A. S. Blunden

Transmission of Equine Influenza Virus to English Foxhounds

We retrospectively demonstrated that an outbreak of severe respiratory disease in a pack of English foxhounds in the United Kingdom in September 2002 was caused by an equine influenza A virus (H3N8). We also demonstrated that canine respiratory tissue possesses the relevant receptors for infection with equine influenza virus.

Dynamics of Influenza Virus Infection and Pathology

ABSTRACT A key question in pandemic influenza is the relative roles of innate immunity and target cell depletion in limiting primary infection and modulating pathology. Here, we model these interactions using detailed data from equine influenza virus infection, combining viral and immune (type I interferon) kinetics with estimates of cell depletion. The resulting dynamics indicate a powerful role for innate immunity in controlling the rapid peak in virus shedding. As a corollary, cells are much less depleted than suggested by a model of human influenza based only on virus-shedding data. We then explore how differences in the influence of viral proteins on interferon kinetics can account for the observed spectrum of virus shedding, immune response, and influenza pathology. In particular, induction of high levels of interferon (“cytokine storms”), coupled with evasion of its effects, could lead to severe pathology, as hypothesized for some fatal cases of influenza.

Relationships between the histological grade of cutaneous mast cell tumours in dogs, their survival and the efficacy of surgical resection

The histological grade of 340 cutaneous mast cell tumours derived from 280 dogs was determined by an established histological grading system; 87 of the tumours (26 per cent) were well differentiated, 199 (59 per cent) were intermediately differentiated and 54 (16 per cent) were poorly differentiated. The one-year survival rates for the dogs with tumours of these three grades were significantly different (P=0-0001), being 100 per cent, 92 per cent and 46 per cent, respectively. The median survival time for the dogs with poorly differentiated tumours was 278 days, significantly shorter than that for the dogs with either intermediately or well-differentiated tumours, which were both over 1300 days. Regrowth of the tumours was identified in 10 (19 per cent) of the dogs with poorly differentiated tumours, 12 (6 per cent) of the dogs with intermediately differentiated tumours and one of the dogs with well-differentiated tumours; only three of the tumours which regrew had initially had complete margins. The results suggest that wide surgical margins are not a prerequisite for a successful long-term outcome in dogs with well-differentiated cutaneous mast cell tumours.

A survey of equine abortion, stillbirth and neonatal death in the UK from 1988 to 1997.

REASONS FOR PERFORMING STUDY A detailed review of laboratory records for equine abortion is fundamental in establishing current disease trends and suggesting problems important for further research. OBJECTIVES To review the causes of abortion and neonatal death in equine diagnostic submissions to the Animal Health Trust over a 10 year period. METHODS The diagnoses in 1252 equine fetuses and neonatal foals were reviewed and analysed into categories. RESULTS Problems associated with the umbilical cord, comprising umbilical cord torsion and the long cord/cervical pole ischaemia disorder, were the most common diagnoses (38.8%: 35.7% umbilical cord torsion and 3.1% long cord/cervical pole ischaemia disorder). Other noninfective causes of abortion or neonatal death included twinning (6.0%), intrapartum stillbirth (13.7%) and placentitis, associated with infection (9.8%). E. coli and Streptococcus zooepidemicus were the most common bacteria isolated. Neonatal infections not associated with placentitis accounted for 3.2% of incidents; and infections with EHV-1 or EHV-4 for 6.5%. CONCLUSIONS Definitive diagnosis of equine abortion is possible in the majority of cases where the whole fetus and placenta are submitted for examination. POTENTIAL RELEVANCE Given the high incidence of umbilical cord torsion and related problems as causes of abortion in UK broodmares, more research on factors determining umbilical cord length and risk of torsion is essential.

Effects of stage and number of tumours on prognosis of dogs with cutaneous mast cell tumours

Between 1997 and 1999, 280 dogs with mast cell tumours were identified, of which 59 (21 per cent) had multiple tumours. Follow-up data for survival analysis were available for 145 dogs with single tumours and 50 dogs with multiple tumours. There was no significant difference between the survival times of the two groups; the survival rates after 12 and 24 months were 88 per cent and 83 per cent, respectively, for the dogs with single tumours, and 86 per cent at both intervals for the dogs with multiple tumours. Eight of the dogs with single tumours had lymph node metastases (stage II disease) and these dogs had a median survival time of 431 days, whereas the 50 dogs with multiple tumours (classified as stage III disease) and the dogs with single tumours (classified as stage I disease) had not reached their median survival times. Golden retrievers appeared to be predisposed to developing multiple tumours in the population studied, with an odds ratio of 3·8. This study found no evidence that dogs with multiple tumours had different survival times than those with single tumours, although there was evidence that the presence of lymph node metastasis generally carried a poorer prognosis.

Association of Ki67 index with prognosis for intermediate-grade canine cutaneous mast cell tumours.

Intermediate-grade mast cell tumours (MCT) represent a heterogeneous population of tumours. The prognosis for the majority of dogs is excellent following surgical excision, but a minority die because of their disease. A previous study identified Ki67 expression as a predictor of prognosis in all three grades of MCT. The purpose of this study was to validate those results in a new group of dogs, with intermediate-grade MCT only. Ki67 immunohistochemistry was performed on intermediate-grade MCT from 163 dogs with known outcome. Digital microscopy images were taken from each tumour, and an index calculated of Ki67-positive cells. Ki67 index as a binary variable with a cut-off value of 1.8% was confirmed to be associated with prognosis (hazard ratio = 19.1, P < 0.0001) for this cohort of dogs. The 1-year, 2-year and 3-year survival probabilities (with standard errors) of 127 dogs with a Ki67 index <or=1.8% were [0.95 (0.024), similar for all] and for 36 dogs with a Ki67 index >1.8% were 0.54 (0.100), 0.45 (0.101) and 0.33 (0.104), respectively.

Palliative intracavitary carboplatin therapy in a cat with suspected pleural mesothelioma

A 12-year-old neutered male oriental shorthair cat was referred to the Animal Health Trust for investigation of pleural effusion. Ultrasonography revealed marked irregular thickening of the pleural surface of the cranial and caudal mediastinum. Cytological examination of the pleural fluid and fine needle aspirates of the thickened pleura suggested a diagnosis of mesothelioma. Following complete drainage of the thoracic cavity under ultrasound guidance, 180 mg/m2 carboplatin diluted in 60 ml sterile water was infused into the pleural space (30 ml in each hemithorax). This resulted in complete resolution of clinical signs for 34 days (having required thoracocentesis on four occasions in the preceding 4 weeks). The procedure was repeated using 200 mg/m2 carboplatin, and there was a further 20-day period where the cat was free of clinical signs. Further treatment was declined and the cat was euthanased 120 days after initial presentation. This is the first report of successful palliative chemotherapy for suspected feline mesothelioma and suggests that intracavitary carboplatin could be considered in tumours affecting the pleural cavity.

Replication of equid herpesvirus 4 in endothelial cells and synovia of a field case of viral pneumonia and synovitis in a foal

Equid herpesvirus 4 (EHV-4) infection was diagnosed as the cause of interstitial pneumonia in a 6-week-old conventionally reared Welsh pony foal, by cocultivation and immunolabelling with specific monoclonal antibodies, EHV-4 specific amplification of viral DNA, and immunohistological examination of infected tissues. The case was novel in that replication of the EHV-4 isolate in endothelial cells and in the synovial epithelium was a feature. Restriction digests of this isolate were compared with those of seven respiratory and one abortigenic EHV-4 isolate, and no differences in restriction pattern were evident. The implications of these findings for the pathogenesis of EHV-4 infection are discussed.

Systemic infection by equid herpesvirus-1 in a Grevy's zebra stallion (Equus grevyi) with particular reference to genital pathology.

A severe multi-systemic form of equid herpesvirus-1 infection is described in an adult zebra stallion. There was multifocal necrotizing rhinitis, marked hydrothorax and pulmonary oedema, with viral antigen expression in degenerating epithelial cells, local endothelial cells and intravascular leucocytes of the nasal mucosa and lung. Specific localization of EHV-1 infection was seen in the testes and epididymides, including infection of Leydig cells and germinal epithelium, which would have facilitated venereal shedding of virus in life. The case provided a unique opportunity to study hitherto undescribed aspects of the pathogenesis of naturally occurring EHV-1 infection in the male equine genital tract. Restriction digests of the isolate demonstrated a pattern similar to that of EHV-1 isolates previously recovered from aborted zebra and onager fetuses.

Eosinophilic fibrosing gastritis and toxoplasmosis in a cat

A 3-year-old, neutered male Tiffany cat was presented to the Animal Health Trust for investigation of pyrexia and a gastric lesion. Radiography and ultrasound showed severe thickening of the gastric wall and regional lymphadenopathy. There was altered gastric wall layering, predominately due to muscularis thickening. Histopathology confirmed eosinophilic fibrosing gastritis. The cat also had evidence of generalised Toxoplasma gondii infection, which may have been responsible for the gastric changes.