Suspected renal interstitial cell tumor causing polycythemia in two dogs

Here we report a case series of two dogs diagnosed as renal interstitial cell tumor (RICT) accompanied by elevated serum erythropoietin level and marked polycythemia. RICT is a rare tumor in dogs, originating from renal interstitial cells. While several renal tumors such as renal lymphoma, adenocarcinoma, carcinoma, sarcoma, fibrosarcoma and nephroblastoma may cause polycythemia, polycythemia caused by RICT has never been reported in dogs. The tumors in both dogs were solitary and lied within cortex or cortico-medullary junction. Histopathology revealed spindle-shaped cells suggesting mesenchymal origin, with no mitotic figures suggesting that the tumors in both dogs were benign. Following surgical removal of the affected kidney, serum erythropoietin level and polycythemia normalized in both dogs.

Multiple myeloma and primary erythrocytosis in a dog

A 13-year-old spayed female mixed breed dog was referred for impaired ambulation, limb tremors, back pain, hypergammaglobulinemia on cellulose acetate electrophoresis, and mild proteinuria. Conventional radiology and magnetic resonance imaging (MRI) suggested multifocal neoplastic bone lesions. At the referral examination, lameness and bright red mucous membranes were observed. Severe erythrocytosis, a monoclonal peak in the β-2 globulin detected by capillary zone electrophoresis, severe proteinuria, bone marrow infiltration of plasma cells, and low serum erythropoietin concentrations were reported. The final diagnosis was multiple myeloma associated with severe primary erythrocytosis. This presentation in a dog is interesting because the combination of both disorders is rare in humans and has not been reported in dogs. Key clinical message: Although rare, multiple myeloma and primary erythrocytosis can occur together in dogs.

Secondary inappropriate polycythemia with splenic hemangiosarcoma in a young adult cat

A 20-month-old castrated male Korean shorthair cat was presented with a 3-week history of intermittent vomiting and anorexia, absolute erythrocytosis, and elevated erythropoietin levels. A diagnosis of splenic hemangiosarcoma was made by histopathology and immunohistochemical identification of factor VIII. Paraneoplastic erythrocytosis caused by a splenic hemangiosarcoma in a cat is described.

Tetralogy of Fallot with concurrent patent foramen ovale and tricuspid valve dysplasia in a dog

The echocardiographic findings of a young Pomeranian-cross dog with tetralogy of Fallot, patent foramen ovale, and tricuspid valve dysplasia are described. Ongoing medical management of hypoxemia and erythrocytosis was carried out and the dog survived to 2 years of age. Treatment options for tetralogy of Fallot are discussed.

Bilateral renal T-cell lymphoma with hepatic infiltration and secondary polycythemia in a dog: Utility of cytology slides

This is a case of bilateral renal T-cell lymphoma associated with secondary erythrocytosis in a dog. This case is distinctive in using clonality combined with immunocytochemistry to support the diagnosis, thus emphasizing the utility of cytology slides when histology is unavailable. This combination may be a unique canine lymphoma entity.

Granulosa theca cell tumor with erythrocytosis in a llama

A 2.5-year-old, female llama with weight loss and lethargy had a packed cell volume (PCV) of 45% which increased to 57% over 3 wk. Transrectal ultrasonography revealed a mass of mixed echogenicity involving the right ovary, which was removed. A histopathological diagnosis of granulosa theca cell tumor was made. This is the first report of its kind in a llama.

Primary erythrocytosis in a Japanese black calf: a case report

An 8-month-old Japanese Black heifer with severe erythropoietic symptoms was subjected to clinical, histological and cytological examinations. During the 1 month clinical observation period, severe increases in RBC count, packed cell volume and haemoglobin concentration were observed. The plasma erythropoietin (Epo) concentration of the heifer (20.7 mIU/ml) was similar to that observed in normal control heifers. Blood gas examinations of the arterial and venous blood revealed low levels of partial pressure O(2) (PaO(2)), partial pressure CO(2) (PaCO(2)) and O(2) saturation (SaO(2)), while the blood pH was within the normal range. Gross lesions could not be detected. However, microscopic observation revealed severe proliferation of erythroblasts in the bone marrow and in the spleen without evidence of neoplastic changes. Based on these clinical and pathological examinations, we diagnosed the heifer as being the first case of primary erythrocytosis in Japanese Black cattle.

Secondary Erythrocytosis Associated with Schwannoma in a Dog

An 11-year-old, spayed female mixed-breed dog showed clinical signs of right forelimb lameness and pain by palpation around the neck. Radiography and computed tomography (CT) revealed an extradural mass at the 6th and 7th cervical vertebrae, which compressed the spinal cord. The mass was surgically removed and histopathologically diagnosed as schwannoma. The dog recovered her normal gait after hemilaminectomy and removal of the mass. Ten months after the surgery, the tumor recurred with absolute erythrocytosis and was surgically removed again. This removal temporarily resolved the erythrocytosis with a decrease in plasma erythropoietin (EPO) concentration. EPO protein was detected immunohistochemically in the tumor cells. Erythrocytosis in this dog may be caused by ectopic EPO produced in the schwannoma tissues.

Secondary erythrocytosis associated with high plasma erythropoietin concentrations in a dog with cecal leiomyosarcoma

A 14-year-old mixed-breed dog was examined because of severe absolute erythrocytosis (PCV, 70%). Plasma erythropoietin (EPO) concentration was consistently high, even though results of arterial blood gas analyses were normal. Radiography, ultrasonography, urinalysis, and serum biochemical analyses did not reveal any cardiac, pulmonary, or renal abnormalities that could cause the erythrocytosis, and erythrocytosis secondary to inappropriate EPO secretion was diagnosed. The PCV was maintained at approximately 60% by means of periodic phlebotomy, and the dog died of acute renal failure 2 years later. At necropsy, a cecal leiomyosarcoma was identified. Immunohistochemical staining of sections of the tumor revealed intracellular vacuoles containing EPO, and EPO mRNA was detected in the tumor by use of a reverse transcriptase-polymerase chain reaction assay These results suggested that ectopic production of EPO by a cecal leiomyosarcoma was the cause of erythrocytosis in this dog.

Hydroxyurea for treatment of polycythemia secondary to right-to-left shunting patent ductus arteriosus in 4 dogs

Four adult dogs with polycythemia secondary to reversed patent ductus arteriosus (rPDA) were treated with hydroxyurea, a myelosuppressive agent, for 6-22 months. Regardless of initial hematocrit, clinical signs attributed to the presence of polycythemia improved with hydroxyurea treatment. Chronic hydroxyurea therapy (40-50 mg/kg PO q48h) was well tolerated in this group of animals; mild, clinically silent thrombocytopenia and leukopenia were detected in some animals but resolved with decreased dosage or dose frequency. Chronic hydroxyurea therapy may provide an alternative to repeated phlebotomy for therapy of polycythemia secondary to rPDA.

Effects of phlebotomy on haemodynamic characteristics during exercise in standardbred trotters with red cell hypervolaemia

Five Standardbred trotters with red cell hypervolaemia (RCHV) were compared before and after removal of approximately 22% (36 ml/kg bwt) of the total blood volume in order to evaluate the haemodynamic responses, haemorheological alterations and oxygen transport during exercise to fatigue. Data were recorded during submaximal exercise at 4 different speeds on a treadmill and then during continued running at the highest speed step until fatigue. Oxygen uptake (VO2), pulmonary artery pressure (PAP), systemic artery pressure (SAP), heart rate (HR), haematocrit and haemoglobin concentrations (Hb) were measured. Arteriovenous O2 content difference (C(a-v)O2), pulmonary vascular resistance (PVR) and total systemic resistance (TSR) were calculated. Whole blood and plasma viscosity and erythrocyte aggregation tendency were determined with a rotational viscometer. Endoscopy was performed after exercise. ANOVA was used for statistical analysis. Phlebotomy resulted in a decrease in haematocrit and Hb during the course of exercise. Blood and plasma viscosity were lower and erythrocyte aggregation tendency was higher after phlebotomy. Throughout exercise, including submaximal work and continued running to fatigue, PAP, SAP, PVR, TSR and C(a-v)O2 were lower after phlebotomy. HR was higher after phlebotomy during submaximal exercise. Oxygen delivery and VO2 were lower after phlebotomy in the period from submaximal exercise to fatigue. Run time to fatigue was shorter after phlebotomy. Four horses showed exercise-induced pulmonary haemorrhage (EIPH) before phlebotomy and the degree of bleeding was diminished but not abolished after phlebotomy. The reductions in PVR, TSR, PAP and SAP after phlebotomy were probably a result of reduced blood viscosity. In conclusion, although a 22% reduction in blood volume improved the haemodynamic and haemorheological parameters and the degree of EIPH, it was found that RCHV trotters have to rely on high oxygen delivery to the working muscles for maintenance of maximal performance.

Long-term clinical management of right-to-left ("reversed") patent ductus arteriosus in 3 dogs

A small number of dogs with patent ductus arteriosus (PDA) have right-to-left flow of blood through the ductus, leading to polycythemia and clinical signs associated with hyperviscosity. Three dogs with right-to-left-shunting PDA are described. Treatment consisted solely of phlebotomy, performed on an outpatient basis when indicated by exacerbation of clinical signs, for a total of 11-68 times on each dog. Each treatment entailed the removal of a mean of 19% (maximum 28%) of circulating blood volume, divided into 2 phlebotomies several hours apart, without intravenous fluid replacement. Subjectively, marked clinical improvement was noted. Intermittent clinical signs decreased in frequency and severity in all dogs. Adverse effects were rare (1 for 98 phlebotomies) and reversible. Dogs lived > 2 to > 8 years during treatment. Outpatient phlebotomy without fluid replacement was safe, and was associated with subjective improvement and prolonged survival in these dogs.

Hepatoblastoma with erythrocytosis in a young female horse

A 2.5-year-old female Thoroughbred was examined because of lethargy, anorexia, and weight loss. Analysis of a CBC revealed erythrocytosis and an increase in PCV. Serum biochemical analysis revealed increases in activities of several hepatic enzymes. Ultrasonography revealed hepatomegaly and a heterogeneous appearance of the hepatic parenchyma. The horse did not improve despite supportive care, and it was euthanatized. Necropsy revealed numerous raised white to gray foci in the liver. Histologically, these foci consisted of neoplastic cells that resembled fetal hepatocytes, embryonal-type cells, and cells with features intermediate between those 2 cell types. Immunohistochemical staining revealed that hepatocytes stained strongly with anti-alpha-fetoprotein. On the basis of these results, hepatoblastoma was diagnosed. Diagnosis of hepatoblastoma is difficult, because it can appear histologically similar to other hepatic tumors, such as hepatocellular carcinomas. Definitive diagnosis requires histologic evaluation of tumor architecture and cell morphology. Immunohistochemical staining for alpha-fetoprotein in tumor cells may serve as a tumor marker but is not pathognomonic of hepatoblastoma. Paraneoplastic syndromes, such as erythrocytosis, can accompany hepatoblastoma. The prognosis for horses with hepatoblastoma is grave.

A rare case of patent ductus arteriosus in a dog with glomerular mesangiolysis

Rare case of patent ductus arteriosus (PDA) was observed in a 2-year and 9 month-old Miniature Dachshund which had been diagnosed as severe cardiac failure. Pulmonary artery from the right ventricle connected to dilated ductus arteriosus, and pulmonary artery-ductus arteriosus-descending aorta formed a continuous duct, which seemed to be the main route of bloodstream. Ascending aorta from the left ventricle was hypoplastic, and connected to the dilated ductus arteriosus. Glomerular mesangiolysis due to heart failure was also observed in the kidney.

[Convulsions in relation to polycythemia: literature review and case description]

Polycythemia--characterized by an excessive number of erythrocytes--is a rare disease in the dog with a chronic progressive course and unspecific symptoms. There are several forms: a primary, a secondary adequate or a secondary inadequate polycythemia. The clinical workup is done step by step and after stabilization of critical patients, the remaining therapy must address the primary cause. We report on a five year old male Leonberger dog suffering from secondary, inadequate polycythemia. He was presented with apathy, gait disturbances and disorientation. On the basis of the diagnostic workup a pathological process in the kidneys was postulated. Initially focal seizures became generalized later, most probably because of formation of a forebrain thrombus with secondary hypoxia. Even after emergency treatment the general state deteriorated. The course indicated possible sepsis. Because of the critical picture with secondary complications and the poor prognosis, the dog was euthanised. The histopathological results showed T-cell renal lymphoma and secondary injury to the forebrain.

Polyuria and polydipsia and disturbed vasopressin release in 2 dogs with secondary polycythemia

In dogs, secondary polycythemia (SP) may be associated with polyuria and polydipsia (PU/PD). The pathogenesis of this PU/PD has not yet been explained. We hypothesized that hyperviscosity and increased blood volume in SP might affect vasopressin (VP) release, resulting in PU/PD. This hypothesis was tested in 2 dogs with SP caused by renal neoplasia and PU/PD. Osmoregulation of VP release was studied by a modified water deprivation test and by investigating the VP response to hypertonic saline infusion. Water deprivation test results were consistent with an inability to produce concentrated urine despite increasing plasma osmolality. During hypertonic saline infusion, the osmotic threshold of VP release was markedly increased in both dogs, resulting in a delayed VP response to increasing plasma osmolality. The sensitivity of VP release was low normal in both dogs. We conclude that blood hyperviscosity and increased blood volume led to impaired VP release and polyuria.

[Polycythemia caused by liver carcinoma in cattle and sheep]

Polycythemia associated with hepatic carcinoma was diagnosed in a 10-year-old cow, an 8-month-old heifer and a 3-year-old sheep. The cow was referred to our clinic because of weight loss, reduced appetite, hematuria, marked reddening of the mucosa of the tear canal, oral cavity and vestibule and an increased hematocrit. Clinical examination also revealed injected scleral vessels. The erythrocyte count, the PCV, hemoglobin concentration and the activities of the hepatic enzymes were increased. Ultrasonographic examination revealed a very large liver with a focal echogenic lesion. Based on all findings, a diagnosis of polycythemia associated with a liver tumor, was made. The cow was slaughtered. Multifocal liver tumors were diagnosed histologically as hepatocellular carcinoma. The heifer and sheep had similar clinical and hematological findings. Hepatocellular carcinoma was diagnosed in the heifer and cholangiocellular carcinoma in the sheep. It was concluded that in all three patients, polycythemia was caused by hepatic carcinoma.

Serum erythropoietin values in polycythemic cats

Serum erythropoietin (EPO) concentrations and clinicopathological features were evaluated in 31 cats with absolute polycythemia (i.e., packed cell volume [PCV], 52% to 84%). Five cats had high serum EPO values and were classified as having secondary polycythemia. The remaining 26 cats had EPO values in the low or normal range. Four of these 26 cats had clinical evidence of secondary polycythemia and therefore were classified as having secondary polycythemia. In the remaining 22 cases, no signs of secondary polycythemia could be found, and primary polycythemia was diagnosed. A low or normal serum EPO value in a polycythemic cat is consistent with primary polycythemia, but does not exclude secondary polycythemia.

Concurrent renal adenocarcinoma and polycythemia in a dog

Concurrent renal adenocarcinoma and polycythemia were diagnosed in a 19-month-old, female Rhodesian ridgeback. An unusually early presentation for this neoplasm, it is the second reported case of renal adenocarcinoma in a dog less than two years of age. Concurrent renal adenocarcinoma and polycythemia have been reported previously in four older dogs. In the dog of this report, clinical signs included brick-red mucous membranes, lethargy, a periodic systolic heart murmur, and engorged retinal vessels. A large retroperitoneal mass and pulmonary metastatic nodules were present at the time of diagnosis. Red blood cell count, packed cell volume, and hemoglobin concentration were greatly increased (12,940,000 red blood cells/microliter; 73.2%; and 26.6 g/dl, respectively). Histopathological diagnosis was renal adenocarcinoma. Polycythemia was the result of excessive erythropoietin production by the neoplasm.

Polycythemia in a llama

The PCV of a llama increased from 50.8 to 74.0% during a 19-month period. The llama remained clinically normal unless stressed, when it would become dyspneic and tachypneic. Thoracic auscultation revealed sounds consistent with pneumonia, but were probably attributable to pulmonary congestion resulting from polycythemia. A diagnosis of secondary absolute polycythemia was made on the basis of high serum erythropoietin concentrations and no evidence of hypoxia. Necropsy revealed congestion of the lungs and liver. Cause of the polycythemia was not determined. Polycythemia should be considered as a differential diagnosis in a llama with exercise intolerance and harsh bronchovesicular sounds.

Serum erythropoietin concentrations measured by radioimmunoassay in normal, polycythemic, and anemic dogs and cats

Serum erythropoietin (Epo) concentrations were measured by radioimmunoassay (RIA) in normal, polycythemic, and anemic dogs and cats. The serum Epo concentration in normal dogs (n = 25) ranged from 7 to 37 mU/mL (median, 20 mU/mL); and in normal cats (n = 11) ranged from 9 to 38 mU/mL (median, 18 mU/mL). Polycythemic animals (PCV > 55% in dogs, > 45% in cats) were classified as those with primary (polycythemia vera), secondary, or polycythemia of uncertain etiology. Dogs with polycythemia vera (PV, n = 8) had a median serum Epo concentration in the normal range (17 mU/mL); cats with PV (n = 7) also had a median serum Epo concentration that was within the normal range (10 mU/mL). In the category of secondary polycythemias, dogs (n = 7) (median, 30.7 mU/mL) and cats (n = 2) had normal Epo concentrations. The median serum Epo concentration was significantly decreased (P < .05) in dogs with PV compared with dogs with secondary polycythemias. The median serum Epo concentrations in dogs (n = 13) and cats (n = 5) with anemias not due to chronic renal disease were significantly increased (P < .05) compared with normal dogs and cats. In cats with anemias due to chronic renal disease (n = 5) the median serum Epo concentration was not significantly different from normal cats. The measurement of the serum EPO concentration may be useful in assessment of anemia or polycythemia but the overlap of values with the normal range in all groups evaluated limit its diagnostic use.

Metabolic response to standardised exercise test in standardbred trotters with red cell hypervolaemia

Plasma concentrations of lactate, amino acids, ammonia and products of purine catabolism were studied before, during and after a standardised incremental exercise test in 29 Standardbred trotters admitted to the clinic for exercise tolerance testing. According to their red cell volume the horses were divided into red cell normovolaemic and red cell hypervolaemic (polycythaemic) groups. The exercise-response curve for taurine differed significantly in the two groups, whereas all the other amino acids behaved similarly. The [branched-chain amino acid]/[alanine] ratio, a proposed indicator for the use of amino acids in gluconeogenesis, was at rest significantly higher in the polycythaemic horses. Post-exercise concentrations of ammonia and allantoin, both end products of ATP breakdown, were lower in the polycythaemic horses. No differences were observed in the VLA4 and V200 markers for lactate and heart rate responses to incremental exercise, the oxidative capacity of the gluteus medius muscle, the enzyme activities or the post-exercise concentration of lactate, uric acid and hypoxanthine. It is concluded that horses with red cell hypervolaemia behave in a submaximal standardised exercise test on a treadmill in the same way as do red cell normovolaemic horses. The results suggest that the rate of amino acid utilisation in gluconeogenesis and the ability of amino acids to produce energy aerobically may be elevated in polycythaemic horses.

Increasing incidence of anemia among clinically ill Georgia broilers: 1988-89 vs. 1990

The incidence of anemia in clinically ill Georgia broilers climbed from 66.4% (324/488) during 1988-89 to 80.9% (531/656) during 1990. The incidence of polycythemia fell from 1.6% (8/488) during 1988-89 to 1.5% (10/656) during 1990. Specifically, compared with 1988-89, the 1990 incidence of anemia increased significantly in chicks at age 7 days (P = 0.0002) and 28 days (P = 0.05). We have no certain explanation for this shifting incidence of anemia in clinically ill Georgia broilers. Anemic chicks have plasma that contains virus particles with morphologic characteristics consistent with a virus (chicken anemia agent [CAA]) known to cause anemia in chickens. If CAA is the predominant etiology for anemia in clinically ill Georgia broilers, then our observation could be easily explained. The increasing rate of anemia could indicate a decline in broiler health over time.

Incidence of anemia and polycythemia in clinically ill Georgia broilers

The incidence of anemia and polycythemia was established in clinically ill Georgia broilers that were tested for packed cell volume (PCV) during 1988 and 1989. More than 66% (324/488 = 66.4%) of PCV-tested broiler chicks were anemic, and less than 2% (8/488 = 1.6%) of PCV-tested chicks were polycythemic. The incidence of anemia was significantly (P less than 0.001) higher than expected (2.5%) at age 7 days (56.9%), 14 days (83.9%), 21 days (74.7%), 28 days (58.7%), and 35 days (57.9%). The incidence of polycythemia was significantly (P less than 0.001) higher than expected (2.5%) in 35-day-old broilers (21.1%) but was not significantly different from the expected rate in broilers at age 7 days (0%), 14 days (1.8%), 21 days (0.3%), and 28 days (4.3%). The established rates for anemia were much higher than we would have hypothesized. This led us to believe that either 1) an etiology for anemia is present in epizootic proportions in Georgia broilers, or 2) the standard method for establishing reference intervals for anemia in animals does not apply to broiler chicks.

Packed cell volume reference intervals to aid in the diagnosis of anemia and polycythemia in young broiler chickens

Packed cell volume (PCV) reference intervals were established for use in diagnosing anemia and polycythemia in young broiler chickens. Blood samples were collected from one hundred twenty 3-to-49-day-old clinically healthy conventionally reared broiler chickens. PCVs were determined and analyzed. PCVs regressed significantly (P less than 0.025) on age, which shows that neonatal physiologic anemia occurs in broiler chickens, as well as in mammals and specific-pathogen-free (SPF) chickens. The definition for anemia in broiler chicks varies with age. We defined anemia as a PCV less than or equal to 26%, 29%, 33%, 32%, 33%, 33%, 31%, and 28% for broiler chickens, 3, 7, 14, 21, 28, 35, 42, and 49 days old, respectively. We define polycythemia as a PCV greater than or equal to 42%, 43%, 41%, 40%, 42%, 42%, 41%, and 40% for broiler chickens 3, 7, 14, 21, 28, 35, 42, and 49 days old, respectively. Otherwise, broiler chickens have PCVs within established reference intervals. Results provide guidelines for detecting anemia and polycythemia in young broiler chickens of various ages.

Packed cell volume reference intervals to aid in the diagnosis of anemia and polycythemia in young leghorn chickens

Packed cell volume (PCV) reference intervals were established for use in diagnosing anemia and polycythemia in young chickens. Blood samples were collected from 3-to-35-day-old specific-pathogen-free leghorn chicks. PCVs were determined and analyzed. PCVs regressed significantly (P less than 0.0001) on age, which shows that neonatal physiologic anemia occurs in chicks as well as in mammals. The definition for anemia in chicks varies with age. We defined anemia as a PCV less than or equal to 23%, 25%, 26%, 28%, 31%, and 30%, respectively, for chicks 3, 7, 14, 21, 28 and 35 days old. We defined polycythemia as a PCV greater than or equal to 36%, 37%, 38%, 37%, 41%, and 40%, respectively, for chicks 3, 7, 14, 21, 28, and 35 days old. Healthy chicks have PCVs within established reference intervals. Results provide guidelines to detect anemia and polycythemia in young leghorn chicks of various ages.

Pulmonary artery, aortic and oesophageal pressure changes during high intensity treadmill exercise in the horse: a possible relation to exercise-induced pulmonary haemorrhage

This study investigated changes in packed cell volume (PCV), pulmonary artery and aortic pressures, and the interaction between oesophageal pressure and pulmonary artery and aortic pressures during strenuous exercise in the horse. It was hypothesised that oesophageal pressure changes summate with pulmonary artery and aortic pressures during exercise and contribute to exercise-induced pulmonary haemorrhage (EIPH). Acute treadmill exercise (10 m/sec, 3 degrees incline) produced increases in heart rate (HR) from 50 to 202 beats/min; mean pulmonary artery pressure (PAP) from 28 to 80 mmHg; mean aortic pressure (AP) from 108 to 157 mmHg; and PCV from 0.35 to 0.52 litres/litre. EIPH was observed in three of seven horses after treadmill exercise, but no differences in the above variables were observed between the two groups of horses. Electronic subtraction of the oesophageal pressure signal from PAP and AP signals indicated peak transmural pressures of approximately 150 mmHg pulmonary and 175 mmHg aortic pressure. The elevated PAP associated with exercise appeared related more to increased HR and less to PCV (blood viscosity) or AP (bronchial). Both pulmonary artery and aortic peak transmural vascular pressures were substantially influenced by oesophageal pressure changes; peak and mean pulmonary artery and aortic pressures were significantly higher than resting pressures, and may conceivably contribute to EIPH.

Transient glomerulonephropathy associated with primary erythrocytosis in a dog

Proteinuria (urine protein/creatinine ratio, 13.6) resolved after control of primary erythrocytosis in a dog. Hydroxyurea and doxorubicin administration and phlebotomy were used initially to manage erythrocytosis. Remission was maintained for approximately 2 years. Glomerulonephropathy, characterized by absence of routine histologic or immunofluorescent changes and ultrastructural evidence of basement membrane deterioration and podocyte fusion, was documented. These lesions may have been a result of hypoxia and/or hyperviscosity secondary to erythrocytosis.

Hepatocellular carcinoma associated with erythrocytosis and hypoglycemia in a yearling filly

A yearling Arabian-type filly with a history of poor growth, erythrocytosis, hypoglycemia, and high liver enzyme activities was admitted to the hospital for evaluation. Three days after admission, the filly collapsed, deteriorated rapidly despite treatment, and was euthanatized. A metastatic hepatocellular carcinoma with capsular rupture and hemoperitoneum were found at necropsy. Primary liver tumors are rare in horses, and hepatocellular carcinoma has been reported in only 1 other horse. The systemic manifestations of the tumor in this filly included weakness, weight loss, inappetence, erythrocytosis with tumor production of erythropoietin, persistent hypoglycemia with normal serum insulin concentrations, serum alpha-fetoprotein (normally present only during fetal life), and terminal massive hemoperitoneum, all features of the syndrome in man.

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.

Polycythemia associated with renal fibrosarcoma in a dog

A 10-year-old Beagle-type dog with intermittent vomiting and anorexia had an absolute polycythemic condition. A renal mass was detected and removed by total nephrectomy. After surgery, the hematologic values returned to normal, suggesting that the tumor was the cause of the polycythemia. The histologic diagnosis was fibrosarcoma. In dogs, secondary polycythemia has otherwise been reported with renal carcinoma and lymphosarcoma.

Use of the flexible film isolator as a single circuit hypoxic chamber for small animals

PVC isolators are now widely used for housing animals and provide a readily available pretested air-tight chamber (Pendry, 1984; Trexler, 1984). We have adapted a flexible film isolator for use as a hypoxic chamber for small animals. The environment within the chamber can be easily and continuously monitored with indwelling probes, obviating the need for a separate circuit for gas analysis. This design has been used for long-term studies of chronic hypoxia.

Paraneoplastic disorders in dogs with hematopoietic tumors

Often overlooked in the presence of neoplasia, PNDs constitute significant clinical entities in dogs with hematopoietic tumors. They may cause morbidity and mortality in such patients, with effects more severe than those caused by the associated tumor. Accurate clinical evaluation of these disorders is important in differential diagnosis and treatment, for failure to realize that cancer can produce many clinical signs similar to those of other diseases may lead to incorrect diagnosis and delayed therapy. Early recognition of the problem underlying the PND is essential to selecting the proper therapeutic approach and maximizing the patient's chances for remission and survival. The presence of these disorders may complicate or rule out the preferred therapy in some cases of hematopoietic neoplasia, because the addition of cytotoxic drugs may worsen the existing PND, predisposing the dog to a variety of complications. Appropriate management of the PND may be of more immediate importance than treatment of the tumor. The study and recognition of PNDs in dogs with hematopoietic tumors may be valuable for a number of reasons: to facilitate early diagnosis of the tumor, for the observed abnormalities may represent tumor cell markers; to allow assessment of premalignant states; to aid in the search for metastases; to help quantify and monitor response to therapy; to aid in the evaluation of tumor recurrence or progression; to aid in identifying specific pathophysiologic processes by which cancer produces systemic effects; and to provide insight into the study of malignant transformation. Recognition of PNDs is relevant to the diagnosis and treatment of many problems in veterinary cancer medicine. With increasing emphasis on diagnosis and treatment of canine hematopoietic tumors, PNDs will be recognized with greater frequency and will assume greater importance in the therapeutic management of those patients. Research in veterinary and human cancer medicine needs to be directed toward identifying more definitively those substances and pathways that are responsible for PNDs, because therapy directed toward arresting the specific pathophysiologic processes causing the PND may offer the best approach for successful management of cancer.

Laboratory aspects of cancer

Hematologic alterations unrelated to neoplastic bone marrow involvement include polycythemia, anemia, leukocytosis, leukopenia, thrombocytosis, thrombocytopenia and coagulopathies. Serum globulin levels may be increased or decreased, depending on the type of neoplasm. Plasma fibrinogen and fibrin degradation product concentrations are usually elevated in cancer patients, whereas cancer patients with DIC have low plasma fibrinogen concentrations. Hypercalcemia can be a sequel of osseous metastases. Neoplasia may cause the nephrotic syndrome in some patients. Effusions should be examined microscopically for signs of malignancy. Elevated serum enzyme levels are not specific in neoplastic disease.

Diagnosis of canine primary polycythemia and management with hydroxyurea

Severe polycythemia was found in 3 dogs with PCV 68% to 70%. Direct RBC mass determinations were increased in all dogs, confirming absolute polycythemia. Cause for secondary polycythemia was not found in any of the dogs; serum erythropoietin concentrations were undetectable, consistent with primary polycythemia. The polycythemia and associated clinical signs were controlled successfully for extended periods (mean, 16.6 months), using phlebotomy followed by oral administration of hydroxyurea in loading and in daily maintenance dosages.

A retrospective study of canine hemangiosarcoma and its association with acanthocytosis

A retrospective study was conducted on cases of canine hemangiosarcoma diagnosed at the Western College of Veterinary Medicine between 1969 and 1979. A total of 33 dogs were assessed with respect to breed, age, sex and site of neoplasia. Hemangiosarcoma was most common in older dogs and there was no sex predilection. Incidence was highest in German Shepherds. The primary sites in order of most frequent occurrence were spleen, right atrium and liver. Acanthocytes were found in six of 12 dogs examined. There was no association between acanthocytosis and such factors as breed, primary site of the neoplasm and splenic or hepatic involvement.

A normobaric hypoxia facility for preparing polycythemic mice for assay of erythropoietin

A normobaric hypoxia chamber was designed in which large numbers of mice (up to 250) were made polycythemic, after which they were used in an erythropoietin assay. The hypoxic atmosphere was composed of air diluted with N2 gas generated from liquid N2. Continuous exposure of mice to 8% O2 for 11 da resulted in a polycythemia of sufficient magnitude and duration to provide appropriate erythropoietic conditions for the erythropoietin assay. The chamber, which has been in almost continuous operation for 3 yr, requires little attention and maintenance and has proved to be reliable, safe, and economical.