Geoffrey T. Fosgate

Magnetic Resonance Imaging in Dogs with Neurologic Impairment Due to Acute Thoracic and Lumbar Intervertebral Disk Herniation

BACKGROUND Magnetic resonance imaging (MRI) is a correlate to physical examination in various myelopathies and a predictor of functional outcome. OBJECTIVES To describe associations among MRI features, neurological dysfunction before MRI, and functional outcome in dogs with disk herniation. ANIMALS One hundred and fifty-nine dogs with acute thoracolumbar disk herniation. METHODS Retrospective case series. Signalment, initial neurological function as assessed by a modified Frankel score (MFS), and ambulatory outcome at hospital discharge and >3 months (long-term) follow-up were recorded from medical records and telephone interview of owners. Associations were estimated between these parameters and MRI signal and morphometric data. RESULTS Dogs with intramedullary T2W hyperintensity had more severe pre-MRI MFS (median 2, range 0-4) and lower ambulatory proportion at long-term follow-up (0.76) than those dogs lacking hyperintensity (median MFS 3, range 0-5; ambulatory proportion, 0.93) (P=.001 and .013, respectively). Each unit of T2W length ratio was associated with a 1.9 times lower odds of long-term ambulation when adjusted for pre-MRI MFS (95% confidence interval 1.0-3.52, P=.05). Dogs with a compressive length ratio >1.31 (which was the median ratio within this population) had more severe pre-MRI MFS (median 3, range 0-5) compared with those with ratios < or =1.31 (median MFS 3, range 0-4; P=.006). CONCLUSIONS AND CLINICAL IMPORTANCE MRI features were associated with initial injury severity in dogs with thoracolumbar disk herniation. Based on results of this study, the T2W length ratio and presence of T2W intramedullary hyperintensity appear to be predictive of long-term ambulatory status.

MAGNETIC RESONANCE IMAGING FEATURES OF INTRACRANIAL ASTROCYTOMAS AND OLIGODENDROGLIOMAS IN DOGS

Astrocytomas and oligodendrogliomas represent one third of histologically confirmed canine brain tumors. Our purpose was to describe the magnetic resonance (MR) imaging features of histologically confirmed canine intracranial astrocytomas and oligodendrogliomas and to examine for MR features that differentiate these tumor types. Thirty animals with confirmed astrocytoma (14) or oligodendroglioma (16) were studied. All oligodendrogliomas and 12 astrocytomas were located in the cerebrum or thalamus, with the remainder of astrocytomas in the cerebellum or caudal brainstem. Most (27/30) tumors were associated with both gray and white matter. The signal characteristics of both tumor types were hypointense on T1-weighted images (12 each) and hyperintense on T2-weighted images (11/14 astrocytomas, 12/16 oligodendrogliomas). For astrocytomas and oligodendrogliomas, respectively, common findings were contrast enhancement (10/13, 11/15), ring-like contrast enhancement (6/10, 9/11), cystic regions within the mass (7/14, 12/16), and hemorrhage (4/14, 6/16). Oligodendrogliomas were significantly more likely to contact the brain surface (meninges) than astrocytomas (14/16, 7/14, respectively, P=0.046). Contact with the lateral ventricle was the most common finding, occurring in 13/14 astrocytomas and 14/16 oligodendrogliomas. No MR features were identified that reliably distinguished between these two tumor types. Contrast enhancement was more common in high-grade tumors (III or IV) than low-grade tumors (II, P=0.008).

Effect of Sample Quality on the Sensitivity of Endoscopic Biopsy for Detecting Gastric and Duodenal Lesions in Dogs and Cats

BACKGROUND The quality of histopathology slides of endoscopic biopsies from different laboratories varies, but the effect of biopsy quality on outcome is unknown. HYPOTHESIS The ability to demonstrate a histologic lesion in the stomach or duodenum of a dog or cat is affected by the quality of endoscopic biopsy samples submitted. More endoscopic samples are needed to find a lesion in poor-quality tissue specimens. ANIMALS Tissues from 99 dogs and 51 cats were examined as clinical cases at 8 veterinary institutions or practices in 5 countries. METHODS Histopathology slides from sequential cases that underwent endoscopic biopsy were submitted by participating institutions. Quality of the histologic section of tissue (inadequate, marginal, adequate), type of lesion (lymphangiectasia, crypt lesion, villus blunting, cellular infiltrate), and severity of lesion (normal, mild, moderate, severe) were determined. Sensitivity of different quality tissue samples for finding different lesions was determined. RESULTS Fewer samples were required from dogs for diagnosis as the quality of the sample improved from inadequate to marginal to adequate. Duodenal lesions in cats displayed the same trend except for moderate duodenal infiltrates for which quality of tissue sample made no difference. Gastric lesions in dogs and mild gastric lesions in cats had the same trend, whereas the number of tissue samples needed to diagnose moderately severe gastric lesions in cats was not affected by the quality of tissue sample. CONCLUSIONS AND CLINICAL IMPORTANCE The quality of endoscopically obtained tissue samples has a profound effect on their sensitivity for identifying certain lesions, and there are differences between biopsies of canine and feline tissues.

Practical Sample Size Calculations for Surveillance and Diagnostic Investigations

The likelihood that a study will yield statistically significant results depends on the chosen sample size. Surveillance and diagnostic situations that require sample size calculations include certification of disease freedom, estimation of diagnostic accuracy, comparison of diagnostic accuracy, and determining equivalency of test accuracy. Reasons for inadequately sized studies that do not achieve statistical significance include failure to perform sample size calculations, selecting sample size based on convenience, insufficient funding for the study, and inefficient utilization of available funding. Sample sizes are directly dependent on the assumptions used for their calculation. Investigators must first specify the likely values of the parameters that they wish to estimate as their best guess prior to study initiation. They further need to define the desired precision of the estimate and allowable error levels. Type I (alpha) and type II (beta) errors are the errors associated with rejection of the null hypothesis when it is true and the nonrejection of the null hypothesis when it is false (a specific alternative hypothesis is true), respectively. Calculated sample sizes should be increased by the number of animals that are expected to be lost over the course of the study. Free software routines are available to calculate the necessary sample sizes for many surveillance and diagnostic situations. The objectives of the present article are to briefly discuss the statistical theory behind sample size calculations and provide practical tools and instruction for their calculation.

Time-space clustering of human brucellosis, California, 1973-1992

Infection with Brucella spp. continues to pose a human health risk in California despite great strides in eradicating the disease from domestic animals. Clustering of human cases in time and space has important public health implications for understanding risk factors and sources of infection. Temporal-spatial clustering of human brucellosis in California for the 20-year period 1973–1992 was evaluated by the Ederer-Myers-Mantel, Moran’s I, and population-adjusted Moran’s I procedures. Cases were clustered in concentrated agricultural regions in the first 5-year interval (1973–1977). Time-space clustering of human brucellosis cases in California late in the 20-year study period may reflect the distribution of Hispanic populations. Public health programs in California should focus on educating Hispanic populations about the risk of consuming dairy products, such as soft cheeses, made from unpasteurized milk.

Magnetic resonance imaging for the differentiation of neoplastic, inflammatory, and cerebrovascular brain disease in dogs

BACKGROUND The reliability and validity of magnetic resonance imaging (MRI) for detecting neoplastic, inflammatory, and cerebrovascular brain lesions in dogs are unknown. OBJECTIVES To estimate sensitivity, specificity, and inter-rater agreement of MRI for classifying histologically confirmed neoplastic, inflammatory, and cerebrovascular brain disease in dogs. ANIMALS One hundred and twenty-one client-owned dogs diagnosed with brain disease (n = 77) or idiopathic epilepsy (n = 44). METHODS Retrospective, multi-institutional case series; 3 investigators analyzed MR images for the presence of a brain lesion with and without knowledge of case clinical data. Investigators recorded most likely etiologic category (neoplastic, inflammatory, cerebrovascular) and most likely specific disease for all brain lesions. Sensitivity, specificity, and inter-rater agreement were calculated to estimate diagnostic performance. RESULTS MRI was 94.4% sensitive (95% confidence interval [CI] = 88.7, 97.4) and 95.5% specific (95% CI = 89.9, 98.1) for detecting a brain lesion with similarly high performance for classifying neoplastic and inflammatory disease, but was only 38.9% sensitive for classifying cerebrovascular disease (95% CI = 16.1, 67.0). In general, high specificity but not sensitivity was retained for MR diagnosis of specific brain diseases. Inter-rater agreement was very good for overall detection of structural brain lesions (κ = 0.895, 95% CI = 0.792, 0.998, P < .001) and neoplastic lesions, but was only fair for cerebrovascular lesions (κ = 0.299, 95% CI = 0, 0.761, P = .21). CONCLUSIONS AND CLINICAL IMPORTANCE MRI is sensitive and specific for identifying brain lesions and classifying disease as inflammatory or neoplastic in dogs. Cerebrovascular disease in general and specific inflammatory, neoplastic, and cerebrovascular brain diseases were frequently misclassified.

Evaluation of an abdominal fluid scoring system determined using abdominal focused assessment with sonography for trauma in 101 dogs with motor vehicle trauma

OBJECTIVE Evaluate an abdominal fluid scoring (AFS) system using an abdominal focused assessment with sonography for trauma (AFAST) protocol. DESIGN Prospective study. SETTING Private veterinary emergency center. ANIMALS One hundred and one client-owned dogs with motor vehicle trauma. Interventions- AFAST performed on admission and 4 hours post-admission. MEASUREMENTS AND MAIN RESULTS An AFS was assigned to each dog based on the number of AFAST fluid-positive quadrants identified using a 4-point scale: AFS 0 (negative for fluid in all quadrants) to AFS 4 (positive for fluid in all quadrants). Free abdominal fluid was identified in 27 of 101 dogs (27%). Dogs with AFS scores of 3 or 4 (14/27 [52%] AFS-positive dogs) experienced more marked decreases in packed cell volume and total plasma protein, increases in alanine aminotransferase, and needed more blood transfusions than dogs with lower AFS scores and AFS-negative dogs. Serial AFAST was performed in 71% of dogs (71/101); 17% (12/71) of these cases changed AFS score, and 75% (9/12) of the changes were higher (worsened) AFS, correlating with increasing amounts of free abdominal fluid. Ninety-eight percent of the study population was a primary presentation. Overall, median time from trauma to initial AFAST was 60 minutes, and median AFAST examination time was 3 minutes. CONCLUSIONS Initial and serial AFAST with applied AFS allowed rapid, semiquantitative measure of free abdominal fluid in traumatized patients, was clinically associated with severity of injury, and reliably guided clinical management. Where possible, AFAST and AFS should be applied to the management of blunt trauma cases.

Epidemiology of Necrotizing Meningoencephalitis in Pug Dogs

Background: Although the histopathologic features of necrotizing meningoencephalitis (NME) have been described previously, little information is available concerning the signalment, geographic distribution, seasonal onset, treatment, and survival of affected dogs. Animals: Sixty Pugs with NME and 14 contemporaneous control Pugs with other intracranial diseases (non‐NME group). Methods: Pugs that were euthanized or died because of intracranial disease were prospectively obtained. All dogs had necropsy, histopathology, and testing for various infectious diseases and were subsequently divided into NME and non‐NME groups. Signalment, geographic distribution, seasonal onset, treatment, and survival were compared between groups. Results: In Pugs with NME, median age at onset of clinical signs was 18 months (range, 4–113 months). A greater proportion of female dogs were present in the NME group (40/60) compared with the control group (6/14). Pugs with NME had a significantly lower mean weight (7.81 kg) than control Pugs (9.79 kg) (P= .012). Mean survival in Pugs with NME was 93 days (range, 1–680 days), with dogs receiving any form of treatment living significantly longer than those that were not treated (P= .003). Anticonvulsive drugs were the only treatment significantly associated with longer survival (P= .003). Conclusions and Clinical Importance: NME appears to be a common cause of intracranial signs in Pugs, based on the high proportion of NME dogs reported in this population. Pugs with NME are most commonly young adult female dogs. Although further investigation is needed to determine the optimal treatment of NME, anticonvulsive drugs appear to beneficially affect duration of survival.

Associations between dietary factors and pancreatitis in dogs

OBJECTIVE To estimate associations between dietary factors and pancreatitis in dogs. Design-Retrospective case-control study. ANIMALS 198 dogs with a clinical diagnosis of pancreatitis and 187 control dogs with a diagnosis of renal failure without clinical evidence of pancreatitis. PROCEDURES Information on signalment, weight, body condition, dietary intake, medical history, diagnostic tests performed, concurrent diseases, treatments, duration of hospitalization, and discharge status was extracted from medical records. Information on dietary intake, signalment, weight, and medical, surgical, and environmental history was collected through a telephone questionnaire. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals. RESULTS On the basis of information extracted from the medical record, ingesting unusual food items (OR, 4.3) increased the odds of pancreatitis. On the basis of information gathered through the telephone questionnaire, ingesting unusual food items (OR, 6.1), ingesting table scraps the week before diagnosis (OR, 2.2) or throughout life (OR, 2.2), and getting into the trash (OR, 13.2) increased the odds of pancreatitis. Multivariable modeling indicated that reporting exposure to > or = 1 dietary factor during the telephone questionnaire (OR, 2.6), being overweight (OR, 1.3) or neutered (OR, 3.6), previous surgery other than neutering (OR, 21.1), and the interaction between neuter status and previous surgery other than neutering (OR, 0.1) were associated with the odds of pancreatitis. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that dietary factors, being neutered, and previous surgery other than neutering increased the odds of pancreatitis in dogs.

A questionnaire-based evaluation of the veterinary cordon fence separating wildlife and livestock along the boundary of the Kruger National Park, South Africa

Veterinary cordon fences are used in Southern Africa to separate wildlife from domestic animals in order to prevent transmission of infectious diseases. Such fences are a control method recognized by the World Organization for Animal Health (OIE) for establishing disease-free zones in beef exporting countries. However, few studies have evaluated the ecological impact of these physical barriers or their effectiveness at a multispecies level. We examined the permeability of one such barrier, along 357 km of the western and southern boundary of the Kruger National Park (KNP) during 2007. Information was gathered using a semi-structured questionnaire implemented among 32 teams of fence maintenance workers. Data were analyzed to identify (a) the main causes of fence damage, (b) the seasonality, location and duration of fence repairs, (c) high permeability areas for elephant (Loxodonta africana), kudu (Tragelaphus strepsiceros), impala (Aepyceros melampus), buffalo (Syncerus caffer) and warthog (Phacochoerus africanus), and (d) the influence of fence electrification, rivers and elephant damage on the frequency of observation of wildlife species outside the KNP estimated during the year. Human and elephant damage were the most common reasons for fence repairs. Elephant and buffalo were the most and least common large mammal species reported observed outside the KNP (1076 and 162 reports/year), respectively. Cattle incursions into the KNP were also reported in 44% of the fence sections. Electrification of the fence was an important factor explaining differences in estimated wildlife species observations outside the KNP during the year. Correlations between estimations of observed species suggested that fence gaps created by elephants might be used by the other wildlife species. Estimated annual counts of kudu, impala and buffalo, but not warthog, were found to correlate with elephant observations. Negative binomial regression models were developed to explore the relationships between observed estimations of different wildlife species outside the KNP the fence, electrification of fence sections and the presence of watercourses, suggesting that kudu, impala and buffalo could use elephant induced fence damage to leave the KNP. The questionnaire was able to evaluate fence integrity and identify sections where integrity was sub-optimal for separating wildlife from domestic livestock species. If combined with more quantitative methods and applied on a routine basis, it could provide an efficient and cost-effective method for monitoring the effectiveness of physical barriers to contain wildlife within protected areas such as is the case with veterinary cordon fences in Southern Africa.