Morphology and morphogenesis of hereditary microphthalmia in Texel sheep.

The study presents a morphological description of inherited microphthalmia in Texel sheep and the morphogenesis of the lesion during embryonal development. The eyes of 28 newborn and young lambs with microphthalmia were examined morphologically. Blind rams with microphthalmia were crossed with ewes known to be carriers of the "microphthalmia factor", to obtain embryos of different age with and without microphthalmia for morphogenesis studies. The microphthalmic eyes showed an anteriorly located conus-shaped mass composed of connective tissue with cartilage, smooth muscle and fat tissue, particularly in the posterior part of the conus, and often islets of lacrimal glands and cystic structures lined with squamous epithelium in the anterior part. The iris, ciliary body and ciliary processes were incorporated in the periphery of the broad base of the conus. The conus was covered by a detached and folded but normally developed retina. The morphogenetic study showed an abnormal development of the lens vesicle. In embryos aged 24 days, the lens consisted of a solid unorganized proliferation of epithelial cells without formation of a lens capsule. An extensive overgrowth of primitive mesenchymal tissue followed, with infiltration and disintegration of the lens. In a later stage (45 days) a conus-shaped mass was seen in the anterior part of the eyes, which at 56 days consisted of mesenchymal tissue with focal differentiation to cartilage and epithelial structures in the anterior part of the conus. The primary event proved to be abnormal development of the lens vesicle, with disintegration of the lens and subsequent overgrowth of mesenchymal tissue. The mesenchymal tissue later differentiated in various directions, whereas the epithelial structures found in the microphthalmic eyes at days 56 and 132 and in the newborn lambs seemed to be remnants of the epithelial lens vesicle.

Canine balloon and signet-ring cell melanomas: a histological and immunohistochemical characterization.

Seven tumours that were composed of balloon (n=4) or signet-ring (n=3) cells were investigated for a putative melanocytic origin. The tumours were located in the skin or the mouth cavity. In one case a sample from inguinal lymph node metastasis was available. Two antibodies used in man for the immunohistochemical diagnosis of melanomas, namely anti-Melan-A and anti-tyrosinase, were examined for their cross-reactivity with the corresponding canine antigens. The Melan-A antibody labelled all balloon cell tumours and one signet-ring cell tumour, whereas the anti-tyrosinase antibody was not reactive in any of the tumours. The Melan-A antibody also labelled a variety of canine epithelioid and spindle cell melanomas; non-melanocytic tumours were all negative. This study confirmed the occurrence of balloon and signet-ring cell melanomas in dogs. Melan-A antibody was found to be useful in the diagnosis of pigmented and non-pigmented canine melanomas.

Feline nasal and paranasal sinus tumours: clinicopathological study, histomorphological description and diagnostic immunohistochemistry of 123 cases.

Histological examination was performed in 123 cats with primary nasal and paranasal sinus tumours; 117 had undergone surgical biopsy and six necropsy. Special stains and immunohistochemistry were performed on poorly differentiated cases. Ninety-two percent (113/123) of the tumours were malignant. There was an increased risk for old cats (mean age of 10.9 years), and a male predilection (59% males). Clinical signs and breeds varied with the histological type of tumour. Thirty-nine percent (48/123) of the cases presented with nasal discharge, 21% (26/123) with dyspnea, 20% (24/123) with facial swelling, and 15% (19/123) with epistaxis. Forty-three percent (53/123) of the tumours were of epithelial origin. Adenocarcinomas (18/53) and squamous cell carcinomas (17/53) were the most common epithelial tumours. Fifty percent (26/53) of the epithelial tumours originated from the pseudo-stratified respiratory epithelium of the nasal cavity, 28% (15/53) from the stratified squamous epithelium of the vestibule, 9% (5/53) from olfactory epithelium, 9% (5/53) from submucosal glands and 4% (2/53) from minor salivary glands. Malignant lymphoma (35/123) was the most common tumour. Seventy-one percent (25/35) of the malignant lymphomas were B-cell tumours and 29% (10/35) were T-cell tumours. Six cases of malignant lymphomas were proved to be epitheliotropic T-cell lymphomas. This is the first report of a primary nasal epitheliotropic T-cell lymphoma in cats.

Primary and metastatic carcinomas in the digits of cats.

In the period 1993-1998, digital carcinomas in 64 cats were examined. In all animals primary complaints were painful digit(s). Eight cats had a primary squamous cell carcinoma which involved one digit or two adjacent digits of one leg. Fifty-six cats had metastases of a pulmonary carcinoma in the digits, and in general multiple digits of different legs were involved. In many of these cats metastases also occurred in other organs, including the skin and muscles. No primary sweat gland carcinomas of the digits were seen. Primary squamous cell carcinomas of the digits were characterized by cornification and the absence of PAS-positive cells, PAS-positive secretory material. Immunohistochemically, these neoplasms stained negative with the monoclonal antibody CAM 5.2 directed against Keratin 8 (K 8). The metastases of pulmonary carcinomas to the digits showed one or more of the following histological features: goblet cells, ciliated epithelial cells, PAS-positive cells or lakes, and/or a PAS-positive lining of luminal membranes and no cornification. Immunohistochemically, they showed positive staining for CAM 5.2 (K8). Thoracic radiographs from three cats with a primary squamous cell carcinoma showed no abnormalities, whereas all cases of metastases from a pulmonary carcinoma to the digits available for follow-up showed evidence of a primary pulmonary carcinoma on radiography and/or postmortem examination (25 out of 56). The conclusion of this study was that most carcinomas in the digits of cats were metastases of a primary pulmonary carcinoma (87.5%). Primary squamous cell carcinomas occurred infrequently. The prognosis of metastases of a pulmonary carcinoma in the digits is poor with an average survival time of 4.9 weeks, in contrast to 29.5 weeks in cats with a squamous cell carcinoma. These data stress the importance of taking thoracic radiographs of cats with digital tumours before surgical intervention.

Familial amyloidosis in cats: Siamese and Abyssinian AA proteins differ in primary sequence and pattern of deposition.

Familial AA amyloidosis is a hereditary trait in Abyssinian cats, with the kidney as the main target organ. The amino acid sequence of the amyloid A protein of the Abyssinian cat has been described earlier. Recently, familial amyloidosis has been found in Siamese cats, with the liver as the main target organ. In the present paper, we describe the complete amino amid sequence of the major constituent protein, of two Siamese cats. Siamese hepatic protein AA showed homology with, but was different from all feline SAA and AA sequences hitherto reported. Two substitutions (46Q-R and 52A-V) from the Abyssinian protein sequence were identified, one of which (46Q-R) is a non-homologous substitution not found in mammalian SAA, but is present in two bird AA amyloid proteins. This shows the presence of an unique amyloidogenic SAA isotype in Siamese cats. Both the Siamese and the Abyssinian sequence are amyloidogenic, thus making identification of amyloidogenic residues difficult. Apart from the apparent inherent amyloidogenicity of SAA, it can not be excluded that certain amino acid substitutions could enhance its amyloidogenicity but also could contribute to tissue predilection in amyloidosis.

Salinomycin-induced polyneuropathy in cats: morphologic and epidemiologic data.

In April 1996, an outbreak of toxic polyneuropathy in cats occurred in the Netherlands. All cats had been fed one of two brands of dry cat food from one manufacturer. Chemical analyses of these foods, stomach contents, and liver and kidney of affected cats revealed contamination with the ionophor salinomycin. Epidemiologic and clinical data were collected from 823 cats, or about 1% of the cats at risk. In 21 affected cats, postmortem examination was performed. The affected cats had acute onset of lameness and paralysis of the hindlimbs followed by the forelimbs. Clinical and pathologic examination indicated a distal polyneuropathy involving both the sensory and motor nerves.

Lymphangiosarcomas in cats: a retrospective study of 12 cases.

Clinical, macroscopic, and histologic features of 12 lymphangiosarcomas in cats are described. Nine tumors were located in the subcutaneous tissue at the caudoventral abdominal wall (eight cats) or in the neck (one cat). The remaining three cats had lymphangiosarcomas around the cranial mesenteric artery (two cats) or precardial in the mediastinum (one cat). Macroscopically, the tumors were noncircumscribed, white, edematous, and intermixed with fat tissue. Histologic features varied from cleft-forming and cavernous growth to papilliform and solid patterns. Follow-up data were available for seven cats with subcutaneous lymphangiosarcomas. All these cats died or were euthanatized within 6 months after surgery because of poor wound healing, local recurrence, or distant metastases. The cats with abdominal or thoracic masses were either euthanatized at surgery or within 6 months after the first surgery because of recurrent chylothorax, chyloperitoneum, or distant metastases.

Polycystic kidney and liver disease in cats.

This paper reviews 27 cases of polycystic disease of the kidneys and/or liver in cats. The multiple cysts in the kidneys were rounded in all but one case, as described in adult polycystic kidney disease in humans. In 68% of the cats presented with polycystic kidneys, there were also cystic changes of the liver (uni- or multilocular cysts and/or congenital hepatic fibrosis (CHF)). In 1 cat polycystic changes of kidneys and liver were accompanied by cysts in the pancreas. In 5 cases there was severe pancreas fibrosis. Twenty-one of the 27 cats were Persian or Persian-crossbred.

Multiple endocrine neoplasias in a dog: corticotrophic tumour, bilateral adrenocortical tumours, and pheochromocytoma.

In a 10-year-old ovariohysterectomized standard Schnauzer, the finding of dexamethasone-resistant hypersecretion of cortisol, the results of computed tomography, and elevated plasma concentrations of ACTH suggested the presence of both adrenocortical tumour and pituitary-dependent hyperadrenocorticism. The dog made an uneventful recovery after bilateral adrenalectomy and remained in good health for 31/2 years with substitution for the induced hypoadrenocorticism. Then the enlarged pituitary caused neurological signs and eventually euthanasia was performed. The surgically excised right adrenal contained a well-circumscribed tumour of differentiated adrenocortical tissue and in the left adrenal there were two adrenocortical tumours and a pheochromocytoma. The unaffected parts of the adrenal cortices were well developed and without regressive transformation. At necropsy there were no metastatic lesions. The cells of the pituitary tumour were immunopositive for ACTH and had characteristics of malignancy. The present combination of corticotrophic tumour, adrenocortical tumours, and pheochromocytoma may be called 'multiple endocrine neoplasia' (MEN), but does not correspond to the inherited combinations of diseases known in humans as the MEN-1 and the MEN-2 syndromes. It is suggested that the co-existence of hyperadrenocorticism and pheochromocytoma may be related to the vascular supply of the adrenals. Some chromaffin cells of the adrenal medulla are directly exposed to cortical venous blood, and intra-adrenal cortisol is known to stimulate catecholamine synthesis and may promote adrenal medullary hyperplasia or neoplasia.

[Acute blindness due to trauma in a Welsh pony-colt]. / Acute blindheid ten gevolge van trauma bij een Welsh ponyveulen.

A healthy, 10-day-old Welsh A pony colt was totally blind 1 day after arrival at a studfarm. Both eyes appeared normal on external inspection. The young animal had been very distressed during the 40-km journey to the studfarm. Intravenous corticosteroids were administered for 2 days, but did not result in any observable improvement. The animal was euthanized at the owner's request. Both eyes with the optic nerves were removed for histological examination. Both optic nerves showed Wallerian degeneration, a well-known response of peripheral nerves to trauma. The foal, which was not tethered during transportation, probably sustained a blunt trauma in the trailer. This case highlights the importance of taking adequate measures to prevent young animals from sustaining blunt trauma during transport.

Primary hyperparathyroidism in two cats.

Primary hyperparathyroidism (PHP) is an infrequently diagnosed disorder in cats. In this report the signs and symptoms of two cats with hypercalcaemia due to PHP are described, together with diagnostic approach, results of treatment, and immunohistochemical findings. A 9-year-old and a 13-year-old neutered male domestic shorthair cat were presented with signs of lethargy, anorexia, and vomiting. Both cats had persistent hypercalcaemia and normo- to hypophosphataemia. Cytological examination of a fine-needle aspiration biopsy sample of a palpable cervical mass revealed groups of benign glandular-epithelial cells in one cat. In the other cat no cervical mass was palpable. In this cat plasma parathyroid hormone (PTH) levels were measured repeatedly and these values exceeded the maximum reference value on two occasions. Following exclusion of other causes of hypercalcaemia both cats were subjected to neck surgery and in both a solitary parathyroid adenoma was removed. The adenomas contained an abundance of PTH, as demonstrated by immunohistochemical techniques. Plasma calcium and phosphate concentrations returned to within, reference ranges postoperatively. Recovery was uncomplicated and there were no signs of recurrence on follow-up examinations.

Generalized AA-amyloidosis in Siamese and Oriental cats.

During a 7 year period (1987-1994), 194 Siamese cats including a colour variant designated Oriental cat, were presented for post-mortem examination. Twelve of these animals (6.2%) were diagnosed with amyloidosis. Major gross pathological findings included enlarged pale livers with haemorrhages, pale and swollen spleens, and dilated intestines. Deposits of amyloid were found in these tissues. The amyloid was found to cross-react with anti dog AA-antiserum when examined with peroxidase antiperoxidase (PAP) staining (four cases). Amyloid fibrils were purified by the water extraction method and its major constituting protein (AA) was isolated by gel filtration. Amino acid sequence analysis of this protein from a Siamese cat and an Abyssinian cat revealed a significant difference between these breeds. In the Siamese protein AA two amino acid substitutions (46 R for Q and 52 V for A) were encountered. This finding indicates the existence of a new feline amyloid A protein occurring in the Siamese breed which differs from presently known (apoS)AA-proteins. Additionally, the pedigree analysis of affected cats suggests a familial trait.

Cutaneous malignant melanomas in 57 cats: identification of (amelanotic) signet-ring and balloon cell types and verification of their origin by immunohistochemistry, electron microscopy, and in situ hybridization.

Cutaneous malignant melanomas in cats, both melanotic and amelanotic, were diagnosed in 57 of 1.530 skin tumors during the period 1991-1995. All melanomas occurred in domestic shorthaircats of ages 3-19 years (mean = 11.5 years). Postmortem examination was performed on 16 cats. All had metastases in the regional lymph node and several organ systems. The average time of survival after surgical removal of the tumor was 4.5 months. Histologically, five types of melanomas could be distinguished: epithelioid, spindle, mixed, signet-ring, and balloon cell. Whereas all epithelioid, spindle, and mixed epithelioid/spindle cell types showed pigmentation, signet-ring and balloon cell types were often amelanotic. Immunohistochemical examination of the melanomas revealed a positive staining for S-100, vimentin, and neuron-specific enolase. The melanomas were negative for muscle cell markers, except in some of the signet-ring cell melanomas; 13 of 21 tumors showed a weak positive staining for polyclonal desmin. Electron microscopic examination of signet-ring cell melanomas revealed an abundance of intermediate filaments, whereas in some of these tumors a few cells with melanosomes were found. Nonisotopic in situ hybridization for mRNA encoding for tyrosinase verified the melanocytic origin of the amelanotic signet-ring and balloon cell melanomas.

[Epidemic of nutritional polyneuropathy in the cat. Final report of the investigational team]. / Epidemie van alimentaire polyneuropathie bij de kat. Eindverslag onderzoeksteam.

In June 1996 companion animal practitioners received a report prepared by the Faculty Investigative Team on the outbreak of polyneuropathy among cats, and at the end of August a 'definitive' bulletin was circulated by Spillers Petfoods. The coccidiostatic drug salinomycin, which was present in the vitamin premix supplied by a third party, was considered the cause of the neuropathy. The investigative team is of the opinion that all veterinary practitioners in the Netherlands should receive a conclusive report about the epidemic because of the unique nature of the epidemic, which despite its sudden outbreak could be well documented, and because aspects of the affair merit the attention of veterinary practitioners.

[A case of oleander poisoning in a cat]. / Een geval van oleanderintoxicatie bij de kat.

This case history describes clinical symptoms and pathological changes in a cat that are consistent with those of oleander intoxication. The clinical symptoms were characterized by vomiting, diarrhoea, and ventricular extrasystoles. On post-mortem examination focal degeneration and necrosis of the myocardium was seen, as well as haemorrhage of myocardium and wall of the gastrointestinal tract. An overview is given of the literature on the diagnosis, pathogenesis, and treatment of oleander intoxication in different animals and in humans.