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- Author or Editor: John P. Buchweitz x
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Abstract
OBJECTIVE
To determine the pharmacokinetics of voriconazole after single IV or orally administered boluses in common ravens (Corvus corax).
ANIMALS
8 healthy common ravens.
PROCEDURES
Voriconazole (5 mg/mL, 10 mg/kg IV) was administered to 8 birds, and then plasma voriconazole concentrations were measured at various time points by high-pressure liquid chromatography with mass spectrometry. Starting 6 months later in a randomized 3-treatment 3-period regimen, birds received a single oral dose of voriconazole suspension (10 mg/mL; 6, 12, and 24 mg/kg PO). The study period was May 2015 to March 2016.
RESULTS
Voriconazole (10 mg/kg IV) achieved an initial plasma concentration of 6.31 µg/mL when measured over 21 hours. After oral administration of voriconazole at 6, 12, and 24 mg/kg, the relative bioavailability was 67.5%, 209%, and 183%, respectively. For the 6-mg/kg dose, the maximum plasma concentration was reached at 30 minutes after administration and remained in the therapeutic range of 0.5 to 1 µg/mL for approximately 15 hours. The 12- and 24-mg/kg doses resulted in concentrations in a potentially toxic range.
CLINICAL RELEVANCE
Voriconazole was well tolerated. All 4 doses resulted in plasma concentrations of voriconazole > 0.5 µg/mL, which is the minimum inhibitory concentration recommended for pathogenic species of Aspergillus fungi known to affect birds. A single dose of voriconazole administered as 10 mg/kg IV or 6 mg/kg PO resulted in recommended target plasma concentrations. Administration of voriconazole 6 mg/kg PO 2 to 3 times daily may be adequate for treatment without exceeding the toxic range.
Abstract
OBJECTIVE To measure blood lead concentrations (BLCs) in dogs living in Flint, Mich, following a declared water crisis and to assess potential associations of BLCs with demographic data, water sources, and clinical signs in these dogs.
DESIGN Cross-sectional study.
ANIMALS 284 dogs residing in Flint, Mich (test population), and 47 dogs residing in East Lansing, Mich (control population), and immediately adjacent areas.
PROCEDURES Blood samples were collected at free screening clinics in Flint (test population) and at the Michigan State University College of Veterinary Medicine Veterinary Medical Center (control population). Owners of test population dogs completed questionnaires providing demographic and clinical information. Hematologic evaluations were performed; BLCs were measured by inductively coupled plasma–mass spectrometry.
RESULTS 4 of 284 test population dogs had BLCs > 50 ppb; an additional 20 had BLCs > 20 ppb. Overall, BLCs of test population dogs were higher than those of control dogs. Within the test population, young dogs (≤ 2 years of age) had higher BLCs than old dogs (≥ 6 years of age). Only 7.2% of test population dogs were drinking unfiltered tap water at the time of screening; however, dogs that had been receiving filtered or bottled water for ≤ 3 months before screening had higher BLCs than did those that received such water for > 3 months.
CONCLUSIONS AND CLINICAL RELEVANCE Taken together, findings suggested that the impact of the Flint water crisis extended to companion animals. Results highlighted the importance of maintaining awareness of lead exposure and considering both human and animal well-being in cases of environmental toxicant exposures.
Abstract
OBJECTIVE
To compare the cause of death (COD; whether by natural death or euthanasia for poor quality of life caused by a primary pathological condition) between search-and-rescue (SAR) dogs deployed to the World Trade Center, Pentagon, or Fresh Kills Landfill on Staten Island following the 9/11 terrorist attacks and SAR dogs that were not deployed to these sites.
ANIMALS
95 deployed SAR dogs (exposed dogs) and 55 nondeployed SAR dogs (unexposed dogs).
PROCEDURES
Following natural death or euthanasia, 63 dogs (44 exposed and 19 unexposed) underwent a necropsy examination. For the remaining 87 dogs, the COD was categorized on the basis of information obtained from medical records or personal communications.
RESULTS
The median age of death was 12.8 years for exposed dogs and 12.7 years for unexposed dogs. The COD was not impacted by deployment status. In the 150 exposed and unexposed dogs, degenerative conditions were the most common COD followed by neoplasia. Respiratory disease was infrequent (overall, 7 [4.7%] dogs); 4 of 5 cases of pulmonary neoplasia occurred in unexposed dogs. However, in dogs that underwent necropsy, pulmonary particulates were reported significantly more often in exposed dogs (42/44 [95%]), compared with unexposed dogs (12/19 [63.2%]).
CONCLUSIONS AND CLINICAL RELEVANCE
No difference was found in the COD on the basis of disease category and organ system involved between exposed and unexposed SAR dogs. The long life spans and frequency of death attributed to degenerative causes (ie, age-related causes) suggested that the risk of long-term adverse health effects in this population of SAR dogs was low.
Abstract
OBJECTIVE To determine brain region affinity for and retention of gadolinium in dogs after administration of gadodiamide and whether formalin fixation affects quantification.
ANIMALS 14 healthy dogs.
PROCEDURES 13 dogs received gadodiamide (range, 0.006 to 0.1 mmol/kg, IV); 1 control dog received a placebo. Dogs received gadodiamide 3 to 7 days (n = 8) or 9 hours (5) before euthanasia and sample collection. Brain regions were analyzed with inductively coupled mass spectrometry (ICP-MS) and transmission electron microscopy. Associations between dose, time to euthanasia, and gadolinium retention quantities (before and after fixation in 5 dogs) were evaluated.
RESULTS Gadolinium retention was seen in all brain regions at all doses, except for the control dog. Exposure 3 to 7 days before euthanasia resulted in 1.7 to 162.5 ng of gadolinium/g of brain tissue (dose-dependent effect), with cerebellum, parietal lobe, and brainstem affinity. Exposure 9 hours before euthanasia resulted in 67.3 to 1,216.4 ng of gadolinium/g of brain tissue without dose dependency. Transmission electron microscopy revealed gadolinium in examined tissues. Fixation did not affect quantification in samples immersed for up to 69 days.
CONCLUSIONS AND CLINICAL RELEVANCE Gadodiamide exposure resulted in gadolinium retention in the brain of healthy dogs. Cerebellum, parietal lobe, and brainstem affinity was detected with dose dependency only in dogs exposed 3 to 7 days before euthanasia. Fixation had no effect on quantification when tissues were immersed for up to 69 days. Physiologic mechanisms for gadolinium retention remained unclear. The importance of gadolinium retention requires further investigation.
Abstract
OBJECTIVE To evaluate pharmacokinetics of ammonium tetrathiomolybdate (TTM) after IV and oral administration to dogs and effects of TTM administration on trace mineral concentrations.
ANIMALS 8 adult Beagles and Beagle crossbreds (4 sexually intact males and 4 sexually intact females).
PROCEDURES Dogs received TTM (1 mg/kg) IV and orally in a randomized crossover study. Serum molybdenum and copper concentrations were measured via inductively coupled plasma mass spectrometry in samples obtained 0 to 72 hours after administration. Pharmacokinetics was determined via noncompartmental analysis.
RESULTS For IV administration, mean ± SD terminal elimination rate constant, maximum concentration, area under the curve, and half-life were 0.03 ± 0.01 hours−1, 4.9 ± 0.6 μg/mL, 30.7 ± 5.4 μg/mL•h, and 27.7 ± 6.8 hours, respectively. For oral administration, mean ± SD terminal elimination rate constant, time to maximum concentration, maximum concentration, area under the curve, and half-life were 0.03 ± 0.01 hours−1, 3.0 ± 3.5 hours, 0.2 ± 0.4 μg/mL, 6.5 ± 8.0 μg/mL•h, and 26.8 ± 8.0 hours, respectively. Oral bioavailability was 21 ± 22%. Serum copper concentrations increased significantly after IV and oral administration. Emesis occurred after IV (2 dogs) and oral administration (3 dogs).
CONCLUSIONS AND CLINICAL RELEVANCE Pharmacokinetics for TTM after a single IV and oral administration was determined for clinically normal dogs. Absorption of TTM after oral administration was variable. Increased serum copper concentrations suggested that TTM mobilized tissue copper. Further studies will be needed to evaluate the potential therapeutic use of TTM in copper-associated chronic hepatitis of dogs.
