Thoracolumbar myelopathies in pug dogs.

BACKGROUND: Constrictive myelopathy (CM) involving a fibrous band around the spinal cord is a newly recognized disease in pug dogs. OBJECTIVES: To identify the frequency of CM based on diagnostic imaging supplemented with necropsy; to determine whether a relationship exists between the sites of CM and other described T3-L3 myelopathies; and to determine the frequency of caudal articular process dysplasia (CAPD). ANIMALS: Thirty-two client-owned pug dogs diagnosed with a chronic, progressive T3-L3 myelopathy based on neurological examination performed by a board-certified neurologist. METHODS: This is a prospective study. All dogs underwent computed tomography (CT) and magnetic resonance imaging (MRI) reviewed by a board-certified radiologist. Magnetic resonance imaging abnormalities were categorized into diseases; CM only, CM plus other non-CM condition(s), or non-CM condition. Sites of CAPD were reported on CT. Nineteen dogs underwent necropsy. RESULTS: Magnetic resonance imaging revealed 3 dogs with CM only, 17 with CM plus at least 1 other myelopathy, 11 dogs with non-CM myelopathies only, and 1 with no MRI abnormalities. Nineteen of 32 dogs had >1 myelopathy diagnosis on MRI whereas 15/32 had >1 site of spinal cord compression. All dogs had CAPD at >1 site in the T3-L3 vertebral column on CT. CONCLUSIONS AND CLINICAL IMPORTANCE: Constrictive myelopathy affected more than half of pug dogs presenting with chronic thoracolumbar myelopathies. Most had multilevel disease, concurrent myelopathies, or both. There was no apparent relationship between anatomic locations of CAPD and most severe myelopathy or myelopathy type.

Eastern Equine Encephalomyelitis in Michigan: Historical Review of Equine, Human, and Wildlife Involvement, Epidemiology, Vector Associations, and Factors Contributing to Endemicity.

Eastern equine encephalomyelitis (EEE) is a mosquito-borne viral disease that is an emerging public health concern in the state of Michigan. Although Michigan has one of the highest incidence rates of EEE in the United States, much of the information known about cases in humans, equines, and other animals residing in Michigan is unpublished. This article summarizes such information and explores spatial trends in the historic distribution of EEE in Michigan. Outbreaks in Michigan have occurred over an 80-yr interval, involving only horses in 1942-1943 and 1973-1976, and then episodically from 1980 to 2020, and involving horses, humans, and wild and domestic animals. An estimated 1,036 equine cases (confirmed and suspected) and 36 confirmed human cases have occurred, including 10 in 2019 (6 deaths) and 4 in 2020 (2 deaths). Human cases ranged in age from 1 to 81 yr; 70% were male, and fatality rate of 34.3%. Equine and human cases occurred from July to October, peaked in August, and cluster in space in southwestern and southeastern lower Michigan. Cases occurred in glacial outwash and ice-contact landscapes in glacial interlobate zones. EEE virus (EEEV) was recovered from Culiseta melanura, Coquillettidia perturbans, five species of Aedes, and other mosquito species near horse and human case sites. Virus isolations or presence of neutralizing antibodies in several passerine species of birds suggest broad EEEV-bird associations. White-tailed deer and other wildlife were also affected. Geographic spread to northern areas of the state suggests expansion of this disease system into new and unsuspected foci.

Comparison of Effects of Trichuris muris and Spontaneous Colitis on the Proximal Colon Microbiota in C3H/HeJ and C3Bir IL10-/- Mice.

The nematode Trichuris muris has been shown to interact with specific enteric bacteria, but its effects on the composition of its host's microbial community are not fully understood. We hypothesized that Trichuris muris-infected mice would have altered colon microbiota as compared with uninfected mice. Colon histopathology and microbial community structure and composition were examined in mouse models of colitis (C3BirTLR4-/- IL10-/- and C3H/HeJ TLR4-/- IL10+/+ mice) with and without T. muris infection, in uninfected C3BirIL10-/- mice with and without spontaneous colitis, and in normal C3H/ HeJ mice. T. muris-infected mice developed colon lesions that were more severe than those seen in IL10-deficient mice. Ap- proximately 80% of infected IL10-/- mice had colon neutrophilic exudates, and some had extraintestinal worms and bacteria. The composition and structure of proximal colon microbiota were assessed by using terminal restriction fragment length polymorphism analysis targeting the bacterial 16S rRNA gene. Colon microbiota in C3BirIL10-/- and C3H/HeJ mice differed both qualitatively and quantitatively. Trichuris infection significantly altered the relative abundance of individual operational taxonomic units [OTU] but not the composition (presence or absence of OTU) of colon microbiota in the 2 mouse genotypes. When C3BirIL10-/- and C3H/HeJ mouse OTU were considered separately, Trichuris was found to affect the microbiota of C3BirIL10-/- mice but not of C3H/HeJ mice. Even though 34 of the 75 (45%) C3BirIL10-/- mice had spontaneous colitis, neither qualitative nor quantitative differences were detected in microbiota between colitic or noncolitic C3BirIL10-/- mice or noncolitic C3H/HeJ mice. Therefore, Trichuris-infected mice developed distinct microbial communities that were influenced by host background genes; these alterations cannot be attributed solely to colonic inflammation.

Restoring pars intermedia dopamine concentrations and tyrosine hydroxylase expression levels with pergolide: evidence from horses with pituitary pars intermedia dysfunction.

BACKGROUND: Pituitary pars intermedia dysfunction (PPID) develops slowly in aged horses as degeneration of hypothalamic dopaminergic neurons leads to proliferation of pars intermedia (PI) melanotropes through hyperplasia and adenoma formation. Dopamine (DA) concentrations and tyrosine hydroxylase (TH) immunoreactivity are markedly reduced in PI tissue of PPID-affected equids and treatment with the DA receptor agonist pergolide results in notable clinical improvement. Thus, we hypothesized that pergolide treatment of PPID-affected horses would result in greater DA and TH levels in PI tissue collected from PPID-affected horses versus untreated PPID-affected horses. To test this hypothesis, pituitary glands were removed from 18 horses: four untreated PPID-affected horses, four aged and four young horses without signs of PPID, and six PPID-affected horses that had been treated with pergolide at 2 µg/kg orally once daily for 6 months. DA concentrations and TH expression levels in PI tissues were determined by high performance liquid chromatography with electrochemical detection and Western blot analyses, respectively. RESULTS: DA and TH levels were lowest in PI collected from untreated PPID-affected horses while levels in the pergolide treated horses were similar to those of aged horses without signs of PPID. CONCLUSIONS: These findings provide evidence of restoration of DA and TH levels following treatment with pergolide. Equine PPID is a potential animal model of dopaminergic neurodegeneration, which could provide insight into human neurodegenerative diseases.

Development of a minimally invasive approach to equine cervical articular facet joints for placement of an ND:YAG LASER.

The purpose of this study was to develop a minimally invasive approach to equine cervical articular facet joints for application of an ND:YAG LASER and to evaluate the effects of the laser fiber on the surrounding tissue. Under general anesthesia, an ND:YAG LASER was used to apply 2000 J of energy to 5 cervical articular facet joints in 3 horses (15 joints total). Horses were euthanized and the cervical facets and spinal cords were examined grossly and histologically. Gross pathology of the articular facets revealed evidence of articular cartilage charring and diffuse roughening of the surface. Histopathology confirmed coagulative necrosis. This novel technique allowed access to the cervical articular facet joints with the ND:YAG LASER and has the potential to allow performance of a minimally invasive facilitated ankylosis procedure. Further validation in sedated, standing horses is required to establish safety and efficacy of this technique.

Développement d'une approche minimalement invasive pour les facettes vertébrales lombaires équines pour le placement d'un LASER ND:YAG. Le but de cette étude était de développer une approche minimalement invasive pour l'application d'un LASER ND:YAG sur les facettes vertébrales lombaires équines et l'évaluation des effets de la fibre laser sur les tissus environnants. Sous anesthésie générale, un LASER ND:YAG a été utilisé pour appliquer 2000 J d'énergie à 5 facettes vertébrales lombaires chez 3 chevaux (total de 15 articulations). Les chevaux ont été euthanasiés et les facettes vertébrales et les colonnes vertébrales ont été examinées macroscopiquement et histologiquement. La pathologie macroscopique des facettes vertébrales lombaires a révélé des preuves de carbonisation du cartilage dens articulaires et un durcissement diffus de la surface. L'histopathologie a confirmé la nécrose decoagulatio. Cette technique nouvelle a permis l'accès aux facettes vertébrales lombaires avec le LASER ND:YAG et a le potentiel de permettre la réalisation d'interventions d'ankylose minimalement invasives. De nouvelles études de validation chez des chevaux debout sous sédation sont requises pour établir l'innocuité et l'efficacité de cette technique.(Traduit par Isabelle Vallières).

Metronidazole-but not IL-10 or prednisolone-rescues Trichuris muris infected C57BL/6 IL-10 deficient mice from severe disease.

Trichuris muris infected C57BL/6 mice are a frequently studied model of immune mediated resistance to helminths. Our objective was to characterize dose-dependent gastrointestinal (GI) disease and pathology due to Trichuris in C57BL/6 mice with varying degrees of IL-10 sufficiency. These mice can serve as a model for other animals (dogs, cattle) and humans where IL-10 polymorphisms have been associated with disease susceptibility and may affect susceptibility to whipworm. C57BL/6 IL-10(+/+), IL-10(+/-) and IL-10(-/-) mice were infected with T. muris (J strain) in a dose response study. T. muris produced dose-dependent disease in IL-10(-/-) mice. Ninety percent of mice receiving the high dose (75 ova) had severe disease necessitating early euthanasia, while the medium dose (50 ova) resulted in 100% early euthanasia of males/75% of females, and the low dose (25 ova) in 100% early euthanasia of males/25% of females. Having some IL-10 as in heterozygotes did not rescue all infected mice from effects of the high dose. 2/21 IL-10(-/-), 1/17 IL-10(+/-), and 0/17 IL-10(+/+) mice in the high dose group had severe peritonitis and extra-intestinal bacteria confirmed by fluorescent 16S rDNA analysis of peritoneal organ surfaces. Three of twenty one IL-10(-/-) had demonstrable extra-intestinal T. muris adults. Although free from viral pathogens, 12/21 IL-10(-/-), 6/17 IL-10(+/-), and 4/17 IL-10(+/+) infected mice had hepatitis, while control mice of all genotypes did not. Mice had evidence of inflammation of serosal surfaces of liver, spleen and GI tract even when extraintestinal Trichuris were not found. Blinded histopathology scoring revealed that even when infected IL-10(-/-) mice displayed few, if any, clinical signs, levels of gut inflammation did not vary significantly from those mice euthanized early due to severe disease. To examine whether antibiotics or corticosteroids could reverse severe disease and lesions, IL-10(-/-) mice infected with T. muris were treated with metronidazole or prednisolone prior to and throughout 40 days of infection. Mice given prednisolone had severe disease and lesions with the highest mortality rate. Mice given metronidazole had a significantly lower mortality rate than those given prednisolone, but GI lesions were of similar severity and distribution including peritonitis. Mortality was associated with extraintestinal worms and bacteria and further supported a role for enteric bacteria in this pathogenesis.

Disseminated pheochromocytoma in a North American river otter (Lontra canadensis).

A 21-yr-old male North American river otter (Lontra canadensis) with a chronic history of degenerative osteoarthritis was evaluated for acute posterior paralysis. Because no definitive cause was identified and a poor prognosis was expected, the otter was euthanatized. A malignant neoplasm of adrenal gland origin with disseminated metastases to the central nervous system, lymph nodes, diaphragm, pancreas, spleen, and liver was diagnosed on postmortem examination. No clinical signs of disseminated neoplasia had been noted throughout the otter's history. The adrenal neoplasm was composed of nests of epithelial cells surrounded by a fine fibrovascular stroma. Neoplastic cells were immunohistochemically positive for chromogranin A, PGP9.5, metencephalin, and endorphin and negative for melan A and inhibin, confirming a diagnosis of a malignant pheochromocytoma. On the basis of the necropsy finding, metastasis of the pheochromocytoma might have contributed to the observed clinical signs.

Diagnostic sensitivity and specificity of in situ hybridization and immunohistochemistry for Eastern equine encephalitis virus and West Nile virus in formalin-fixed, paraffin-embedded brain tissue of horses.

Immunohistochemistry (IHC) and in situ hybridization (ISH) can be used either to detect or to differentiate between Eastern equine encephalitis virus (EEEV) and West Nile virus (WNV) within formalin-fixed, paraffin-embedded (FFPE) brain tissue of horses. To compare the diagnostic sensitivity and specificity of ISH and IHC, FFPE brain tissue from 20 EEEV-positive horses and 16 WNV-positive horses were tested with both EEEV and WNV oligoprobes and EEEV- and WNV-specific antibodies. Reverse transcription polymerase chain reaction (RT-PCR) for detection of EEEV and WNV was used as the gold standard to confirm infection. All horses that tested positive for EEEV by RT-PCR also tested positive by IHC and ISH, except for 1 case that was false-negative by ISH. In contrast, all horses that tested positive for WNV by RT-PCR tested negative by IHC and only 2 horses tested positive by ISH. No false-positives were detected with either method for both viruses. Both IHC and ISH are highly specific and sensitive diagnostic methods to detect EEEV in equine FFPE brain tissues, although neither appear effective for the diagnosis of WNV in equine neurologic cases.

Sensitivity and specificity of monoclonal and polyclonal immunohistochemical staining for West Nile virus in various organs from American crows (Corvus brachyrhynchos).

BACKGROUND: Based on results of earlier studies, brain, heart and kidney are most commonly used for West Nile virus (WNV) detection in avian species. Both monoclonal and polyclonal antibodies have been used for the immunohistochemical diagnosis of WNV in these species. Thus far, no studies have been performed to compare the sensitivity and specificity of monoclonal and polyclonal antibodies in detecting WNV in American crows (Corvus brachyrhynchos). Our objectives were to determine 1) the comparative sensitivities of monoclonal and polyclonal antibodies for immunohistochemical (IHC) diagnosis of WNV infection in free-ranging American crows, 2) which organ(s) is/are most suitable for IHC-based diagnosis of WNV, and 3) how real-time RT-PCR on RNA extracted from formalin-fixed paraffin-embedded tissues compared to IHC for the diagnosis of WNV infection. METHODS: Various combinations, depending on tissue availability, of sections of heart, kidney, brain, liver, lung, spleen, and small intestine from 85 free-ranging American crows were stained using a rabbit-polyclonal anti-WNV antibody as well as a monoclonal antibody directed against an epitope on Domain III of the E protein of WNV. The staining intensity and the extent of staining were determined for each organ using both antibodies. Real-time RT-PCR on formalin-fixed paraffin-embedded tissues from all 85 crows was performed. RESULTS: Forty-three crows were IHC-positive in at least one of the examined organs with the polyclonal antibody, and of these, only 31 were positive when IHC was performed with the monoclonal antibody. Real-time RT-PCR amplified WNV-specific sequences from tissue extracts of the same 43 crows that were IHC-positive using the polyclonal antibody. All other 42 crows tested negative for WNV with real-time PCR and IHC staining. Both antibodies had a test specificity of 100% when compared to PCR results. The test sensitivity of monoclonal antibody-based IHC staining was only 72%, compared to 100% when using the polyclonal antibody. CONCLUSION: The most sensitive, readily identified, positively staining organs for IHC are the kidney, liver, lung, spleen, and small intestine. Real-time RT-PCR and IHC staining using a polyclonal antibody on sections of these tissues are highly sensitive diagnostic tests for the detection of WNV in formalin-fixed tissues of American crows.

An integrative and case-based approach to the teaching of general and systemic pathology.

Since 1993, the pre-clinical phase of the professional (DVM) curriculum at Michigan State University College of Veterinary Medicine has included two pathology courses in which both anatomic and clinical pathologists collaborate to teach concepts in general and systemic pathology. Topics such as inflammation, circulatory disturbances, and neoplasia are taught in this collaborative manner in the year 1 General Pathology course, and pathology of the digestive system (including liver and pancreas), urinary system, and lymphoid system are "team-taught" in the year 2 Clinical and Systemic Pathology course. We feel that this approach gives students an appreciation of the whole-body dynamics of a disease process as it occurs in bone marrow, peripheral blood, body fluids, and tissues and that it leads to a deep understanding of pathologic processes. In addition, the use of "active learning" instructional strategies grounded in case discussions further enhances students' understanding of important concepts by demonstration of practical applications and serves to generate strong interest in learning the subject matter. Integration of concepts of pathology with those taught concurrently in other courses, such as those in physiology and microbiology, is also an important component of pathology instruction in the pre-clinical curriculum.

Increased student self-confidence in clinical reasoning skills associated with case-based learning (CBL).

UNLABELLED: Second-year veterinary students were surveyed at the beginning and end of a 15-week semester regarding their confidence in performing three clinical reasoning skills: (1) making Problem Lists; (2) making Rule-Out Lists; and (3) selecting appropriate diagnostic tests. Each week during the semester, these skills were practiced in small-group case discussions. Changes in self-confidence were analyzed and studied in light of faculty assessments of student competence in performance of the three skills. RATIONALE: The purpose of the study was to determine if students' self-confidence in performing three clinical reasoning skills increased with practice. METHODOLOGY: On the first and last days of class, students rated their confidence in each of the three skills on a scale of 0 to 10. Mean confidence scores for the whole class both for time points and for each of the three skills were analyzed. RESULTS: There were significant increases in students' self-confidence in all three clinical reasoning skills over the semester each year. A greater percentage of students expressed improved confidence in selecting appropriate diagnostic tests than in the other two skills in three of the four years studied. CONCLUSIONS: Students' self-confidence in performing three clinical reasoning skills improved over the course of a semester in which they practiced the skills in a CBL format. Subjective faculty assessment of students' competence in these skills generally indicated improvement. However, no meaningful conclusions about the correlation of skill competence and student confidence could be drawn because of inadequacies in the measurement of student performance.

Canine spongiform leukoencephalomyelopathy is associated with a missense mutation in cytochrome b.

Two families of dogs (Australian cattle dogs and Shetland sheepdogs) with an inherited "spongiform leukoencephalomyelopathy" were identified, with widespread vacuolation of white matter of the brain and spinal cord. Affected dogs of both breeds developed tremors at 2-9 weeks of age followed by progressive neurological worsening with ataxia, paresis, paralysis, spasticity, and cranial nerve dysfunction. The modes of inheritance of both families were most likely maternal. The cerebrospinal fluid (CSF) analysis showed elevated ratio of 3-OH butyrate to acetoacetic acid. Mitochondrial DNA sequencing showed a G to A transition at 14,474 nt (G14474A, GenBank accession no. NC002008 ) that results in an amino acid change of valine-98 to methionine (V98M) of mitochondrial encoded cytochrome b. Western blot analysis showed increased levels of core I and core II but decreased level of cytochrome c1 of the complex III and cytochrome c oxidase of the complex IV of the respiratory chain.

Beta-mannosidosis mice: a model for the human lysosomal storage disease.

Beta-mannosidase, a lysosomal enzyme which acts exclusively at the last step of oligosaccharide catabolism in glycoprotein degradation, functions to cleave the unique beta-linked mannose sugar found in all N-linked oligosaccharides of glycoproteins. Deficiency of this enzyme results in beta-mannosidosis, a lysosomal storage disease characterized by the cellular accumulation of small oligosaccharides. In human beta-mannosidosis, the clinical presentation is variable and can be mild, even when caused by functionally null mutations. In contrast, two existing ruminant animal models have disease that is consistent and severe. To further explore the molecular pathology of this disease and to investigate potential treatment strategies, we produced a beta-mannosidase knockout mouse. Homozygous mutant mice have undetectable beta-mannosidase activity. General appearance and growth of the knockout mice are similar to the wild-type littermates. At >1 year of age, these mice exhibit no dysmorphology or overt neurological problems. The mutant animals have consistent cytoplasmic vacuolation in the central nervous system and minimal vacuolation in most visceral organs. Thin-layer chromatography demonstrated an accumulation of disaccharide in epididymis and brain. This mouse model closely resembles human beta-mannosidosis and provides a useful tool for studying the phenotypic variation in different species and will facilitate the study of potential therapies for lysosomal storage diseases.

Agreement in histologic assessments of the pituitary pars intermedia in aged horses.

OBJECTIVE: To evaluate concordance among veterinary pathologists in the assessment of histologic findings in the pars intermedia of pituitary gland sections from aged horses with mild signs suggestive of pituitary pars intermedia dysfunction (PPID). Sample Population-10 pituitary glands from aged horses. PROCEDURE: 7 pathologists were provided with signalment, clinical signs, and a single H&E-stained pituitary gland section from 10 aged horses with mild signs suggestive of PPID. Pathologists described histologic findings for each section and stated whether findings were consistent with PPID. Agreement among pathologists and with antemortem diagnostic test results was calculated. RESULTS: Overall, only fair agreement was found among the pathologists as to which horses had histologic findings consistent with disease (mean +/- SE kappa value, 0.34 +/- 0.069). Interpretation of individual sections varied, with minimal agreement (4 or 5/7 pathologists) for 5 of 10 sections evaluated. Postmortem assessment was in agreement with an antemortem endocrine diagnostic test result 79% of the time. CONCLUSIONS AND CLINICAL RELEVANCE: Validation of antemortem diagnostic testing for PPID in horses often relies on the results of postmortem histologic evaluation. The lack of consensus in histologic interpretation of pituitary glands from aged horses with mild clinical signs in our study indicates that postmortem histologic evaluation of pituitary glands is an inappropriate standard in validation of antemortem diagnostic tests for detection of early PPID. Caution should be used when interpreting diagnostic test results in horses in which early PPID is suspected.

Effect of daily administration of pyrantel tartrate in preventing infection in horses experimentally challenged with Sarcocystis neurona.

OBJECTIVE: To determine whether daily administration of pyrantel tartrate can prevent infection in horses experimentally challenged with Sarcocystis neurona. ANIMALS: 24 mixed-breed specific-pathogen-free weanling horses, 10 adult horses, 1 opossum, and 6 mice. PROCEDURE: Sarcocystis neurona-naïve weanling horses were randomly allocated to 2 groups. Group A received pyrantel tartrate at the labeled dose, and group B received a nonmedicated pellet. Both groups were orally inoculated with 100 sporocysts/d for 28 days, 500 sporocysts/d for 28 days, and 1000 sporocysts/d for 56 days. Blood samples were collected weekly, and CSF was collected monthly. Ten seronegative adult horses were monitored as untreated, uninfected control animals. All serum and CSF samples were tested by use of western blot tests to detect antibodies against S. neurona. At the end of the study, the number of seropositive and CSF-positive horses in groups A and B were compared by use of the Fisher exact test. Time to seroconversion on the basis of treatment groups and sex of horses was compared in 2 univariable Cox proportional hazards models. RESULTS: After 134 days of sporocyst inoculation, no significant differences were found between groups A and B for results of western blot tests of serum or CSF There were no significant differences in number of days to seroconversion on the basis of treatment groups or sex of horses. The control horses remained seronegative. CONCLUSIONS AND CLINICAL RELEVANCE: Daily administration of pyrantel tartrate at the current labeled dose does not prevent S. neurona infection in horses.