Russell L. Tucker

Lead bullet fragments in venison from rifle-killed deer: potential for human dietary exposure.

Human consumers of wildlife killed with lead ammunition may be exposed to health risks associated with lead ingestion. This hypothesis is based on published studies showing elevated blood lead concentrations in subsistence hunter populations, retention of ammunition residues in the tissues of hunter-killed animals, and systemic, cognitive, and behavioral disorders associated with human lead body burdens once considered safe. Our objective was to determine the incidence and bioavailability of lead bullet fragments in hunter-killed venison, a widely-eaten food among hunters and their families. We radiographed 30 eviscerated carcasses of White-tailed Deer (Odocoileus virginianus) shot by hunters with standard lead-core, copper-jacketed bullets under normal hunting conditions. All carcasses showed metal fragments (geometric mean = 136 fragments, range = 15–409) and widespread fragment dispersion. We took each carcass to a separate meat processor and fluoroscopically scanned the resulting meat packages; fluoroscopy revealed metal fragments in the ground meat packages of 24 (80%) of the 30 deer; 32% of 234 ground meat packages contained at least one fragment. Fragments were identified as lead by ICP in 93% of 27 samples. Isotope ratios of lead in meat matched the ratios of bullets, and differed from background lead in bone. We fed fragment-containing venison to four pigs to test bioavailability; four controls received venison without fragments from the same deer. Mean blood lead concentrations in pigs peaked at 2.29 µg/dL (maximum 3.8 µg/dL) 2 days following ingestion of fragment-containing venison, significantly higher than the 0.63 µg/dL averaged by controls. We conclude that people risk exposure to bioavailable lead from bullet fragments when they eat venison from deer killed with standard lead-based rifle bullets and processed under normal procedures. At risk in the U.S. are some ten million hunters, their families, and low-income beneficiaries of venison donations.

Computed Tomography and Magnetic Resonance Imaging in Equine Musculoskeletal Conditions

There is a growing interest in the use of computed tomography (CT) and magnetic resonance (MR) imaging in equine orthopedic patients. It is well established that CT and MR imaging offer superior diagnostic information in a wide variety of musculoskeletal injuries in human beings and small animals. The highly detailed cross-sectional images obtained with these two modalities can often demonstrate pathologic changes undetected with other common imaging techniques. Based on their multiple applications in human beings and small animals, CT or MR imaging may prove to be the optimal diagnostic imaging technique for several types of musculoskeletal disorders of horses.

Computed Tomography and Magnetic Resonance Imaging of the Equine Head

Horses are frequently presented with clinical conditions warranting diagnostic imaging of the head. Unfortunately, evaluation of the equine head can be difficult using conventional radiography. The anatomic complexity and superimposition of the osseous, dental, and soft tissue structures complicate radiographic interpretation and diagnoses. Multiple radiographic projections may be necessary to image specific regions, and side-to-side comparison is often essential.

Outcomes and complications associated with ventral screws, pins, and polymethyl methacrylate for atlantoaxial instability in 12 dogs.

Clinical outcomes and complications of a technique used for atlantoaxial stabilization were evaluated in a group of 12 dogs. At surgery, the atlantoaxial joint was realigned and rigidly fixated using cortical bone screws, K-wire, and polymethyl methacrylate. Results in nine dogs were graded as excellent. Results in two dogs were judged as good. One dog was euthanized 17 months after surgery for recurrent cervical pain. Eight dogs had no postoperative complications. The surgical technique described provided an adaptable method for the correction of atlantoaxial instability.

Desmitis of the Distal Digital Annular Ligament in Seven Horses: MRI Diagnosis and Surgical Treatment

OBJECTIVE (1) To describe the clinical signs and abnormalities observed on magnetic resonance imaging (MRI) in 7 horses with desmitis of the distal digital annular ligament (DDAL); (2) to describe the normal magnetic resonance (MR) appearance and thickness of the DDAL in health; and (3) to describe a tenoscopic surgical technique for treating horses with desmitis of the DDAL. STUDY DESIGN Retrospective study. ANIMALS Horses (n=7) with desmitis of the DDAL. METHODS MR examinations of 20 sound horses were reviewed to determine the normal appearance of the DDAL. Dimensions obtained from these images were compared with MR findings from 7 horses with DDAL desmitis. Desmitis of the DDAL was treated by tenoscopic surgery and outcome assessed. RESULTS Horses with DDAL desmitis had lameness (grade 2-3 out of 5) that improved after a palmar digital nerve block. The affected DDAL was enlarged and had an abnormal signal on MR images of the feet. After tenoscopy and DDAL transection, 5 horses returned to athletic performance, including 2 horses that failed to respond to medical treatment and rest before surgery. CONCLUSION Primary desmitis of the DDAL is a cause of lameness in horses. Transection of the DDAL allowed 5 horses with this injury to return to athletic performance. CLINICAL RELEVANCE DDAL desmitis should be included in the differential diagnoses of horses with lameness that improves after a palmar digital nerve block but have no abnormalities observed on radiographs of the feet. Tenoscopic surgical transection of the DDAL is an effective treatment for some horses.

Biliary excretion of technetium-99m-sestamibi in wild-type dogs and in dogs with intrinsic (ABCB1-1Δ mutation) and extrinsic (ketoconazole treated) P-glycoprotein deficiency.

P-glycoprotein (P-gp), the product of ABCB1 gene, is thought to play a role in the biliary excretion of a variety of drugs, but specific studies in dogs have not been performed. Because a number of endogenous (ABCB1 polymorphisms) and exogenous (pharmacological P-gp inhibition) factors can interfere with normal P-gp function, a better understanding of P-gps role in biliary drug excretion is crucial in preventing adverse drug reactions and drug-drug interactions in dogs. The objectives of this study were to compare biliary excretion of technetium-99m-sestamibi ((99m)Tc-MIBI), a radio-labelled P-gp substrate, in wild-type dogs (ABCB1 wild/wild), and dogs with intrinsic and extrinsic deficiencies in P-gp function. Dogs with intrinsic P-gp deficiency included ABCB1 mut/mut dogs, and dogs with presumed intermediate P-gp phenotype (ABCB1 mut/wild). Dogs with extrinsic P-gp deficiency were considered to be ABCB1 wild/wild dogs treated with the P-gp inhibitor ketoconazole (5 mg/kg PO q12h x 9 doses). Results from this study indicate that ABCB1 mut/mut dogs have significantly decreased biliary excretion of (99m)Tc-MIBI compared with ABCB1 wild/wild dogs. Treatment with ketoconazole significantly decreased biliary excretion of (99m)Tc-MIBI in ABCB1 wild/wild dogs. P-gp appears to play an important role in the biliary excretion of (99m)Tc-MIBI in dogs. It is likely that concurrent administration of a P-gp inhibitor such as ketoconazole will decrease P-gp-mediated biliary excretion of other substrate drugs as well.

Combined intramedullary and external skeletal fixation of metatarsal and metacarpal fractures in 12 dogs and 19 cats.

OBJECTIVE To report surgical technique, clinical experiences, and long-term outcomes of combined intramedullary/external skeletal fixation of metatarsal (MT) and metacarpal (MC) fractures in dogs and cats. STUDY DESIGN Case series. ANIMALS Dogs (n = 12); 19 cats. METHODS Clinical and radiographic records of animals managed by combined intramedullary/external fixation of MT/MC fractures were reviewed. Signalment, fracture configuration, complications, and subjective clinical findings were recorded. Surgical technique involved retrograde intramedullary pin placement into fractured MT/MC bones, and transverse pin placement in the base of the MT/MCs or tarsal/carpal bones. Contoured pin ends were enshrouded dorsally in epoxy resin and implants maintained until fracture union. Postoperative clinical and radiographic reassessment was performed where possible. RESULTS Small breed dogs (n = 12) and 19 cats were operated. Fixator removal occurred in < 10 weeks in all cases. Complications included synostosis (n = 2), pin tract discharge (7), excessive postoperative swelling (8), skin abrasions from the frame (2), and paw distortion associated with frame impingement (2). Long-term radiography documented degenerative changes associated with MT-phalangeal or MC-phalangeal joints in 2 dogs; 7 cats, but changes were typically graded mild or moderate and affected only 1 or 2 joints. CONCLUSIONS Combined intramedullary/external fixation of MT/MC fractures is viable, particularly juxta-articular fractures. Pin penetration of MT-phalangeal or MC-phalangeal joints may cause morbidity and requires further study.

Clinical features and magnetic resonance imaging characteristics of diskospondylitis in dogs: 23 cases (1997–2010)

OBJECTIVE To describe the signalment, clinical features, and most common MRI characteristics in dogs with diskospondylitis and investigate whether a correlation exists between the degree of spinal cord compression and neurologic status of the patient. DESIGN Retrospective case series. ANIMALS 23 dogs. PROCEDURES The medical records and imaging database of the Veterinary Teaching Hospital at Washington State University were retrospectively cross-referenced for cases of diskospondylitis in dogs from 1997 through 2010. Signalment, clinical signs, MRI characteristics, and results of bacteriologic cultures of urine, blood, CSF, or intervertebral disk material were reviewed. RESULTS On T2-weighted sequences, vertebral endplates were most often of mixed signal intensity, whereas the vertebral body was hypointense. The intervertebral disk space was most often hyperintense on T2-weighted and short tau inversion recovery sequences and of mixed signal intensity on T1-weighted sequences. Paravertebral soft tissue hyperintensities were noted commonly on T2-weighted and short tau inversion recovery sequences. Heterogenous contrast enhancement of endplates and intervertebral disk spaces also occurred commonly, whereas contrast enhancement of vertebral bodies and paravertebral soft tissues was uncommon. Intramedullary spinal cord intensity was noted at 10 of 27 sites on T2-weighted sequences. Static spinal cord compression occurred in 17 of 23 dogs, and a significant direct correlation was found between the percentage of spinal cord compression and the patient neurologic score. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that diskospondylitis in dogs has a characteristic MRI appearance, and in some patients, MRI may aid in the identification of severe spinal cord compression, which could warrant surgical intervention.

IN VITRO EVALUATION OF CANINE GRANULOCYTES LABELED WITH 99mTC‐HEXAMETHYLPROPYLENEAMINE OXIME:

Technetium-99m hexamethylpropyleneamine oxine (99mTc-HMPAO) and Indium-111 oxine (111In-oxine) labeled canine gramulocytes were evaluated in vitro over a six hour period. Labeling efficiency for 99mTC-HMPAO and 111In-oxine labeled granulocytes was 39.6%± 8.0% and 60.6%± 17.6% (mean ± SD) respectively. The mean in vitro elution of the radiolabel ranged from 8.7-14.0% for the 99mTc-HMPAO grannulocytes and from 6.1-9.0% for the 111In-oxine granulocytes. Mean cell viability, for the 99mTc-HMPAO, 111In-oxine and non-radiolabeled control granulocytes ranged from 97.8-99.4%, 96.4-98.5% and 98.2-99.0%, respectively. The phagocytic ability of the 99mTc-HMPAO, 111In-oxine and control granulocytes ranged from 47.5-54.1%, 38.9-56.2% and 46.6-57.8% respectively over the six hour study period. Although labeling efficiency using 111In-oxine was significantly (P=0.05) better than 99mTc-HMPAO, there was no significant difference in label retention of the two radiolabels. There was no significant difference in viability or phagocytic function during the six hour study period. Considering the potential cost advantage and the superior imaging qualities of Technetium-99m relative to Indium-111, 99mTc-HMPAO appears to be a good alternative to 111In-oxine as a granulocyte label.

IMAGING DIAGNOSIS—METASTATIC ADRENAL PHEOCHROMOCYTOMA IN A DOG

A 10-year-old Akita mix became acutely paraplegic. Upon magnetic resonance imaging, multiple, slightly T2-hyperintense, T1-isointense extradural masses, relative to spinal cord were found in the vertebral canal. The retroperitoneal masses had mixed T2-signal intensity. The contrast enhancement pattern for the spinal masses was both homogenous and heterogenous. The diagnosis was metastatic pheochromocytoma. Signal intensity of the tumors in this dog was similar to reports of pheochromocytoma in human beings.