GRANULOMATOUS AND NEOPLASTIC DISEASES OF THE SKIN OF HORSES

Lesions encountered in a clinicopathological study of cutaneous lesions resembling 'swamp cancer' from horses in North Queensland included 37 cases of subcutaneous phycomycosis, 5 of which were also infected with Habronema sp larvae. In addition 9 cases of primary cutaneous habronemiasis, 58 sarcoids, 12 fibromas, 8 fibrosarcomas, 10 squamous cell carcinomas, 4 haemangiomas, 3 melanomas, 1 papilloma, 1 palpebral adenocarcinoma and 7 cases of simple granulation were diagnosed. Subcutaneous phycomycosis resulted in the most extensive lesions. These were rapidly growing and provided the poorest prognosis of all conditions studied. The incidence of phycomycosis in north Queensland was high in comparison to more temperate areas and appeared to be related to the wetter seasons. Young horses were more commonly affected. A fungus isolated from 3 phycomycotic lesions was tentatively identified as Hyphomyces destruens as no sporulation was observed.     

An Archean Geomagnetic Reversal in the Kaap Valley Pluton, South Africa

The Kaap Valley pluton in South Africa is a tonalite intrusion associated with the Archean Barberton Greenstone Belt. Antipodal paleomagnetic directions determined from the central and marginal parts of the pluton record a geomagnetic reversal that occurred as the pluton cooled. The age of the reversal is constrained by an 40Ar/39Ar plateau age from hornblende at 3214 +/- 4 million years, making it the oldest known reversal. The data presented here suggest that Earth has had a reversing, perhaps dipolar, magnetic field since at least 3.2 billion years ago.     

Polymerase chain reaction and other laboratory techniques in the diagnosis of long incubation rabies in Australia

SUMMARY Blood and post-mortem tissues from a 10-years-old girl were submitted to the Australian Animal Health Laboratory. Clinical signs and histopathological lesions had suggested a diagnosis of rabies, but, an unusually long incubation period of at least 5 years did not encourage such a diagnosis. Serological examinations by the rapid fluorescent focus inhibition test revealed a dramatic increase in rabies virus-neutralising antibody during the 10-day period of hospitalisation. The results of a fluorescent antibody test on brain smears, and an immunoperoxidase test on formalin-fixed sections of brain were also consistent with a diagnosis of rabies. Attempts to isolate virus were unsuccessful. Polymerase chain reactions (PCRs) were conducted on a 10% suspension of a post-mortem sample from the patient's brain, using primers based on the published sequence of the Pasteur virus strain of rabies virus. 413 and 513 bp fragments from the nucleoprotein gene and a 403 bp fragment from the glycoprotein gene were amplified. Subsequent sequencing of these fragments, and comparison with equivalent regions of known rabies viruses, confirmed that the fragments originated from a virus belonging to the rabies virus serotype. This case demonstrated the advantage of using a range of laboratory techniques to obtain a definitive diagnosis. In particular, a PCR-based test may allow a diagnosis, even in the face of conditions that preclude virus isolation such as apparently occurred in this case. Finally, this case demonstrated that an unusually long incubation period should not discourage a tentative clinical diagnosis of rabies.     

Immunoglobulin containing cells in normal and inflamed accessory sex glands of bulls

The peroxidase-antiperoxidase (PAP) technique was used to identify cytoplasmic immunoglobulins in the accessory sex glands of 15 normal bulls and 13 bulls with inflammation of the ASG. Immunoglobulin containing cells (ICC) of the types IgA, IgM, total IgG, IgG1 and IgG2 were measured and their percentages expressed. In accessory sex glands from normal bulls, IgA containing cells were the most frequent in prostate and bulbourethral glands (86.7% and 86.1%, respectively of all ICC present) whereas in the ampulla, IgG containing cells comprised 78.6% of the ICC. IgG1 and IgG2 containing cells were present in all the accessory sex glands in approximately equal numbers. Frequencies of IgM containing cells in the ampulla, prostate and bulbourethral glands were 6.3%, 4.0% and 3.7%, respectively. Although all isotypes of ICC were present in the seminal vesicle, the very low number precluded accurate quantification. In inflamed ampulla, seminal vesicle, bulbourethral gland and colliculus seminalis, IgG containing cells were the most frequent ICC with values of 66.2%, 83.0%, 69.0% and 53.5%, respectively; IgA containing cells were the second in prevalence with values of 21.5%, 10.3% 19.3% and 40.5%, respectively. The contribution of ICC to the locally protective immunoglobulins in accessory sex gland secretions is discussed.