Magnetic resonance imaging and histological classification of intracranial meningiomas in 112 dogs

BACKGROUND: Intracranial meningiomas are the most common primary brain tumors in dogs. Classification of meningiomas by tumor grade and subtype has not been reported, and the value of magnetic resonance imaging (MRI) characteristics for predicting tumor subtype and grade has not been investigated. HYPOTHESIS: Canine intracranial meningiomas are a heterogenous group of tumors with differing histological subtypes and grades. Prediction of histopathological classification is possible based on MRI characteristics. ANIMALS: One hundred and twelve dogs with a histological diagnosis of intracranial meningioma. METHODS: Retrospective observational study. RESULTS: Meningiomas were overrepresented in the Golden Retriever and Boxer breeds with no sex predilection. The incidence of specific tumor grades was 56% benign (Grade I), 43% atypical (Grade II), and 1% malignant (Grade III). Grade I histological subtypes included meningothelial (43%), transitional (40%), microcystic (8%), psammomatous (6%), and angiomatous (3%). No statistically significant (P < .05) associations were found among tumor subtype or grade and any of the MRI features studied. CONCLUSIONS AND CLINICAL IMPORTANCE: Meningiomas in dogs differ from their counterparts in humans mainly in their higher incidence of atypical (Grade II) tumors observed. MRI characteristics do not allow for prediction of meningioma subtype or grade, emphasizing the necessity of histopathology for antemortem diagnosis. The higher incidence of atypical tumors in dogs may contribute to the poorer therapeutic response in dogs with meningiomas as compared with the response in humans with meningiomas.     

Cross-Sectional Imaging Characteristics of Pituitary Adenomas, Invasive Adenomas and Adenocarcinomas in Dogs: 33 Cases (1988–2006)

Background: Pituitary tumors in dogs can be adenomas, invasive adenomas, or adenocarcinomas. In people, invasive adenomas and pituitary adenocarcinomas carry a worse prognosis than adenomas.
Hypothesis/Objective: To identify differentiating features on cross-sectional imaging in dogs with pituitary adenomas, invasive adenomas, and adenocarcinomas.
Animals: Thirty-three dogs that had computed tomography (CT) or magnetic resonance imaging (MRI) performed and a necropsy diagnosis of pituitary adenoma ( n = 20), invasive adenoma ( n = 11), or adenocarcinoma ( n = 2).
Methods: Medical records were retrospectively reviewed for signalment, history, and diagnosis. CT and MR images were reviewed for characteristics of pituitary tumors.
Results: Mean (± standard deviation) age for dogs with pituitary adenomas (10.6 ± 2.9 years) was greater than that of those with invasive adenomas (8.3 ± 2.7 years, P = .04). Eighteen out of 20 (90%) dogs with adenomas had contrast-enhancing masses. Thirteen out of 20 (65%) had homogeneous enhancement. Mean adenoma height was 1.2 ± 0.7 cm. Eight out of 20 (40%) adenomas were round and 8/20 (40%) compressed surrounding brain. Eleven out of 11 dogs (100%) with invasive adenomas had contrast-enhancing masses. Seven out of 11 (64%) masses were homogeneous. Mean invasive adenoma height was 1.8 ± 0.7 cm, which was significantly greater than adenomas ( P = .03). Mass shape varied from round to oval to irregular. Six out of 11 (55%) masses compressed surrounding brain. Clinical and imaging features were variable for 2 dogs with adenocarcinomas.
Conclusions and Clinical Relevance: Invasive adenoma should be suspected if a dog with a pituitary tumor is <7.7 years of age and has a mass >1.9 cm in vertical height. Adenocarcinomas are uncommon and metastatic lesions were not seen with imaging.     

Expression of vascular endothelial growth factor in tumors and plasma from dogs with primary intracranial neoplasms

OBJECTIVE: To quantitatively evaluate expression of vascular endothelial growth factor (VEGF) in intracranial tumors in dogs and determine whether relationships exist between circulating and intratumoral VEGF concentrations and tumor type and grade. ANIMALS: 27 dogs with primary intracranial neoplasms and 4 unaffected control dogs. PROCEDURES: Plasma and brain tumor samples were obtained from each dog, and plasma and intratumoral concentrations of VEGF were measured by use of an ELISA. RESULTS: Dogs with meningiomas (n = 11) were significantly older than dogs with oligodendrogliomas (7) or astrocytomas (9). Measurable VEGF was detected in all tumors, and a significant negative correlation between age and intratumoral VEGF concentration was detected. Age-adjusted comparisons identified significant differences in intratumoral VEGF concentrations among all tumor types; the highest VEGF concentrations were associated with astrocytomas. Within each tumor type, increasing tumor grade was significantly associated with increasing VEGF expression. Plasma VEGF concentrations were detectable in 9 of 27 dogs; the proportion of dogs with astrocytomas and a detectable circulating VEGF concentration (7/9 dogs) was significantly higher than the proportion of dogs with meningiomas (1/11 dogs) or oligodendrogliomas (1/7 dogs) with a detectable circulating VEGF concentration. CONCLUSIONS AND CLINICAL RELEVANCE: Overexpression of VEGF appears common in canine astrocytomas, oligodendrogliomas, and meningiomas. In the neoplasms examined, intratumoral VEGF concentrations correlated well with tumor malignancy. The VEGF expression patterns paralleled those of analogous human tumors, providing evidence that dogs are a suitable species in which to study angiogenesis and intracranial neoplasia for human application.     

Canine orbital meningiomas: a review of 22 cases

Clinical and pathologic features of primary orbital meningiomas in the dog were reviewed. Twenty-two meningiomas, confined to the orbit, were identified from the Comparative Ophthalmic Pathology Laboratory of Wisconsin from 1981 to 1997. The dogs ranged in age from 3 to 17 years (mean = 9.2 years). The clinical presentation, reported in 20 cases, was indicative of a retrobulbar mass and included exophthalmos and orbital swelling (18/20), and papilledema or abnormalities of the posterior segment (7/20). Visual acuity was reported in 15 cases; of those, 12 dogs were blind in the affected eye. Follow-up information was obtained on 17 cases; six dogs developed local recurrence of the neoplasm. Two dogs with recurrent neoplasms simultaneously developed blindness in the opposite eye. Extension along the optic nerve to the optic chiasm was suspected. No metastasis was found at the time of the study. Enucleation with excisional biopsy was effective therapy to date in 11 cases (0.2–4.5 years follow-up time). All neoplasms were located within the vicinity of the optic nerve and, when sectioned through the optic nerve head, appeared to completely envelope the nerve. The neoplastic cells were arranged in tight whorls and bundles characteristic of meningiomas. Most tumors had islands of chondroid and osseous metaplasia (17/22). Ocular invasion was limited to small foci in the posterior choroid or optic nerve head of six dogs. Immunoperoxidase stains on 10 cases were positive for vimentin and S-100, but negative for cytokeratin. Electron microscopy revealed complex interdigitations between cell membranes and few desmosomal intercellular attachments. Primary orbital meningiomas have a characteristic histologic appearance and may recur locally after surgical excision.     

Paranasal meningioma in the dog: a clinicopathologic study of ten cases

Paranasal meningiomas were diagnosed in ten dogs based on gross and light microscopic examinations of tissue specimens, and, in one case, electron microscopic examination. Seven of ten dogs were female (average age was 13 years). Most dogs (7/10) had seizures on examination. Two dogs with meningioma located in the nasal cavity had nasal discharge, and one had epistaxis. Tumors originated in the nasoparanasal region (eight) and frontal region of the cranial cavity (two). The histologic types of meningioma included psammomatous (two), transitional (three), meningotheliomatous (two), fibroblastic (two), and angioblastic (one). Tumors were malignant and extended to the brain in eight cases. These tumors differed from intracranial meningiomas mainly in their more anaplastic nature and aggressive behavior.     

Pheochromocytoma in 50 Dogs

Fifty dogs with pheochromocytoma were identified in a retrospective study of a 9-year period. For 24 of 50 dogs (48%), the tumor was an incidental finding during necropsy or surgery. Presenting signs were referrable to the nervous system in 7 of the 26 symptomatic dogs (27%); were referrable to the cardiopulmonary system in 7 of 26 dogs (27%); or were nonspecific, reflecting general systemic disease, in 17 of 26 dogs (65%). Abnormal clinical findings were highly varied but were also generally referrable to the cardiopulmonary and nervous systems. Six of 7 dogs (86%) evaluated were hypertensive (systolic range, 164 to 325 mm Hg; diastolic range, 110 to 198 mm Hg). Serum biochemical findings were nonspecific, although 11 of 39 dogs (28%) were hypercholesterolemia Abdominal fluid samples were analyzed in 6 dogs; 3 were nondiagnostic, and 3 were interpreted as lymphosarcoma. The imaging studies that were of most value included abdominal radiographs (mass identified in 9 of 16 dogs [56%]), caudal vena caval angiography (tumor thrombus correctly diagnosed in 4 of 7 dogs [57%]), and abdominal ultrasonography (mass seen in 5 of 6 dogs [83%] and tumor thrombus seen in 3 of 5 dogs [60%]). Local tumor invasion was present in 26 of 50 dogs (52%), regional lymph node mestatases in 6 of 50 dogs (12%), and distant metastases in 12 of 50 dogs (24%). Cause of death was tumor-related in 19 of 50 dogs (38%) and non-tumor related in 28 of 50 dogs (54%).     

Single fraction stereotactic radiation therapy (stereotactic radiosurgery) is a feasible method for treating intracranial meningiomas in dogs

The aim of this retrospective, pilot study was to evaluate stereotactic radiosurgery as a method for treating intracranial meningiomas in dogs. Included dogs had an imaging diagnosis of presumed intracranial meningioma, were treated using a standardized stereotactic radiosurgery protocol, and had a follow‐up time of >6 months after stereotactic radiosurgery. A single fraction of 16 Gy stereotactic radiosurgery was delivered to the tumor, with an internal simultaneously integrated boost to a total dose of 20–24 Gy to the central portion of the tumor. Thirty‐two dogs were sampled. One dog was euthanized in the periprocedural period, and 10 of the remaining 31 dogs (31%) experienced an acute adverse event (defined as declining neurologic function due to tumor progression or treatment‐associated complication within the first 6 months after stereotactic radiosurgery), three of which were fatal. Too few subjects (n = 6) had cross‐sectional imaging after stereotactic radiosurgery to determine an objective response rate; however, 17/30 (57%) dogs assessed for response had a perceived clinical benefit from treatment. The overall median survival time was 519 days (95% confidence interval: 330–708 days); 64% and 24% of dogs were alive at 1 and 2 years after stereotactic radiosurgery, respectively. Dogs with infratentorial tumor location and high gradient indices had shorter survival. There were no factors identified which were predictive of acute adverse event. Survival times reported herein are similar to what has previously been reported for other stereotactic and traditional fractionated radiotherapy protocols. Findings therefore supported the use of stereotactic radiosurgery as an alternative method for treating dogs with presumed intracranial meningiomas.     

Canine intracranial primary neoplasia: 173 cases (1986-2003)

This study investigates the clinical and pathologic findings associated with 173 primary brain tumors in our hospital population of dogs that presented between the years 1986 and 2002. Of the 173 primary brain tumors, 78 (45%) were meningiomas, 29 (17%) were astrocytomas, 25 (14%) were oligodendrogliomas, 12 (7%) were choroid plexus tumors, and 7 (4%) were primary central nervous system lymphomas. Smaller numbers of glioblastomas (n = 5), primitive neuroectodermal tumors (n = 5), histiocytic sarcomas (n = 5), vascular hamartomas (n = 4), and unclassified gliomas (n = 3) were identified. One dog had both a meningioma and an astrocytoma. Most tumors were located within the telencephalon, and seizures were the most common clinical presenting complaint. Of 168 tumors for which a location in the brain was recorded at postmortem examination, 79 were found to involve more than 1 brain division. Other neoplasms unrelated to the primary brain tumor were identified on postmortem examination in 39 dogs (23%). Intrathoracic and intraabdominal neoplasms were present at necropsy in 13 and 24 cases, respectively. Based on the results of this study, thoracic radiographs and abdominal ultrasonography may be indicated to look for extracranial neoplasia prior to advanced imaging of the brain or intracranial surgery.     

Evaluation of progesterone and estrogen receptor expression in 15 meningiomas of dogs and cats

OBJECTIVE: To evaluate progesterone and estrogen receptor expression in meningiomas of the CNS in dogs and cats. ANIMAL: 8 dogs (1 of which was treated with gestrinone) and 5 cats with intracranial meningiomas and 2 dogs with spinal cord meningiomas; tissue samples were also obtained from 1 clinically normal dog and 1 clinically normal cat. PROCEDURE: Meningioma tissue was obtained during surgery or at necropsy; samples were processed for histologic classification and immunohistochemical evaluation of the proportion of tumor cells with progesterone and estrogen receptors. Correlation among receptor expression, tumor grade, and histologic subtypes was determined. RESULT: Several histologic subtypes of intracranial meningiomas were detected among tissue samples. In the cats, all intracranial meningiomas were benign. Progesterone receptor immunoreactivity was detected in 14 of 15 meningiomas. Progesterone receptor expression was identified in > 80% of cells in 8 intracranial meningiomas (4 dogs and 4 cats) and 2 spinal cord meningiomas. In samples of malignant transitional and granular cell meningiomas in dogs, progesterone receptors were detected in 32 and 4.8% of cells respectively. In 1 cat, 38% of tumor cells had progesterone receptors. In a dog treated with gestrinone, no progesterone receptors were detected in the intracranial meningioma. Estrogen receptors were only detected in the tumor of 1 dog. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate a high proportion of progesterone receptors in cells of meningiomas of the CNS in dogs and cats. Antiprogesterone treatment may have a role in the treatment of unresectable or recurrent meningiomas in dogs and cats.     

Characteristics of cisternal cerebrospinal fluid associated with intracranial meningiomas in dogs: 56 cases (1985-2004)

OBJECTIVE: To determine CSF characteristics associated with intracranial meningiomas in dogs. DESIGN: Retrospective case series. ANIMALS: 56 dogs with intracranial meningiomas. PROCEDURES: Medical records of dogs with a histopathologic diagnosis of intracranial meningioma, in which CSF analysis had been performed, were reviewed. Information concerning total nucleated cell counts (TNCCs) and differential nucleated cell counts, RBC counts, and total protein concentration in CSF; seizure history and glucocorticoid administration; and location of meningiomas was recorded. RESULTS: TNCCs < 5 cells/microL were detected in 41 of 56 (73%) dogs; 5 of 56 (9%) dogs had TNCCs > 50 cells/microL. Analysis of CSF revealed predominantly neutrophilic pleocytosis in < 20% of dogs. There was a significant association between meningioma location (caudal portion of the cranial fossa or middle and rostral portion of the cranial fossae) and increased TNCCs (> or = 5 cells/microL). CONCLUSIONS AND CLINICAL RELEVANCE: Results were significantly different from those routinely reported in the veterinary literature. Neutrophilic pleocytosis, especially with TNCCs > 50 cells/microL, was not typical in CSF samples from dogs with intracranial meningiomas. Neutrophilic pleocytosis may not be detected in CSF samples from dogs with meningiomas located within the middle or rostral portion of the cranial fossae.     

Endoscopic-Assisted Intracranial Tumor Removal in Dogs and Cats: Long-Term Outcome of 39 Cases

Background: The benefits of endoscopic assistance to remove intracranial tumors in small animals are not described.
Objective: To evaluate the effectiveness of endoscopic-assisted intracranial tumor removal in dogs and cats.
Animals: Thirty-three dogs and 6 cats with intracranial tumors.
Methods: Retrospective study. CBC, serum chemistry profile, coagulation testing, blood typing, and systemic tumor staging, which included 3-view thoracic radiographs and abdominal ultrasound examination, were performed to detect other significant underlying disease in preparation of the animal for surgery. Magnetic resonance imaging was used in 37/39 cases to image the brain tumor. Surgical approach was dictated by the location of the tumor. Histopathologic examination of the tumor tissue was performed in all cases. Animals were followed throughout their postoperative course for complications and survival times. Statistical analysis (Kaplan-Meier curves) was performed to obtain median survival times in dogs with meningiomas.
Results: Use of an endoscope resulted in visualization of residual tumor and potentially more complete removal of the brain tumors. There were no clinically important complications associated with the use of the endoscope. Median survival time was 2,104 days for dogs with forebrain meningiomas surgically removed with endoscopic assistance and 702 days for dogs with caudal brain meningiomas.
Conclusions and Clinical Importance: These results demonstrate that the use of an endoscope to assist in brain tumor removal is apparently safe and might result in improved survival times.     

Ki-67 and Vascular Endothelial Growth Factor Expression in Intracranial Meningiomas in Dogs

Background: Tumor proliferation in human intracranial meningiomas can be defined by the reactivity of the monoclonal antibody MIB-1 to the Ki-67 antigen. Vascular endothelial growth factor (VEGF), a pro-angiogenic factor, is a predictive marker for survival of dogs with intracranial meningiomas.
Hypothesis: Ki-67 is expressed in canine intracranial meningiomas and is associated with VEGF expression. Ki-67 expression is a prognostic marker for patient outcome.
Animals: Seventy client-owned dogs with WHO grade I intracranial meningiomas.
Methods: Retrospective study assessing the degree of immunostaining for Ki-67 by MIB-1 and VEGF expression in intracranial meningioma tissue from dogs. MIB-1 Labeling Index (LI) was calculated with Image J NIH-software. Extent, intensity, and distribution of VEGF-expression was assessed semiquantitatively. Cross tabulations with Fisher's exact tests and nonparametric Spearman's rank correlations were performed to identify associations between VEGF expression and MIB-1 LI. Fifteen dogs underwent postsurgical radiotherapy and were included in survival analysis. The effect of MIB-1 LI on survival was examined by Kaplan-Meier and Cox proportional hazards regression procedures.
Results: Ki-67 staining was positive in 91% (64/70) and VEGF expression was detected in 96% (67/70). There was no significant association between VEGF expression and MIB-1 LI. MIB-1 LI was not associated with survival.
Conclusions and Clinical Importance: MIB-1 antibody can be used to document cell proliferation in intracranial meningiomas in dogs, but does not predict outcome. No association between VEGF as a marker of angiogenesis and tumor proliferation was found. Angiogenesis might be a more important predictor of meningioma activity in dogs than is Ki-67.     

Clinical and pathologic features of thyroid tumors in 26 dogs

Thyroid tumors were diagnosed in 26 dogs between 1977 and 1984. A total of 23 of the 26 tumors were carcinomas, and 3, detected as incidental findings at necropsy, were adenomas. The median patient age was 9.5 years. Dogs of the Beagle breed were affected most commonly (5 dogs). The most common physical abnormalities in carcinoma patients were cervical swelling, dyspnea, and coughing. A total of 25 of 26 dogs were clinically euthyroid. Aspiration cytology provided diagnostic information in 8 of 17 cases. In dogs with thyroid carcinoma, a cervical soft tissue lesion was identified consistently by use of radiography and scintigraphy with sodium pertechnetate. Pulmonary metastases were detected radiographically in 8 of 21 dogs with thyroid carcinoma. Thoracic nuclear imaging confirmed the radiographic findings in 11 of 14 dogs. Surgical excision of the thyroid mass was the primary treatment for 17 dogs with carcinoma. Eight dogs died within 2 years (median, 7 months) of surgery because of primary tumor regrowth or metastases. Four dogs were alive at a range of 3 to 48 months after surgery, and 4 dogs died from unrelated causes. Necropsy of 7 dogs with thyroid carcinoma revealed neoplastic infiltration of the cervical blood vessels and pulmonary metastases in each dog. The most common histologic patterns of thyroid carcinoma were solid or compact cellular (11 dogs) and mixed solid-follicular tumors (8 dogs). Dogs with a solid carcinoma had a median survival time of 10.5 months (6 dogs), and dogs with a mixed solid-follicular tumor had a median survival time of 8 months (3 dogs).     

Definitive‐intent intensity‐modulated radiation therapy provides similar outcomes to those previously published for definitive‐intent three‐dimensional conformal radiation therapy in dogs with primary brain tumors: A multi‐institutional retrospective study

Radiotherapy with or without surgery is a common choice for brain tumors in dogs. Although numerous studies have evaluated use of three‐dimensional conformal radiotherapy, reports of definitive‐intent, IMRT for canine intracranial tumors are lacking. Intensity‐modulated radiation therapy has the benefit of decreasing dose to nearby organs at risk and may aid in reducing toxicity. However, increasing dose conformity with IMRT calls for accurate target delineation and daily patient positioning, in order to decrease the risk of a geographic miss. To determine survival outcome and toxicity, we performed a multi‐institutional retrospective observational study evaluating dogs with brain tumors treated with IMRT. Fifty‐two dogs treated with fractionated, definitive‐intent IMRT at four academic radiotherapy facilities were included. All dogs presented with neurologic signs and were diagnosed via MRI. Presumed radiological diagnoses included 37 meningiomas, 12 gliomas, and one peripheral nerve sheath tumor. One dog had two presumed meningiomas and one dog had either a glioma or meningioma. All dogs were treated in the macroscopic disease setting and were prescribed a total dose of 45‐50 Gy (2.25‐2.5 Gy per fraction in 18‐20 daily fractions). Median survival time for all patients, including seven cases treated with a second course of therapy was 18.1 months (95% confidence of interval 12.3‐26.6 months). As previously described for brain tumors, increasing severity of neurologic signs at diagnosis was associated with a worse outcome. Intensity‐modulated radiation therapy was well tolerated with few reported acute, acute delayed, or late side effects.     

Immunohistochemical staining patterns of canine meningiomas and correlation with published immunophenotypes

This study examined immunohistochemical staining patterns for several meningioma variants involving either the brain or spinal cord of dogs. Formalin-fixed, paraffin-embedded tissue from 15 tumors was obtained. The selected tumor group included seven meningothelial, three transitional, two malignant (anaplastic), one myxoid, one papillary, and one osteomatous meningiomas. Tumors were evaluated for reactivity to the following six immunohistochemical markers: vimentin, pancytokeratin, glial fibrillary acidic protein (GFAP), S100, neuron-specific enolase (NSE), and synaptophysin. Vimentin expression was detected in all meningiomas, and 14 of 15 tumors demonstrated intense vimentin staining in more than 50% of the neoplastic cells. Pancytokeratin expression was present in 11 of 15 neoplasms; however, positive staining frequently was focal and often involved a small percentage of the neoplastic cells. GFAP expression was detected in a single, anaplastic meningioma. Although expression of NSE and S100 was detected in 12 of 25 meningiomas, the intensity of the staining and the percentage of positive neoplastic cells was highly variable. Synaptophysin was uniformly negative. These results will help to establish immunohistochemical profiles for meningiomas that will improve our ability to correctly differentiate these neoplasms of meningeal origin from central nervous system tumors originating from other sites.     

Atypical and malignant canine intracranial meningiomas may have lower apparent diffusion coefficient values than benign tumors

Canine intracranial meningiomas can be graded based on histological classification as benign (grade I), atypical (grade II), and anaplastic or malignant (grade III). In people, grade II/III meningiomas behave more aggressively, have a higher potential for recurrence after surgical resection, and have lower apparent diffusion coefficient (ADC) values with diffusion weighted imaging (DWI). In this retrospective analytical cross‐sectional study, 42 dogs had ADC values quantified in an attempt to differentiate tumor histologic grade. Our hypothesis was that ADC values would be significantly lower in grade II and III versus grade I meningiomas in dogs. On each ADC image, a polygonal region of interest (ROI) was hand‐drawn along the lesion's periphery, excluding fluid‐filled and hemorrhagic regions. Mean ADC value (ADC_mean) and minimum ADC value (ADC_min) were calculated. Additionally, two smaller, ovoid ROI were drawn within the lesion with mean ADC calculated (ADC_{mean sR} and ADC_{min sR}). Normalized ADC values using white matter were also calculated (ADC_n and ADC_{n sR}). Grades of each tumor were assigned based on histopathology review. Association between ADC parameters and histological grade was tested by means of two‐sample t‐tests. There were 14 grade I (33.3%), 25 grade II (59.5%), and three grade III (7.2%) meningiomas. ADC_{mean sR} and ADC_{min sR} were significantly lower when comparing grade II/III to grade I (P < .05). Grade II tumors had significantly lower ADC_mean, ADC_{mean sR}, ADC_{min sR}, ADC_n, and ADC_{n sR} than grade I meningiomas. This preliminary study supports the potential of ADC values to help predict the histological grade of intracranial meningiomas in dogs.     

Multiple meningiomas in three dogs

Three dogs with seizures were diagnosed with multiple intracranial meningiomas. Two of the three dogs were golden retrievers, and ages ranged from 9 to 11 years. Treatment consisted of surgery and radiation (n=2) or chemotherapy (n=1). In all three cases, the masses were two distinct tumors as determined by imaging, surgery, or necropsy. In two dogs, the meningiomas had the same histological pattern, while in one dog the histological subtypes were different.     

Idiopathic lymphoplasmacytic rhinitis in dogs: 37 cases (1997-2002)

OBJECTIVE: To determine clinical signs and rhinoscopic, computed tomographic, and histologic abnormalities in dogs with idiopathic lymphoplasmacytic rhinitis. DESIGN: Retrospective case series. ANIMALS: 37 dogs. PROCEDURE: Clinical information was obtained from medical records. Nasal computed tomographic images and histologic slides of biopsy specimens were reviewed. RESULTS: Dogs ranged from 1.5 to 14 years old (mean, 8 years); most (28) were large-breed dogs. Nasal discharge was unilateral in 11 of 26 (42%) dogs and bilateral in 15 of 26 (58%) dogs. In dogs with unilateral disease, duration of clinical signs ranged from 1.5 to 36 months (mean, 8.25 months; median, 2 months), and in dogs with bilateral disease, duration of signs ranged from 1.25 to 30 months (mean, 6.5 months; median, 4 months). Computed tomography (n = 33) most often revealed fluid accumulation (27/33 [82%]), turbinate destruction (23/33 [70%]), and frontal sinus opacification (14/33 [42%]). Rhinoscopy (n = 37) commonly demonstrated increased mucus and epithelial inflammation; turbinate destruction was detected in 8 of 37 (22%) dogs. Bilateral biopsy specimens from all 37 dogs were examined. Four dogs had only unilateral inflammatory changes. The remaining 33 dogs had bilateral lesions; in 20, lesions were more severe on 1 side than the other. CONCLUSIONS AND CLINICAL RELEVANCE: Findings suggest that idiopathic lymphoplasmacytic rhinitis is a key contributor to chronic nasal disease in dogs and may be more common than previously believed. In addition, findings suggest that idiopathic lymphoplasmacytic rhinitis is most often a bilateral disease, even among dogs with unilateral nasal discharge.