Insulin-Secreting Pancreatic (Islet Cell) Carcinoma in a Cat

A functional, insulin-secreting pancreatic (islet cell) carcinoma was diagnosed in a 17-year-old male Siamese cat. Diagnosis was made on the basis of clinical signs (i.e., seizures and stupor) that resolved temporarily after correction of hypoglycemia with feeding or intravenous administration of glucose, the finding of an inappropriately increased serum insulin concentration in the face of hypoglycemia, and prolonged resolution of hypoglycemia after surgical removal of the tumor. Primary islet cell tumor of the pancreas was confirmed by biopsy. The cat died 18 months later, and necropsy revealed metastases to regional lymph nodes and liver. Specimens of the tumor and metastatic lesions both stained positively for insulin.     

Central Diabetes Insipidus in a Dog With a Pro-Opiomelanocortin-Producing Pituitary Tumor ot Causing Hyperadrenocorticism

Central diabetes insipidus was diagnosed by vasopressin measurements during hypertonic stimulation in a 9-year-old male giant Schnauzer with polyuria and polydipsia. The impaired release of vasopressin was believed to be caused by a large pituitary tumor, which was visualized by computed tomography. Studies of the function of the anterior lobe and the pars intermedia of the pituitary gland were conducted, and high concentrations of ACTH and α-melanotrophic hormone (α-MSH) were found without concomitant hyperadrenocorticism. Studies of the molecular size of the immunoreactive ACTH in plasma by gel filtration revealed that most of the circulating immunoreactivity was not ACTH but its precursor pro-opiomelanocortin (POMC) and low-molecular-weight POMC-derived peptides. The pituitary tumor of this dog probably originated from melanotrophic cells of the pars intermedia. The sensitivity of the pituitary-adrenocortical system for the suppressive effect of dexamethasone was unaffected.     

Omeprazole in a Dog With Gastrinoma

A 9-year-old male German Shepherd Dog was presented with the primary complaints of vomiting, profuse watery diarrhea, anorexia, and severe weight loss. The dog developed hematemesis and melena, which were unresponsive to treatment with an H₂-receptor antagonist and a gastrointestinal protectant. A marked neutrophilia, panhypoproteinemia, hypokalemia, and mildly increased activities of alkaline phosphatase and alanine aminotransferase were the only relevant abnormalities found on a CBC, serum biochemical profile, and urinalysis. An exploratory laparotomy revealed several small nonresectable masses at the root of the mesentery, which were identified histologically as a neuroendocrine neoplasm. Immunohistochemical staining of the neoplasm was positive for gastrin and negative for insulin, glucagon, pancreatic polypeptide, and vasoactive intestinal polypeptide. Fasting serum gastrin concentrations were high. Zollinger-Ellison syndrome was diagnosed, and the dog was treated with omeprazole, an H+, K+-ATPase inhibitor. All clinical signs resolved, and the dog remains asymptomatic 2 years later. Omeprazole may be the gastric acid antisecretory drug of choice for dogs with gastrinoma.     

Fanconi's Syndrome in a Dog With Primary Hypoparathyroidism

An 11 -year-old castrated male mixed breed dog was referred for evaluation of muscle twitching, polyuria, polydipsia, anorexia, and periocular alopecia. Primary hypoparathyroidism was diagnosed by documenting decreased serum concentrations of parathyroid hormone and ionized calcium. Neurological, gastrointestinal, and dermatological signs resolved after calcium repletion. Initially, 1,25-dihydroxycholecalcif erol PO was required to correct the hypocalcemia. Dihydrotachysterol, in combination with oral calcium supplementation, was used for long-term maintenance of normal serum calcium concentration. Aminoaciduria, glucosuria, and hyperchloremic metabolic acidosis were consistent with a diagnosis of Fanconi's syndrome. This diagnosis was further supported by the presence of hypokalemia and increased urinary fractional excretion of sodium, potassium, calcium, phosphorus, and magnesium. Renal tubular dysfunction resolved after oral supplementation with calcium and vitamin D₃. Fanconi's syndrome in this dog may have been caused by decreased serum concentration of 1,25-dihydroxycholecalciferol, which was secondary to decreased parathyroid hormone production.     

Tumor-Associated Erythrocytosis in a Dog With Nasal Fibrosarcoma

Erythrocytosis (hematocrit, 79%) was diagnosed in an 8-year-old, neutered female, mixed-breed dog with an intranasal fibrosarcoma. Both serum and tumor erythropoietin (Ep) activities were elevated, as determined by the polycythemic exhypoxic mouse model, and the Ep activity was neutralized in that model by rabbit anti-Ep antibodies. Tumor resection normalized the hematocrit.     

Monoclonal Gammopathy in a Dog With Visceral Leishmaniasis

One dog with visceral leishmaniasis associated with monoclonal gammopathy is described. Most dogs with visceral leishmaniasis present with hyperproteinemia due to a polyclonal gammopathy, but the possibility of monoclonal gammopathy must be considered. Because dogs accompany their owners when they travel, the diagnosis of leishmaniasis should be considered if an animal with monoclonal gammopathy has visited an area where the disease is endemic. The observation of Leishmania in the macrophages of a bone marrow, lymph node smear, or skin biopsy specimen is diagnostic.     

Monoclonal Gammopathy in a Dog With Chronic Pyoderma

A monoclonal gammopathy composed of immunoglobulin G, with concurrent light-chain proteinuria and generalized lymph node plasmacytosis, was associated with chronic pyoderma in a dog. A uniform population of plasma cells was observed cytologically and histologically in multiple lymph node specimens. A diagnosis of monoclonal gammopathy of unknown significance was eventually made by exclusion of other known causes of monoclonal gammopathy, resolution after antibiotic therapy, and no evidence of lymphoproliferative disease after 11 months of follow-up and subsequent necropsy. This report expands the diagnostic considerations for monoclonal gammopathies in the dog.     

Necrolytic Migratory Erythema in a Dog with a Glucagon-Secreting Endocrine Tumor

Abstract— A 5-year-old mongrel dog developed necrolytic migratory erythema secondary to a glucagon-secreting α cell tumor. The dog was anemic, glucose intolerant, and hyperglucagonemic but liver function tests were within normal limits. Metastatic tumor cells were found in the liver but the primary tumor was not identified.
Résumé— Un chien croisé mâle de 5 ans a développé un Erythème nécrolytique migrant secondaire à un glucayonome. L'animal était anémié, présentait une intolérance au glucose et une hyperglucagonémie, avec des tests fontcionnels hépatiques dans les limites des valeurs usuelles. Des cellules métastaiques tumorales ont été retrouvées dans le foie, mais la tumeur primitive n'a pas été identifiée.
Zusamenfassung —Ein 5 Jahr alter Mischingshund entwickelte sekundär auf einen Glukagon-sezernierenden Tumor ein nekroyltisches Erythema migrans. Das Tier war anämisch, Glukose-intolerant und hyperglukagonämische; die Leberfunktionstests befanden sich jedoch innerhalb normaler Grenzwerte. Matastatische Tumorzellen waren in der Leber nachweisbar, der Primärtumor konnte jedoch nicht identifizert werden.
Resumen  Un perro cruzado de 5 años desarrollo un eritema necrolítico migratorio, secundario a un tumor de celulas secretoras de glucógeno. El perro era anémico, presentaba intolerancia a la glucosa, e hiperglucogenia, pero los resultados de los tests que evaluaban la función hepática feuron normales. Se encontraron células tumorales metastásicas procedentes del hígado, pero el tumor primario no se identificó. Se encontraron células tumorales metastásicas procedentes del hígado, pero el tumor primario no se identificicó.     

Prostatic Adenocarcinoma with Concurrent Sertoli Cell Tumor in a Dog

A case of metastatic prostatic adenocarcinoma with concurrent Sertoli cell tumor is presented in an old, miniature Schnauzer dog. The prostatic neoplasm was highly anaplastic and had metastasized widely. Clinical signs were compatible with increased estrogen production. It is interesting to note that the prostatic carcinoma, usually considered to be androgen dependent, developed and metastasized, despite the presence of apparently increased estrogen levels.     

Incessant Atrial Tachycardias in a Dog With Tricuspid Dysplasia

In a dog, tricuspid regurgitation due to congenital tricuspid dysplasia resulted in extreme right heart enlargement and right heart failure. Incessant supraventricular tachycardias were present, requiring the intravenous administration of verapamil to reduce the ventricular rate. Oral therapy using a combination of verapamil and quinidine was partially effective in controlling the ventricular rate during the following week. At that time, electrophysiologic studies were performed. They revealed that a succession of several atrial tachycardias with different cycle lengths, including one episode of atrial flutter, was present. Atrial activity was spanning the majority of the cycle length in all these arrhythmias. Epicardial mapping was performed during the atrial flutter. This enabled the detection of a depolarization wave-front traveling counterclockwise from the dorsolateral right atrium toward the right appendage, following the tricuspid valve annulus. No areas of abnormal conduction were detected. Because programmed electric stimulation maneuvers could not be performed, definitive conclusions about the mechanism of the arrhythmia could not be drawn. The two most likely possibilities were circus movement using part of the dilated tricuspid valve annulus as an anatomic barrier or a leading circle type of re-entry.     

Lupus-Type "Anticoagulant" in a Dog With Hemolysis and Thrombosis

A circulating anticoagulant was detected in a 2-year-old Chesapeake Bay Retriever with hemolytic anemia, nephrotic syndrome, thrombocytopenia, polyarthropathy, and pulmonary thromboembolism. A persistent prolongation of the activated partial thromboplastin time (aPTT) was detected, and it did not correct with repeated administration of fresh frozen plasma. The aPTT was still prolonged, with a 1:1 mixture of patient's plasma and normal dog plasma in vitro, suggesting the presence of a circulating inhibitor. Results of assays to characterize the inhibitor were compatible with those described for the lupus anticoagulant in human patients with systemic lupus erythematosus. Paradoxically, patients having the lupus anticoagulant are at increased risk for thrombosis. Pulmonary thromboembolism has been described as a frequent complication of immune-mediated hemolytic anemia in the dog, and the presence of a circulating anticoagulant should be considered as a potential mechanism.     

Echocardiography and Surgery in a Dog With Left Atrial Rupture and Hemopericardium

Endocardial splitting and left atrial rupture were diagnosed in a dog with mitral regurgitation that experienced the sudden onset of collapsing episodes, weakness, depression, labored breathing, and weak pulses. Thoracic radiographs showed a rounded cardiac silhouette with prominent left atrium consistent with hemopericardium due to left atrial rupture. Two-dimensional echocardiography confirmed the presence of severe mitral valve disease, pericardial fluid, and a laminated blood clot caudal to the left ventricle. A sterile emergency thoracotomy was performed, the hemopericardium and blood clot were removed, and the rupture site in the left atrium was repaired with reinforced sutures. The dog recovered from surgery but died the next day, presumably from a ventricular arrhythmia.     

Thrombocytopathia and Light-Chain Proteinuria in a Dog Naturally Infected With Ehrlichia canis

A 6–year-old dog was presented for evaluation of recurrent epistaxis. Platelet counts, biochemical tests, and coagulation tests were within the normal range, but a mucosal bleeding time was prolonged; there was hyperproteinemia and a monoclonal gammopathy. Heterogeneity of light chains appeared in urine, however, thus suggesting that the gammopathy was polyclonal. Platelet aggregation tests showed decreased responsiveness to collagen. An Ehrlichia canis indirect fluorescent-antibody titer was positive (1:40). Treatment with tetracycline, melphalan, and prednisone resulted in a rapid clinical improvement that persisted for at least 3 years.