement were matched with control cows on the basis of herd of origin, breed, age, and calving date. Frequency of specific periparturient events during the period from 2 weeks prior to parturition to diagnosis of abomasal displacement, as well as milk production during the preceding lactation period, were compared between case and control cows.

RESULTS

Multivariate analyses indicated that case cows were significantly more likely to have had retained placenta, ketosis, a stillborn calf, metritis, twins, or parturient paresis than were control cows. Dystocia, mastitis, and milk production during the previous lactation period were not associated with abomasal displacement.

CLINICAL IMPLICATIONS

Results indicated that a variety of periparturient events were associated with development of abomasal displacement among dairy cows.

Alterations in bovine serum biochemistry profiles associated with prolonged consumption of endophyte-infected tall fescue

Tall fescue (Festuca arundinacea) is a forage grass that is widely used in pastures in the eastern US for cattle, sheep and horses. The endophytic fungus Neotyphodium coenophialum is endemic in tall fescue pastures in the US. The turfgrass industry intentionally infects fescue cultivars with strains of the fungus to impart desirable growth and disease tolerance qualities to the plants. In contrast, ergot and pyrrolizidine alkaloid toxins produced by fungus-infected plants have been incriminated causally in bovine tall fescue toxicosis, a poorly defined syndrome of morbidity that occurs in cattle that consume endophyte-infected tall fescue (E+TF). We compared the serum biochemistry profiles from cattle that grazed E+TF with those from control cattle that grazed on endophyte-free tall fescue (E-TF). Cattle were bled on 7 dates from April 1 to August 30, 1996 and on 5 dates from May 1 to July 30, 1997. Cattle that grazed E+TF retained rough winter haircoats and had lesser weight gains, typical of tall fescue toxicosis, compared to those grazing E-TF. They had decreased activities of alkaline phosphatase and alanine aminotransferase. Compared to controls, they had lower values for serum prolactin and globulin concentrations. The concentration of creatinine and the albumin/globulin ratio were increased in the cattle grazing E+TF. Isozyme determination of alkaline phosphatase indicated that the decrease in serum activity of cattle grazing E+TF was due to decreases in both intestinal and bone isozymes. Serum protein electrophoresis indicated that the decrease in serum globulin concentration was due to decreases in both alpha and gamma globulin fractions of this protein. The data collected in these experiments add to our understanding of the alterations that occur in the serum chemistry profiles when cattle consume E+TF for prolonged periods of time.

Evaluation of renal hemodynamics in awake and isoflurane-anesthetized cats with pulsed-wave Doppler and quantitative renal scintigraphy

The feasibility and reproducibility of obtaining the pulsed-wave Doppler measurements of resistive index (RI) and pulsatility index (PI) were investigated in intrarenal arteries of normal, nonsedated cats, and cats anesthetized with isoflurane. In addition, relative renal function and relative renal blood flow were evaluated using quantitative renal scintigraphy. The percentage of injected dose uptake, time to peak activity, and two indices of renal blood flow (K/A ratio and flow index) obtained during the first pass of 99mTc-MAG3, were determined for both awake and anesthetized cats. Results indicate that measuring RI and PI in nonsedated cats is readily accomplished and that the results are reproducible within an animal. Mean RI and PI values in the awake cats were 0.55 and 0.8, respectively. Significant differences between the awake and anesthetized cats were found for all pulsed-wave Doppler and quantitative renal scintigraphic measurements evaluated.

Evaluation of surgical scrub methods for large animal surgeons

OBJECTIVE

The objective of this study was to determine the effectiveness of a 5-minute surgical scrub using either a one-brush or a two-brush technique in clean and dirty surgical procedures, and to compare the efficacy of povidone iodine with chlorhexidine as surgical scrub solutions.

STUDY DESIGN

Prospective clinical trial.

METHODS

Nine veterinarians scrubbed their hands on eight separate occasions using either povidone iodine or chlorhexidine gluconate. A 5-minute scrub and either a one-brush or two-brush technique used in both clean and dirty operations were evaluated by taking glove juice samples before scrubbing, immediately after scrubbing, and 30, 60, 90, and 120 minutes after scrubbing. Glove juice samples were cultured and the colonies were counted. Percent reductions of bacterial forming units were calculated for all eight scrub procedures.

RESULTS

All scrub procedures provided an adequate percent reduction in colony forming units (CFU) during the 2-hour sampling period. The number of CFU immediately after scrubbing were significantly lower than prescrub. At 120 minutes, there were significantly fewer CFUs than presecrub, but there were more than immediately after scrubbing. No significant difference in reduction in CFUs were detected between one-brush and two-brush techniques. Both chlorhexidine and povidone iodine scrub solutions adequately reduced bacterial colony counts for 120 minutes after scrubbing regardless of the amount of contamination before skin preparation.

CONCLUSIONS

Bacterial counts after a hand scrub procedure using a one-brush technique were not significantly different than after a procedure that used a two-brush technique. Povidone iodine and chlorhexidine are equally effectively in decreasing bacterial numbers on the skin, given a variety of contamination levels present before the scrub procedure.

CLINICAL RELEVANCE

Surgeons may use either chlorhexidine or povidone iodine for antiseptic preparation of their hands before surgery. A two-brush technique is not necessary.

Effect of high volume epidural morphine, ketamine and butorphanol on halothane minimum alveolar concentration in ponies

This study determined the effects of epidurally administered morphine, ketamine and butorphanol on halothane minimum alveolar concentration (MAC) in ponies. Seven ponies were anaesthetised with thiopentone and succinylcholine, intubated and anaesthesia maintained with halothane. Ventilation was controlled and blood pressure was maintained within normal limits. Following the determination of baseline halothane MAC for the pelvic and thoracic limbs the ponies were given morphine (0.1 mg/kg bwt), ketamine (0.8 or 1.2 mg/kg bwt), butorphanol (0.05 mg/kg bwt) or saline, epidurally, to a final volume of 0.15 ml/kg bwt. The halothane MAC for the pelvic and thoracic limbs was redetermined following each treatment. The baseline halothane MAC for the control group was mean +/- s.e. 0.85 +/- 0.02% and no significant change occurred after saline administration. Morphine significantly (P = 0.002) decreased MAC from, mean +/- s.e. 0.90 +/- 0.05% to 0.77 +/- 0.06% in the pelvic limb. Ketamine significantly decreased MAC in the pelvic limb from mean +/- s.e. 0.86 +/- 0.06% to 0.71 +/- 0.04%, and 0.82 +/- 0.03% to 0.71 +/- 0.02%, for the low (P = 0.008) and high dose (P = 0.001), respectively. No significant change in MAC occurred following butorphanol. No treatment reduced halothane MAC for the thoracic limb.

Effect of acepromazine and butorphanol on halothane minimum alveolar concentration in ponies

The effect of i.v. acepromazine (0.05 mg/kg bwt), butorphanol (0.05 mg/kg bwt) and a combination of acepromazine and butorphanol on halothane minimum alveolar concentration (MAC) was determined in 7 mixed-breed ponies. Ventilation was controlled, and blood pressure and temperature were maintained within normal limits. Following the determination of baseline MAC, treatments were administered to each pony in a random manner. The control treatment was normal saline. The baseline halothane dMAC for the control group was 0.91 +/- 0.04%, and no significant change occurred after saline administration. Acepromazine decreased (P = 0.0001) the halothane MAC from mean +/- s.e. 0.92 +/- 0.02% to 0.58 +/- 0.04%, and the combination of acepromazine and butorphanol, decreased (P = 0.003) halothane MAC, from mean +/- s.e. 0.95 +/- 0.04% to 0.59 +/- 0.06%. This represents a decrease of 36.9 and 37.8%, respectively. However, the difference between these 2 treatments was not significant. Butorphanol did not significantly change the mean group value for MAC; nevertheless, 3 ponies had an increase, one a decrease, while the MAC did not change in the remaining 3 ponies following butorphanol treatment.

Treatment of blastomycosis with itraconazole in 112 dogs

One hundred twelve client-owned dogs with blastomycosis were treated with itraconazole, 5 or 10 mg/kg/d. The first group of 70 dogs treated in 1987 and 1988 received 10 mg/kg/d (group 1), and the second group of 42 dogs treated after October 1988 received 5 mg/kg/d (group 2). Even though the groups were treated at different times, the dogs were similar in age and gender distribution, number of sites involved, and percent and severity of pulmonary involvement. The proportion of dogs cured with a 60-day course of itraconazole was similar for both groups (53.6% versus 54.3%) and for a second historical control group treated with amphotericin B (57%); the recurrence rate was also similar, 20%, 21.4%, and 20%, respectively. Dogs treated with itraconazole had similar mortality rates (25.7% at 5 mg/kg/d; 25% at 10 mg/kg/day) to those treated with amphotericin B (23%). Seventeen of the 23 dogs that died (74%), did so during the first week of treatment; these early deaths were usually attributed to respiratory failure. The only site of infection that was significantly associated with failure (death or recurrence) was the brain. There was a marked difference in survival times between dogs without lung disease or with mild lung disease compared with dogs with moderate or severe lung disease. Serum itraconazole concentrations reached steady state by 14 days of treatment. Dogs receiving 5 mg/kg/d of itraconazole (group 2) had mean serum concentrations of 3.55 +/- 2.81 mg/mL (range, 0.67 to 10.8 micrograms/mL), whereas dogs receiving 10 micrograms/kg/d (group 1) had mean concentrations of 13.46 +/- 8.49 micrograms/mL (range, 1.8 to 28 micrograms/mL) (P < or = .001). There was no association between cure and serum itraconazole concentrations. Dogs in group 1 had significantly more adverse effects than dogs in group 2 (P = .046). Anorexia was the most common adverse effect, occurring in 14.9% of dogs in group 1. Only 8% of dogs in group 2 had adverse effects. Serum concentrations of itraconazole were positively correlated with serum alkaline phosphatase and alanine aminotransferase activities. Our findings indicate that itraconazole administered at a dose of 5 mg/kg/d is the drug of choice for blastomycosis in dogs.

Cerebrospinal fluid acid-base status during normocapnia and acute hypercapnia in equine neonates

OBJECTIVE

To determine normal acid-base status of the CSF and to compare it with changes during acute hypercapnia in equine neonates.

ANIMALS

10 clinically normal foals between 1 and 12 days old.

PROCEDURE

CSF and arterial and venous blood samples were collected every 15 minutes during 45 minutes of normocapnia and 90 minutes of hypercapnia in isoflurane-anesthetized foals. CSF samples were collected via a subarachnoid catheter placed in the atlanto-occipital space.

RESULTS

Comparison of blood and CSF gases during normocapnia indicated that CSF was significantly more acidic than blood. The lower pH was attributable to higher CO2 and lower bicarbonate concentrations than those in blood. During hypercapnia, CSF CO2 increased and pH decreased parallel to changes in blood, but changes were not a great as similar changes in venous blood, indicating that some degree of buffering occurs in the CSF of foals.

CONCLUSIONS

Normal CSF acid-base status in equine neonates is similar to that in other domestic species. The blood-brain and blood-CSF interfaces in neonates allow rapid diffusion of CO2, but allow only slow diffusion of bicarbonate. Equine neonates are capable of buffering respiratory-induced acid-base changes in the CSF, but the buffering capacity is less than that of the vascular compartment.

CLINICAL RELEVANCE

Neonatal foals may develop severe respiratory compromise, resulting in hypoxemia and hypercapnia. Because the ability of the CSF to buffer acid-base changes in neonates is reduced, hypercapnia may contribute to the CNS abnormalities that often develop in sick neonates. Thus, normal blood gas values should be maintained in diseased equine neonates.

Serum granulocyte colony-stimulating factor (G-CSF) and interleukin-1 (IL-1) concentrations after chemotherapy-induced neutropenia in normal and tumor-bearing dogs

Hematopoiesis is regulated by complex interactions of hematopoietic growth factors known as colony-stimulating factors and interleukins. We used sensitive bioassays to quantitate serum granulocyte colony-stimulating factor (G-CSF) and interleukin-1 (IL-1) concentrations in normal and tumor-bearing dogs following administration of myelosuppressive chemotherapy (vincristine, doxorubicin, cyclophosphamide). Serum G-CSF and IL-1 increased during the neutrophil nadir in 13 of the 16 dogs. Serum G-CSF concentrations were significantly increased in normal and in tumor-bearing dogs on neutropenic compared to non-neutropenic days. Serum IL-1 concentrations increased significantly on neutropenic days in normal dogs but not in tumor-bearing dogs. A marked neutrophilia was observed in normal dogs, but not in tumor-bearing dogs, following the increases in serum G-CSF and IL-1 concentrations (days 7, 8, and 9, p < 0.05). Normal dogs produced significantly more G-CSF on neutropenic days compared to dogs with lymphoma. On non-neutropenic days, serum IL-1 concentrations were significantly increased in dogs with lymphoma and in dogs with nonlymphoid malignancies compared to normal dogs. These results suggest an important role for G-CSF and IL-1 in hematopoietic recovery after chemotherapy-induced myelosuppression and document an altered hematopoietic regulation in animals with malignancy compared to normal subjects.

Blood ionized calcium concentrations in horses before and after the cross-country phase of three-day event competition

Blood ionized calcium (Ca2+) and pH; plasma lactate concentrations; and total protein, total calcium (CaT), albumin, and phosphorus concentrations in serum were determined in 40 healthy horses before (T1), at the finish line (T2), and 10 minutes after the finish (T3) of the cross-country phase of a 3-day-event competition. Mean (+/- SEM) Ca2+ concentrations decreased from 6.22 +/- 0.04 mg/dl at T1 to 5.04 +/- 0.07 mg/dl at T2 (P < or = 0.05). This decrease was accompanied by a nonsignificant increase in CaT between T1 and T2. The mean (+/- SEM) percent ionization of calcium decreased significantly (P < or = 0.05), from 50.9 +/- 2.75% at T1 to 40.3 +/- 3.58% at T2. Significant increases in mean albumin, total protein, phosphorus, and lactate concentrations and a significant decrease in mean pH were observed at T2 (P < or = 0.05). At T3, mean Ca2+ and percent ionization had increased, but remained significantly less than resting values. Mean CaT was significantly decreased at T3, compared with values at T1 and T2. Correlation of mean Ca2+ concentration with all other measured variables at each time was evaluated; correlation coefficients between mean Ca2+ and all other variables were low (r2 < or = 0.38), indicating low biological significance.

Effects of housing and colostrum feeding on serum immunoglobulins, growth, and fecal scores of Jersey calves

Ninety-six Jersey calves were used to evaluate the effects of housing and method of colostrum feeding on serum Ig concentrations, incidence and severity of scours, intake, and BW changes from birth to 35 d of age. Calves were separated from the dam and fed 2 L of colostrum in nipple-bottles or allowed to nurse the dam for 3 d. Calves were housed in individual hutches or wooden pens in a barn. Intake of colostrum by calves allowed to nurse the dam was not controlled. Serum IgG and IgM concentrations at 24 h of age were greater for calves that nursed the dam. Scours were less severe when calves were housed in hutches, but number of days scouring was unaffected by treatment. Calves fed colostrum in nipple-bottles and housed in the barn consumed more starter than did other calves from 3 to 5 wk of age. The BW were greater for calves allowed to nurse the dam and housed in hutches. Feed efficiency over the 35-d study was improved when calves nursed the dam. Optimal transfer of passive immunity and housing in hutches appeared to maximize health and growth in this study.

Aggregate risk study of exposure to endophyte-infected (Acremonium coenophialum) tall fescue as a risk factor for laminitis in horses

Loline and ergot alkaloids found in endophyte-infected (Acremonium coenophialum) tall fescue (EITF) cause vasoconstriction of equine vessels in vitro. An aggregate risk study was used to evaluate the association between horses exposed to EITF and development of laminitis. Veterinary teaching hospitals participating in the Veterinary Medical Data Base were grouped by whether equine accessions were likely to have been at high, moderate, or low risk for exposure to EITF. From 1980-1990, there were 185,781 accessions, of which 5,536 had diagnosis of laminitis. Proportion of equine accessions with laminitis reported by veterinary teaching hospitals for high, moderate, and low risks, were 3.41, 3.04, and 2.00 cases/100 accessions, respectively (P < 0.0001). Comparison of the proportion of accessions with laminitis in the high- and moderate-risk groups with that in the low-risk group revealed significant differences between risk groups over all months (P = 0.063) and differences from month to month within risk groups (P = 0.0001). If the difference among risk groups is attributed entirely to exposure to EITF, the population-attributable risk is 7 cases/1,000 admissions, or 15% of all admissions for laminitis at veterinary teaching hospitals in our data base. Preliminary data support an association between horses exposed to EITF and increased risk of laminitis; however, studies at the individual animal level are indicated to confirm this hypothesis.

Effects of housing and colostrum feeding on the prevalence of selected infectious organisms in feces of Jersey calves

Neonatal Jersey calves (n = 96) were used to evaluate effects of housing (individual hutches or wooden pens in a barn) and colostrum feeding (calves were separated from the dam and fed 2 L of colostrum in nipple-bottles or allowed to nurse the dam for 3 d) on the prevalence of selected organisms in feces. Prevalence of Cryptosporidium and Eimeria were reduced, and prevalence of rotavirus tended to be reduced, when calves were housed in hutches. Prevalence of coronavirus was unaffected by treatment. Weekly prevalence of Giardia was increased when calves were left to nurse the dam for 3 d. Mean prevalence of Cryptosporidia (wk 1 to 4), Eimeria (wk 4 to 5), Giardia, rotavirus, and coronavirus (wk 1 to 5) were 34.7, 20.6, 27.1, 15.8, and 4.9%, respectively. Escherichia coli (K99 positive) were observed in 3 of 174 samples cultured. Methods of housing and colostrum feeding affected acquisition of enteropathogens in this study.

Effect of subclinical infection with Actinobacillus pleuropneumoniae in commingled feeder swine

Sequential serologic analysis for Actinobacillus pleuropneumoniae was done on 240 commingled feeder swine at 1 and 21 days after purchase and at slaughter. At the beginning of the experiment, mean weight of the pigs was 18.6 kg, and the pigs were maintained to a mean slaughter weight of 109.95 kg. A fourfold increase in antibody titer against Actinobacillus pleuropneumoniae was demonstrated in 28 (12%) pigs. Mean adjusted rate of gain for infected pigs was 0.74 +/- 0.10 kg/d and 0.77 +/- 0.09 kg/d for uninfected pigs. Differences in feed efficiency were not detected between infected and uninfected pigs. Our findings suggested that 5.64 additional days are required for pigs with subclinical infection to reach market weight of 113.6 kg, compared with that for uninfected herdmates. A vaccination program to prevent subclinical infection may not be cost effective.

Use of end-tidal CO2 tension to predict arterial CO2 values in isoflurane-anesthetized equine neonates

End-tidal carbon dioxide tension (PetCO2) and arterial carbon dioxide tension (PaCO2) were determined and compared in isoflurane-anesthetized spontaneously breathing equine neonates. End-tidal carbon dioxide and PaCO2 values increased with respect to time. Difference between values of PetCO2 and PaCO2 increased over time. End-tidal carbon dioxide tension was useful to predict changes in and was more closely correlated with PaCO2 early in the anesthetic period (T less than or equal to 60 minutes). The dead space volume to tidal volume (Vd/Vt) ratio increased with respect to time, indicating increase in physiologic dead space in isoflurane-anesthetized foals. The data indicate that the increased difference between widening of the PetCO2 and PaCO2 values over time may have been attributable to hypoventilation and decreased pulmonary capillary perfusion of alveoli.

A survey of ovine parasite control practices in Tennessee

A sample of 126 sheep producers in Tennessee was randomly selected from the members of a statewide organization of sheep producers. Data about the participants' farms, sheep, parasite control practices and sources of information regarding ovine parasite control were obtained by a telephone survey. The response rate was 99%. The typical respondent kept 20 lambs, 20 ewes and 2 rams on three pastures totalling 20 acres. In order of decreasing frequency, anthelmintics were given according to a regular schedule, to coincide with breeding management procedures, or to treat clinical signs of parasitism. Proportions of producers deworming the various classes of sheep zero, one, two, three, four or more than four times annually were as follows: lambs--3, 28, 40, 16, 9 and 8%, respectively; ewes--3, 8, 20, 16, 34 and 22%, respectively; rams--1, 9, 19, 15, 38 and 19%, respectively. The majority of respondents planned to deworm lambs (89%) and ewes (82%) the same number of times in the following year. Of the producers who dewormed sheep two or more times during 1989, 39-49% (ranges include different proportions for lambs, ewes and rams) used the same anthelmintic exclusively, and 51-61% used two or more drug classes. Of the owners using a single anthelmintic exclusively, most (39-66%) used ivermectin, followed by levamisole (19-33%) and benzimidazoles (13-24%). One hundred and three of 124 (83%) producers intended to use the same anthelmintics in the future. Sixty-four of 124 (52%) producers had discontinued using at least one ovine anthelmintic. The most common reasons for discontinuance were dissatisfaction with the clinical response after treatment and inconvenience of administration. Sheep-oriented publications, other sheep producers and veterinarians were considered the most important sources of information about deworming programs and choice of anthelmintics.

Comparison of four test kits for feline leukemia virus antigen

The sensitivity and specificity of 4 commercial FeLV ELISA kits, using blood, were compared with results of virus isolation from blood and immunofluorescent antibody (IFA) testing on blood. Significant differences were not found among the 4 ELISA kits. Marked decrease in sensitivity of the ELISA kits was detected when virus isolation was used as the standard of positivity rather than the IFA test. Virus isolation was a more sensitive indicator of early infection, with marked discrepancy among results obtained by virus isolation, ELISA, and the IFA test. Results became progressively more concordant as infection became fully established. Cats FeLV-positive by virus isolation alone were more likely to eliminate viremia. All cats FeLV-positive by IFA testing remained persistently viremic. Virus isolation, ELISA, and IFA testing appear to differ in their prognostic value. The use of blood rather than serum for the ELISA resulted in several discordant results. Six cats were FeLV-positive by ELISA when blood was tested but were FeLV-negative when serum was tested. Positive ELISA results were obtained for 4 of these cats when serum was tested, using extended incubation to increase sensitivity. It is possible that blood may actually be more sensitive than serum for use of the ELISA method.

Antibody response of kittens after vaccination followed by exposure to feline leukemia virus-infected cats

Protein (western) blot analysis and virus-neutralization assay were used to evaluate the antibody response of specific-pathogen-free kittens to FeLV vaccination and followed by natural exposure. Several kittens had barely detectable reactions to specific FeLV antigens prior to vaccination or exposure. Correlation was not found between protection against persistent viremia and antibody response after vaccination as measured by western blot analysis or virus neutralization assay. A statistically significant (P less than 0.01) difference in the antibody response against p27 antigen after natural exposure to FeLV was observed between persistently viremic kittens and transiently viremic or aviremic kittens. Measurable (P less than 0.05) virus neutralizing antibody titer after FeLV exposure was found only in a small number of kittens that were protected against persistent viremia. Lack of association between humoral response and vaccination-induced protection against persistent FeLV infection suggests an important role for cell-mediated immunity in such protection.

Epidemiology and clinical characteristics of tularemia in Oklahoma, 1979 to 1985

We studied the clinical and epidemiologic characteristics of tularemia in 165 Oklahomans from 1979 to 1985. The ulceroglandular form of the disease was most common (60%), followed by typhoidal (18%), glandular (15%), oropharyngeal (7%), and oculoglandular (1%) forms. The male-female ratio was 3.7:1, and the highest rates of disease were found in the age groups 5 to 14, 35 to 44, and 55 to 74. Ticks were most frequently implicated as the source of infection (84/154 [55%]), followed by rabbits, (58/154 [38%]). Seventy percent of the patients were hospitalized, and four (2.5%) died. The annual number of patients who reported that rabbits were their probable source of exposure to Francisella tularensis and the estimated number of rabbits harvested (ie, killed by hunters) for the year correlated closely with the total number of cases reported from year to year.

Comparison of effects of cimetidine and omeprazole on mechanically created gastric ulceration and on aspirin-induced gastritis in dogs

A double-blind study was conducted to compare gastric ulcer healing time in nontreated dogs with that in dogs treated with either cimetidine or omeprazole. Single ulcers were created in the gastric antrum by use of a suction biopsy capsule. Each dog was given 25 mg of aspirin/kg of body weight orally for 20 days after ulcer induction. Five control dogs were given aspirin only (no anti-ulcer medication) during the 20-day study. Six dogs were given cimetidine at dosage of 10 mg/kg orally every 8 hours, and 6 dogs were given omeprazole orally at dosage of 2 mumol/kg (0.7 mg/kg) once daily. All dogs were examined endoscopically on days 5, 10, 15, and 20 and were given a score for the size of the mechanically created ulcer and a score for the degree of aspirin-induced gastritis. All dogs were euthanatized on day 21, and gastric lesions were examined histologically. Significant differences were not evident in ulcer healing scores or degree of aspirin-induced gastritis among treated and nontreated dogs on days 5, 10, 15, and 20. However, aspirin-induced gastritis was less severe in dogs of the omeprazole group than in dogs of the cimetidine or control group on each day observations were made. The effect of omeprazole given once daily was comparable with that of cimetidine given every 8 hours in lessening aspirin-induced gastritis.

Aldicarb toxicosis in a dairy herd

Aldicarb, an extremely toxic carbamate, caused sudden death of several lactating Holstein cows. Confirmation of this toxic agent as the cause of death was hindered by its rapid breakdown in biological tissue. Therefore, aldicarb was not detected in rumen contents of some of the dead cows, and brain acetylcholinesterase values were essentially normal. The analyses were conducted 2 to 4 days after death of the cows. Rapid testing of tissue samples is necessary if a carbamate insecticide is suspected.

Evaluation of use of dimethyl sulfoxide for intra-articular lavage in clinically normal horses

The antebrachiocarpal and tarsocrural joints of 10 adult horses were randomly assigned to 1 of 4 groups. Groups were formulated and were treated as follows: group 1, control (arthrocentesis only); group 2, buffered lactated Ringer solution; group 3, 10% dimethyl sulfoxide (DMSO; w/v) in lactated Ringer solution; and group 4, 30% DMSO (w/v) in lactated Ringer solution. Joints were lavaged once with the respective solution. Prior to lavage and on days 1, 4, and 8 after lavage, all horses were evaluated for lameness and joint effusion; synovial fluid total and differential WBC counts, synovial fluid total protein concentration, and mucin clot quality were determined. Horses were euthanatized on day 8, and joints were evaluated grossly, histologically, and histochemically. Significant difference was not observed in effect of lactated Ringer solution, 10% DMSO, and 30% DMSO on any measured variable. At 24 hours after treatment, significant (P less than 0.05) difference in synovial fluid WBC numbers and total protein concentration was detected between control and treated joints. Eighty percent of lavaged joints had effusion 24 hours after treatment, compared with 30% of control joints. Gross, histopathologic, or histochemical differences were not detected between treated and control joints. Results of the study indicate that buffered lactated Ringer, 10% DMSO, and 30% DMSO solutions induce similar inflammatory changes in articular structures and significantly greater inflammatory reaction than does arthrocentesis alone.