Oligodendroglial vacuolar degeneration in the bilateral motor cortices and astrocytosis in epileptic beagle dogs

We performed a pathologic examination of the brains of three dogs in an epileptic beagle colony. Histologically, all the cases had diffuse astrocytosis in the cerebral cortex and basal ganglia as well as the hippocampus, whereas they showed acute nerve cell change in the hippocampus and some other areas of the cerebrum. One of these animals showed laminar myelin pallor associated with the presence of many vacuoles in the IV to VI layers of the bilateral motor cortices. Most of the vacuoles contained fine granules stained with luxol-fast-blue stain. Ultrastructural examination revealed that some oligodendrocytes and perineuronal satellite oligodendrocytes in the bilateral cerebral motor cortices of the two affected dogs had many vacuoles surrounded by myelin-like lamellar structures. These findings suggest a possibility that astrocytosis in the cerebrum and vacuolar degeneration of oligodendrocytes in the cerebral motor cortex may be, at least in part, related to the occurrence or development of seizures.     

Study on the inductive factors of hypobiosis of Ostertagia ostertagi in cattle

Two experiments were carried out to determine the causes producing the Ostertagia ostertagi hypobiosis phenomenon in cattle. In the first experiment, the effect of time on third-stage larvae in the environment was studied during a 2-year period. Three experimental paddocks contaminated with O. ostertagi eggs at different times of the year were used, and the levels of hypobiosis were recorded by using 'indicator' and 'tracer' calves. The results suggest that time as such is not a hypobiosis-inductive factor. The second experiment was conducted under laboratory conditions, where the effects of temperature and light on infective larvae were studied. Infective larvae were subjected to different conditions of temperature and light during 6 weeks, and then inoculated to parasite-naive calves, which were slaughtered after 4 weeks. Percentages of hypobiotic larvae in these calves varied from 3.5 to 94.8%, depending on the different storage conditions the larvae underwent before inoculation. Results suggest that increasing temperature and increasing time of light exposure simulating spring conditions would be the factors which act upon third-stage larvae inducing them to a later hypobiotic stage in the host.     

Pulsed-field gel electrophoresis and distribution of the genes zag and fnz in isolates of Streptococcus equi

Streptococcus equi subsp. equi and subsp. zooepidemicus are important pathogens of the equine respiratory tract. Isolates of both subspecies were examined by pulsed-field gel electrophoresis (PFGE). With the exception of eight isolates, a unique band pattern was displayed for each of the 48 subsp. zooepidemicus isolates tested. A method to distinguish isolates of the genetically very homogeneous subsp. equi has hitherto not been available, although several methods have been tested. By the use of PFGE, 50 isolates of subsp. equi could be divided into eleven groups, each with a unique pulsotype. In addition, the recently characterised genes encoding the cell-wall proteins ZAG and FNZ of S. equi subsp. zooepidemicus strain ZV were shown by Southern blots to be present in all 98 tested isolates, including the type strains of the two subspecies. Binding assays showed that the expression of the two genes clearly differentiate between the two subspecies.     

Metabolic changes concerning the effect of castration on some blood constituents in male rabbits

This experiment was conducted to determine the effects of castration on some metabolic alterations concerning proteins, lipids and minerals metabolism in both immature and mature rabbits. Twenty male New Zealand White rabbits (10 immature and 10 mature) were used. Blood samples were collected from the immature and mature intact animals (control non castrated). Moreover, the castrated animal groups (immature and mature) were sampled at 2, 4, 6 and 8 weeks after castration. The obtained results revealed that, castration caused a significant decrease in serum total protein, albumin, alpha 1-globulins and alpha 2-globulins concentrations. Meanwhile, gamma-globulins level was decreased temporarily at 2 weeks after castration in mature rabbits. beta-globulins level revealed non significant decrease at 2 weeks after castration in immature rabbits followed by a non significant increase. In mature rabbits beta-globulins level non significantly increased. A significant decrease in serum total nucleic acid concentrations was observed after castration throughout the experimental periods, whereas the value of serum uric acid level markedly increased after castration. Serum lipids concentrations (total lipids, total cholesterol, phospholipids and non esterified fatty acids) were increased after castration. The value of serum trace elements including copper, iron, zinc and manganese concentrations showed a significant decrease after castration. The decrease in serum copper and zinc levels were markedly observed in mature castrated rabbits. Also, serum sodium and potassium concentrations were decreased after castration. Testosterone propionate administration in mature castrated rabbits restored most of the investigated serum blood parameters to the levels of intact non castrated mature rabbit. It could be concluded that castration (deficiency of testosterone) induced marked decrease in protein synthesis and increased protein degradation, but serum lipids markedly elevated after castration in both immature and mature animals. Also, castration caused a marked decrease in some serum minerals and trace elements.     

Model field study of Sumithion 50 EC and Fusilade S on pheasants.

Toxicological studies on wild animals play an important role in the ecotoxicological examination of pesticides. The applied model tests enable the assessment of toxicological consequences with particular regard to the life and nutrition of wild animals in the ploughed field among plants treated with pesticides. The application of different pesticide formulations on plough-land may pose a simultaneous chemical burden to wild birds. In this model study, manifestations of the interaction between an insecticide and a herbicide were studied in pheasants. The birds were placed on lucerne in cages (48 m2) and sprayed once. The applied doses were: Sumithion 50 EC 1 litre/ha + Fusilade S 6 litres/ha (practical doses) and Sumithion 50 EC 5 litres/ha + Fusilade S 30 litres/ha. The analytically determined pesticide concentration of the lucerne was taken as a basis in the further treatment of fodder. The fodder of pheasants contained the following chemicals: 85 mg/kg Sumithion 50 EC + 510 mg/kg Fusilade S and 425 mg/kg Sumithion 50 EC + 2250 mg/kg Fusilade S. Sporadic deaths observed among the pheasants were of traumatic origin and not due to a toxic effect. The decrease of body weight was significant only at the higher dose levels. Acetylcholinesterase (AChE) activity of the blood decreased significantly in both dose groups. On the basis of the results obtained it can be established that at the dose level used in the practice the pesticides studied do not give rise to a toxic interaction in pheasants.     

Nematophagous fungi in fresh feces of cattle in the Mata region of Minas Gerais state, Brazil.

The capacity to survive gut passage is one of the desirable characteristics for nematophagous fungi to be considered potential biological control agents of gastrointestinal nematodes of livestock. From April 1995 to April 1996, a pool of 10 cow fecal samples and 10 individual samples of feces from heifers, which were raised under partial (cows) or total (heifers) confinement in the Mata Region of Minas Gerais State, Brazil, were examined monthly for the presence of nematophagous fungi. A total of 10 isolates was found in the survey. Eight isolates were recovered from the pooled samples of cow feces and two from the individual samples of heifers. Fungi were present in the cow feces during the dry months of August (two isolates of Arthrobotrys oligospora and one Monacrosporium eudermatum) and September (one isolate of Harposporium lilliputanum and one of M. gephyropagum). Fungi were also recovered at the beginning and middle of the rainy season: one isolate of A. musiformis in October, and one isolate of M. gampsosporum and one unidentified fungus which produced septate hyphae and adhesive buds in December. In the individual samples collected from heifers, fungi were present only in the months of September (end of dry season) and March (end of rainy season). One isolate each of H. lilliputanum and A. oligospora were found, respectively. Additional studies to further characterize these isolates should be encouraged.     

Cervical Myelopathy Associated with Extradural Synovial Cysts in 4 Dogs

Three Mastiffs and 1 Great Dane were presented to the University of Wisconsin Veterinary Medical Teaching Hospital for cervical myelopathy based on history and neurologic examination. All dogs were males and had progressive ataxia and tetraparesis. Degenerative arthritis of the articular facet joints was noted on survey spinal radiographs. Myelography disclosed lateral axial compression of the cervical spinal cord medial to the articular facets. Extradural compressive cystic structures adjacent to articular facets were identified on magnetic resonance imaging (1 dog). High protein concentration was the most important finding on cerebrospinal fluid analysis. Dorsal laminectomies were performed in all dogs for spinal cord decompression and cyst removal. Findings on cytologic examination of the cystic fluid were consistent with synovial fluid, and histopathologic results supported the diagnosis of synovial cysts. All dogs are ambulatory and 3 are asymptomatic after surgery with a follow-up time ranging from 1 to 8 months. This is the 1st report of extradural synovial cysts in dogs, and synovial cysts should be a differential diagnosis for young giant breed dogs with cervical myelopathy.     

Intravenous regional anesthesia (Bier block) in a dog.

Intravenous regional anesthesia was used in an adult dog as part of a balanced approach to general anesthesia for amputation of the 4th digit of its right hind limb. It allowed the concentration of isoflurane to be reduced to 0.5%.     

Organ culture of chicken bursa as a model to study the pathogenicity of infectious bursal disease virus isolates.

In vitro study with chicken bursal organ culture was attempted to assess the pathogenicity of locally isolated infectious bursal disease virus (IBDV) initially isolated from the bursa of naturally infected birds. In bursal organ culture, lymphoblastic transformation was noticed as early as 24 hr postinoculation and reached maximum at 72 hr postinoculation. The other microscopic changes were increased number of macrophages and formation of plasma cells. The IBDV antigen was detected 24 hr onward by coagglutination test with antibody coated Staphylococcus aureus strain Cowan I. On the basis of lesion score, the three isolates of IBDV (A, B, and C) were graded as virulent (B isolate) and moderately virulent (A and C isolates). A similar pattern of pathogenicity was also observed in the in vivo pathogenicity studies in chicken based on bursa: body weight ratio and histopathologic lesion score. The bursal organ culture thus provides a useful experimental model to differentiate the IBDV isolates on the basis of their virulence.     

Pulsed Doppler assessment of left ventricular diastolic function in normal and cardiomyopathic cats.

Left ventricular (LV) diastolic function was evaluated in 16 cats with primary hypertrophic cardiomyopathy (HCM) using pulsed Doppler (PD) assessment of transmitral flow and isovolumic relaxation time. Data obtained was compared to data from 12 healthy, adult, research cats. Compared to normal cats, the HCM group showed significantly (p value less than 0.05) reduced early LV inflow velocities (mean +/- standard error [SE], peak velocity of 0.70+/-0.04 m/s versus 0.54+/-0.04 m/s and integrated velocity of 0.48+/-0.08 m/s versus 0.37+/-0.03 m/s); a reduced rate of deceleration of early inflow (mean+/-SE, -12.0+/-1.0 m/s2 versus -5.1+/-1.1 m/s2); prolonged isovolumic relaxation time (mean +/- SE, 45.7+/-3.3 ms versus 76.0+/-3.1 ms); and increased atrial systolic flow velocities (mean +/- SE, peak velocity of 0.29+/-0.04 m/s versus 0.48+/-0.04 m/s and integrated velocity of 0.21+/-0.03 m/s versus 0.34+/-0.03 m/s). The results suggest that PD provides a noninvasive method of identifying and quantifying functional diastolic impairment in cats with HCM.