Objective—To determine the effects of endotoxin
administration on thyroid function test results and serum
tumor necrosis factor-α (TNF-α) activity in healthy dogs.
Animals—6 healthy adult male dogs.
Procedures—Serum concentrations of thyroxine (T4),
3,5,3'-triiodothyronine (T3), 3,3'5'-triiodothyronine
(rT3), free T4 (fT4), and endogenous canine thyroid
stimulating hormone (TSH), and TNF-α activity were
measured before (day–1; baseline), during (days 0 to
3), and after (days 4 to 24) IV administration of endotoxin
every 12 hours for 84 hours.
Results—Compared with baseline values, serum T3
concentration decreased significantly, whereas rT3
concentration increased significantly 8 hours after initial
endotoxin administration. Serum T4 concentration
decreased significantly at 8 and 12 hours after initiating
endotoxin administration. Serum T4 concentration
returned to reference range limits, then decreased
significantly on days 6 to 12 and 16 to 20. Serum fT4
concentration increased significantly at 12, 24, and 48
hours after cessation of endotoxin treatment, compared
with baseline values. Serum rT3 concentration
returned to reference range, then decreased significantly
days 5 and 7 after stopping endotoxin treatment.
Serum TNF-α activity was significantly
increased only 4 hours after initial endotoxin treatment,
compared with baseline activity.
Conclusions and Clinical Relevance—Endotoxin
administration modeled alterations in thyroid function
test results found in dogs with spontaneous nonthyroidal
illness syndrome. A decrease in serum T4 and T3
concentrations and increase in serum rT3 concentration
indicate impaired secretion and metabolism of
thyroid hormones. The persistent decrease in serum
T4 concentration indicates that caution should be
used in interpreting serum T4 concentrations after resolution
of an illness in dogs. (Am J Vet Res 2003;64:229–234)
Objective—To compare histologic artifacts caused by
carbon dioxide (CO2) or 810-nm diode surgical lasers
used to obtain small biopsy specimens of skin from
Procedure—21 skin biopsy specimens were collected
from each dog. Three biopsy specimens were
obtained with a CO2 or an 810-nm diode laser at 3
operating settings each, and 3 biopsy specimens
were obtained with a 6-mm biopsy punch instrument
(controls). After processing, biopsy specimens were
examined for artifacts related to laser-tissue interactions.
Microscopically visible char was measured
from the lateral edge of each specimen obtained with
Results—There were no significant differences
among mean char distances in biopsy specimens
obtained with the CO2 laser at various settings. Mean
char distance was significantly greater in all skin biopsy
specimens obtained with the diode laser, compared
with those obtained with the CO2 laser. Mean
char distance was significantly greater in biopsy specimens
obtained with the 810-nm diode laser at high
power, compared with biopsy specimens obtained
with the 810-nm diode laser at low power.
Conclusions and Clinical Relevance—Results indicated
that the CO2 laser caused less thermal injury at
margins of skin biopsy specimens; therefore, if a surgical
laser is used for removal of cutaneous masses
or to obtain skin biopsy specimens, use of the CO2
laser is recommended. Veterinarians performing a
biopsy by using a surgical laser should be aware that
laser-induced artifacts may render small biopsy specimens
useless for providing accurate histologic diagnosis.
(J Am Vet Med Assoc 2004;225:1562–1566)
Objective—To determine whether antemortem core needle biopsy and fine-needle aspiration of enlarged peripheral lymph nodes could be used to distinguish between inflammation and lymphosarcoma in cattle.
Animals—25 cattle with enlarged peripheral lymph nodes.
Procedures—Antemortem biopsies of the selected lymph nodes were performed with an 18-gauge, 12-cm core needle biopsy instrument. Fine-needle aspirates were performed with a 20-gauge, 4-cm needle. Specimens were analyzed by pathologists who were unaware of clinical findings and final necropsy findings, and specimens were categorized as reactive, neoplastic, or nondiagnostic for comparison with necropsy results.
Results—Sensitivity and specificity of core needle biopsy ranged from 38% to 67% and from 80% to 25%, respectively. Sensitivity of fine-needle aspiration ranged from 41% to 53%, and specificity was 100%. Predictive values for positive test results ranged from 77% to 89% for core needle biopsy and were 100% for fine-needle aspiration. Predictive values for negative test results were low for both core needle biopsy and fine-needle aspiration.
Conclusions and Clinical Relevance—Results indicated that core needle biopsy and fineneedle aspiration can aid in the antemortem diagnosis of bovine enzootic lymphosarcoma. Results of fine-needle aspiration of enlarged peripheral lymph nodes were more specific and more predictive for a positive test result than were results of core needle biopsy.
OBJECTIVE To determine whether prophylactic administration of valacyclovir hydrochloride versus initiation of treatment at the onset of fever would differentially protect horses from viral replication and clinical disease attributable to equine herpesvirus type-1 (EHV-1) infection.
ANIMALS 18 aged mares.
PROCEDURES Horses were randomly assigned to receive an oral placebo (control), treatment at detection of fever, or prophylactic treatment (initiated 1 day prior to viral challenge) and then inoculated intranasally with a neuropathogenic strain of EHV-1. Placebo or valacyclovir was administered orally for 7 or 14 days after EHV-1 inoculation or detection of fever (3 horses/group). Effects of treatment on viral replication and clinical disease were evaluated. Plasma acyclovir concentrations and viremia were assessed to determine inhibitory concentrations of valacyclovir.
RESULTS Valacyclovir administration decreased shedding of virus and viremia, compared with findings for control horses. Rectal temperatures and clinical disease scores in horses that received valacyclovir prophylactically for 2 weeks were lower than those in control horses. The severity of but not the risk for ataxia was decreased by valacyclovir administration. Viremia was decreased when steady-state trough plasma acyclovir concentrations were > 0.8 μg/mL, supporting the time-dependent activity of acyclovir.
CONCLUSIONS AND CLINICAL RELEVANCE Valacyclovir treatment significantly decreased viral replication and signs of disease in EHV-1–infected horses; effects were greatest when treatment was initiated before viral inoculation, but treatment was also effective when initiated as late as 2 days after inoculation. During an outbreak of equine herpesvirus myeloencephalopathy, antiviral treatment may be initiated in horses at various stages of infection, including horses that have not yet developed signs of viral disease.