Wm Tod Drost

Safety of contrast-enhanced ultrasonography in dogs and cats: 488 cases (2002-2011)

OBJECTIVE To determine the incidence of adverse events within 24 hours after contrast-enhanced ultrasonography (CEUS) in dogs and cats and compare the risk of death within 24 hours after imaging for animals that underwent ultrasonography with and without injection of a contrast agent. DESIGN Retrospective case-control study. ANIMALS 750 animals (411 case dogs, 238 control dogs, 77 case cats, and 24 control cats). PROCEDURES At 11 institutions, medical records were reviewed of dogs and cats that had CEUS performed (cases) as were medical records of dogs and cats with clinical signs similar to those of case animals that had ultrasonography performed without injection of a contrast agent (controls). Information regarding signalment; preexisting disease; type, dose, and administration route of contrast agent used; immediate (within 1 hour after CEUS) and delayed (> 1 and ≤ 24 hours after CEUS) adverse events; and occurrence and cause of death (when available) was extracted from each medical record. Risk of death within 24 hours after ultrasonography was compared between case and control animals. RESULTS Of the 411 case dogs, 3 had immediate adverse events (vomiting or syncope) and 1 had a delayed adverse event (vomiting). No adverse events were recorded for case cats. Twenty-three of 357 (6.4%) clinically ill case animals and 14 of 262 (5.3%) clinically ill control animals died within 24 hours after ultrasonography; risk of death did not differ between cases and controls. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that CEUS was safe in dogs and cats.

Radiographic and echocardiographic assessment of left atrial size in 100 cats with acute left-sided congestive heart failure.

The aims of this study were to evaluate left atrial size in cats with acute left-sided congestive heart failure. We hypothesized that left atrial size as determined by thoracic radiography can be normal in cats with acute left-sided congestive heart failure. One hundred cats with acute left-sided congestive heart failure in which thoracic radiography and echocardiography were performed within 12 h were identified. Left atrial size was evaluated using right lateral and ventrodorsal radiographs. Measurements were compared to two-dimensional echocardiographic variables of left atrial size and left ventricular size. On echocardiography, left atrial enlargement was observed in 96% cats (subjective assessment) whereas maximum left atrial dimension was increased (>15.7 mm) in 93% cats. On radiographs left atrial enlargement (subjective assessment) was found in 48% (lateral view), 53% (ventrodorsal view), and 64% (any view) of cats whereas left atrial enlargement was absent in 36% of cats in both views. Agreement between both methods of left atrial size estimation was poor (Cohens kappa 0.17). Receiver operating characteristic curve analysis identified a maximum echocardiographic left atrial dimension of approximately 20 mm as the best compromise (Youden index) between sensitivity and specificity in the prediction of radiographic left atrial enlargement. Left atrial enlargement as assessed by thoracic radiography may be absent in a clinically relevant number of cats with congestive heart failure. Therefore, normal left atrial size on thoracic radiographs does not rule out presence of left-sided congestive heart failure in cats with clinical signs of respiratory distress.

Transitioning to digital radiography

Objective – To describe the different forms of digital radiography (DR), image file formats, supporting equipment and services required for DR, storage of digital images, and teleradiology. Background – Purchasing a DR system is a major investment for a veterinary practice. Types of DR systems include computed radiography, charge coupled devices, and direct or indirect DR. Comparison of workflow for analog and DR is presented. Summary – On the surface, switching to DR involves the purchase of DR acquisition hardware. The X-ray machine, table and grids used in analog radiography are the same for DR. Realistically, a considerable infrastructure supports the image acquisition hardware. This infrastructure includes monitors, computer workstations, a robust computer network and internet connection, a plan for storage and back up of images, and service contracts. Advantages of DR compared with analog radiography include improved image quality (when used properly), ease of use (more forgiving to the errors of radiographic technique), speed of making a complete study (important for critically ill patients), fewer repeat radiographs, less time looking for imaging studies, less physical storage space, and the ability to easily send images for consultation. Conclusions – With an understanding of the infrastructure requirements, capabilities and limitations of DR, an informed veterinary practice should be better able to make a sound decision about transitioning to DR.OBJECTIVE To describe the different forms of digital radiography (DR), image file formats, supporting equipment and services required for DR, storage of digital images, and teleradiology. BACKGROUND Purchasing a DR system is a major investment for a veterinary practice. Types of DR systems include computed radiography, charge coupled devices, and direct or indirect DR. Comparison of workflow for analog and DR is presented. SUMMARY On the surface, switching to DR involves the purchase of DR acquisition hardware. The X-ray machine, table and grids used in analog radiography are the same for DR. Realistically, a considerable infrastructure supports the image acquisition hardware. This infrastructure includes monitors, computer workstations, a robust computer network and internet connection, a plan for storage and back up of images, and service contracts. Advantages of DR compared with analog radiography include improved image quality (when used properly), ease of use (more forgiving to the errors of radiographic technique), speed of making a complete study (important for critically ill patients), fewer repeat radiographs, less time looking for imaging studies, less physical storage space, and the ability to easily send images for consultation. CONCLUSIONS With an understanding of the infrastructure requirements, capabilities and limitations of DR, an informed veterinary practice should be better able to make a sound decision about transitioning to DR.

COMPARISON OF COMPUTED TOMOGRAPHY AND ABDOMINAL RADIOGRAPHY FOR DETECTION OF CANINE MECHANICAL INTESTINAL OBSTRUCTION.

Vomiting, often caused by mechanical intestinal obstruction, is common in dogs. Equivocal radiographic signs often necessitate repeat radiographs or additional imaging procedures. For our prospective, case-controlled, accuracy study, we hypothesized the following: (1) using computed tomography (CT), radiologists will be more sensitive and specific for detecting mechanical intestinal obstruction and recommending surgery compared to using radiographs; and (2) using measurements, radiologists will be more sensitive and specific using radiographs or CT for detecting mechanical intestinal obstruction and recommending surgery. Twenty dogs had abdominal radiographs and abdominal CT. Seventeen dogs had abdominal surgery and three dogs were not obstructed based on clinical follow-up. Confidence levels (five-point scale) of three experienced radiologists for mechanical intestinal obstruction and recommending surgery were recorded before and after making selected measurements. Eight dogs had surgically confirmed mechanical intestinal obstruction, and 12 dogs did not have obstruction. For detecting mechanical intestinal obstruction, CT was more sensitive (95.8% vs. 79.2%) and specific (80.6% vs. 69.4%) compared to radiographs, but the difference was not statistically significant. For recommending surgery, radiography was more sensitive (91.7% vs. 83.3%) and specific (83.3% vs. 72.2%) than using CT, but differences were not statistically significant. We reported objective CT measurements for predicting small mechanical intestinal obstruction. By incorporating these objective data, the diagnosis of mechanical intestinal obstruction changed in five of 120 instances (radiographs and CT). In no instance (0/120), did the objective data change the recommendation for surgery. Using CT or abdominal radiographs for the detection of canine mechanical intestinal obstruction is sensitive and specific when evaluated by experienced veterinary radiologists.

Correlation Between Histopathologic, Arthroscopic and Magnetic Resonance Imaging Findings in Dogs with Medial Coronoid Disease

OBJECTIVE To describe the magnetic resonance imaging (MRI), arthroscopic, and histopathologic changes in dogs with medial coronoid disease and to identify potential relationships between these findings. STUDY DESIGN Retrospective case series. SAMPLE POPULATION Twenty-five diseased medial coronoid processes (MCP) were collected from 19 dogs with a confirmed diagnosis of medial coronoid disease that were surgically treated by subtotal coronoid ostectomy. A reference group of normal MCP was collected from 9 dogs euthanatized for reasons unrelated to elbow disease. METHODS MCP specimens were evaluated by MRI using a novel grading scheme (all dogs), arthroscopy using a modified Outerbridge scheme (affected dogs only) and histopathology (all dogs). RESULTS The common histopathologic findings were subchondral microfractures, subchondral microfractures continuous with cartilaginous fissures, moderate to severe hypercellularity of the marrow space, trabecular bone necrosis, and articular cartilage degeneration. The severity of cartilage disease in the MCP was moderate to severe in most specimens, even in cases with minimal arthroscopic pathology. Three distinct patterns of bone marrow lesion (BML) were identified adjacent to the MCP, but there was no correlation between BML pattern and either histopathologic or arthroscopic findings. There was moderate correlation between modified Outerbridge scores and MRI scores. No correlation was identified between the histopathologic changes and either MRI or arthroscopic scores. CONCLUSION There was no significant correlation between the clinical scores and histopathologic changes. Ongoing improvements in the resolution of noninvasive imaging techniques will likely improve description and understanding of the MCP disease in dogs.

Biodegradable Microparticles for in vivo Glomerular Targeting: Implications for Gene Therapy of Glomerular Disease

Glomerular disease is the most common cause of kidney failure in the United States. Gene therapy represents a novel approach to the treatment of diseases of the glomerulus, but necessitates safe and accurate tissue targeting, combined with efficient gene transfer into the cells of interest. Our previous work demonstrated effective glomerular gene transfer after arterial injection of replication deficient recombinant adenovirus complexed to 16 μm polystyrene microspheres. The insoluble nature of polystyrene makes glomerular ischemia a potential complication of the procedure. On this basis, we postulated that biodegradable gelatin particles could serve as transport vehicles in this system. To address this question, we assessed the in vivo degradation of Tc-99m labeled gelatin or polystyrene particles in the kidney following selective renal artery injection. Radioactivity declined 2–3 fold faster in a gelatin-injected pig kidney, when compared to polystyrene injected animals. The discrepancy in signal loss between gelatin and polystyrene injected animals could not be explained by differences in the rate of dissociation of Tc-99m from each particle type, and suggest that gelatin particles degrade once lodged in the glomerular capillary. These data suggest that biodegradable gelatin particles may help to minimize ischemic potential when used to shuttle therapeutic DNA to the glomerulus.

Bilateral patellar fractures and increased cortical bone thickness associated with long-term oral alendronate treatment in a cat

Case summary A 14-year-old cat presented with bilateral patellar fractures and radiographically thickened tibial cortices. This cat had been treated with alendronate for 8 years prior to presentation. To remove the subjectivity of the radiographic evaluation, tibial radiographs from 35 apparently healthy geriatric cats were used for comparison. Cortical and diaphyseal thickness were measured at the proximal and distal thirds of the tibia. Our cat had increased cortical bone thickness compared to that of the control cats. Relevance and novel information Treatment with bisphosphonates can lead to brittle bones and fractures after prolonged use in humans. This is the first description of fractures and cortical bone changes that may have been associated with prolonged bisphosphonate use in a cat. Radiographic measurements of cortical bone thickness may identify cats that are at increased risk for bone pathology secondary to prolonged alendronate use.

What is your diagnosis? Fine-needle aspirate of an aggressive bone lesion in a dog

A 2-year-old intact male Labrador Retriever was presented to The Ohio State University Veterinary Teaching Hospital with a history of right forelimb lameness and slight swelling around the right distal antebrachium for 1 month. Results of a CBC and serum biochemical profile were unremarkable. Radiographs of the right antebrachium, acquired by the referring veterinarian, showed an irregular ovoid rim of mineralized perisoteum around the distal right ulna (Figure 1). Accompanying this were other regions of smooth yet irregular periosteal reaction seen circumferentially on the distal ulna and radius. Osteolysis of the craniodistal cortex of the right ulna was present, and an oval radiolucent area was seen in the ulna distal to the irregular periosteal reaction and lytic region. The soft tissues surrounding the distal antebrachium were swollen. A fine-needle aspirate was collected from the cranial aspect of distal radial cortex and stained with Hema 3 (Fisher Diagnostics, Middletown, VA, USA) (Figure 2).

HEMORRHAGIC MYELOMALACIA IN A BICHON FRISE FOLLOWING LUMBAR SPINAL TAP – A CASE REPORT

A 10-year-old spayed female Bichon Frise presented to the neurology service for back pain and pelvic limb weakness for approximately 2 months duration. Neurologic examination revealed T3-L3 and L4-S3 myelopathies with multifocal spinal pain. Magnetic resonance imaging of the vertebral column revealed multiple mild disc protrusions but no obvious cause for the neurologic deficits. Attempts to collect cerebrospinal fluid from the lumbar spine and cerebellomedullary cistern were unsuccessful. Following anesthesia, the dog was noted to be paraplegic with flaccid pelvic limb muscle tone and absent nociception. Repeat magnetic resonance imaging the following day revealed suspect hemorrhage ventral to the spinal cord cranial to the site of the lumbar spinal tap. Exploratory hemilaminectomy revealed purplish discoloration of the dura. Durotomy was performed and severe myelomalacia of the spinal cord was noted. To the authors knowledge, this is the first reported case of myelomalacia suspected secondary to lumbar spinal tap in a dog.

MRI Findings of Suprasellar Germ Cell Tumors in Two Dogs

A 4 yr old border collie presenting for mydriasis and decreased mentation and a 7 yr old Boston terrier presenting for obtundation, head tilt, and paraparesis were both evaluated using MRI. Findings in both included mass lesions of the thalamus and brainstem that were hypo- to isointense on T1-weighted images and hyperintense on T2-weighted images with regions of hypointensity, and robust contrast enhancement and displacement of adjacent structures. Postmortem histopathology findings, tumor location, and a mixed pattern of epithelial cell differentiation were consistent with germ cell tumor in both cases. Germ cell tumor of the suprasellar region is an infrequently reported neoplasm of dogs and imaging findings in this species have not been well described in the prior literature.