Objective—To determine whether Labrador Retrievers participating in field trials develop respiratory alkalosis and hypocapnia primarily in conditions of high ambient temperatures.
Animals—16 Labrador Retrievers.
Procedures—At each of 5 field trials, 5 to 10 dogs were monitored during a test (retrieval of birds over a variable distance on land [1,076 to 2,200 m]; 36 assessments); ambient temperatures ranged from 2.2° to 29.4°C. For each dog, rectal temperature was measured and a venous blood sample was collected in a heparinized syringe within 5 minutes of test completion. Blood samples were analyzed on site for Hct; pH; sodium, potassium, ionized calcium, glucose, lactate, bicarbonate, and total CO2 concentrations; and values of PvO2 and PvCO2. Scatterplots of each variable versus ambient temperature were reviewed. Regression analysis was used to evaluate the effect of ambient temperature (≤ 21°C and > 21°C) on each variable.
Results—Compared with findings at ambient temperatures ≤ 21°C, venous blood pH was increased (mean, 7.521 vs 7.349) and PvCO2 was decreased (mean, 17.8 vs 29.3 mm Hg) at temperatures > 21°C; rectal temperature did not differ. Two dogs developed signs of heat stress in 1 test at an ambient temperature of 29°C; their rectal temperatures were higher and PvCO2 values were lower than findings in other dogs.
Conclusions and Clinical Relevance—When running distances frequently encountered at field trials, healthy Labrador Retrievers developed hyperthermia regardless of ambient temperature. Dogs developed respiratory alkalosis and hypocapnia at ambient temperatures > 21°C.
Objective—To determine the lowest ACTH dose that would induce a significant increase in serum cortisol concentration and identify the time to peak cortisol concentration in healthy neonatal foals.
Design—Prospective randomized crossover study.
Animals—11 healthy neonatal foals.
Procedures—Saline (0.9% NaCl) solution or 1 of 4 doses (0.02, 0.1, 0.25, and 0.5 μg/kg [0.009, 0.045, 0.114, and 0.227 μg/lb]) of cosyntropin (synthetic ACTH) was administered IV. Serum cortisol concentrations were measured before and 10, 20, 30, 60, 90, 120, 180, and 240 minutes after administration of cosyntropin or saline solution; CBCs were performed before and 30, 60, 120, and 240 minutes after administration.
Results—Serum cortisol concentration was significantly increased, compared with baseline, by 10 minutes after cosyntropin administration at doses of 0.1, 0.25, and 0.5 μg/kg. Serum cortisol concentration peaked 20 minutes after administration of cosyntropin at doses of 0.02, 0.1, and 0.25 μg/kg, with peak concentrations 1.7, 2.0, and 1.9 times the baseline concentration, respectively. Serum cortisol concentration peaked 30 minutes after cosyntropin administration at a dose of 0.5 μg/kg, with peak concentration 2.2 times the baseline concentration. No significant differences were detected among peak serum cortisol concentrations obtained with cosyntropin administration at doses of 0.25 and 0.5 μg/kg. Cosyntropin administration significantly affected the lymphocyte count and the neutrophil-to-lymphocyte ratio.
Conclusions and Clinical Relevance—Results suggested that in healthy neonatal foals, the lowest dose of cosyntropin to result in significant adrenal gland stimulation was 0.25 μg/kg, with peak cortisol concentration 20 minutes after cosyntropin administration.
Objective—To establish a protocol to collect temporal-spatial gait analysis variables by use of a portable walkway system in Labrador Retrievers at a walk and to determine reference values.
Animals—56 healthy Labrador Retrievers.
Procedures—6 passes across the walkway (3 passes in each direction) were recorded. Inclusion criteria for a pass were that the dog was at a walk (velocity, 60.0 to 90.0 cm/s) and had minimal head turning. The first 3 passes that met the inclusion criteria were analyzed for each dog.
Results—Mean stride length was 88.4 cm. Mean stance time (ST) of forelimbs and hind limbs was 0.62 and 0.56 seconds, respectively. Mean stance time percentage (ST%; proportion of stance time to total gait cycle time) for forelimbs and hind limbs was 55.6% and 50.2%, respectively. Mean total pressure index (TPI) of forelimbs and hind limbs was 27.1 and 17.4, respectively. Mean number of sensors (NS) activated by each paw strike of forelimbs and hind limbs was 17 and 13, respectively. Mean forelimb-to-hind limb symmetry ratios were 1.11 (ST), 1.10 (ST%), 1.62 (TPI), and 1.37 (NS). Symmetry ratios for left limbs to right limbs, left forelimb to right forelimb, and left hind limb to right hind limb were 1.00.
Conclusions and Clinical Relevance—A protocol for collection of temporal-spatial gait analysis variables with a portable walkway system in Labrador Retrievers at a walk was developed, and reference values for variables and symmetry ratios were reported. Further research will determine the extent to which symmetry ratios differ in dogs with orthopedic disorders. (Am J Vet Res 2010;71:997–1002)
Objective—To evaluate responses of cats with vaccine-
associated sarcomas to treatment with surgery
and radiotherapy, with or without adjunctive
Animals—76 cats (78 tumors).
Procedure—Medical records were reviewed. Factors
potentially associated with survival time, time to
recurrence, and time to development of metastases
Results—Following excision, electron beam radiation,
and, in some cases, chemotherapy, 32 (41%)
cats experienced recurrence, and 9 (12%) cats developed
metastases. One- and 2-year survival rates
were 86 and 44%, respectively. Median survival time
from onset of disease was 730 days (range, 30 to
2,014 days). Median disease-free interval was 405
days (range, 30 to 925 days). Cats that underwent
only 1 surgery prior to radiotherapy had a lower recurrence
rate than did cats that underwent > 1 surgery
and had a significantly longer disease-free interval.
Survival time and disease-free interval decreased as
time between surgery and the start of radiotherapy
increased. Cats that developed metastases had significantly
shorter survival times and disease-free
intervals than did cats that did not develop metastases.
Castrated male cats had a significantly shorter
survival time than did spayed female cats. Cats with
larger tumors prior to the first surgery had shorter survival
times. Twenty-six cats received chemotherapy in
addition to surgery and radiotherapy. Whether cats
received chemotherapy was not associated with
recurrence rate, metastasis rate, or survival time.
Conclusions and Clinical Relevance—Results suggest
that excision followed by electron beam irradiation
may be beneficial for treatment of cats with vaccine-
associated sarcomas. Extent of excision prior to
radiotherapy did not seem to be associated with
recurrence rate. (J Am Vet Med Assoc 2001;219:1582–1589)
Objective—To evaluate onset of protection induced by modified-live virus (MLV) bovine viral diarrhea virus (BVDV) vaccine administered 7, 5, or 3 days before inoculation with type 1b BVDV (strain NY-1).
Procedures—Calves were assigned to 4 groups: an unvaccinated control group or groups vaccinated with MLV vaccine containing BVDV types 1a and 2 at 7, 5, or 3 days, before inoculation with NY-1 BVDV. Blood samples were collected for leukocyte counts, serum virus neutralization, and virus isolation (VI); nasal swab specimens (NSSs) were obtained for VI, and rectal temperatures were monitored for 14 days after inoculation.
Results—No significant differences in leukocyte counts or rectal temperatures were detected after BVDV inoculation in vaccinated calves. Vaccinated calves had reduced viremia and viral shedding after inoculation, compared with results for unvaccinated calves. On day 5 after inoculation, a higher proportion of calves vaccinated 3 days before inoculation had positive VI from NSSs, compared with NSS VI results for calves vaccinated 5 and 7 days before inoculation. Unvaccinated calves had leukopenia on days 3, 5, and 6 and had higher rectal temperatures on days 7 and 8 after inoculation, compared with temperatures before inoculation. All unvaccinated calves had ≥ 1 positive VI result from NSSs 3 to 11 days after inoculation, and 4 became viremic.
Conclusions and Clinical Relevance—MLV BVDV vaccine prevented fever, viremia, and leukopenia in calves challenge inoculated with NY-1 BVDV. A high proportion of calves vaccinated 3 days before inoculation shed BVDV after inoculation.
Objective—To identify subclinical Babesia gibsoni
infection in American Pit Bull Terriers from the southeastern
United States and to determine the genetic
sequence of parasite DNA isolated from these dogs.
Animals—33 American Pit Bull Terriers and 87 dogs
of various other breeds.
Procedure—Blood smears were examined for microscopic
evidence of the parasite, and DNA was
extracted from blood samples and used in a polymerase
chain reaction (PCR) assay designed to amplify
the small subunit ribosomal RNA gene sequence of
B gibsoni. Amplification products of the expected size
were sequenced, and sequences were compared
with published sequences for B gibsoni isolates.
Hematocrit, platelet count, mean platelet volume,
WBC count, and eosinophil count were compared
between dogs with positive PCR assay results and
dogs with negative results.
Results—Results of the PCR assay were positive for
18 of the 33 (55%) American Pit Bull Terriers, including
all 10 dogs with microscopic evidence of parasitemia.
Only 1 of these dogs was clinically ill at the
time blood samples were collected. Results of microscopic
evaluation of blood smears and of the PCR
assay were negative for the 87 other dogs.
Hematocrit and platelet count were significantly
lower in dogs with positive PCR assay results than in
dogs with negative results.
Conclusions and Clinical Relevance—Results suggest
that American Pit Bull Terriers in the southeastern
United States may be subclinically infected with B
gibsoni. However, subclinical infection was not identified
in dogs of other breeds from the same geographic
area. (J Am Vet Med Assoc 2002;220:
Objective—To determine sensitivity and specificity of
cytologic examination used in a clinical setting.
Animals—216 dogs, 44 cats, 4 horses, 2 ferrets, 1
llama, 1 rat, and 1 mouse.
Procedure—Records were reviewed of cases in
which a cytologic diagnosis was followed by a surgical
biopsy or postmortem examination within 3 days
with subsequent histopathologic diagnosis.
Diagnoses were compared for agreement at various
levels, including complete agreement, partial agreement,
no agreement, or no comparison possible
because of insufficient or incorrect cytologic specimen.
Levels of agreement were compared for different
categories of lesions, including neoplastic, inflammatory,
dysplastic-hyperplastic-other, and normal tissue.
Additionally, levels of agreement for neoplastic
lesions were categorized with regard to cell type,
degree of malignancy, and location. Sensitivity and
specificity of cytologic examination were calculated.
Results—At the level of general agreement (complete
and partial agreement), the sensitivity of cytologic
examination ranged from 33.3 to 66.1%,
depending on the location of the lesion. Cytologic
examination was most accurate when used to diagnose
cutaneous and subcutaneous lesions and least
accurate for diagnosis of liver lesions. Cytologic
examination was most effective in diagnosis of neoplastic
disease and least effective in diagnosis of dysplastic
or hyperplastic conditions.
Conclusions and Clinical Relevance—Cytologic
examination is a valuable diagnostic tool, although our
results indicated lower accuracy than previously
reported. False-negative results (missing a diagnosis)
were far more common than false-positive results
(categorizing a healthy animal as diseased); therefore,
if the clinical index of suspicion is high, cytologic
examination should be repeated or another technique
should be selected to rule out the suspected condition.
(J Am Vet Med Assoc 2003;222:964–967)
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.
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.
Objective—To determine the lowest ACTH dose that would induce a maximum increase in serum cortisol concentration in healthy adult horses and identify the time to peak cortisol concentration.
Animals—8 healthy adult horses.
Procedures—Saline (0.9% NaCl) solution or 1 of 4 doses (0.02, 0.1, 0.25, and 0.5 μg/kg [0.009, 0.045, 0.114, and 0.227 μg/lb]) of cosyntropin (synthetic ACTH) were administered IV (5 treatments/horse). Serum cortisol concentrations were measured before and 30, 60, 90, 120, 180, and 240 minutes after injection of cosyntropin or saline solution; CBCs were performed before and 30, 60, 120, and 240 minutes after injection.
Results—For all 4 doses, serum cortisol concentration was significantly increased, compared with the baseline value, by 30 minutes after administration of cosyntropin; no significant differences were detected among maximum serum cortisol concentrations obtained in response to administration of doses of 0.1, 0.25, and 0.5 μg/kg. Serum cortisol concentration peaked 30 minutes after administration of cosyntropin at a dose of 0.02 or 0.1 μg/kg, with peak concentrations 1.5 and 1.9 times, respectively, the baseline concentration. Serum cortisol concentration peaked 90 minutes after administration of cosyntropin at a dose of 0.25 or 0.5 μg/kg, with peak concentrations 2.0 and 2.3 times, respectively, the baseline concentration. Cosyntropin administration significantly affected WBC, neutrophil, and eosinophil counts and the neutrophil-to-lymphocyte ratio.
Conclusions and Clinical Relevance—Results suggested that in healthy horses, administration of cosyntropin at a dose of 0.1 μg/kg resulted in maximum adrenal stimulation, with peak cortisol concentration 30 minutes after cosyntropin administration.