Histomorphometric evaluation of the Göttingen minipig eye.

OBJECTIVE: The Göttingen minipig is becoming a popular nonrodent animal model in ocular research; however, there is a paucity of literature regarding normative ocular reference data in this breed. We, therefore, investigated the characteristics of the cornea, retina, and sclera in order to establish baseline histomorphometric data in male and female Göttingen minipigs. PROCEDURES: This study utilized paraffin-embedded, Davidson's-fixed, control Göttingen minipig eyes (six males and eight females). Hematoxylin and eosin stained slides of the eyes were scanned via an Aperio slide scanner and analyzed using Aperio ImageScope™. Linear measurements were made of the cornea, retina, and sclera. RESULTS: There were no statistically significant differences between males and females in corneal or scleral measurements or total retinal thickness. There were, however, statistically significant differences between the sexes in the thickness of the ventral peripheral ganglion cell layer [13.15 µm (±3.65) in males; 10.68 µm (±3.37) in females; P = 0.03], ventral peripheral inner plexiform layer [23.47 µm (±2.85) in males; 21.16 µm (±3.62) in females; P = 0.03], ventral central outer plexiform layer [7.97 µm (±2.43) in males; 6.63 µm (±1.73) in females; P = 0.02], and ventral peripheral outer plexiform layer [8.79 µm (±1.82) in males; 11.23 µm (±3.11) in females; P = 0.01]. CONCLUSIONS: This study provides normative histomorphometric reference data for the Göttingen minipig eye. These data will aid researchers in study design and interpretation of findings in Göttingen minipig ocular studies.

Pulmonary pythiosis in a canine patient.

A Staffordshire terrier presented for evaluation of a chronic, nonproductive cough that was unresponsive to antibiotic therapy. A large mass identified in the pulmonary hilum was most consistent with tracheobronchial lymphadenopathy on radiographic and computed tomography (CT) images. Bronchoscopy confirmed a mass compressing the dorsal portion of the intrathoracic trachea. Bronchoscopic biopsies of the tracheal mass revealed necrosuppurative and eosinophilic inflammation with intralesional Pythium insidiousum hyphae. Pythiosis should be included as a differential diagnosis for tracheobronchial lymphadenopathy and bronchopneumopathy in dogs, especially when the patient is from or has visited a region endemic for Pythium insidiosum.

Göttingen Minipigs in Ocular Research.

Since their development in the 1960s, Göttingen minipigs have become a popular nonrodent animal model in biomedical research, especially for ocular studies, because of their ease of handling, size, well-monitored genetics, and ocular anatomy that is similar to humans. The purpose of this mini-review is to introduce the reader to the various ways in which this animal model is currently being utilized in ocular research and to provide an overview of the diagnostic modalities that aid in this research. To date, the Göttingen minipig has been used for a variety of ocular research endeavors, including studies evaluating the safety and efficacy of ocular therapeutics, glaucoma etiopathogenesis and treatment, novel biomaterials, surgical procedures, and implantable materials/devices. In addition to histopathologic evaluation of enucleated globes, the majority of these studies make use of advanced in vivo diagnostic techniques, including electroretinography, optical coherence tomography, fundoscopic imaging, and fluorescein angiography.

Central Nervous System B-cell Lymphoma in a Bald Eagle ( Haliaeetus leucocephalus).

An adult bald eagle ( Haliaeetus leucocephalus) presented for nystagmus and an inability to fly. On physical examination, the eagle was open-mouth breathing and tachycardic at 200 beats per minute, had a wrinkled cere and sunken eyes, and was an estimated 10% dehydrated. Additionally, the eagle was extremely weak, with neurologic abnormalities including bilateral proprioceptive deficits, nystagmus, and no pupillary light reflex in the left eye. Despite aggressive treatment, the eagle continued to decline rapidly and subsequently died. On histologic examination, diffuse and widespread infiltration of neoplastic lymphocytes was present in the brain, optic nerves, and pecten. Immunohistochemical PAX-5 labeling confirmed B-cell lymphoma confined to the eye and nervous system. Test results for select avian retroviruses, Marek's disease, West Nile virus, avian influenza viruses, and Mycoplasma were negative. To our knowledge, this is the first report of B-cell lymphoma in a bald eagle. Although rare, this condition is a differential diagnosis in cases of neurologic or ocular diseases in birds.

IMAGING DIAGNOSIS-MAGNETIC RESONANCE IMAGING FEATURES OF A MULTIFOCAL OLIGODENDROGLIOMA IN THE SPINAL CORD AND BRAIN OF A DOG.

An 8-year-old neutered male Toy Poodle was presented with chronic, progressive tetraparesis, and possible seizures. Magnetic resonance images demonstrated an extensive, T1 and T2 hyperintense contrast enhancing mass in the cervical spinal cord. Three nodules were present on the surface of the thalamus, with enhancement most evident on delayed images. A diagnosis of high-grade oligodendroglioma was confirmed with postmortem histopathology and immunohistochemical labeling. Oligodendroglioma should be considered as a differential for T1 hyperintense intraaxial or intramedullary lesions with contrast enhancement. If enhancement is not visualized on postcontrast images, delayed images may be beneficial.

Culture Media Supplemented With 10% Equine Serum Provided Chondroprotection in an In Vitro Co-Culture of Cartilage and Synovial Membrane.

No studies have evaluated the effect of culture in serum-free media (SF) vs. media supplemented with equine serum (ES) on co-culture of synovial membrane and cartilage tissue explants. The study objective was to evaluate the effects of equine serum supplementation on induced production of inflammatory and catabolic mediators from articular cartilage and synovial explants while in co-culture. Articular cartilage and synovial membrane explants were harvested from femoropatellar joints of five adult horses. Cartilage and synovial explants were harvested from the stifle of five horses, placed in co-culture, stimulated with IL-1ß (10 ng/ml) and maintained in culture for 3, 6 and 9 days in 10% ES or SF. At each time point, media was harvested for analysis of cellular viability (Lactate dehydrogenase) and elution of glycosaminoglycans (Dimethylene Blue Binding Assay). Tissue explants were harvested for histopathologic and gene expression analyses. No differences in cell viability were observed between SF and ES groups. SF culture produced an upregulation of TNF-α in synovial membrane and ADAMTS-4 and five in articular cartilage at 9 days of culture. ES produced an upregulation of aggrecan expression in cartilage at 9 days of culture. No differences in tissue viability were found between culture media, but SF media produced a higher glycosaminoglycan concentration in media at 3 days of culture. The addition of 10% ES produced a slight chondroprotective effect in an inflamed co-culture system. This effect should be considered when designing studies evaluating treatment of serum or plasma-based orthobiologic studies in vitro.

Evaluation of the Dose-Dependent Inflammatory Response and No-Observable Adverse Effect Level of Intravitreal Endotoxin in the African Green Monkey.

Purpose: To evaluate the inflammatory effects and no-observed adverse effect level (NOAEL) of intravitreal endotoxin in an African green monkey model of uveitis. Methods: Fifteen green monkeys were administered intravitreal endotoxin ranging from 0.005 to 0.08 endotoxin unit (EU)/eye. Inflammation was evaluated by slit-lamp biomicroscopy, indirect fundoscopy, tonometry, color fundus photography, ocular coherence tomography, laser flare photometry, and histopathology, with analysis of cytokine levels in aqueous and vitreous humor. The inter-rater reliability of a refined nonhuman primate ophthalmic scoring system was evaluated. Results: A dose-dependent inflammatory response was observed beginning at 0.02 EU/eye; no inflammatory response exceeding the vehicle was observed at 0.005 EU/eye. Retinal pathology was minimal, and posterior visualization degraded with increasing inflammation. Inflammation was observed by histopathology at 0.04 EU/eye. Inter-rater reliability of the scoring system was high, with 99.2% of individual scores differing by 1 scale unit or less and 87.2% of summary scores differing by 2 scale units or less. Conclusions: The NOAEL for intravitreal endotoxin in the green monkey is 0.005 EU/eye, with inflammation increasing with increasing dose beginning at 0.02 EU/eye. This updated nonhuman primate ophthalmic scoring system allows for high inter-rater reliability for the quantification of mild to severe inflammation in the green monkey eye. Translational Relevance: Validation of the ophthalmic inflammation scoring system enables application of the green monkey as a valuable translational model. Candidate therapeutics should be confirmed to have endotoxin levels below this threshold before safety testing in this species to enable interpretation of inflammation and minimize impact on animal welfare.

Characterization of Australian Labradoodle dystrophinopathy.

In humans, dystrophin mutations cause the X-linked recessive disorder known as Duchenne muscular dystrophy (DMD). These mutations result in skeletal and cardiac muscle damage with mortality increasingly associated with cardiomyopathy. We have identified a novel dystrophin mutation in exon 21 in a line of Australian Labradoodles; affected dogs develop progressive clinical signs including poor weight gain and weight loss, gait abnormalities, exercise intolerance, skeletal muscle atrophy, macroglossa, ptyalism, dysphagia, kyphosis, and a plantigrade stance. Echocardiographic abnormalities include hyperechoic foci in the left ventricular papillary muscles, septal hypokinesis, and decreased left ventricular systolic and diastolic volume and internal diameter. Holter recordings found a Mobitz type II second-degree atrioventricular (AV) block in one affected dog. Analysis of phosphocreatine-to-ATP ratios (PCr/ATP) (obtained via cardiac magnetic resonance imaging and spectroscopy evaluation), found no statistically significant difference in the mean PCr/ATP between groups. Histopathologic skeletal muscle changes included fibrofatty infiltration, myocyte degeneration, necrosis, and regeneration, lymphohistiocytic inflammation, and mineralization; cardiac changes were limited to a focal area of mineralization adjacent to the sinoatrial node in the dog with a second-degree AV block. Due to rapidly progressive clinical signs, a severe phenotype, and potential for cardiac involvement, Australian Labradoodle dystrophinopathy may be a useful model to further study DMD pathogenesis.

Gliomatosis Cerebri in the Brain of a Cat.

An eight-year-old, neutered, female, long-haired cat was presented with a three-week history of progressive lethargy, unlocalized pain in the cervical and lumbar spine, and unwillingness to move. An MRI (magnetic resonance imaging) of the brain revealed poorly circumscribed regions of non-contrast-enhancing heterogeneous T2 hyperintensity within the ventral forebrain and midbrain. A mass effect and evidence of increased intracranial pressure, including transtentorial herniation of the midbrain and herniation of the cerebellar vermis through the foramen magnum, were also observed. Due to progressive clinical decline and MRI results, the cat was humanely euthanized. Gross examination of the brain confirmed caudal transtentorial and foramen magnum herniation. The ventral aspect of the forebrain, midbrain, and brainstem were soft and had loss of detail, but lacked a grossly discernible mass. Histopathological examination found a poorly delineated neoplastic mass composed of hyperchromatic cells with indistinct cytoplasm, ovoid to elongate or curved nuclei, and indistinct nucleoli. The cells lacked immunoreactivity for Olig2, GFAP, Iba1, CD3, and Pax5. Based on the cellular morphology, immunolabeling characteristics, and anatomical location, a diagnosis of gliomatosis cerebri was made. Although uncommon, gliomatosis cerebri should be considered as a differential diagnosis in cats with central nervous system disease.

A case of basal cell carcinoma of the nictitating membrane in a dog.

A case of a basal cell carcinoma (BCC) of the nictitating membrane (NM) in a 9-year-old female spayed dachshund is reported. Computed tomography and resection of the NM followed by cryosurgery was performed. Although uncommon, BCC should be considered as a differential diagnosis for tumors of the NM.