Clinical and histological features of primary progressive, familial thyroiditis in a colony of borzoi dogs

A six-year study of clinical data and the morphologic changes involved in lymphocytic thyroiditis in a colony of related borzoi dogs was conducted. Lesions observed included initial degenerative thyroidal parenchymal changes which progressed to subacute inflammation with subsequent fibrosis and end stage thyroid gland disease. This study encompasses three successive generations of this borzoi colony and documents the progression of the histologic changes from the initial thyroid gland degenerative lesions to the end stage parenchymal atrophy. Spontaneous, familial thyroiditis has not been reported previously in the borzoi breed.     

Untersuchungen zur Form der Schilddrüse (Glandula thyreoidea) beim Geflügel mit besonderer Berücksichtigung der jahreszeitlichen Schwankungen

The thyroid glands of 31 chickens at the age of 17 to 24 months were investigated. Different methods of anatomical preparation, casts of vessels and scanning electron microscopy were used. The thyroid gland of birds is a paired organ. It is located on the ventral surface of the base of the neck within the thoracic inlet. The left thyroid gland is placed more cranially than the right one. Each thyroid gland is closely connected to the common carotid artery on the medial side, from which it is supplied and to the jugular vein on the lateral side. It is a reddish-brown organ and of lenticular profile. The gland measures on average 10 mm in length, 6 mm in width and 2 mm in thickness, and is covered by a thin connective tissue capsule which holds adipose cells. It seems that each thyroid follicle is surrounded by a net of capillaries. The investigation by scanning electron microscopy proved that the follicles are oval with a pyramidal top on each end. The cuboidal epithelium cells leave impressions in the colloid. Epithelium cells carry microvilli on the follicle side surface. Described seasonal changes of the thyroid gland in size and activity were able to be confirmed by the examination of the organ in July and December. In winter the follicular cells were higher and the follicles had a greater volume.     

Perineuronal Nets in the Central Nervous System

The remnant of ultimobranchial (UB) body in the thyroid gland of adult buffalo was studied. This remnant appeared in the form of irregular and elongated follicles of various size and shape with folded lumen. These structures occupied a peripheral location beneath the capsule, as well as being embedded mostly in the vascular connective tissue of the thyroid. Calcitonin cells were predominantly localized in the UB follicles. Scanning electron microscopy revealed that surface of most UB follicular cells was almost flat and polyhedral or hexagonal in shape. Other follicles possessed cells with dome shaped apical surface demarcated by a shallow intercellular depression. The luminal surface of the follicular cell lining was studded with microvilli that appeared with various density and length and were numerous at the cellular borders. Interestingly, most of UB follicular cells were provided with single cilium, projecting over the cell surface. Notably some UB follicles presented various stages of apocrine activities.     

Surface Ultrastructure of Ultimobranchial Remnants in the Thyroid Gland of Buffalo (Bos bubalis)

The remnant of ultimobranchial (UB) body in the thyroid gland of adult buffalo was studied. This remnant appeared in the form of irregular and elongated follicles of various size and shape with folded lumen. These structures occupied a peripheral location beneath the capsule, as well as being embedded mostly in the vascular connective tissue of the thyroid. Calcitonin cells were predominantly localized in the UB follicles. Scanning electron microscopy revealed that surface of most UB follicular cells was almost flat and polyhedral or hexagonal in shape. Other follicles possessed cells with dome shaped apical surface demarcated by a shallow intercellular depression. The luminal surface of the follicular cell lining was studded with microvilli that appeared with various density and length and were numerous at the cellular borders. Interestingly, most of UB follicular cells were provided with single cilium, projecting over the cell surface. Notably some UB follicles presented various stages of apocrine activities.     

Passive hemagglutination for detection of autoantibodies against thyroglobulin in dogs

Primary hypothyroidism in dogs is mainly caused by autoimmune thyroiditis or idiopathic follicular atrophy of the thyroid gland (Gosselin et al. 1982). Serologically, autoimmune thyroiditis can be diagnosed by detection of autoantibodies against thyroid antigens in hypothyroid dogs (Mizejewski et al. 1971, Gosselin et al. 1980). Passive hemagglutination test (PHT) has been the serological test, most widly used for detection of antibodies (Mizejewski et al. 1971, Gosselin et al. 1982, Vollset & Larsen 1987).     

Quantitative morphologic study of the pituitary and thyroid glands of dogs administered L-thyroxine.

To determine the effects of long-term thyroxine treatment, histomorphometric analysis was performed on the pituitary and thyroid glands of healthy dogs, dogs treated for 9 weeks with a replacement dose of L-thyroxine, and dogs at 6 weeks after cessation of thyroxine treatment. In treated dogs, the volume density of thyrotropes decreased during thyroxine treatment and increased 6 weeks after cessation of treatment, compared with thyrotropes of healthy nontreated dogs. The activity of the thyroid gland was decreased in dogs during thyroxine treatment, as evidenced by decreases in epithelial volume density, epithelial height, and follicular area, and increase in colloid volume density, compared with thyroid gland activity in nontreated dogs. After cessation of thyroxine treatment, the thyroid gland had decreased colloid area, follicular area, and epithelial volume density, and increased interstitial volume density, compared with the thyroid gland of healthy nontreated dogs. Thyroxine treatment resulted in suppression of pituitary thyrotropes and thyroid follicular activity.     

Nodular thyroid hyperplasia in a cynomolgus monkey

Nodular thyroid hyperplasia was found in a 4-year-old male cynomolgus monkey (Macaca fascicularis). The monkey was clinically normal; however, necropsy revealed multiple variably sized nodules in both lobes of the thyroid gland. In contrast to the fairly uniform diameter of the lumen of follicles in the surrounding gland, the diameter of the follicular lumen within the hyperplastic nodules was highly variable and ranged from nonexistent to cystlike. Occasionally, in the larger follicles there were papillary infoldings of epithelium. The hyperplastic nodules were partially encapsulated by a fibrous capsule and showed little compression of the surrounding tissue. The follicular cells and colloid comprising the hyperplastic nodule were immunohistochemically positively stained with the antibody for thyroglobulin. Ultrastructurally, the cells forming follicles had numerous microvilli along the luminal surface, and lysosomal bodies and dilated rough endoplasmic reticulum in the cytoplasm. All these morphologic findings are consistent with nodular thyroid hyperplasia, which is rare in nonhuman primates.     

Light and electron microscopic study of the thyroid gland of the camel (Camelus dromedarius)

The thyroid gland of sexually immature dromedary camels was studied using both light and electron microscopy. The thyroid gland contained follicles of different sizes in both summer and winter. However, most of the follicles were large in summer and small in winter. The large follicles were lined by very low cuboidal or semi-squamous follicular cells whereas the small ones were lined by high cuboidal or low columnar follicular cells. Electron microscopy showed that the very low cuboidal follicular cells were poor in organelles and were considered hypoactive. High cuboidal follicular cells on the other hand, were rich in organelles that included mitochondria, cisternae of rough endoplasmic reticulum, secretory vesicles, colloid droplets, heterosomes and autophagic vacuoles; they were considered to be very active. The possible role played by these organelles is synthesis of thyroglobulin and liberation of tri- and tetraiodothyronine is discussed. A few degenerate follicular cells were infrequently encountered in the camel thyroid. Parafollicular (C) cells were not seen in this study either with light or electron microscopy.     

Immunohistochemistry of ultimobranchial thyroid carcinomas in seven slaughtered cows and one bull.

Eight thyroid gland epithelial tumors were found in 7 cows and 1 bull in a retrospective study of thyroid gland lesions in slaughtered cattle. All tumors were classified as ultimobranchial thyroid carcinomas based on morphology and immunohistochemistry. All tumors consisted of solid sheets and nests of polygonal to oval epithelial cells, with more sparsely dispersed colloid-filled follicles. Connective tissue separating nests of epithelial cells varied from delicate fibrovascular stroma to dense collagenous stroma. Fusiform epithelial cells with rare neural fibers and ganglion cells were present in 1 tumor. Cells within solid areas of these tumors were immunoreactive for calcitonin, calcitonin gene-related peptide, neuron-specific enolase, and synaptophysin. Colloid and follicle cells were immunoreactive for thyroglobulin. Few follicle cells also were reactive for calcitonin gene-related peptide. Neoplastic cells invaded the fibrous capsules in all 8 cattle. These tumors represented proliferation of a mixed population of undifferentiated cells, C cells, and thyroid follicular epithelial cells, presumably derived from the thyroid ultimobranchial bodies. These ultimobranchial carcinomas in slaughtered cattle are comparable to ultimobranchial tumors described in dairy bulls and the intermediate type of thyroid gland carcinomas (mixed thyroid medullary carcinomas) described in human beings.     

Spontaneous Adult-Onset Hypothyroidism in a Cat

Spontaneous adult-onset hypothyroidism, confirmed by a thyroid-stimulating hormone stimulation test, thyroid biopsy, and response to replacement therapy, is described in a female cat. Clinical signs consisted of profound apathy, hypothermia, poor hair growth, severe seborrhea sicca, and a puffy face. Cutaneous histological changes consisted of epidermal and follicular hyperkeratosis, teloginization of hairs, and dermal mucin deposition. There was no adnexal atrophy. Lymphocytic thyroiditis, equivalent to Hashimoto's thyroiditis, was shown by thyroid biopsy. Clinical signs rapidly responded to thyroxine replacement therapy. Glucose intolerance was coexistent with the hypothyroidism, but was not dramatically influenced by thyroxine therapy and probably was an independently occurring endocrinopathy. (Journal of Veterinary Internal Medicine 1993; 7:272–276. Copyright © 1993 by the American College of Veterinary Internal Medicine.)     

Experimental thyroid autoimmunity in the dog

Thyroid autoimmunity was induced in 6 crossbred dogs by a single injection of thyroid extract in complete Freund's adjuvant alone, or followed by reimmunization with thyroid extract and incomplete Freund's adjuvant or peanut oil. Total thyroxine levels, autoantibodies to thyroglobulin and thyroid microsomal antigen and thyroid histopathological changes were sequentially monitored for up to 150 days. All dogs developed fluxuating levels of thyroid autoantibodies detectable by enzyme-linked immunosorbent-assay (ELISA). Histopathological damage was observed in one or more thyroid gland biopsies in 4 of the dogs, in 3 cases the lesions were of lymphocytic thyroiditis, in the fourth dog the lesion was a granulomatous reaction. Histopathological thyroid damage was observed in biopsies taken during periods of maximal autoantibody titer. Fixed immunoglobulin was not demonstrable in thyroid gland biopsies by direct immunofluorescence. In 5 dogs total thyroxine levels fell to below the normal range at some period during the study. However in only one dog did this correlate with a time when biopsy findings revealed histopathological thyroid damage. High levels of thyroid autoantibody may indicate histopathological thyroid damage in dogs, however lower levels of thyroid antibody may be found without evidence of histological damage or alteration in thyroid function.     

Neuromuscular abnormalities associated with hypothyroidism and lymphocytic thyroiditis in three dogs

Various degrees of persistent or paroxysmal paresis involving only the hindlimbs or all four limbs were observed in 3 dogs with hypothyroidism and lymphocytic thyroiditis. Clinical features included lethargy, obesity, alopecia, insidious and progressive paresis, hypotonia, and slow segmental reflexes in 2 dogs. Obesity, alopecia, paroxysmal paresis, and behavior change were observed in the third dog. Laboratory tests indicated that thyroid function was less than normal in all 3 dogs. Abnormal electromyographic potentials and slow motor nerve conduction velocities were found in each dog. Muscle biopsy specimen abnormalities included selective type-II myofiber atrophy in all dogs, whereas one dog had angular atrophy of type-I and type-II myofibers indicative of denervation. A substance that stained with para-aminosalicylic acid was observed within vacuoles of type-I myofibers in one dog. Lymphocytic thyroiditis characterized by lymphocytic infiltration of excised thyroid glands was observed in all dogs.     

Intracardiac ectopic thyroid carcinosarcoma in a dog

A 13-year-old spayed female Labrador Retriever with a 1-year history of progressive exercise intolerance was diagnosed with an interventricular mass in the heart via echocardiogram. The animal's general condition progressively declined over the next 8 months, and it was euthanatized. The intracardiac mass, which protruded into the lumen of the right ventricle, was removed at necropsy and fixed in 10% buffered formalin. Histopathologic diagnosis was an ectopic thyroid carcinosarcoma based on the presence of 3 distinct neoplastic tissue types. Intermixed within the tumor were neoplastic thyroid follicles containing colloid and solid nests of thyroid follicular epithelial cells, vascular channels and clefts filled with blood and lined by neoplastic endothelium, and osteoid surrounded by spindle cells and often rimmed by large multinucleated cells. Immunohistochemical reaction for thyroglobulin was positive in the tumor cells forming the colloid-filled follicles and solid nests of epithelial cells. Neoplastic endothelium was positive for factor VIII-related antigen. The thyroid gland was located in its normal anatomic position and was histologically normal, ruling out the possibility that the intracardiac tumor was a metastatic lesion. To the authors' knowledge this is the first reported case of an intracardiac ectopic thyroid carcinosarcoma, and possibly the first ectopic thyroid carcinosarcoma in any location in any species.     

Thyroid follicular adenocarcinoma in a ferret

A 5-year-old male castrated ferret was presented to the Washington State University College of Veterinary Medicine for evaluation of progressive hair loss and a large, rapidly growing ventral neck mass. The patient had been diagnosed previously with an insulinoma, which was managed medically. Fine-needle aspirates of the neck mass were performed. The cytologic results were most consistent with epithelial neoplasia, likely a carcinoma; thyroid origin was considered likely based on tumor location and cell morphology. The tumor grew rapidly, and the owners elected euthanasia 1 week after examination. At necropsy, a circumscribed, ovoid mass disrupted the right cervical musculature next to the right lobe of the thyroid gland. Histopathologic evaluation revealed an infiltrative mass consisting of cuboidal cells arranged in solid sheets and irregular follicles enclosing colloid. The cells were large, with prominent nucleoli, and had a high mitotic rate. The histopathologic diagnosis was consistent with thyroid follicular adenocarcinoma. Immunochemical findings confirmed thyroglobulin production by neoplastic cells, but to a lesser extent than in normal ferret thyroid tissue. To our knowledge, this is the first case of thyroid follicular adenocarcinoma to be reported in a ferret, with only 1 other case of thyroid carcinoma, a C-cell carcinoma, described previously.     

Focal cutaneous vasculitis and alopecia at sites of rabies vaccination in dogs

A focal cutaneous lesion developed at the site of previous rabies vaccine administration in 13 dogs. Ten of the affected dogs were Poodles. The interval between vaccination and first observation of the lesion varied from 3 to 6 months. Skin lesions were hyperpigmented, alopecic macules, 2 to 5 cm in diameter. The consistent histologic lesion was vasculitis affecting arterioles of the deep dermis and subcutis. Other histologic lesions included epidermal, follicular, and adnexal atrophy, hyperpigmentation, chronic septal panniculitis, fat necrosis, and focal lymphocytic nodules in the deep dermis and subcutis. Rabies-specific fluorescence was seen in the walls of dermal blood vessels and in the epithelium of hair follicles in each of 3 dogs tested. Immunoglobulin G was detected in similar locations in one of 3 dogs tested. No difference in serum neutralizing anti-rabies antibody titers were detected between 5 affected dogs tested and 4 clinically normal dogs.     

Keratoconjunctivitis sicca: histopathologic study of nictitating membrane and lacrimal glands from 28 dogs

Forty nictitating membrane glands and 9 main lacrimal glands were obtained for histologic evaluation from 28 dogs with keratoconjunctivitis sicca as the result of azosulfapyridine toxicity, canine distemper, multisystemic autoimmune disease (Sj?gren's syndrome-like syndrome), congenital origin, and unilateral and bilateral idiopathic keratoconjunctivitis sicca. Similar glands from 6 control dogs were studied. The most prevalent (87%) histopathologic finding was variable degrees of multifocal chronic adenitis, characterized by acinar atrophy and replacement with increased numbers of plasma cells and lymphocytes within increased amounts of interacinar fibrous connective tissue stroma. Occasional tubular structures were dilated and filled with neutrophils and cellular debris.     

Surface Ultrastructure of Ultimobranchial Epithelium in the Thyroid Gland of Donkey (Equus asinus)

Surface ultrastructural observation of the thyroid gland in donkey revealed the coexistence of certain unusual follicles or cysts, the ultimobranchial (UB) follicles, which exhibited large diameters and less regular outlines. In addition, several small follicles, cell nests or solid cellular masses were also demonstrated in association with these structures. Surface of most UB follicular cells was almost hexagonal in shape, studded with sparse or dense pleomorphic microvilli, which were much denser at the cellular borders. Each follicular cell bore single cilium that projecting over the cell surface. Interestingly, bleb-like apocrine protrusion of the apical cytoplasm of some follicular cells was frequently demonstrated. These apocrine blebs (or aposomes) were varied in shape, size and showed smooth or irregular surface. In addition to such aposomes, deep to shallow circumscribed or eroded areas of the apical cell surface was frequently demonstrated. These findings indicate that the UB follicular cells in donkeys, similar to those of camels, exhibit an apocrine activity alongside with the usual merocrine mode of secretion.     

Anti‐isthmus autoimmunity in a novel feline acquired alopecia resembling pseudopelade of humans*

Pseudopelade is a primary scarring (cicatricial) alopecia of humans characterized by lymphocyte‐rich inflammation centred around the hair follicle isthmus. Lymphocyte folliculotropism is associated with isthmus apoptosis and, ultimately, follicular destruction and dermal fibrosis. In a cat, an acquired alopecia was diagnosed as pseudopelade based on the following criteria: (i) an adult‐onset, patchy to diffuse nonpruritic hair loss; (ii) an early folliculo‐destructive phase in which lymphocytes and dendritic cells accumulated in and around the follicular isthmus; and (iii) a late stage in which the lower segments of hair follicles underwent atrophy and were replaced by fibrosing tracts. Additionally, immunological investigations characterized the cytotoxic phenotype of isthmotropic lymphocytes and demonstrated the presence of circulating IgG autoantibodies specific for multiple follicular antigens. Altogether, the results of the present study suggest an immune‐mediated pathogenesis for this case of feline pseudopelade, similarly to that causing alopecia areata in humans and other mammalian species.     

Congenital hypothyroidism with goiter in toy fox terriers

Congenital hypothyroidism with goiter was observed to segregate as a simple autosomal recessive trait in Toy Fox Terriers (TFTs). Neonatal affected pups exhibited inactivity, abnormal hair coat, stenotic ear canals, and delayed eye opening. Palpable ventrolateral cervical swellings were evident by 1 week of age. Serum thyroid hormone and thyroid-stimulating hormone concentrations were low and high, respectively. Histologic examination of the cervical masses disclosed cuboidal to columnar follicular epithelial cell hyperplasia with widely varying follicular size, shape, and amount of colloid. Oral thyroid hormone replacement therapy restored near-normal growth and development. At 8 weeks of age, radioiodine uptake and perchlorate discharge testing indicated an iodine organification defect. Biochemical analysis of thyroid tissue from affected dogs demonstrated enzymatic iodine oxidation deficiency and lack of sodium dodecyl sulfate-resistant thyroglobulin dimers, suggesting thyroid peroxidase deficiency. A nonsense mutation in the thyroid peroxidase gene of affected dogs was discovered and demonstrated to segregate with the disease. A DNA-based carrier test was developed and currently is used by TFT breeders to prevent this disorder.     

Canine mesenchymal hamartoma of the eyelid

Objective Characterization of a benign disease syndrome involving the eyelids of dogs, describing the signalment, clinical appearance, anatomic location, and pathologic features. Animal studied The records and submitted tissue of 10 dogs with mesenchymal hamartomatous lesions of the periocular connective tissues were retrieved from the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW) database. Procedure The submitted tissue in each case was stained with hematoxilyn & eosin and Masson’s Trichrome stain and examined histopathologically. Clinical information was collected from the submission requests. The clinical history, treatment, and follow‐up are described in more detail for one of the 10 dogs. Results Seven different breeds, including four Golden Retrievers, were represented. The ages of affected dogs ranged from 6 to 11 years. Eight of 10 lesions were located at the temporal canthus, ranging in diameter from 0.6 to 3 cm. Clinically, the masses were subcutaneous, firm, lobular soft‐tissue growths, which were in some cases adherent to the underlying orbital rim, and in others, freely palpable between the skin and conjunctiva of the eyelid. Histologically, all had distinct margins but were not encapsulated and contained normal appearing collagen‐rich connective tissue with some adipose tissue. Five also contained fully differentiated skeletal muscle tissue arranged in poorly formed aggregates or as individual muscle fibers. Conclusion Mesenchymal hamartoma of the eyelid has not been previously described. The mass has a predisposition to occur at the temporal canthus and should be included in the list of differential diagnoses of benign eyelid masses in dogs.