Tumorigenic, invasive, karyotypic, and immunocytochemical characteristics of clonal cell lines derived from a spontaneous canine anaplastic astrocytoma.

Tumor cells from a spontaneously arising canine astrocytoma were isolated and cloned. Three clonally derived cell lines (DL3580 clone 1, DL3580 clone 2, and DL3580 clone 3) were developed and found to express glial fibrillary acidic protein (GFAP) as well as epidermal growth factor receptor (EGFR/c-erbB1). The cell lines were tumorigenic as subcutaneous xenografts or as intracranial implants in athymic mice, or both. Both the monolayer astrocytoma cells and the xenograft tumor cells from clone 2 were aneuploid, with a modal number of 84 chromosomes per metaphase; clones 1 and 3 were also aneuploid with modal numbers of 82 and 75/79, respectively. The histology of both the initial spontaneously occurring tumor in the dog and the intracranial astrocytoma in athymic mice demonstrated features of diffuse infiltration into normal brain. These newly developed canine glioma cell lines are karyotypically stable for 1 yr in culture and carry the same marker chromosomes as the parental lines. These glioma cell lines may serve as models for investigating mechanisms of glioma invasion into brain. Additionally, clonal cell lines with divergent properties isolated from the same tumor may assist in studies of the molecular basis of astrocytoma progression and heterogeneity.

Brainstem auditory-evoked potential assessment of congenital deafness in Dalmatians: associations with phenotypic markers.

To screen for congenital deafness, brainstem auditory-evoked potential (BAEP) testing was performed on 1031 Dalmatians from three geographically separated areas. Phenotypic marker assessment was done to determine markers possibly associated with deafness. Markers included sex, hair coat color, pigmentation of different areas of skin (eye rims, nose, and ears), presence of a patch, spot size and marking (density of spotting), sire and dam BAEP status, and presence of iris and retinal tapetal pigmentation. Combined data from all test sites showed 8.1% bilateral deafness (N = 83 dogs) and 21.6% unilateral deafness (N = 223), or an overall 29.7% incidence of hearing disorders. Significant (P less than 0.05) associations with deafness for the data from all test sites combined were seen for patch, sire and dam BAEP, iris pigment, and retinal pigment. However, results differed for several of the significant phenotypic markers when analyses were done on the data from the individual test sites; changes from significant to not significant were found. This suggested the existence of multiple populations of deafness patterns, and reinforced the precautionary conclusion that associations of phenotypic markers with deafness are not necessarily functionally significant.

Clinical and pathologic features of ceroid lipofuscinosis in two Australian cattle dogs.

A lysosomal storage disease was diagnosed in 2 Australian Cattle Dog siblings, using light and electron microscopic evaluation. Both dogs developed clinical signs of disease at about 1 year of age. Vision and motor function deteriorated over several months; by 2 years of age, the dogs were blind and had progressive ataxia. Cytoplasmic inclusions with ultrastructural patterns characteristic of ceroid lipofuscin were observed in most neurons examined and in the cells of several other parenchymatous tissues. Biochemical studies, including determination of lysosomal enzyme activities, excluded several other lysosomal storage diseases. In these dogs, the clinical and pathologic features of the disease were similar to those of the juvenile subtype of ceroid lipofuscinosis (Batten disease) in human beings.

Congenital portacaval shunts in two cats: diagnosis and surgical correction.

Congenital portacaval shunts causing signs of hepatic encephalopathy were diagnosed and surgically corrected in 2 cats. A tentative diagnosis of portacaval shunt in each case was based on history, results of physical examination, and a high venous ammonia concentration. A definitive diagnosis was established by mesenteric portography and by direct visualization of the shunt vessel during surgery.

Muscular dystrophy in a litter of golden retriever dogs.

Clinicopathologic findings from two golden retriever dogs with an inherited, progressive, degenerative muscle disease that were studied until 27 and 40 months of age are described. Initial clinical signs included stilted gait and simultaneous advancement of their pelvic limbs. Further gait restriction and muscle hypertrophy eventually occurred. Serum creatine kinase was dramatically elevated (greater than 10,000 U/L). There were persistent "spontaneous" high-frequency discharges (pseudomyotonia) on electromyographic evaluation. Features of both muscle fiber degeneration (hyaline fibers, myophagocytosis) and regeneration (small basophilic fibers) were seen on light microscopy. Similar ultrastructural changes (fiber hypercontraction, increased myoblasts) were present. On morphometric histochemical evaluation, mean fiber diameter of both type 1 and 2 fibers was increased compared with controls in two of three muscles examined. There was no apparent fiber type predominance. Scattered ragged red fibers were seen, but this appeared to be a nonspecific finding of either muscle fiber regeneration or degeneration. These findings and potential contributing pathophysiologic mechanisms are discussed in relation to Duchenne muscular dystrophy.

Distal sensorimotor polyneuropathy in mature Rottweiler dogs.

A polyneuropathy recognized in mature Rottweiler dogs is characterized by paraparesis that progresses to tetraparesis, spinal hyporeflexia and hypotonia, and appendicular muscle atrophy. Although signs may appear acutely, the course tends to be gradually progressive (up to 12 months or longer in some dogs) and may be relapsing. Nerve and muscle biopsies were examined from eight affected Rottweilers (six male and two female) between ages 1.5 and 4 years. Pronounced neurogenic atrophy was present in skeletal muscle samples. Changes in sensory and motor peripheral nerves included loss of myelinated nerve fibers, axonal necrosis, and variable numbers of fibers with inappropriately thin myelin sheaths. Ultrastructural findings included myelinated fibers showing myelinoaxonal necrosis, demyelinated fibers often associated with macrophage infiltration, many axons with myelin-like membranous profiles, increased endoneurial collagen, occasional axonal atrophy, and numerous Büngner bands. Lesions in unmyelinated fibers included increased numbers of Schwann cell profiles and loss of axons in Schwann cell subunits. Morphologic and morphometric studies indicated preferential loss of medium (5.5-8 microns) and large (8.5-12.5 microns) fibers, which was more severe in distal parts of nerves than in more proximal regions and nerve roots. The cause was not determined; however, histopathologic studies suggest this condition is a dying-back distal sensorimotor polyneuropathy that has morphologic and morphometric similarities to hereditary motor and sensory neuropathy (HMSN) type II in humans.

Use of whole body hyperthermia as a method to heat inaccessible tumours uniformly: a phase III trial in canine brain masses.

In this study, whole body hyperthermia (WBH) was assessed as a means of heating intracranial tumours uniformly. Twenty-five dogs received radiation therapy and 20 the combination of radiation and WBH. Total radiation dose was randomly assigned and was either 44, 48, 52, 56 or 60 Gy. Because of WBH toxicity, intercurrent disease or tumour progression, seven of the 45 dogs received less than the prescribed radiation dose. For WBH, the target rectal temperature was 42 degrees C for 2h and three treatments were planned. In five of the 20 dogs randomized to receive WBH, only one WBH treatment was given because of toxicity. WBH toxicity was severe in six dogs, and resulted in death or interruption in treatment. Most tumours did not undergo a complete response, making it impossible to differentiate tumour recurrence from brain necrosis as a cause of progressive neuropathy. Therefore, survival was the major study endpoint. There was no survival difference between groups. One-year survival probability (95% CI) for dogs receiving radiation therapy alone was 0.44 (0.25, 0.63) versus 0.40 (0.19, 0.63) for dogs receiving radiation and WBH. There was no difference in the incidence of brain necrosis in the two treatment groups. Results suggest that use of WBH alone to increase the temperature of intracranial tumours as a means to improve radiation therapy outcome is not a successful strategy.