An inherited night blindness in Wiltshire sheep.

Twelve cases of adult-onset blindness were identified in a flock of 130 polled Wiltshire sheep in New Zealand over a 3-year period. Affected sheep developed night blindness between 2 and 3 years of age, which progressed to complete blindness by 4 to 5 years of age. Fundic examination findings included progressive tapetal hyperreflectivity and attenuation of retinal blood vessels. Histologically, the retinas had a selective loss of rod photoreceptors with initial preservation of cone photoreceptors. Retinal degeneration was not accompanied by any other ocular or central nervous system abnormalities, and pedigree analysis suggested an inherited basis for the disease. Mating an affected Wiltshire ram to 2 affected Wiltshire ewes resulted in 6 progeny that all developed retinal degeneration by 2 years of age, while mating of the same affected ram to 6 unaffected ewes resulted in 8 unaffected progeny, consistent with autosomal recessive inheritance. Homozygosity mapping of 5 affected Wiltshire sheep and 1 unaffected Wiltshire sheep using an OvineSNP50 Genotyping BeadChip revealed an identical-by-descent region on chromosome 5, but none of the genes within this region were considered plausible candidate genes. Whole-genome sequencing of 2 affected sheep did not reveal any significant mutations in any of the genes associated with retinitis pigmentosa in humans or progressive retinal atrophy in dogs. Inherited progressive retinal degeneration affecting rod photoreceptors has not been previously reported in sheep, but this disease has several similarities to inherited retinal dystrophies in other species.

ß-Mannosidosis in German Shepherd Dogs.

A neurological disease was investigated in 3 German Shepherd pups from the same litter that failed to grow normally, appeared stiff, were reluctant to move, and were deaf. They developed intermittent seizures and ataxia and had proprioceptive defects. Histopathology showed severe vacuolation of neurons, astrocytes in nervous tissue, renal tubular epithelial cells, and macrophages in nervous tissue, spleen, and liver. Vacuoles appeared empty with no storage material stained by periodic acid-Schiff (PAS) or Sudan black stains, leading to a diagnosis of a lysosomal storage disease and in particular an oligosaccharidosis. Biochemical and genomic studies showed that this was ß-mannosidosis, not previously diagnosed in dogs. A c.560T>A transition in exon 4 of the MANBA gene was found, which segregated in these and other family members in a manner consistent with it being the causative mutation of an autosomal recessive disease. This mutation led to substitution of isoleucine to asparagine at position 187 of the 885 amino acid enzyme, a change expected to have functional significance.

Accuracy of magnetic resonance imaging for estimating intramedullary osteosarcoma extent in pre-operative planning of canine limb-salvage procedures.

The objective of this work was to compare the accuracy of radiographs and magnetic resonance imaging (MRI) for estimating appendicular osteosarcoma margins. The accuracy of computed tomography (CT) and bone scintigraphy was also assessed when these studies were available. Eight dogs with appendicular osteosarcoma underwent radiographic and MRI of affected limbs. In addition, bone scintigraphy was performed in six dogs and CT examination was performed in five dogs. Two observers jointly measured tumor length on all imaging studies. Correlative gross and histologic evaluation of all affected limbs was performed to determine tumor extent as measured from the nearest articular surface. Results from imaging studies were compared to gross and microscopic morphometry findings to determine the accuracy of each modality for determining tumor boundaries. MRI images were accurate with a mean overestimation of actual tumor length of 3 +/- 13%. T1-weighted non-contrast images were superior in identifying intramedullary tumor margins in most instances whereas contrast-enhanced images provided supplemental information in two dogs. Lateromedial and craniocaudal radiographs overestimated tumor length by 17 +/- 28% and 4 +/- 26%, respectively. Scintigraphy and CT overestimated tumor margins by 14 +/- 28% and 27 +/- 36%, respectively. MRI appears to be an accurate diagnostic imaging modality in determining intramedullary osteosarcoma boundaries. MRI should be considered as part of a pre-operative assessment of appendicular osteosarcoma, particularly when a limb-sparing procedure is contemplated.

Photosensitivity in a Kennel of Harrier Hounds.

Résumé- Une dermite s'est développé subitement dans un chenil de 30 chiens courants chez 12 d'entre eux. A la fois des males et des femelles étaient atteints et les lésions étaient limitées aux régions non pigmentées, principalement la face, les membres et la région inguinale. Initiallement les lésions étaient un érythème, un œdéme et une exsudation. Des croutes brunes se sont ensuite formées, et chez la plupart des animaux trés atteints, la peau a laissé la place à un escarre brun agglutiné dans les poils. Un pus malodorant était accumulé sous l'escarre. Les chiens moyennement atteints ont guerie sans traitement et les plus atteints ont guerie après exérèse des escarres et antibiothérapie. Aucun des chiens n'est mort et la plupart ont retrouvé une peau normale au bout de 3 mois. Cliniquement et histologiquement, ces lésions étaient compatibles avec une photosensibilisation, mais il a été impossible de retrouver l'agent causal. [Fairley, R. A., MacKenzie, I. S. Photosensitivity in a kennel of harrier hounds (Photosensibilisation dans un chenil de chiens courants). Resumen- Una condición de la piel se desarrolló de repente en 12 de 30 perros harrier. Afectó a machos y hembras y las lesiones se limitaban a areas de piel sin pigmento, principalmente la cara, patas e ingle. Inicialmente, la piel afectada estaba eritematosa, edematosa y húmeda. Entonces se formaban costras marrones y, en los perros más gravemente afectados, la piel se desprendia dejando una costra marrón seca enredada en el pelo. Debajo de la costra se acumulaba un exudado purulento maloliente. Los perros levemente afectados mejoraron sin tratamiento y los más gravemente afectados lo hicieron despues de tratamiento antibiotico y extirpación de la costra y el pus acumulado. Ninguno de los perros murió y la piel de la mayoria de ellos era normal en 3 meses. Clinica e histologicamente, las lesiones eran compatibles con una condición de fotosensibilidad de la piel, pero las investigaciones no lograron encontrar ningún agenté fotodinámico responsable. [Fairley, R. A., Mackenzie, I. S. Photosensitivity in a kennel of harrier hounds (Fotosensibilidad en una perrera de perros harrier). Abstract- A skin condition developed suddenly in 12 out of 30 harrier hounds. Both males and females were affected and lesions were confined to areas of unpigmented skin, mainly on the face, legs and groin. Initially the affected skin was erythematous, edematous and moist. Brown crusts then formed, and in the most severely affected dogs the skin sloughed leaving a dry brown eschar matted in the hair. A foul-smelling purulent exudate accumulated under the eschar. The mildly affected dogs improved without treatment and the most severely affected dogs improved following antibiotic treatment and the removal of the eschar and the accumulated pus. None of the dogs died and the skin of most dogs was normal within 3 months. Clinically and histologically, the lesions were compatible with a photosensitive skin condition, but investigations failed to find any responsible photodynamic agent.