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| Clinicopathological Newsletter | October 2006 / issue 6 | |
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Testicular teratoma in a mouse (Mus muscularis) By: Ines Hoffmann, Veterinary Pathologist. A pet mouse was presented for a scrotal mass and subsequently euthanized. Histological examination showed a testicular tumour comprised of a variety of haphazardly arranged well differentiated tissues from several germ layers as well as morphologically undifferentiated tissue. The differentiated tissues include nervous tissue, striated muscle, cartilage and less well differentiated connective tissue. There are also tubular structures lined by ciliated respiratory epithelium and intestinal epithelium with goblet cells.  Figure 1. Low power overiew of lesion (obj x1, HE stain). Click to enlarge.
 Figure 2. High power view of an internal structure resembling a bronchus (obj x10, HE stain.) Click to enlarge.
 Figure 3. High power view of an internal structure resembling neural tissue(obj x40, HE stain.) Click to enlarge. Teratomas are uncommon tumours in domestic animals arising from pluri-potential stem cells which can differentiate into derivatives of all three germ layers (endoderm, mesoderm and ectoderm). Teratomas and their malignant counterpart, teratocarcinomas, typically arise in the testis or ovaries, although there have been reports of extragonadal tumours. Teratomas of the testicle occur more commonly in stallions, where they often occur in cryptorchid testes, but have been described in the dog, cat, bull, boar and mouse. Teratomas of the ovary have been described in most domestic animals, but are most common in the bitch. Extragonadal teratomas have been reported in the kidney of a llama, the adrenal glands of ferrets and the placenta of a mare. Reference: 1. Maclachlan N.J. and Kennedy P.C.. Tumours of the Genital System in:Meuten D.J. Tumours of Domestic Animals, 2002, Iowa State Press 2. Jagdish et al. Renal teratoma in a llama. Canadian Veterinary Journal, 2004, November 45(11):938 – 940 3. Williams B.H. . Adrenal Teratoma in Four domestic Ferrets, Veterinary Pathology 38, 328-331(2001) 4. Gurfield et al. Equine Placental Teratoma, Veterinary Pathology 40, 586-588 (2003) |
In this issue:
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JOURNAL Reviews(with e-links) Mammary carcinomas are the most common malignant tumours of female dogs, and have been very well recognised for decades. During this period of time there has been a steady stream of papers concerning prognostic factors in mammary tumours but this is testament to the fact that the prognosis of these tumours when they occur is often uncertain. The following are notes on the prognostic significance of various factors in the dogs in this study. The conclusion is that tumour stage, tumour size and ovariohysterectomy status were significant prognostic factors associated with survival 2 years after surgery in dogs of malignant mammary tumours. 2.DIFFERENTIATING BENIGN AND MALIGNANT CAUSES OF LYMPHOCYTOSIS IN FELINE BONE MARROW. Weiss DJ. J Vet Intern Med (2005);19:855-859 Link Judith Hargreaves MVB MRCVS MRCPath In this study, approximately 6% of bone marrow submissions showed an increased number of small lymphocytes and it can be very difficult to differentiate benign from malignant causes. Cats with chronic lymphocytic leukaemia tend to be older with lymphocytes that are slightly larger, often with cleaved or lobulated nuclei. Chronic lymphocytic leukaemia and thymoma gave a diffuse distribution of lymphocytes which were predominantly T-cells. Immune-mediated anaemias and inflammatory diseases were associated with reactive lymphocytosis and the cells were often organised into aggregates and predominantly B-cells. 3.ASSOCIATION BETWEEN OVARIHYSTERECTOMY AND FELINE MAMMARY CARCINOMAS. Overley B, Shofer FS, Goldschmidt MH, Sherer D, Sorenmo KU. J Vet Intern Med. 2005 Jul-Aug;19(4):560-3. Link Trevor Whitbread BSc. BVSc. MRCVS DipECVP There has been much discussion and debate over the years on incidence of mammary tumours in the bitch and their association with age at ovariohysterectomy and influence of hormones. There has not been a similar debate concerning development of mammary carcinoma in the cat. A recent paper in JVIM has shown that cats spayed prior to 6 months of age had a 91% reduction in the risk of mammary carcinoma compared with intact cats and those spayed prior to 1 year had an 86% reduction. Parity did not affect feline mammary carcinoma development and there were too few cats that had progestagen exposure in the survey to determine any association. |
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LATEST NEWS Canine influenza virus causes clinical disease that mimics kennel cough. As a result, infection with the virus is frequently mistaken for infections caused by the Bordetella bronchiseptica/parainfluenza virus complex. Clinical disease may be mild or severe. In the mild form, the most common clinical sign is a soft, moist cough that persists for 10 to 30 days. Many dogs have a purulent nasal discharge and a low-grade fever. The nasal discharge is usually caused by secondary bacterial infections. Some dogs are more severely affected with clinical signs of pneumonia, such as a high-grade fever (104ºF to 106ºF) and increased respiratory rate and effort. Pneumonia is often precipitated or complicated by a secondary bacterial infection. Morbidity associated with canine influenza is estimated at 80%; mortality in confirmed cases to date has ranged from 5 to 8%. Workers at the AHT in the UK undertook a retrospective analysis of an outbreak of unexplained respiratory disease in foxhounds in Essex UK, in September 2002. Antibodies to H3N8 virus were found in serum samples from hounds that recovered from infection during the 2002 outbreak. There are no current reports of similar outbreaks of fatal respiratory disease as reported in the USA. UK data suggests that equine influenza is not currently circulating in the UK pet dog population. It is not known whether the outbreak in the UK was introduced from the USA or whether this represents a separate / novel introduction of virus from horses to dogs. As dog-to-dog transmission has been established to occur in the USA, there is a possibility that the virus could now be introduced into the UK with influenza-infected dogs entering the UK under the Pet Passport Scheme.
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SIDE STORY A clinical report appearing in the Oct. Journal of the American Veterinary Medical Association (JAVMA) discusses the sometimes fatal conditions developed by dogs that have ingested xylitol. Xylitol, a sweetener found in many sugar-free chewing gums, sweets, baked goods and toothpastes, is a naturally occurring ingredient that may have far-reaching negative health effects on dogs. |
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