Genital neoplasms treated by en bloc resection and penile retroversion in horses: 10 cases (1977-1986)

The medical records of 10 horses with invasive neoplasms of the penis, prepuce, and/or superficial inguinal lymph nodes in which treatment involved en bloc resection and penile retroversion were reviewed. All were geldings and ranged in age from 12 to 25 years (mean, 19 years). Evaluation of biopsy specimens obtained before surgery confirmed lymphosarcoma in 1 horse and squamous cell carcinoma in 9 horses. Typical history included swelling, ulceration, and abscessation of the penis and prepuce and large superficial inguinal lymph nodes. Complications after surgery included dehiscence of the urethrostomy site (4 horses), dehiscence of the ventral skin incision (1 horse), urine scalding of 1 hind limb (1 horse), cystitis (1 horse), severe hemorrhage (1 horse), and diarrhea (1 horse). One horse was euthanatized during hospitalization, because of severe dehydration secondary to diarrhea. At necropsy, firm nodules were scattered in the pulmonary parenchyma, myocardium, thyroid gland, parathyroid glands, cranial mediastinum, kidneys, and hilar lymph nodes. Microscopic examination of the nodules revealed undifferentiated carcinoma. Nine horses were discharged from the hospital between 1 and 5 weeks after surgery. The mean follow-up interval was 27 months (range, 6 to 96 months). Eight horses had no evidence of recurrence. One horse had recurrence of neoplasm at 6 months and was euthanatized 12 months later.     

What is your diagnosis? Ventral neck mass in a dog

Abstract: A 14‐year‐old male Labrador Retriever was presented for lethargy and collapse. On physical examination, numerous abnormalities were found, including a large ventral neck mass (100 cm³) in the area of the thyroid gland. Fine‐needle aspirates revealed 2 apparent populations of cells: one suspected to be a well‐differentiated thyroid carcinoma, and the other consisting of large pleomorphic to spindloid cells suggestive of sarcoma. Two days later, the dog died at home. A full necropsy was not performed, but examination of the head and neck revealed a well‐encapsulated mass adjacent to the cranial trachea and larynx. A section of the mass was evaluated histologically and a diagnosis of anaplastic thyroid carcinoma was made. Immunohistochemical evaluation with antibodies to thyroglobulin, cytokeratin, and vimentin confirmed distinct populations of malignant epithelial and malignant mesenchymal cells, and the diagnosis was amended to thyroid carcinosarcoma. Thyroid carcinosarcoma is a rare neoplasm in dogs in which the cell type comprising the mesenchymal component can vary. Immunochemistry to demonstrate the 2 cell types may be necessary to differentiate thyroid carcinosarcoma from anaplastic thyroid carcinoma.     

Carcinoma of an accessory genital gland in a 23‐year‐old Camargue gelding

This report describes the case management, histopathological and post mortem findings in a 23‐year‐old gelding with a peri‐rectal mass. The mass was debulked surgically and submitted samples revealed it to be a poorly differentiated carcinoma. In the post operative period the horse developed signs of abdominal pain and dysuria and was subjected to euthanasia. Post mortem examination revealed a large infiltrative mass located between the rectum and urethra, consistent with a carcinoma of an accessory genital gland, most likely the seminal vesicle.     

Parotid salivary gland carcinoma in a geriatric horse

This case report describes a geriatric gelding with a 2 month history of fast‐growing masses within the parotid and submandibular regions. The horse was dyspnoeic on presentation and upper airway endoscopy revealed partial airway obstruction at the level of the pharynx, secondary to a space‐occupying mass. Cytological evaluation of multiple fine‐needle aspirates obtained from the masses were suggestive of salivary gland neoplasia, therefore the horse was subjected to humane euthanasia. A computed tomographical scan was obtained post mortem and revealed a large multi‐lobulated mass involving both guttural pouches, resulting in 80% occlusion of the naso‐ and oropharynx. Histopathology confirmed a parotid salivary gland carcinoma (papillary‐cystic type). Salivary gland tumours are extremely rare in horses, with only a few cases reported in the literature. Treatment of these malignancies proves to be challenging, requiring complete parotidectomy or surgical debulkment, in combination with adjunctive therapy.     

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.     

Treatment of primary hyperparathyroidism in a Miniature Horse using chemical ablation of abnormal parathyroid tissue localized by 3‐phase computed tomography

A 15‐year‐old Miniature Horse mare with persistently increased plasma calcium (total and ionized) and serum parathyroid hormone concentrations was presented for suspected primary hyperparathyroidism. Ultrasonography of the thyroid region identified an enlarged heterogeneous mass axial to the right thyroid lobe suggestive of an enlarged parathyroid gland, which was further confirmed using sestamibi nuclear scintigraphy and 3‐phase computed tomography. Percutaneous ultrasound‐guided ethanol ablation of the mass, a method not previously described in the horse, was performed under general anesthesia resulting in rapid normalization of plasma ionized calcium and serum parathyroid hormone concentrations. Ablation of abnormal parathyroid gland tissue may be a suitable alternative to surgical resection in certain cases of primary hyperparathyroidism in the horse.     

PCR for antigen receptor rearrangement (PARR) clonality testing in a horse with a solitary retropharyngeal lymphoma

A 19-year-old Quarter Horse gelding was evaluated for respiratory distress and a rapidly enlarging retropharyngeal mass. Initial evaluation revealed severe respiratory distress, and a large, firm mass, visibly appreciable as 12 × 12 cm, in the left retropharyngeal and perilaryngeal region, with surrounding left and right retropharyngeal swelling. No significant abnormalities were present on complete blood count and serum biochemistry analyses. Endoscopy revealed severe pharyngeal collapse restricting airflow without gross abnormalities of the pharyngeal mucosa other than inflammation and irritation. A multilobular retropharyngeal mass, diffusely heterogeneous in echogenicity, was present adjacent to, but not occluding, the carotid artery as assessed by ultrasonography. Initial needle aspirate suggested lymphoma. Tissue biopsy and histopathology confirmed a round cell tumour. A temporary tracheotomy was performed to provide respiratory relief, and the horse was managed on oral antibiotics and anti-inflammatory medications while awaiting histopathological results. The decision was made to humanely euthanise the horse after biopsy results indicated lymphoma. Definitive diagnosis of T cell rich, large B cell lymphoma was made by combination of cytology, immunohistochemistry and molecular clonality PCR (PARR) testing. Lymphoma should be considered in horses with focal masses of the retropharyngeal region. Although treatment was not pursued, PARR testing was successful in this case and may be helpful for accurate characterisation of lymphoma in horses to more precisely determine prognosis and the most effective treatment plans, as it has been in human patients and small animals.     

The effects of different iodide availabilities on thyroid function during development in Japanese quail

Japanese quail (Coturnix japonica) were used to study the effects of different egg iodide (I) availabilities on thyroid function during development. Low (less than 50 micrograms 1/kg feed in the maternal diet) and high (1200 micrograms 1/kg feed) I availability were compared to control levels (800 micrograms 1/kg feed), a standard supplementation for game bird feed. We measured thyroid gland content of I, triiodothyronine (T3) and thyroxine (T4), plasma concentrations of T3 and T4, hepatic 5' monodeiodinase (5'-D) activity, and the response of the thyroid gland to thyrotrophin (TSH) stimulation. Embryos, on day 14 of the 16.5-17 day incubation period, and 1-day chicks were used for most studies but thyroid gland hormone content and plasma hormone concentrations were determined for more stages. With high I, thyroidal I content was elevated but thyroidal T4 and T3 were not different from controls. Plasma T3 and T4, the thyroid gland response to TSH stimulation, and hepatic 5'-D activity did not differ between control and high I. Reduced body weight occurred with high I. In general, thyroid gland weight was not altered, but some high I birds exhibited thyroid hypertrophy and altered thyroid gland function. With low I availability, thyroid gland contents of I and T4 were reduced but thyroidal T3 content was maintained. The thyroid gland response to TSH stimulation, plasma thyroid hormone concentrations, and the developmental patterns of plasma thyroid hormones, hepatic 5'-D activity, body weight and thyroid weight were not different between control and low I groups. Developing Japanese quail exhibit excellent ability to adjust thyroid function over a wide range of I availabilities. Regulation appears to occur at the level of thyroid hormone synthesis in the thyroid gland, which allows most aspects of thyroid dynamics to remain unchanged in the maintenance of circulating thyroid hormone concentrations.     

Antemortem diagnosis of cholangiocellular carcinoma in a horse.

A 10-year-old Tennessee Walking Horse gelding was admitted to the veterinary teaching hospital for evaluation of intermittent fever, lethargy, and anorexia. Initial laboratory analyses revealed anemia and hyperfibrinogenemia. Abdominocentesis and thoracentesis yielded fluid samples with high nucleated cell counts and total protein concentrations. The tentative diagnosis was nonseptic peritonitis. The horse did not improve after 4 days of antimicrobial treatment, and pitting edema of the ventral midline developed. Thoracic radiography and ultrasonography revealed consolidation of the ventral aspect of the lung fields and pleural effusion. Pleuroscopy of the right hemithorax revealed pleural effusion and a soft-tissue mass in the caudal portion of the mediastinum. Findings on biopsy of the liver and mediastinal mass led to a presumptive diagnosis of metastatic cholangiocellular carcinoma. The horse was euthanatized, and the diagnosis was confirmed at necropsy.     

Functional cystic thyroid adenoma in a cat

A 9-year-old cat with hyperthyroidism was referred for radioactive iodine treatment. The cat also had a ventral cervical mass that the owners reported had been present for several years and had increased in size during the past few weeks. On physical examination, the mass was found to have caused lateral displacement of the trachea, esophagus, jugular vein, and common carotid artery. The mass was aspirated and was determined to be cystic in nature. Concentrations of thyroid hormones in the cystic fluid were similar to serum concentrations, and nuclear scintigraphy revealed thyroactive tissue lining the cyst wall. Magnetic resonance imaging suggested that the cyst originated from the right lobe of the thyroid gland. The cat was treated with sodium iodide I 131 but died 4 days later, presumably as a result of aspiration of gastric or esophageal contents. A necropsy was not performed, but histologic examination of a biopsy specimen of the mass indicated that it was a cystic thyroid adenoma.     

Hemithyroidectomy in a horse with confirmed hyperthyroidism

A 23-year-old Quarter Horse gelding was admitted to the hospital because of cachexia and hyperactive behavior of 1 year's duration. At admission the horse was severely emaciated, tachycardic with a grade V/VI diastolic murmur, pyrexic, polydipsic, enophthalmic, and alopecic. The right lobe of the thyroid gland was noticeably larger than typical. The horse was also hyperexcitable and had a ravenous appetite. A presumptive diagnosis of hyperthyroidism was made on the basis of clinical signs and high plasma thyroid hormone concentrations. Confirmation of the diagnosis was made on the basis of results of a triiodothyronine-suppression test. Following endocrine testing, the affected portion of the thyroid gland was removed and identified histologically as an adenoma. Return or plasma thyroid hormone concentrations to reference range values and resolution of the clinical signs of disease following hemithyroidectomy provided further conformation of the diagnosis. On the basis of finding in this horse, it appears that horses with hyperthyroidism may be successfully treated by hemithyroidectomy.     

Dyspnea Caused by an Obstructive Tracheal Leiomyoma in a Horse: A Rare Case

Tracheal leiomyoma is a rare neoplasm of the respiratory tract in animals. This primary benign tumor arises from smooth muscle cells of the trachea. We report a 13-year-old female horse with clinical signs of severe airways obstruction. It had dyspnea, exercise intolerance, chronic progressive respiratory noises, and cyanosis in mucosa membranes. Radiography revealed a foreign body obliterating the luminal trachea. Endoscopic biopsy showed a 3 × 3-cm ovoid mass attached to the dorsal aspect of the trachea. Hematoxylin and eosin and Masson's trichrome stains showed dense spindle cells forming irregular bundles disposed in short interlacing fascicles. Nuclei were elongated with blunt ends, eosinophilic cytoplasm with indistinguishable cell borders, and low mitotic activity. This study is considered the first reported case of an obstructive intratracheal leiomyoma in the horse.     

Septic arthritis and granulomatous synovitis caused by infection with Mycobacterium avium complex in a horse

A 12-year-old American Saddlebred gelding was referred to a veterinary teaching hospital for evaluation of a chronic lameness problem in the right radiocarpal joint. The horse had been treated for osteoarthritis of the right radiocarpal joint with multiple injections of cortisone during the past 3 years. The horse was severely lame on the right forelimb at a trot. Radiography and computed tomography revealed a 3 x 2-cm lytic defect in the distal portion of the radius and periarticular bone proliferation around the right radiocarpal joint. Ultrasonography of the distal portion of the radius revealed a soft tissue mass in the palmarolateral aspect of the joint. Proliferative synovium with a large amount of fibrin was observed in the dorsal and palmar aspects of the joint via arthroscopic examination of the right radiocarpal joint. Histologic examination of synovial biopsy specimens revealed proliferative granulomatous synovitis with giant cells. Mycobacterium avium complex was cultured from the synovial fluid. Infection with M avium complex should be considered in horses with chronic recurring arthritis associated with granulomatous synovitis.     

Effect of recombinant human thyroid stimulating hormone on serum thyroxin and thyroid scintigraphy in euthyroid cats

This study investigated the thyroidal response to administration of recombinant human thyroid stimulating hormone (rhTSH) by means of serum total thyroxine (TT(4)) concentration and pertechnetate uptake by the thyroid gland in six healthy euthyroid spayed female cats. A pertechnetate scan was performed on day 1 to calculate thyroid/salivary gland (T/S) uptake ratio. On day 3, 25 microg rhTSH was injected intravenously. Six hours later the thyroid scan was repeated as on day 1. Blood was drawn for serum TT(4) measurement prior to injection of rhTSH and performance of the pertechnetate scan. Statistically significant differences in mean serum TT(4) concentration, T/S uptake ratio before and 6h after rhTSH administration and T/S uptake ratio between left and right lobes were noted. We can conclude that 25 microg rhTSH increases pertechnetate uptake in the thyroid glands of cats, this should be taken into account when thyroid scintigraphy after rhTSH administration is interpreted.     

Changes in blood levels of progesterone, triiodothyronine and thyroxine and the results of quantitative histological analysis of the placentoma and corpus luteum in cows after prolonged labor

Changes in the cell structure of the placentoma and the corpus luteum were subjected to quantitative histological investigation, parallel with the examination of the concentrations of progesterone (P4), triiodotyronine (T3) and tyroxin (T4) during parturition (Oth hour) and two and six hours after parturition. The hormone concentrations were determined by the RIA method. The results of the quantitative histological analysis of the placentomae and the corpus luteum suggest that when the placenta is retained there is a significantly higher number of maintained epithelial cells in the placentoma crypts and a higher number of unchanged small, dark and large, light lutein serraetion cells in the biopsy of the corpus luteum during the period under investigation. The morphological finding significantly correlates with higher concentrations of P4 in the blood of the cows with retained placenta, as compared with those whose placenta was not retained. It can be derived from the pattern of changes in T3 and T4 concentrations, compared with P4 and with the histological finding, that there is a functional relationship between the placentoma, corpus luteum, and the thyroid gland.     

Prostatic Masses in Geldings: Two Cases

Prostatic masses were detected in two geldings that were presented to our referral hospital for evaluation of dysuria. The masses were detected during transrectal palpation and ultrasonography of the prostate gland and were further evaluated using urethral endoscopy. A 10-year-old gelding underwent intraurethral debulking of the prostatic mass. Histopathological diagnosis was prostatic cystadenoma. The mass regrew within 9 months, and the horse was euthanized due to deteriorating clinical control of urinary continence. In another case, a 12-year-old gelding was scheduled for transurethral debulking; however, the owners decided against treatment and the horse was euthanized due to progression of clinical disease. Postmortem examination revealed the prostate to be nearly completely obliterated by the mass. Histopathological diagnosis was adenocarcinoma incorporated into a spindle cell population of unknown histogenesis. To our knowledge, these represent the first reported cases of equine prostatic cystadenoma and adenocarcinoma. In both horses, referring complaint was dysuria, and identification of the prostatic mass was made on palpation and ultrasonographic examination per rectum. Treatment options for prostatic masses in horses are limited because of the difficulty of obtaining prostatic tissue via biopsy, the surgical inaccessibility of the gland, and the apparent low incidence of occurrence. We have subsequently identified prostatic masses in two additional geldings, both also presenting for dysuria. However, the exact nature of these two apparent prostatic masses has not been definitively diagnosed with histopathological examinations to date. The prostate should be evaluated in male horses presenting for dysuria.     

Ultrasonographic characteristics of splenic and hepatic lymphosarcoma in three horses.

Splenic and hepatic ultrasonography were beneficial for diagnosis of lymphosarcoma in 3 horses with anorexia, weight loss, and lethargy. Ultrasonographic abnormalities of the spleen included a large, complex, hypoechoic mass in 1 horse, multiple well-marginated, hypoechoic nodules in 1 horse, and diffuse hyperechogenicity in another horse. Ultrasonographic abnormalities of the liver included a spherical, hypoechoic nodule in 1 horse and diffuse hyperechogenicity in another. Histologic examination of ultrasound-guided biopsy specimens or aspirates revealed lymphosarcoma. Necropsy findings confirmed diagnosis of lymphosarcoma in all horses. Necropsy findings of the liver and spleen correlated well with antemortem ultrasonographic images.     

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.     

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.