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in Journal of the American Veterinary Medical Association

SUMMARY

The ionophore A23187 was used to facilitate release and continued development of Anaplasma marginale in short-term erythrocyte cultures. Addition of 10 μM A23187 to the cultures resulted in significant decrease in percentage of parasitized erythrocytes (ppe) by 24 hours after treatment; further development and increase in PPE was not observed. In contrast, the ppe of untreated cultures, those treated with dimethyl sulfoxide (dmso) only and with 1 μM A23187 increased slightly during that time. Total erythrocyte count decreased in treated cultures in excess of that expected after samples of the medium were taken for analysis. The greatest cell loss and increased hemoglobin concentration in culture medium was observed in cultures treated with 10 μM A23187 and with an equivalent volume of dmso. The dmso appeared to cause hemolysis of some erythrocytes, but not of infected cells selectively. Release of A marginale inclusion bodies was seen by electron microscopy in samples from the 10 μM A23187-exposed cultures. At 30 minutes after treatment, free initial bodies were frequently seen. Inclusion body membranes and individual A marginale were associated with membranes of adjacent erythrocytes. Individual rickettsiae were seen in cell depressions and appeared to be entering erythrocytes. However, neither further invasion nor development of the parasite in erythrocytes was observed. Ionophore A23187 appeared to promote release of A marginale from erythrocytes, but did not enhance infection of erythrocytes or development of organisms in vitro.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine whether underfilling blood collection tubes leads to in vitro reduction in serum measured total CO2 concentration ([TCO2]m) in canine and feline blood samples sufficient to create the impression of metabolic acidosis (pseudometabolic acidosis) or high anion gap.

Sample Population

Blood samples from healthy client-owned animals (16 dogs, 17 cats).

Procedure

Venous blood samples were collected in random order for determination of serum [TCO2] and blood gas tensions. Blood gas analysis was performed on iced, capped blood samples. In dogs, serum [TCO2] was measured in 1-, 3-, and 10-ml samples in 10-ml type-B tubes and in a 3-ml sample in 3-ml type-A tubes. In cats, serum [TCO2] was determined in 1-, 2-, and 3-ml samples in 3-ml type-A tubes and in a 3-ml sample in 10-ml type-B tubes.

Results

For dogs, serum [TCO2] in full-tube, 10-ml samples was a mean ± SD, 2.0 ± 1.1 mmol/L greater than that in 3-ml samples and 3.7 ± 1.3 mmol/L greater than the value in 1 -ml samples; both differences were significant at P < 0.0001. The serum [TCO2] in full 3-ml samples was lower by 0.4 ± 0.6 mmol/L than the value in full-tube 10-ml samples (P=0.019). For cats, serum [TCO2] in full-tube, 3-ml samples was 0.5 ± 0.6 mmol/L greater than that in 2-ml samples (P = 0.004) and was 1.5 ± 0.8 mmol/L greater than the value in 1-ml samples (P < 0.0001). Serum [TCO2] in 3-ml samples of feline blood in 10-ml tubes was 0.8 ± 0.8 mmol/L lower than that in samples from full 3-ml tubes (P = 0.0007). In dogs and cats, [TCO2] in fully filled collection tubes was approximately 6 mmol/L higher when calculated from blood gas analysis data than when chemically determined in serum.

Conclusions and Clinical Relevance

Underfilling blood collection tubes results in a false decrease in serum [TCO2], which can contribute in part to descrepancies between blood gas and chemical analyses as estimates of plasma bicarbonate concentration. This, and other in vitro effects of sample handling and collection, may result in a false assessment of metabolic acidosis in dogs and cats, (Am J Vet Res 1997; 58:343-347)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To compare sensitivity of a complement fixation (CF) test and competitive ELISA (cELISA) for detection of Anaplasma marginale in experimentally infected steers.

Animals—40 crossbred (Angus-Simmental) steers.

Procedures—Steers were inoculated with 2.6 × 109 A marginale–infected erythrocytes (day 0). Blood samples were collected on days 9, 13, 20, 28, 34, 41, 61, 96, 126, and 156 days after inoculation. The percentage of parasitized erythrocytes (PPE) was determined by microscopic examination of stained blood films, and sera were evaluated with the CF test and cELISA by use of USDA-approved methods. Sensitivity and agreement (κ statistic) between the 2 methods were determined. Persistent infections were confirmed by inoculation of blood obtained from infected steers into susceptible, splenectomized calves.

Results—9 days after inoculation, sensitivity of the cELISA was 47.5%, whereas the CF test failed to identify seropositive steers. After day 13, sensitivity of the cELISA and CF test was 100% and 20%, respectively. During peak parasitemia (day 20), sensitivity of the cELISA and CF test was 100%. Thereafter, sensitivity of the CF test fluctuated between 7.5% and 37.5%, whereas sensitivity of the cELISA remained at 100%. Overall sensitivity of the cELISA and CF test was 94.8% and 26.5%, respectively (κ statistic, 0.039).

Conclusions and Clinical Relevance—The cELISA had superior sensitivity for serologic detection of A marginale.The CF test and cELISA each had a high percentage of false-negative results during the prepatent period. These findings are relevant for export certification and anaplasmosis prevention or eradication programs.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare the incidence of behavior problems following tendonectomy or onychectomy in cats, as well as attitudes of owners following these procedures.

Design—Nonrandomized clinical trial.

Animals—18 cats that underwent tendonectomy and 39 cats that underwent onychectomy.

Procedure—Owners of cats that underwent tendonectomy or onychectomy between February 1993 and May 1998 were contacted by telephone and asked several questions regarding reasons for surgery as well as complications and behavioral changes in cats following surgery.

Results—The most common reason for considering tendonectomy or onychectomy was to avoid damage caused by the cat scratching household materials. Avoidance of injury to humans or animals was chosen more often by owners whose cats underwent onychectomy than those that underwent tendonectomy. Tendonectomy was more likely to have been recommended by veterinarians than onychectomy. Significantly more cats that underwent tendonectomy (67%) than onychectomy (44%) returned to normal activity within 3 days after surgery. Significant differences were not detected regarding behavior problems after surgery.

Conclusions and Clinical Relevance—Although tendonectomy and onychectomy involved some medical complications and behavior changes following surgery, owners had positive attitudes regarding both surgeries after the immediate postoperative period. Tendonectomy may be a humane alternative to onychectomy, although owners need to be advised that nail trimming is still necessary in cats after surgery. ( J Am Vet Med Assoc 2001;218:43–47)

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in Journal of the American Veterinary Medical Association

Objective

To test efficacy and safety of recombinant human erythropoietin (r-HuEPO) administration in dogs and cats with naturally developing chronic renal failure.

Design

Case series.

Animals

6 client-owned dogs and 11 client-owned cats with chronic renal failure.

Procedures

r-HuEPO was administered intravenously or subcutaneously. Erythropoietic effects were monitored by determining CBC, performing cytologic examination of bone marrow aspirates, and measuring serum iron concentration before and during treatment. Development of adverse effects was monitored by performing sequential clinical assessments, CBC, and serum biochemical tests and by measuring indirect blood pressure and anti-r-HuEPO antibody titers.

Results

Administration of r-HuEPO increased RBC and reticulocyte counts, hemoglobin concentration, and Hct comparably in dogs and cats. Assessments of clinical well-being, including appetite, energy, weight gain, alertness, strength, and playfulness, were improved variably. Adverse effects, including anemia, anti-r-HuEPO antibody production, seizures, systemic hypertension, and iron deficiency, were demonstrated inconsistently in dogs and cats.

Clinical Implications

Anemia contributes to clinical manifestations of chronic renal failure in dogs and cats. Administration of r-HuEPO has the potential to resolve anemia and improve clinical well-being. However, its administration poses risks of antibody production and adverse effects associated with correction of RBC mass. Use of r-HuEPO in dogs and cats requires conscientious assessment of risks and benefits until homologous forms of erythropoietin are available. (J Am Vet Med Assoc 1998; 212:521-528)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine effects of exercise performed while breathing cold air on expression of cytokines and influx of neutrophils in airways of horses.

Animals—9 adult horses.

Procedures—In a crossover study, bronchoalveolar lavage fluid (BALF) was obtained 24 and 48 hours after each of 2 submaximal exercise sessions performed by horses while breathing warm (25°C) or cold (−5°C) air. Total and differential nucleated cell counts were determined for each BALF sample. Relative mRNA expression of cytokines in BALF cells was quantified by use of a reverse transcription–PCR assay.

Results—Horses had a modest but significant influx of neutrophils into the airways 24 hours after a single exercise session while breathing cold air. No other cell types were increased at 24 or 48 hours after exercising while breathing cold air. Continued increases in expression of cytokines interleukin (IL)-5 and-10 as well as proinflammatory cytokines IL-1, -6, and -8 were detected 24 hours after exercising while breathing cold air. Forty-eight hours after exercising while breathing cold air, expression of IL-10 was still higher than that for IL-10 after horses exercised while breathing warm air. Expression of tumor necrosis factor-α was significantly increased at 48 hours after exercising while breathing cold air.

Conclusions and Clinical Relevance—Exposure of intrapulmonary airways to cold air alters immunologic responses of horses for at least 48 hours. The increased expression of cytokines that suppress cell-mediated immunity may predispose athletes to viral infections of the respiratory tract following exercise in cold weather.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether seasonal variations exist in endogenous plasma ACTH, plasma α-melanocyte—stimulating hormone (α-MSH), serum cortisol, and serum insulin concentrations and in the results of a dexamethasone suppression test for older, clinically normal geldings in Alabama.

Design—Cohort study.

Animals—15 healthy mixed-breed geldings (median age, 14 years).

Procedures—Sample collection was repeated monthly for 12 months. Dexamethasone (0.04 mg/kg [0.02 mg/lb], IM) was administered and cortisol concentrations were determined at 15 and 19 hours. Radioimmunoassays were used to measure ACTH, α-MSH, cortisol, and insulin concentrations at each testing time. Hormone concentrations were compared between months via repeated-measures ANOVA and correlated with age within each month.

Results—A significant time effect was found between months for α-MSH and insulin concentrations. Endogenous cortisol and ACTH concentrations remained within existing reference ranges. Significant correlations were detected between age and ACTH concentration for several fall and winter months and between age and insulin concentration for September.

Conclusions and Clinical Relevance—Older horses have higher ACTH concentrations in several fall and winter months and higher insulin concentrations in September than do younger horses. Seasonally specific reference ranges are required for α-MSH and insulin concentrations, with significantly higher concentrations detected in the fall. Practitioners should be advised to submit samples only to local laboratories that can provide such reference ranges for their local geographic region.

Full access
in Journal of the American Veterinary Medical Association