\ "- WNWINllllNHNH“HlHlW11NlHlUllUllWlll)‘ 105 195 THS IIIIIIGIIIIAII INNEIIIIIIIIIIII III 3 1293 00067 0384 ‘V LEEMRY Michiganmeie 1,. University ? This is to certify that the thesis entitled CANINE PROGRESSIVE LYMPHOCYTIC THYROIDITIS PATHOGENETIC AND GENETIC IMPLICATIONS presented by Dale H. Conaway has been accepted towards fulfillment of the requirements for Masters degreein Pathology \\ (\Z/ér’ L 12 flj/fl—rgrk’? Major professor Dateficg/OIZQ / 6? 4/ 0—7639 MSU is an Affirmative Action/Equal Opportunity Institution )V1E31.I RETURNING MATERIALS: Place in book drop to LlaRAalgs remove this checkout from .—;—. your record. FINES WIII be charged if book is I . returned after the date stamped below. my? in .' v'. . :le 901v CANINE PROGRESSIVE LYMPHOCYTIC THYROIDITIS PATHOGENETIC AND GENETIC IMPLICATIONS BY Dale H. Conaway A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree MASTER OF SCIENCE Department of Pathology 1984 CANINE PROGRESSIVE LYMPHOCYTIC THYROIDITIS PATHOGENETIC AND GENETIC IMPLICATIONS BY Dale H. Conaway AN ABSTRACT OF A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree MASTER OF SCIENCE Department of Pathology 1984 PO: and Cha gic fam ref siVI ABSTRACT CANINE PROGRESSIVE LYMPHOCYTIC THYROIDITIS PATHOGENETIC AND GENETIC IMPLICATIONS BY Dale H. Conaway A six year study examining clinico—pathologic changes and genetic data has documented the progressive histomorphologic thyroid gland changes and a possible mode of inheritance involved in lymphocytic thyroiditis (LT) in a colony of related Borzoi dogs. This study encompasses three successive generations of this colony of dogs and uniquely documents the histopathologic progression from the initial thyroid gland degenerative lesions to end stage parenchymal atrOphy. The purpose of this study was to: (1) identify two LT positive animals from this colony of animals which were clinically hypothyroid, successfully reproduce the disorder and determine the frequency in their offspring and; (2) characterize the disease progression utilizing histopatholo— gic, clinical and electron microscopic findings. Preliminary evidence suggests that canine progressive familial LT eventually terminates in an entity commonly referred to as idiopathic follicular atrophy and that this disease in Borzoi dogs is inherited as an autosomal reces— sive trait. TO CARLA JOY and HATTIE two jewels of inspiration and encouragement ii Spj of ACKNOWLEDGEMENTS Special thanks to my major advisor and chairman of my graduate committee, Dr.George A.Padgett,for allowing me the opportunity to pursue a research career, a goal I have long endeavored to attain. I greatfully acknowledge the “A—19" crew for moral support and help. To Dr. Tracie Bunton, I am deeply indebted for her excellent academic input and electron microscopic work. To my wife, Carla Joy, who supplied the necessary spiritual, emotional and inspirational strength through some of the most critical and trying times of this thesis. MA REE DIE TABLE OF CONTENTS INTRODUCTION . . . . . . . . . . . . . LITERATURE REVIEW . . . . . . . . . . PART I PATHOGENETIC IMPLICATIONS MATERIALS AND METHODS . . . . . . . . Animals . . . . . . . . . . . . . Blood Collectio . . . . . . . . Thyroid Hormone Assays . . . . . TSH Stimulation Tests . . . . . Thyroglobulin Autoantibody Assay Antinuclear Antibody Assay (ANA) Immunoglobulin Assay . . . . . . Histologic Studies . . . . . . . Electron Microscopic Studies . . Data Analysis . . . . . . . . . . RESULTS . . . . . . . . . . . . . . . Clinical Evaluation . . . . . . . Histologic Examination . . . . . DISCUSSION . . . . . . . . . . . . . . LIST OF REFERENCES . . . . . . . . . . iv Page l4 l4 16 36 41 PART II MATERIALS AND METHODS RESULTS DISCUSSION LIST OF REFERENCES VITA Animals Thyroid Biopsy Thyroid Hormone GENETIC IMPLICATIONS o Assays 46 46 46 48 55 57 59 Figure la lb 10 LIST OF FIGURES Compares the control T4 values with affected T4 mean values after 12 months and after 24 months . . . . . . . . . Compares the control T3 values with T values after 12 months and after 2 months . . . . . . . . . . . . . . . . Photomicrograph of a thyroid gland from a 2.5 year old Borzoi dog . . . . . . . . . Photomicrograph of a thyroid from 2.5 year old male Borzoi with follicular atrophy . . Photomicrograph of thyroid gland with acute inflammatory changes. 2.5 year old female Borzoi dog . . . . . . . . . . . . . . . . . Photomicrograph of focal lymphocytic thy— roiditis in a 2.5 year old male Borzoi dog . Photomicrograph of focal lymphocytic thy— roiditis in a 2.5 year old female Borzoi dog 0 a o o a o o o o o o u o o o a o o o o Photomicrograph of chronic inflammation involving thyroid gland. 3.5 year old female Borzoi dog . . . . . . . . . . . . . Transmission electron micrograph of severely affected thyroid gland with lymphocyte between follicular cells . . . . Transmission electron micrograph of severely affected thyroid gland depicting electron dense deposits in the region of the basal lamina . . . . . . . . . . . . . . Transmission of electron micrograph of severely affected thyroid gland with plasma cells present . . . . . . . . . . . Vi Page 21 21 23 23 25 25 27 27 29 31 33 Figure 11 12 13 14 15 Photomicrograph of thyroid gland with dense fibrous connective tissue re— placing thyroid gland parenchyma from 3.5 year old male Borzoi dog . . . . . . . Photomicrograph depicting end stage lymphocytic thyroiditis from an 8 year old female Borzoi dog . . . . . . . . . . Borzoi pedigree chart through four generations . . . . . . . . . . . . Photomicrograph of severe lymphocytic thyroiditis with diffuse infiltration of lymphocytes, plasma cells and macro— phages . . . . . . . . . . . . . . . . . . Photomicrograph of lymphocytic thyroiditis with local destruction of thyroid gland parenchyma . . . . . . . . . . . . . . Page 35 35 52 54 54 HD T3 T4 TSH CCH ANA LT HD T3 T4 CCH ANA LIST OF ABBREVIATIONS Lymphocytic Thyroiditis Hashimoto's Disease Triiodothyronine Thyroxine Thyroid Stimulating Hormone Chromic Chloride Hemaglutination Antinuclear Antibody Assay Immunoglobulin viii and inv inf glm thh prot lesi Offs baSe Path affe< INTRODUCTION A six year study examining clinico—pathologic changes and genetic data has documented the histomorphologic changes involved in lymphocytic thyroiditis (LT) and a possible mode of disease inheritance in a colony of related Borzoi dogs. The lesions observed included initial degenerative thyroid parenchymal changes which progressed to subacute inflammation with subsequent fibrosis and end stage thyroid gland disease. This study encompasses three successive generations of this colony and uniquely documents the histopathologic progression from the initial thyroid gland degenerative lesions to end stage parenchymal atrophy. Two litter mates which had LT were bred and the ten offspring produced have all been diagnosed as LT positive based upon thyroid biopsy. A wide range of thyroid gland pathology was demonstrated in this litter which were all affected by 2.5 years of age. The purpose of this study was two fold; l)identify two LT positive animals from this colony of Borzoi dogs which were clinically hypothyroid, successfully reproduce the disorder and determine the frequency in their offspring and, 2) characterize the disease in a time—course fashion, as it pr e1 pr! pat yea prc the progressed, utilizing the clinical, thyroid histologic and electron inicroscopic findings to monitor the disease progression. Histopathologic changes of six related animals were documented as well. The various stages of thyroid gland pathology, in animals ranging from two and one half to eight years of age, revealed a unique disease progression and provided histologic evidence for the pathogenesis of LT in the canine. fOur more Care Stagg at aL ages Peri( LITERATURE REVIEW Chronic lymphocytic thyroiditis, or Hashimoto‘s Disease (H.DJ, has been increasing in frequency in the U.S.rnaking it the most frequent thyroid disorder in our population. One survey of 5,000 school children estimated a frequency of 1.3%.27 Moreover, the disease probably accounts for most instances of idiopathic acquired hypothyroidism.28 It has become so prevalent in some areas that collo- quialisms have been applied, such as Gulf Coast Thyroidi— tis.29 The frequency of H.D. based on histological diagnosis of surgically removed thyroid glands rose steadily in the 0.8. from .2% in 1930 to 10% in 1960. Some of this increase may be due to increased recognition, but evidence also supports a real and continuing increase in incidence.1 The incidence at autopsy is approximately .8%. It is fourtimesmorecommon hiwomenthan himen,andfourtimes more common in whites than in blacks. In white females, a careful epidemiological study in Baltimore revealed a staggering incidence of 9% among thyroid operations and 2% at autopsy.1 Hashimoto's disease occurs most frequently between the ages of 30 and 50 years of age, but may occur during any period in life. It has also been identified as the most 3 IIIOE aub but lym degl ca5e tati epit the Path trat foll Path< inCll dim common cause of goiter in children, accounting for 50% of childhood goiters. The original description of this chronic disorder with its distinctive histologic appearance was given by Hashimoto in 1912.30 Until the demonstration of circulating thyroid autoantibodies, H.D. could only be diag— nosed with certainty by biopsy of the thyroid. The demon— stration of high titers of circulating autoantibodies in most patients with H.D. has led to the use of the term autoimmune thyroiditis to describe the disorder. The histopathological changes vary in type and extent, but in general, consist of a combination of a diffuse lymphocytic infiltration, followed by obliteration and degeneration of thyroid follicles with fibrosis. In most cases, there is destruction of epithelial cells and fragmen— tation of the follicular basement membrane. The remaining epithelial cells may be larger and show oxyphilic changes in the cytoplasm; these so called Askanazy cells are virtually pathognomonic of H.D. The interstitial tissue is infil- trated with lymphocytes which may form typical lymphoid follicles with germinal centers.29'l The definative diagnosis of H.D. is based on histo— pathological findings, but several other features can lead to a clinical diagnosis. Symptoms commonly encountered include dysphagia, tenderness in the thyroid region and difficulty in breathing. be fir fun hon Pro CODC eume The of t by e dimi conc Duri reSp dimi and quate can} aUtOe deter globu and r media The results of the common tests of thyroid function may be variable depending upon the stage of the disease. At first, the tests indicate the presence of thyroid hyper— function without overproduction of metabolically active hormone. The thyroid I131 uptake is often increased and the Protein Bound Iodine (PBI) slightly elevated, but serum T4 concentration is normal, and hence PBI—T4 iodine difference is abnormally large.29 At this stage, the patient is eumetabolic, as indicated by a normal basal metabolic rate. The glandular hyperfunction is reflected by hypersecretion of thyroid stimulating hormone (TSH) since it is suppressed by exogenous hormone. With the passage of time, evidence of hyperfunction diminishes, and the Thyroid I131 uptake, PET and serum T4 concentration progressively approach subnormal levels. During this period, serum TSH may be increased, and the response to exogenous TSH may be subnormal, indicating diminished thyroid reserve. Ultimately, laboratory indices and the clinical state of the patient will reflect inade— quate secretion of the hormone.29'31 The diagnosis of H.D. can be confirmed by the finding of high titers of thyroid autoantibodies in the serum. In HJL, autoantibodies can be detected against four components of the thyroid: thyro— globulin, nonthyroblobulin colloid, microsomal antibodies and nuclear component.ll H.D.is now widely believed to be autoimmunologically mediated.6r32r33r31 Involvement of the immune system in the patl obse feat gla1 imul year in ' timc thy] anti the fam: both auto diSe eryt Pati expe inCr hYpo idiO} pathophysiology appears evident even with simple clinical observation. Hypergammaglobulinemia will often be a common feature, along with lymphocytic infiltration of the thyroid gland.14 In 1956, the first clear evidence demonstrating immunologic abnormalities in H.D. was reported. In that year Roitt et a1 discovered antibodies against thyroglobulin in the serum of patients with HJL34 At about the same time, Rose and Witebsky induced experimental autoimmune thyroiditis for the first time by injecting thyroid self— antigen mixed with Freund's adjuvant into rabbits.35 Part of the evidence favoring an autoimmune etiology of the disease has also been derived from the reports of familial aggregations of disease, or autoantibodies, or both, and the concurrence of thyroiditis with other putative autoimmune disorders.32 Siblings of patients with H.D. have an increased frequency and higher titers of thyroid autoan— tibodies than do controls, as well as an increased frequency of thyroid disease.32 Other autoimmune diseases, Sjogrens syndrome, Addison's disease, acquired hemolytic anemia, and systemic lupus erythematosus, have all been reported to be more frequent in patients with H.D. than in other individuals.36'37 Many experienced endocrinologists have noted in their patients an increased concordance of H.D. with such disorders as hypogonadism, diabetes mellitus, pernicious anemia, and idiopathic hypoparathyroidism.l well expel immu duce procr prod mice mode spec chic breec fact Spon natu years terpg more inVel color 16.2% adult In tl logic ”0 c] The use of animal models in the study of HJL has been well—documented. Since Witebsky and Rose38 reported the experimental induction of thyroiditis in rabbits by active immunization, allergic inflammatory lesions have been pro— duced in various organs of several lab animals by similar procedures. Experimental autoimmune thyroiditis has been produced in guinea pigs, dogs, chickens, rats, monkeys and mice. Spontaneous autoimmune thyroiditis has been reported 39 40 and the dog.2'24'19 These animal in chickens, rats, models have aided in the understanding of human organ— specific autoimmune diseases. The obese strain (OS) of chickens was developed about 18 years ago by selective breeding for the phenotypic trait of hypothyroidism.41 The fact that the clinical symptoms were attributable to a spontaneous arising thyroiditis which was autoimmune in nature was recognized 5 years later.39'42 In subsequent years the avian model was established as the closest coun— terpart to human H.D. More recently, the dog has moved into focus as an even more viable animal model in the study of H.D. Most of the investigations hi dogs with thyroiditis have been on colonies of laboratory beagles.2'25'19 Tucker25 detected a 16.2% incidence in thyroiditis in their colony of young adult beagles with males and females being equally affected. In this colony, thyroiditis was diagnosed by careful histo— logical examination of the thyroid gland, since there were no clinical signs of hypothyroidism or macroscopic lesions. ‘71 Al;;, The tory exam tanc Mize beag Anti coll atel the occu demo the Prim Pass Ularl tial] thyrc Much fIOm indir itSei Spec; Prob] The focal lymphocytic thyroiditis observed in these labora— tory beagles was not associated with significant alterations in thyroid function. Lymphocytic thyroiditis in dogs appears to represent an example of an autoimmune disease with a pattern of inheri- tance similar to that observed with H.D. in humans.2'43 Mizejewski et al19 reported that thyroiditis in laboratory beagles was similar serologically to human thyroiditis. Antibodies were present against thyroglobulin, a second colloid antigen, and a microsomal antigen. They, unfortun— ately, were unable to find a positive correlation between the occurrence of the thyroglobulin antibody titers and the occurrence or severity of thyroiditis. Gosselin et al11 demonstrated antibody titers against thyroglobulin in 48% of the pet dogs they examined at Ohio State University with primary hypothyroidism by utilizing the Chromic chloride passive hemagglutination test (CCHL An animal model of autoimmune thyroiditis is partic— ularly attractive for a number of reasons. It could poten— tially increase our understanding of human forms of chronic thyroiditis and related autoimmune diseases of the thyroid. Much of the genetic and immunopathological data obtained from studies of animals could be translated directly or indirectly back to the human disease. Chronic thyroiditis itself serves as a prototype for the larger group of organ specific autoimmune diseases that represent a significant problem in human medicine. In this group are the several an in: aut as tan due Fin Spo exp. glol autoimmune endocrine disorders, such as juvenile onset, insulin—dependent diabetes mellitus and idiopathic failure of the parathyroid and adrenal glands. The endocrinopathies that affect the thyroid, adrenal, parathyroid, pancreatic islets, as well as gastric mucosa, all seem to be associated not only by a similar pathogenetic mechanism but also by an overlapping familial incidence, suggesting common genetic defects. Other organ—specific autoimmune disorders include the anti—receptor diseases such as myasthenia gravis, the syndrome of extreme insulin resis— tance and acanthosis nigricans, and forms of thyrotoxicosis due to the production of thyroid—stimulating antibodies. Finally, autoimmune thyroiditis provides a spectrum of animal models for the study of autoimmunity ranging from a spontaneous, genetically determined disease to an induced experimental reaction to a defined protein antigen, thyro— globulin. PATHOGENET IC IMPLICAT IONS Borz dogs sis, usin tube cent Off -200 radi The frOn mea: thes MATER IALS and METHODS Animals The dogs used in this study consisted of 10 inbred Borzoi which were born July 11, 1981, and 6 closely related- dogs The dogs were vaccinated against distemper, leptospiro- sis, hepatitis and parvovirus. Blggd Collection Blood was collected at monthly intervals from birth using 22 gauge, 1 1/2 inch needles and 10cc Klotz vacutainer tubes. The specimens were allowed to clot and placed in a centrifuge at 1000 RPM for 15 minutes. Serum was then drawn off and placed in 3 ml plastic test tubes and frozen at —200C until analyzed. Thyroid Hormone Assays and TSH Stimulation Tests Serum T3 and T4 were determined at 30 day intervals by radioimmunoassay using the Becton—Dickinson Solid Phase Kit. The studies examined serum samples over a 24 month period from January 1982 to December 1983. TSH stimulation tests were performed every 6 months to measure the thyroid's quantitative response. Comparing these results with normal controls we were able to ascertain ll thy thy inj for Chrl rep< DI. mod Anti darc Cor; m tita tOri 12 thyroid function. Ten (IU) international units of bovine thyrotropin (bTSH) were administered intravenously. Blood samples were obtained before (pre) and 4 hours after (post) injection of bTSH. Pre and post serum samples were analyzed for T3 and T4 concentrations using radioimmunoassay. Immunologic Studies Thyroglobulin Autoantibody Assay The thyroglobulin autoantibodies were evaluated by the Chromic chloride hemagglutination (CCH) test. The CCH tests reported in this study were completed in the laboratory of Dr. Charles C. Capen using the procedure of Poston23 as modified by Gosselin et. a1.11 Antinuclear Antibody Assay (ANA) Antinuclear Antibodies (ANA) were assayed using stan— dardized kits purchased from Microbiological Research Corporation, Bountiful, Utah 84010. Immunoglobulin Studies (19) Canine immunoglobulins for IgA, IgG and IgM were quan— titated using standardized kits purchased from Miles Labora— tories, Research Product Division, Elkhart, Indiana. Histologic Studies Thyroid gland biopsies were performed on each animal in this study between the ages of 2 and 8 years of age. Tissue hyc‘ adj wit of Ara Zei test CODE 13 sections were fixed in 10% neutral buffered formalin, embedded in paraffin, sectioned and stained with hematoxylin and eosin. Electron Microscopic Studies Small sections of tissue were fixed in paraformalde- hyde/glutaraldehyde fixative in cacodylate buffer, which was adjusted to 550 mOsm and pH 7.4. They were then post fixed with 1.0% osmium tetroxide, dehydrated with a graded series of ethanol, infiltrated with propylene oxide and embedded in Araldite 502. Ultrathin sections were examined using a Zeiss 2 transmission electron microscope. Data Analysis The results were analyzed utilizing the student's t- test two—tailed, (unpaired) differences with a P<0.05 were considered to be significant. F‘I * '*"”"“" Cli unr pUPl rem; lym] exhj age The Prod thes hYpo RESULTS Clinical Evaluation In 1978, a study was launched to determine the cause of hypothyroidism in a colony of Borzoi dogs in Buckley, Michi— gan. All animals were owned by a Borzoi breeder and were part of the same kennel. The index case was a female who initially had low T3 levels (0.59 ng/ml) and low T4 levels (11.7 ng/ml) which over a period of 3 years fell to near zero ng/ml for both T3 and T4. Canine T3 levels less than 0.70 ng/ml and canine T4 levels less than 15 ng/ml are d.21 The index case was bred to an considered hypothyroi unrelated male from another kennel, and a litter of eight puppies was produced, one of which died perinatally. Of the remaining seven dogs, three exhibited a moderate to severe lympho—plasmacytic thyroiditis. These three dogs all began exhibiting clinical signs of hypothyroidism by two years of age (skin abnormalities, weight gain, low T3-T4 levels). The prospective mating of two of these affected littermates produced a litter of ten dogs, four females and six males. Over a 24 month period starting in January of 1982, these ten littermate Borzoi dogs were evaluated for thyroid function, immunological abnormalities, and clinical signs of hypothyroidism. During this period, skin abnormalities in 14 ”'1 two of t lesions quently were grc bilatera dog at 1 normal L46 ng/ at 1 1/2 118 ng‘ taken a marked with ba ceous g in the Th test w. antoant was de litter therg affect Clear Immiml kits ( Sampl. OCtOb. 15 two of the littermates, were observed. Initially, these lesions began on the head and facial regions and subse— quently spread to the trunk and limbs. The skin changes were grossly characterized by a dry, scaley, nonpuritic bilateral alopecia. Skin lesions were observed in the first dog atILyear of age and at that time his T4 levels were low normal (17.8 ng/ml) but his T3 values were abnormally low L46 ng/ml). The second animal developed skin abnormalities at 1 1/2 years of age. T4 and T3 levels at this time were 13.8 ng/ml and 0.66 ng/ml, respectively. Skin biopsies taken at this time from this animal were characterized by marked infundibular keratin plugging, follicular atrophy with basket weave orthokeratosis and atrophy of the seba— ceous glands. No other significant skin lesions developed in the other eight littermates during this 24 month period. The chromic chloride passive hemagglutination (CCH) test was utilized to detect the presence of thyroglobulin autoantibodies. A 1:40 antibody titer against thyroglobulin was detected in the paternal parent of the ten affected littermates at age two. A 1:20 antibody titer against thyroglobulin was detected in the serum of one of the ten affected littermates. All serum samples tested for antinu— clear antibody (ANA) in this colony of ten were negative. Immunoglobulin (IG) levels were assayed with standardized kits (Miles Laboratories, Elkhart, Indiana). In five serum Samples taken from each of the ten littermates, between October of 1982 and December of 1983, only one dog, at 2 year eleC' beta mean year T41l comp aPPI twel the: (Fig cont] cont valu mOnt 9I0u Outp( Signi gene 185A Pf0g~ 16 years of age, had abnormally high levels of IgG. Serum electrophoresis on this sample confirmed an elevation of the beta two and gamma one region of the gamma globulin peak. Thyroid hormone levels of T4 in affected dogs (combined means) showed a steady decrease in the first and second years of this study (Fig. la). These levels were compared to nine control Borzoi of the same age in both sexes. The T4 levels in affected dogs were significantly lower when compared to the control group. Mean control T4 levels were approximately 24t4.1 ng/ml. In affected dogs in the first twelve months, T4 levels were 18.3i3.4 ng/ml (P<0.025) in the second twelve months they were 15.8i2.3 ng/ml (P<.001) (Fig. 1). The mean T3 values were significantly different from controls in the second twelve months only. When comparing control mean T3 values (0.93i0.15 ng/ml) to the mean T3 values in the experimental group during the second twelve months (l.23iO.15 ng/ml) the T3 values in our experimental group were significantly higher, P<0.015. Thyroid gland output as measured via thyrotropin (TSH) stimulation was not significantly different in the two groups. Histologic Examination Histologic alterations were present in three successive generations of related Borzoi dogs. The thyroid gland lesions described present a unique documentation of the progression of the disease state in this family of dogs. Thy deg The cat aff A f sep‘ sub thit tor inf l7 Thyroid gland changes for our purposes will be classified as degenerative—non—inflammatory, inflammatory and end—stage. The inflammatory lesions will be further divided into three catagories: acute, subacute and chronic. A relatively normal thyroid gland, from a minimally affected dog illustrates (Fig. 2) variable sized follicles. A few follicles are smaller than normal; the follicular separation is artifactual. The degenerative but non—inflamed gland exhibited focal zones of follicular atrophy (Fig. 3). Acute inflammatory changes were characterized by a subendothelial margination of neutrophils with medial thickening and proliferation (Fig. 4). Subacute inflamma— tory changes varied in their extent and intensity. Focal infiltration of lymphocytes and plasma cells, with local follicular destruction (Fig. 5) is also apparent. The most severe, subacute inflammatory change is characterized by a diffuse infiltration of lymphocytes, plasma cells and macro— phages (Fig.6). Lymphoid nodules were common with exten— sive parenchymal destruction and subsequent loss of normal architechture. Thyroid C cells (parafollicular cells) are more prominent in the more normal appearing follicles (Fig. 6—inset). A more chronic progression of this stage of subacute inflammation (Fig. 7) has fewer plasma cells with narrowed follicular lumens containing little or no colloid. Follicles present are lined by columnar follicular cells. This section was taken from the 3 1/2 year old maternal parent of the animals previously discussed. fin era of' dim ture inte were basa thyr fuse dist tiSS tiSs Pare! disee adipC mal resid SUe idio; Canin 18 Electron microscopic studies paralleled histopathologic findings beginning with occasional individual lymphocytes observed migrating between epithelial cells (Fig. 8). Dis— creet electron dense deposits were present with the region of the basal lamina (Fig. 9). C cells in this stage of the disease appeared unaffected. The most severe stage of sub— acute thyroiditis (comparable to Fig. 6) was ultrastruc— turally characterized by plasma cells and lymphocytes in the interstitium, with occasional neutrophils. Plasma cells were situated perivascularly, or subjacent to the follicular basal lamina (Fig.10). Chronic LT was characterized by replacement of the thyroid gland with dense fibrous connective tissue and dif— fusely scattered lymphocytes. Follicular remnants were distorted, presumably due to subsequent fibrous connective tissue contraction around these structures (Fig. 11). This tissue biopsy was taken from the 3 1/2 year old paternal parent of the animals represented in Figures 2-6. The apparent end stage of the progression of this disease was characterized by fewer follicles with extensive adipose connective tissue replacement of atrophied parenchy— mal structures (Fig. 12). There was still evidence of residual inflammatory cell infiltrates present in this tis- sue as well. The described changes were consistent with idiopathatic—follicular atrophy, as characterized in the canine.12 This histopath section (Fig. 12) depicts the '3 a} a: - ' I 1: e-FH present in L i ll . few!“ :1 my“) {—7 ,,___,, f WI 20 Fig 1a. Compares the control T4 mean values with affected T4 mean values. T4 values in the control group were significantly higher (P<.025) than affected after 12 months and after 24 months (P<.001). Each vertical bar (I) represents one standard deviation from the mean. Fig 1b. Compares the control T3 mean values with affected T3 mean values. T3 values in the control group were significantly lower than T3 values in the affected group after the 24 month period only (P<.015). Each vertical bar (I) represents one standard deviation from the mean. J ng/ml (NH ng/ml h affected roup were 12 months 1 bar (I) h affected :ted grOUP rtical bar Ill- 440 30 _ 20 E 3 C l0 0 T 3 2.0 _ |.5 E P» C LO .5 21 Normal I:I Affected IEI number of dogs examined Am Em l2 months 24 months Fig. la 9 ‘m I % [a Fig. lb 12 months 24 months 22 Fig 2. Thyroid gland from 2.5 year old Borzoi dog with moderate decrease in the size of follicles. Fig 3. Severely degenerated thyroid gland follicles (arrows) with follicular atrophy and narrowing of lumens (non—inflammatory). From 2.5 year old Borzoi dog. fijI III. dog with follicles of lumens 24 Fig 4. Thyroid gland with acute vascular changes present. Neutrophils (arrows) are seen infiltrating endothelial walls (inset) with subsequent endothelial proliferation and thickening. From 2.5 year old Borzoi dog. Fig 5. Focal infiltrates of lymphocytes and plasma cells in close proximity to a large blood vessel (V) causing local thyroid parenchymal destruction. From 2.5 year old Borzoi dog. 25 t. n e S e I p S e lelial walls ration and :ma cells in using local old Borzoi .. yo...“ 4" k. a. o . . . .t p 3. . . Hill >1. (.1 . a...» 1 1......) _ 2.9... l. s... 7.... . . , . . if». _ KO 26 Fig 6. Severe lymphocytic thyroiditis with diffuse infiltration of interstitium and parenchyma with lymphocytes, plasma cells, and macrophages. C cells (arrow) were more prominent (inset) in this stage of the disease. From 2.5 year old Borzoi dog. Fig 7. Thyroid gland from 3.5 year old Borzoi dog with foci of inflammatory cells. Severe loss of thyroidal architecture. Decrease in follicular lumens (L) with absence of colloid. th diffuse ‘hyma with ells (arrow) he disease. 1 with fOCi thyroidal (L) with Fig 8. 28 Transmission electron micrograph. Lymphocyte (Ly) between follicular cells (Ep). Note also electron dense deposits cell (C). (arrows). Follicular'1nnnen an, parafollicular II” 0 fig _3 i V1 (LI 6 t Y c o .m :tron dense follicular 30 Fig 9. Transmission electron micrograph. Note electron dense deposit (arrows) in region of basal lamina. Follicu— lar cell nucleus (Nu). ;e electron FollicU- o 31 III. II. 32 Note plasma Fig 10. Transmission electron micrograph. cells (P1) adjacent to the follicular epithelial cell (Ep) basal lamina. vessel (v). Bar = 1 um. 33 Note Plasma al Cell (Ep) 34 Fig 11. Dense fibrous connective tissue replacement of thyroid gland parenchyma. Bizarre shaped lumens (LL No colloid present. Note scattered foci of chronic inflammatory cells. From four year old Borzoi dog. Paternal parent. Fig 12. End stage thyroid gland disease. Adipose connective tissue (A) replacement of thyroid parenchyma. A few small follicles (arrows) remain. From eight year old Borzoi dog. Maternal grandparent. a . 1.. Lacement of N .. INK. ix. Iv?» Ivy—(L I! .. N0 ens (L). 3f chronic Borzoi dom A e 5 0 p .l d A nchyma. ht year old w ‘H‘ cytic study family Si tients, gammagl animal levels g more th were cor Primary Alt Signing age and levels w fICdnt d affected (P<.025). months We DISCUSSION Clinical hypothyroidism in dogs associated with lympho— cytic thyroiditis has been reported.ll'12'l3'18 Our 6 year study documents progressive thyroid gland disease in a family of Borzoi dogs. Similarities noted in our canine study and in human pa— tients, with LT, were the presence of abnormally high gammaglobulin levels present in the most severely affected animal in the third generation pedigree. Elevated IgG levels are associated with antibodies being produced against 14,15 more than one specific antigen. Skin abnormalities were compatible with dermatopathology seen in patients with primary hypothyroidism in both man and dogs.3'4'9 Although the thyroid stimulating hormone tests were not significantly altered in the affected dogs when compared to age and breed matched controls, differences in T3 and T4 levels were significant. During the first 12 months a signi— ficant decrease in thyroxine (T4) levels were seen in the affected dogs when compared to age—breed matched controls (P<.025). Decreases in T4 levels during the second 12 months were even more significant (P<.001). These decreases were presumably due to progressive, primary thyroid gland disease. 36 perim when incre convei cant level corre ducth T3 ob obser by no incre gland in th 0f th humar comps thyro hyper rate ttho does befor Sion roidi repre 37 Triiodothyronine levels, during the second 12 month period, were significantly higher in our affected animals when compared to age-breed matched controls (P<.015). This increase in T3 levels may be attributed to an abnormal conversion of free—T4 (fT4) to T3. In one study, a signifi— cant inverse correlation was observed between serum T4 levels and the conversion rate of T4 to T3, while a positive correlation existed between the conversion rate and T3 pro— duction rates.5 The latter findings are consistent with our T3 observations. Increases in T4 to T3 conversion rates observed in hypothyroidism may reflect decreased T4 disposal by nondeiodative pathways.l7 Alternatively, there may be an increased synthesis and secretion of T3 by the thyroid gland. Manifestations of hyperthyroidism have been reported in the early phases of lymphocytic thyroiditis in about 50% of the human patients.26 Transient hyperthyroidism in some human patients with lymphocytic thyroiditis appears to be compatible with the transient, unregulated discharge of thyroid follicle contents.9'lo This transient phase of hyperthyroidism, could explain the increase in T3 production 8 Acute rate in our colony, as reported in a human study. thyroiditis is one of the known thyroid disease states that does give rise to increased plasma T3 levels, which rise before plasma T4 levels.16 The increase in T4 to T3 conver— sion rates, secretion and synthesis of T3 in subacute thy— roiditis has not been fully explained. These phenomena may represent compensatory mechanisms, seen in degenerative thyroi the mo It is gland of T3 tion c hyperf stage obseri nostic thatf hypotl as di< destrr shoul level Chang dence of LT Years alter At tt by 06 C011 are ( 38 thyroid gland diseases, that facilitate the production of the most biologically active of the thyroid hormones (T3). It is generally accepted that the effects of the thyroid gland are expressed primarily through the hormonal actions of T3 which is derived principally from peripheral deiodina— 20 tion of T4. In humans, the thyroid gland in LT may be hyperfunctional, normal or hypofunctional depending on the stage of the disease.l'10 Because of significant T3 data observed in this study, the question relative to the diag— nostic value of T3 is raised. Our data appears to indicate that T3 has diagnostic value in potential cases of primary hypothyroidism. In individual dogs, T3 values fluctuated, as did T4 values, until a significant amount of parenchymal destruction was evident. The data indicates that T3 levels should be viewed relative to stage of the disease, T4 levels, and T4 to T3 conversion rates. The unique documentation of the histopathological changes observed in this family of dogs has provided evi— dence of the progressive steps involved in the pathogenesis of LT. Three successive generations, animals ranging from 2 years to 8 years of age, were biopsied and examined. Our observations indicate that the first thyroidal alterations are subtle follicular changes (Fig. 2 and 3). At this stage there is follicular degeneration characterized by decrease in size and numbers of glandular elements, with collapse of the follicular lumens. These initial changes are degenerative, but noninflammatory. W Aggt vasc lami chang the < plem vesse binat the i of wl ment queni gress tive next disea atrOp Onin old ( lar c media geHIC effeC funct 39 Inflammatory changes are observed in the next phase. Acute inflammatory changes are apparent in this manifest vasculitis (Fig. 4). Ultrastructural findings of basal laminal deposits (Fig. 10), along with acute vascular changes suggests immune complex involvement in this phase of the disease. When significant quantities of immune com— plexes accumulate, they tend to be deposited in blood vessels.24 The formation of immune complexes via the com— bination of antigen with antibody has been determined to be the initiating step in a number of biological processes, one of which leads to neutrophil accumulation and the develop— ment of acute vasculitis (Fig. 4L7'24 Subacute inflammatory changes (Fig. 5,6,7) with subse— quent parenchymal destruction appears as the disease pro- gresses. Chronic inflammatory changes with fibrous connec— tive tissue replacement of the thyroid parenchyma appears next (Fig. 11). Histologically, the and stage of this disease state manifest itself as idiopathathic follicular atrophy.12 Idiopathic follicular atrophy appears much later on in thecdisease process seen here in an animal eight years old (Fig. 12). The presence of lymphocytes migrating between follicu- lar cells (Fig. 8) suggest the involvement of a cell- mediated hypersensitivity in this disease as well. Anti- genic stimulation of T cells lead to the formation of effector cells with a variety of different specific 6 Some T cells may differentiate into specific functions. cytotoxir the sens The from dog and mai‘ data th progres nomenor immune Th canine of fol] the th diseam as idi 4O cytotoxic cells capable of destroying target cells bearing the sensitizing antigens.24'l7 The thyroid gland changes depicted in figures 2-6 are from dogs of the same litter. These littermates were housed and maintained in the same environment. These histologic data then clearly illustrate the diversity in rates of progression of the disease in individual dogs. This phe- nomenon may be attributed to biological variations of the immune response in individual animals. The results of this study indicated that familial canine LT progresses spontaneously from the initial lesions of follicular degeneration to inflammatory destruction of the thyroid gland. The end stage of this thyroid gland disease was characterized by an entity commonly referred to as idiopathic follicular atrophy. REFERENCES Beal, G.Nq Solomon, DJL: Hashimoto's and Graves' disease. In: Immunological Diseases, ed. Sampter, M” pp.1261—1277, 3rd ed. Little, Brown and Company, Bos— ton, 1978. Beierwaltes, W.H” Nishiyama, RJL: Dog thyroiditis: occurrence and similarities to hashimoto's struma. Endocrinology 83:501-508, 1968. Belshaw, B.E., Rijnberk, A.: Radioimmunoassay of plas— ma T4 and T3 in the diagnosis of primary hypothyroidism in dogs. Journ. Am. Ani. Hosp. Assoc. 15:17—23, 1979. Belshaw, B.En Rijnberk, A.: Hypothyroidism. In: Current Veterinary Therapy, ed. Kirk, R.W., pp. 994— 998, 7th ed., W.B. Saunders Company, Philadelphia, 1980. Bianchi, R., Mariani, G” Molea, N” Vitek, F” Cazzu- la, F” Carpi, A” Mazzuca, N” Toni, M.GJ Peripheral metabolism of thyroid hormones in man. I. Direct measurement of the conversion rate of thyroxine to 3,5,3‘-triiodothyronine (T3) and determination of the peripheral and thyroidal production of T . Journal of Clinical Endocrinology and Metabolism 56:1152—1163, 1983. Calder, E.A., Irvine, W.J.: Cell mediated immunity and immune complexes in thyroid disease. Clinics in Endo— crinology and Metabolism 4:287—318, 1975. ngang, T.G” Befus, A.DJ The role of complement in the induction and regulation of immune responses. A Review. Immunology 51:207—224, 1984. Faber, J., Lumholtz, I.B., Kirkegaard, C., Nielsen, K.S., Friis, T.: Metabolic clearance and production rates of 3,3'—diiodothyronine and 3',T—diiodothyronine and 3'—monoiodothyronine in hyper and hypothyroidism. Clinical Endocrinology 16:199-206, 1982. Freitas, J.EJ Autoimmune thyroid disease. Interna— tional Journal of Dermatology 20:207—212, 1981. 41 11. 14. 15. 19. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 42 Gorman, C.A., Duick, D.S., Woolner, L.B., Wahner, H.W.: Transient hyperthyroidism in patients with lymphocytic thyroiditis. Mayo Clin. Proc. 53:359—365, 1978. Gosselin, S.J., Capen, C.C., Martin, S.L., Targowski, S.PJ Biochemical and immunological investigations on hypothyroidism in dogs. Canine Jour. of COmparative Medicine 44:158—168, 1980. Gosselin, S.J., Capen, C.C., Martin, S.L.: Histologi— cal and ultrastructural evaluation of thyroid lesions associated with hypothyroidism in dogs. Vet. Path. 18:299—309, 1981. Gosselin, S.J., Capen, C.C., Martin, S.L., Krakowka, S.: Autoimmune lymphocytic thyroiditis in dogs. Veteri— nary Immunology and Immunopathology 3:185—201, 1982. Kidd, A., Okita, N., Row, V.V., Volpe, R.: Inununolo— gic aspects of Graves' and Hashimoto's disease. Meta— bolism 19:80—95, 1980. Knecht, H., Saremaslani, P., Hedinger, C.: Immunohis— tological findings in Hashimoto's thyroiditis, focal lymphocytic thyroiditis and thyroidis de Quervain. Virchows Archives 393:201—231, 1981. LaGanga, T.S.: Laboratory aids in thyroid problems. pp. 1—28, Bio-Science Laboratories, Van Nuys, Califor— nia, 1981. LoPresti, J.S., Warren, D.W., Kaptein, E.M., Croxson, M.S” Nicoloff, J.TJ Urinary immunoprecipitation method for estimation of thyroxine to triiodothyronine conversion in altered thyroid states. Journ. of Clini- cal Endocrinology and Metabolism 55:666—670, 1982. Lucke, V.M., Gaskell, C.J” Wotton, P.Ra Thyroid pathology in K—9 hypothyroidism. Journal of Compara— tive Pathology 93:415—421, 1983. Mizejewski, G.Jq Baron, J., Poissant, G.: Immunologic investigations of naturally occurring canine thyroidi— tis. Journal of Immunology 107:1152—1160, 1971. Moroz, L.A., Meltzer, S.I., Bastomski, C.H.: Thyroid disease with monoclonal (IgG) antibody to triiodothyro— nine and thyroxine. Journ. of Clinical Endocrinology and Metabolism 56:1009—1015, 1983. Nesbit, G.H., Izzo, J., Peterson, L., Wilkins, R.Ja Canine hypothyroidism. A retrospective study of 108 cases. Journal of the American Veterinary Medical Asso— ciation 177:1117—1122, 1980. “—v‘ 22. 23. 24. 25. 26. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 43 Pacini, F., Nakamura, H., Degroot, L.J.: Effect of hypo— and hyperthyroidism on the balance between helper and suppressor T cells in rats. ACTA Endocrinologica 103:528—534, 1983. Poston, R.N.: A buffered chromic chloride method of attaching antigens to red cells. Use in haemagglutina— tions. Journal of Immunological Methods 5:91—96, 1974. Tizard, 1.: Physiological and pathological consequen— ces of the immune response. In: An Introduction to Veterinary Immunology, ed. Tizard, I., pp. 105-108, 2nd ed. W.B. Saunders Company, Philadelphia, 1980. Tucker, W.Eq Jr.: Thyroiditis in a group of labora— tory dogs. American Journal of Clinical Pathology 38:70—74, 1962. Volpe, R.: Acute and subacute thyroiditis. Pharma— col. Ther. 1:171-181, 1976. Rallison, M.L” Dobyns, E.M., Keating, F.R” Rall, J.E., Tyler, F.H.: Occurrence and natural history of chronic lymphocytic thyroiditis in childhood. Journ. of Pediatrics 86:675—682, 1975. Fisher, D.A., Oddie, T.H., Johnson, D.E., Nelson, J.C.: The diagnosis of Hasimoto‘s thyroiditis. Journ. of Clin. Endocrinology and Metabolism 40:795-801,1975. Holmes, H.B., Kreutner, A., O'Brien, P.: Hashimoto thyroiditis and it's relationship to other thyroid diseases. Journ. of Surgery, Gynecology and Obstetrics 144:887—889, 1977. Hashimoto, H.: Zur Kenntnis der lymphomatosen Veranderung der Schildduse (Struma lymphomatosaL Arch. Klin. Chir. 97:219—248, 1912. Amino, N., Miyai, J., Onishi, T., Hashimoto, T., Aria, K., Ishibashi, K., Yuichi, K.: Transient hypothyroidism after delivery in autoimmune thyroiditis. Jour. of Clin. Endocrinology and Metabolism 42:296—301. 1976. Goldsmith, R.E” McAdams, A.J” McKenzie, M., Hess, EAL: Familial autoimmune thyroiditis: Maternal-fetal relationship and the role of generalized autoimmunity. Journ. of Clin. Endocrinology and Metabolism 37:265— 275, 1973. 33. 35. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44 Soborn, M., Halberg, P.: Cellular hypersensitivity in Hasimoto's thyroiditis. Acta Med. Scand. 183:101—105, 1968. Roitt, I.M., Doniach, D., Campbell, P.N., Hudson, R.V.: Autoantibodies in Hashimoto's disease (lymphadenoid goitre). Lancet 2:820-821, 1956. N.R” Witebsky, E.: Studies on organ specificity: Changes in the thyroid glands of rabbits following active immunization with rabbit thyroid extracts. Journ. of Immunology. 76:417—427, 1956. Rose, Ardeman, S., Chanarin, I., Krafchick, B., Singer, W.: Addisonian pernicious anemia and intrinsic factor antibodies in thyroid disorders. Journ. of Medicine 35:421, 1966. Becker, K.L” Ferguson, R.Hq McConahey, W.M.: The connective tissue diseases and symptoms associated with Hashimoto's thyroiditis. New England Journ. of Med. 268:277-280, 1963. Witebsky, E., Rose, N.R.: Studies on organ specificity: Production of rabbit thyroid antibodies in the rabbit. Journ. of Immunology 76:408—416, 1956. Cole, R.K., Kite, J.H., Jr., Witebsky, E.: Hereditary autoimmune thyroiditis in the fowl. Science 160:1357— 1358, 1968. Haydu, A., Rona, G.: Spontaneous thyroiditis in laboratory rats. Experientia 25:1325—1326, 1967. Cole, RJL: Hereditary hypothyroidism in the domestic fowl. Genetics 53:102, 1966. Wick, G., Sundick, R.S., Albini, B: A review: The obese strain of chickens: An animal model with spontaneous autoimmune thyroiditis. Clin. Immunopathology 3:272—300, 1974. Volpe, R.: Lymphocytic thyroiditis in the thyroid. S. Werner and S. Ingbar, eds., Harper and Row, 1978. pp. 996—1008, New York: $.74;:?-iaraj,.#.-i~'g--;_j.-. -. J! PART II GENETIC IMPLICATIONS L. Anima 2, Pi dogs, (10, later The In Propo this hepat urge. fOrma hemat Ell/Lo V313 MATERIALS AND METHODS Animals Initially, a mating of 2 unrelated borzoi dogs (1 and 2, Fig. 1) produced 7 offspring (3—9, Fig. 1). Of these 7 dogs, one female (9, Fig. 1) was bred to an unrelated male (10, Fig. l) and produced 8 puppies (ll-18, Fig. 1). Dog 9 later developed LT and became the propositus for this study. The mating of 2 of the affected offsping (11 and 12) of the propositus resulted in a litter of 10 puppies. All dogs in this study were vaccinated for distemper, leptospirosis, hepatitis, rabies and parvo virus. Thyroid Biopsy Thyroid biopsies were performed on 18 animals (1—2, 9— 14, 19—28, Fig.1) between 2 and 8 years of age at the time of biopsy. Tissue sections were fixed in 10% buffered formalin, embedded in paraffin, sectioned and stained with hematoxylin and eosin. Thyroid Hormone Assays Serum T3and T41evels weredetermined at30 dayinter— vals by radioimmunoassay using the Becton—Dickinson solid Phase Kit. The studies examined the fourth generation serum 46 .J' sampl Decem samples over a 24 December 1983. a. r A f mented terize matings study w ism wh dogs i Borzoi 2 were range, had SE chara< repla decre tIVe cells and . affa matj tOL and RESULTS A familial pattern of thyroid gland disease was docu- mented in this group of Borzoi dogs. In order to charac— terize this pattern, we would like to briefly describe the matings and the resultant thyroid gland pathology. In 1978 a study was undertaken to determine the cause of hypothyroid— ism which developed in one dog (9) in a colony of Borzoi dogs in Buckley, Michigan. All animals were owned by a Borzoi breeder and were part of the same kennel. Dogs 1 and 2 were clinically normal with T3—T4 levels within the normal range. These dogs were both biopsied at 8 years of age and had severe thyroid gland alterations. These changes were characterized by follicular atrophy with connective tissue replacement of normal parenchymal structures and marked decrease or absence of normal colloid. Although degenera— tive changes were present in these glands, no inflammatory cells were present. The degenerative changes seen in dogs 1 and 2 are not like the inflammatory lesions present in the affected dogs and these changes may well be age related. Of the seven dogs (3—9, Fig. 1) produced from the mating of dogs 1 and 2, only animal number 9 was available to us for evaluation as the other littermates had been sold and distributed across the country. Thyroid hormone levels 48 1 TV 'VTW tra pla rep degl des‘ app. (Cor ani1 nor] dog: pro< sigr mail disr infa SSVe roid and 0.67 Peri leve (Nes SeVe 49 in dog 9 fell to near zero ng/ml by age 6. Dog 9 was biopsied at 8 years of age and there was a moderate infil— tration of inflammatory cells consisting of lymphocytes and plasma cells. There was prominent connective tissue replacement of glandular structures causing subsequent degenerative changes within the gland. These changes were consistent with idiopathic follicular atrophy, an entity described in dogs (Gosselin et a1., 1981) and this change appears to be the end stage of LT in this colony of dogs (Conaway et al. in preparation for publication). Dog 10, an animal originating in an unrelated kennel, was clinically normal with no observed thyroid gland pathology. Three dogs, (ll—13, Fig. 1) from the group of eight offspring produced by dogs 9 and 10, were LT positive with clinical signs of hypothyroidism. Animals 15—17 (Fig. 1) have re— mained clinically normal with no signs of thyroid gland disease. The status of dog 18 was not determined due to infant death (ID). Dogs 11 and 12, both had a moderate to severe lymphoplasmacytic infiltration of their biopsied thy— roid glands. The T3 level in dog 11 during this time was 0.37 ng/ml and her T4 level was 7.4 ng/ml. The T3 level in dog 12 was 0.67 ng/ml and his T4 level was 5.3 ng/ml during this period. Canine T3 levels less than 0.70 ng/ml and canine T4 levels less than 15 ng/ml are considered hypothyroid (Nesbitt et. a1., 1980). Dog 13, a full sister, also had a severe, diffuse lymphoplasmatic inflammatory infiltrate, witl leve beir PUPS broa desl fror fuse tior witl of i the prep 50 with severe follicular atrophy and degeneration. Her T3—T4 levels were 0.57 and 7.3 ng/ml respectively, both levels being abnormally low. The mating of 11 and 12 produced a litter of ten Borzoi pups, (19—28, Fig. 1) all of which eventually exhibited a broad range of thyroid gland pathology with varying degrees of lymphocyte and plasma cell infiltration and thyroid gland destruction by 2 1/2 years of age. These lesions ranged from a mild infiltration of lymphocytes, to a severe, dif- fuse lymphoplasmacytic inflamation with subsequent destruc— tion of the thyroidal parenchyma (Fig. 2 and 3). Variations in T3 and T4 levels in these 10 dogs appear to correspond with the degree of inflammatory involvement and destruction of the thyroid parenchyma. A more detailed description of the thyroid gland pathology, biochemical, immunological and clinical abnormalities in this colony of dogs, is in preparation for publication. Fig 13. 51 Borzoi Pedigree through four generations. Figure 13 Borzoi Pedigree Chart ‘11 TE I9 20 21 22 23 24 25 26 27 28 D O UNAFFECTED MALE, FEMALE I . AFFECTED MALE, FEMALE ® STATUS UNKNOWN, MALE, FEMALE IZI/g DEAD ID INFANT DEATH 53 Fig 14. Severe lymphocytic thyroiditis with diffuse infiltration of interstitium by lymphocytes, plasma cells, and macrophages. Lymphoid nodules (arrows) were common. Fig 15. Higher magnification depicts local destruction of thyroid parenchyma. Lymphocytes infiltrating follicular lumen (L) that have little colloid remaining. 54 .th diffuse Lasma cells common. truction of follicular Th EV de St ai DISCUSSION Lymphocytic thyroiditis has been defined as an organ specific autoimmune disorder [Jansson, 1983]. Synonyms include struma lymphomatosa, Hashimoto's disease (HD), autoimmune thyroiditis and chronic lymphocytic thyroiditis [Beal and Solomon, 1978]. The aggregation of LT in the same family has been well documented [Goldsmith g£__lq 1973]. The genetic influence in human thyroid autoimmunity was evidenced by identical twins, both of whom were reported to develop HD [Irvine fit ”1., 1961]. Thyroid antibodies were found in over 50 percent of the siblings of LT patients [Hall 23 al., 1960]. In humans, the genetic transmission of LT has been thought to be polygenic [Hall ”E #1., 1972]. Spontaneous autoimmune thyroiditis in the Obese strain (OS) chicken has been shown to be a polygenic trait with some degree of dominance [Cole, 1966]. With all ten offspring of the fourth generation (see pedigree chart) having affected thyroid glands, a different mode of inheritance will be suggested for the dog. The mating of dogs 1 and 2 produced at least one affected offspring, dog 9. Because dogs 1 and 2 were clini— cally and biochemically normal; we conclude that they were 55 botl sive 56 both heterozygous for the mutant gene. An autosomal reces— sive disease is generally manifested clinically only in the homozygote. In the usual mating situation as seen in people, both parents are free of the disease but are hetero— zygous for the mutant gene [Nora and Fraser, 1974]. The prospective mating of dog 9, an affected dog, to 10, a clinically normal animal produced three known affected dogs (ll—l3, Fig. 1) and three normal dogs (15—17, Fig.2) with the status of one animal, 18, unknown due to infant death. This suggests that dog 10 was a heterozygous carrier of the trait. The prospective mating of two known affected ani- mals, 11 and 12, gave the expected results when two homo— zygous recessive animals are mated, 100% affected offspring, which is what we have in the ten offspring in the fourth generation. We conclude from this data that this trait in Borzoi dogs is inherited as an autosomal recessive trait. 10. ‘REFERENCES Beal, G.N” Solomon, D.Ha Hashimoto's and Grave‘s disease. In: Sampter, M. (edJ: Immunological Di— seases, pp. 1261-1277, 3rd ed. Little, Brown and Co” Boston, 1978. Cole, ILK.: Hereditary hypothyroidism in the domestic fowl. Genetics 53:1021—1033, 1966. Cole, R.K., Kite, J.H., Jr., Witebski, E.: Hereditary autoimmune thyroiditis in the fowl. Science 160:1357- 1358, 1968. Goldsmith, R.E., McAdams, A.J., Larsen, P.R., MacKen— zie, M., Hess, E.V.: Familial autoimmune thyroiditis: Maternal—fetal relationship and the role of generalized autoimmunity. Journal of Clinical Endocrinology and Metabolism 37:265—275, 1973. Gosselin, S.J., Capen, C.C., Martin, S.L.: Histologic and ultrastructural evaluation of thyroid lesions asso— ciated with hypothyroidism in dogs. Vet. Pathol. 18:299-309, 1981. Hall, R” Dingle, P.Ru Roberts, DAR: Thyroid antibo— dies: A study of first degree relatives. Clinical Genetics 3:319-324, 1972. Hall, R” Owen, S.G” Smart, G.A.: Evidence for a genetic predisposition to formation of thyroid antibo— dies. Lancet ii, 187—188, 1960. Hashimoto, H.: Zur Kenntnis der lymphomatosen Verande— rung der Schildduse (Struma lymphomatosa). Arch. Klin.Chir.97:219-248,1912. Haydu, A., Rona, G.: Spontaneous thyroiditis in laboratory rats. Experientia 25:1325—1326, 1969. Jansson, R.: Thyroid—infiltrating T—lymphocyte subsets in Hashimoto's thyroiditis. Journal of Clinical Endo- crinology and Metabolism 56:1164—1168, 1983. 57 11. 12. 13. 14. 58 Nesbitt, G.H., Izzo, J., Peterson, L., Wilkins, R.Jn Canine Hypothyroidism: A retrospective study of 108 cases. Journal of the American Veterinary Medical Asso— ciation. 177:1117—1122, 1980. Nora, J.J” Fraser, E2C.: Autosomal recessive di— seases. In: Nora, J., Fraser, F. (eds): Medical Genetics: Principles and Practice. Philadelphia: Lea and Febiger, 1974, VIII: pp. 141- 182. Rallison, M.Lq Dobyns, B.M., Keating, F.R” Rall, J.E., Tyler, F.H.: Occurrence and natural history of chronic lymphocytic thyroiditis in childhood. Journal of Pediatrics 86:675—682, 1975. Tucker, W.E” Jr.: Thyroiditis in a group of labora- tory dogs. Journal of Clinical Pathology 38:70—74, 1962. if VITA The author was born in St. Louis, Missouri on November 27, 1954. He was the youngest of seven children. His elementary and secondary education was completed in St. Louis, cluminating upon graduating from Summer High School in 1973. He then entered undergraduate school at Tuskegee Institute, where he received both his Bachelor of Science degree in Animal and Poultry Husbandry and Doctor of Veterinary of Medicine degree in May 1977 and 1979 respectively. From Tuskegee, he returned to St. Louis where be practiced small animal surgery and medicine for two years. In 1981 he did an epidemiology study at Washington University for a one year period. In January of 1982 he was admitted into the pathology program at Michigan State University. He was awarded an EOP fellowship at that time. After two and one half years, he successfully completed his Master‘s degree in Veterinary Pathology. The author was happily married to Carla Joy Hosey on July 7, 1984. 59 I.\. I I III .I:: . . o .. .Id‘ MICHIGAN STATE UN IIIIII III III "III 31 INhnLNfiffifiEs iIHIIHIIHHIIIIIIHI 293000670384