Pituitary macroadenomas and macroadenocarcinomas in dogs treated with mitotane for pituitary-dependent hyperadrenocorticism: 13 cases (1981-1986)

Pituitary macroadenoma/macroadenocarcinoma (PMA; tumor size greater than or equal to 1 cm in diameter) was diagnosed in 13 dogs after 0.5 to 24 months of mitotane treatment for pituitary-dependent hyperadrenocorticism (PDH). The diagnosis of PDH was established on the basis of results of common tests of the pituitary-adrenocortical axis in conjunction with results of x-ray computed tomography or necropsy. Initial clinical findings and clinicopathologic test results were typical of PDH. Signs referable to the CNS developed in 7 of the 13 dogs. The most common neurologic sign was stupor. Pituitary macroadenoma/macroadenocarcinoma was an unexpected finding in the other 6 dogs, because none had clinical signs of disease referable to the CNS at the time that pituitary tumor was documented. In the 13 dogs, strong correlation existed between tumor volume, compression/invasion of the surrounding nervous tissue, and development of neurologic signs, ie, neurologic signs were most frequently associated with larger tumors. The size of the tumor, however, was not always an indication of whether neurologic signs would be observed. All 7 dogs with neurologic signs were euthanatized because of the deleterious effects of the PMA. Of the 6 dogs without neurologic signs, 2 died of unrelated cause. Alternative treatment (ie, hypophysectomy, 60Co-teletherapy) was used successfully in 2 other dogs. Alternative treatment would seem indicated if PMA is documented in a dog with PDH. However, identification of PMA is dependent on evaluation of x-ray computed tomographic images. Signalment, history, physical examination, and alterations in routine clinicopathologic findings in these 13 dogs of our study were similar to previously reported findings in dogs with PDH but apparently without large pituitary tumors.(ABSTRACT TRUNCATED AT 250 WORDS)     

Irradiation of brain tumors in dogs with neurologic disease

Radiation therapy is the treatment of choice for many primary canine brain tumors. The radiation dose tolerated by surrounding healthy brain tissue can be a limiting factor for radiation treatment and total dose as well as fractionation schedules, and volume effects may play a role in the outcome of patients undergoing radiation therapy. The purpose of this retrospective study was to evaluate the efficacy of radiation therapy in dogs with brain tumors that showed signs of neurologic disease. Forty-six dogs with brain tumors were included in the analysis. In 34 dogs, computer-generated treatment plans were available, and dose-volume data could be obtained. The totally prescribed radiation therapy doses ranged from 35 to 52.5 Gy (mean = 40.9 [SD +/- 2.91) applied in 2.5- to 4-Gy fractions (mean = 3.2). The median overall survival time calculated for deaths attributable to worsening of neurologic signs was 1,174 days (95% confidence interval [CI], 693-1,655 days). Assuming that all deaths were due to disease or treatment consequences, the median survival time was 699 days (95% CI, 589-809 days). No prognostic clinical factors such as the location or size of the tumor or neurologic signs at presentation were identified. With computerized treatment planning and accurate positioning, high doses of radiation (> 80% of the total dose) could be limited to mean relative brain volumes of 35.3% (+/- 12.6). These small volumes may decrease the probability of severe late effects such as infarction or necrosis. In this study, very few immediate or early delayed adverse effects and no late effects were noted, and quality of life was good to excellent.     

Granular cell tumor of the canine central nervous system: two cases.

Although pure granular cell tumors have been reported in various sites in the dog, only one tumor has been reported in the central nervous system. Two dogs presented with neurologic signs had brain lesions detected by magnetic resonance imaging in the area of the olfactory bulbs and frontal cortex. In both dogs, a clinical diagnosis of a granular cell tumor was made from tissues obtained from stereotactic biopsies guided by computed tomography. Surgical removal of the tumors was followed by histopathologic, ultrastructural, and immunocytochemical characterization. Although not conclusive, these studies indicated that the granular cells were not of leucocyte origin but may have been derived from the meninges. One dog died 12 months after surgery, and the other was alive 4 months later.     

Secondary Intracranial Neoplasia in the Dog: 177 Cases (1986–2003)

Background: This study investigates the frequency, location, and clinical findings associated with 177 secondary brain tumors in dogs.
Hypothesis: Secondary intracranial neoplasia is more common than primary intracranial neoplasia in dogs during the time period studied, and hemangiosarcoma (HSA) is the most common secondary intracranial tumor.
Animals: One hundred and seventy-seven client-owned dogs presented to the Matthew J. Ryan Veterinary Hospital between 1986 and 2003.
Methods: Medical records were searched for a diagnosis of intracranial neoplasia in dogs who underwent complete postmortem examination. Of these dogs, those with a diagnosis of primary intracranial neoplasia were excluded.
Results: Of the 177 secondary brain tumors, 51 (29%) were HSAs, 44 (25%) were pituitary tumors, 21 (12%) were lymphosarcomas, and 21 (12%) were metastatic carcinomas. The average age at diagnosis was 9.6 ± 3.0 years. Most tumors were located in the cerebrum, and a mentation change was the most common presenting clinical sign. On postmortem examination, the same tumor that was in the brain was also present in the lung in 84 cases (47%), in the kidney in 62 cases (35%), and in the heart in 55 cases (31%).
Conclusions and Clinical Importance: Secondary intracranial neoplasia in dogs was more common than primary intracranial neoplasia during the time period studied. Many of these dogs had related disease in other body systems that was apparent on diagnostic tests such as thoracic radiography.     

CT-GUIDED BRAIN BIOPSY USING A MODIFIED PELORUS MARK III STEREOTACTIC SYSTEM: EXPERIENCE WITH 50 DOGS

This report describes the results of CT-guided stereotactic brain biopsies performed on 50 consecutive dogs using a modified Pelorus Mark III Stereotactic System. Based on available histopathologic samples (stereotactic biopsy [n = 50], surgery [n = 17], necropsy [n = 9]) the patient population consisted of 34 dogs with primary brain tumors, 2 with invasive nasal adenocarcinomas, and 13 with non-neoplastic brain lesions. Brain tissue was not obtained from one dog. In 22 dogs a final diagnosis was made from tissue subsequently obtained from surgical resection or at necropsy. The final diagnosis was in agreement with the stereotactic biopsy diagnosis in 20 of these 22 dogs. In 17 other dogs without follow-up, stereotactic biopsy provided a diagnosis of a specific primary brain tumor subtype. Postoperative complications associated with the biopsy procedure were assessed in 41 dogs. The other 9 dogs either went directly to surgery (n = 7) or were killed (n = 2) immediately after the biopsy procedure. Thirty-six dogs recovered without apparent clinical complications. Postoperative clinical complications in the remaining 5 dogs included transient epistaxis (1 dog), transient exacerbation of cerebellar signs (1 dog), obtundation progressing to coma (1 dog), and medically uncontrollable seizures (2 dogs). The latter 3 dogs with severe neurologic complications all had large primary brain tumors and had been receiving high doses of phenobarbital and glucocorticoids to control seizures at the time of biopsy. These results suggest that this CT-guided biopsy procedure can provide an accurate pathologic diagnosis of brain lesions detected by CT and MR neuroimaging. Further refinement of both technique and case selection is expected to reduce the rate of clinical complications and to improve the accuracy of the procedure.     

THE RADIOGRAPHIC APPEARANCE OF PRIMARY LIVER NEOPLASIA IN DOGS

The signalment, anamnesis, and histopathologic, gross pathologic, and radiographic findings in 22 dogs with nonvascular, nonhematopoletic primary liver tumors were reviewed. The tumor types represented were hepatoma (8), bile duct cystadenoma (1), hepatocellular carcinoma (5), and cholangiocellular carcinoma (8). The dogs averaged 11.1 years of age. Females were predisposed to cholangiocellular carcinoma. The most common presenting clinical signs were general malaise, anorexia, PU/PD, vomiting, and seizures. Tumors ranged in size from diffuse 0.5-1 cm nodules to an 18-cm solitary mass and were located in any of the liver lobes. Four of the five diffuse tumors were cholangiocellular carcinomas. The most common radiographic appearance for any type of liver tumor was a right cranial abdominal mass causing caudal and left gastric displacement. In 54.5% of the dogs, radiographic evidence of intraperitoneal disease was identified. Nodular interstitial pulmonary masses were seen in 3 of the 22 dogs.     

Neurologic abnormalities as the predominant signs of neoplasia of the nasal cavity in dogs and cats: seven cases (1973-1986)

Neurologic abnormalities were the predominant historic and physical findings in 5 dogs and 2 cats with primary nasal cavity tumors that had invaded the cranial vault. Seizures, behavior changes, and obtundation were the most common signs. Other neurologic signs included paresis, ataxia, circling, visual deficit, and proprioceptive deficit. Although 1 dog and 2 cats had historic findings of mild respiratory disease, no physical abnormalities related to the respiratory tract were found in any of the 7 animals. Nasal cavity neoplasia was suggested by radiographic and computed tomographic studies and was confirmed histopathologically in each case. The nasal tumor types in the 5 dogs were epidermoid carcinoma (n = 1), adenocarcinoma (n = 2), solid carcinoma (n = 1), and anaplastic chondrosarcoma (n = 1). An esthesioneuroblastoma was found in each cat. Radiation therapy was effective for 3 months in palliating the clinical signs in the 2 dogs in which it was used. Neoplasia of the nasal cavity should be considered in the differential diagnosis for animals with neurologic signs suggestive of cerebral disorders.     

Secondary intracranial neoplasia in the dog: 177 cases (1986-2003).

BACKGROUND: This study investigates the frequency, location, and clinical findings associated with 177 secondary brain tumors in dogs. HYPOTHESIS: Secondary intracranial neoplasia is more common than primary intracranial neoplasia in dogs during the time period studied, and hemangiosarcoma (HSA) is the most common secondary intracranial tumor. ANIMALS: One hundred and seventy-seven client-owned dogs presented to the Matthew J. Ryan Veterinary Hospital between 1986 and 2003. METHODS: Medical records were searched for a diagnosis of intracranial neoplasia in dogs who underwent complete postmortem examination. Of these dogs, those with a diagnosis of primary intracranial neoplasia were excluded. RESULTS: Of the 177 secondary brain tumors, 51 (29%) were HSAs, 44 (25%) were pituitary tumors, 21 (12%) were lymphosarcomas, and 21 (12%) were metastatic carcinomas. The average age at diagnosis was 9.6 +/- 3.0 years. Most tumors were located in the cerebrum, and a mentation change was the most common presenting clinical sign. On postmortem examination, the same tumor that was in the brain was also present in the lung in 84 cases (47%), in the kidney in 62 cases (35%), and in the heart in 55 cases (31%). CONCLUSIONS AND CLINICAL IMPORTANCE: Secondary intracranial neoplasia in dogs was more common than primary intracranial neoplasia during the time period studied. Many of these dogs had related disease in other body systems that was apparent on diagnostic tests such as thoracic radiography.     

Clinical and imaging findings,treatments, and outcomes in 27 dogs with imaging diagnosed trigeminal nerve sheath tumors: A multi‐center study

The clinical behavior of canine trigeminal nerve sheath tumors and benefits of previously reported treatments are incompletely defined. Aims of this retrospective, multicenter, observational study were to describe clinical signs, tumor localization characteristics, treatments, and clinical outcomes in a group of dogs with this neoplasm. Databases at four hospitals were reviewed for dogs with a trigeminal nerve sheath tumor diagnosis, magnetic resonance imaging (MRI) studies, and presentation between 2004 and 2014. A single observer recorded medical record findings and two observers recorded MRI characteristics by consensus. A total of 27 dogs met inclusion criteria (15 treated with stereotactic radiation therapy and 12 unirradiated). Two unirradiated dogs were excluded from outcome analyses. The most common presenting signs were masticatory muscle atrophy (26 dogs), neurologic signs referable to intracranial disease (13), and ocular disease (12). Based on MRI findings, all dogs had disease extending centrally at the level of the brainstem. The most commonly affected trigeminal nerve branches were the mandibular (26 dogs), maxillary (22), and ophthalmic (10). Of 15 dogs treated with stereotactic radiation therapy, one had improved muscle atrophy, and six had poor ocular health after treatment. Neurologic signs improved in 4/5 dogs with intracranial signs. Overall median survival time for the 10 unirradiated dogs with available follow‐up was 12 days and 441 days for the 15 stereotactic radiation therapy dogs. Mean survival times between these groups were not significantly different (mean 95% CI for unirradiated dogs was 44–424 days and mean 95% CI for stereotactic radiation therapy dogs was 260–518 days).     

Survival, neurologic response, and prognostic factors in dogs with pituitary masses treated with radiation therapy and untreated dogs

BACKGROUND: Pituitary masses in dogs are not uncommon tumors that can cause endocrine and neurologic signs and, if left untreated, can decrease life expectancy. HYPOTHESIS: Dogs with pituitary masses that received radiation therapy (RT) have more favorable neurologic outcomes and longer survival times compared with untreated dogs. ANIMALS: Nineteen dogs with a pituitary mass identified on CT or MR imaging were irradiated with 48 Gy given in 3 Gy daily-dose fractions. Twenty-seven untreated control dogs had pituitary masses. METHODS: Medical records of dogs with pituitary masses were retrospectively reviewed for clinical signs, mass size, and outcome. RESULTS: Median survival time was not reached in the treated group. Mean survival time in the treated group was 1,405 days (95% confidence interval [CI], 1,053-1,757 days) with 1-, 2-, and 3-year estimated survival of 93, 87, and 55%, respectively. Median survival in the nonirradiated group was 359 days (95% CI, 48-916 days), with a mean of 551 days (95% CI, 271-829 days). The 1-, 2-, and 3-year estimated survival was 45, 32, and 25%, respectively. Dogs that received RT for their pituitary tumors had significantly longer survival times than untreated dogs (P = .0039). Treated dogs with smaller tumors (based on maximal pituitary-to-brain height ratio or area of tumor to area of brain) lived longer than those with larger tumors (P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE: When compared with untreated dogs, RT increased survival and controlled neurologic signs in dogs with pituitary masses.     

Surgical technique, postoperative complications and outcome in 14 dogs treated for hydrocephalus by ventriculoperitoneal shunting

Objective: To report frequency and type of complications, and outcome in dogs with severe neurologic signs secondary to internal, suspected obstructive hydrocephalus treated by ventriculoperitoneal (VP) shunting. Study Design: Case series. Animals: Dogs (n=14). Methods: Medical records (2001–2006) was reviewed for dogs that had VP shunting. Inclusion criteria were complete medical record, progressive forebrain signs unresponsive to medical treatment, normal metabolic profile, negative antibody titers and/or cerebrospinal PCR for Toxoplasma gondii, Neospora caninum, and canine distemper virus, magnetic resonance images of the brain, confirmed diagnosis of VP shunting, and follow‐up information. Results: Hydrocephalus was idiopathic in 5 dogs and acquired (interventricular tumors, intraventricular hemorrhage, inflammatory disease) in 9 dogs. Four dogs developed complications 1 week to 18 months postoperatively, including ventricular catheter migration, infection, shunt under‐drainage, kinking of the peritoneal catheter, valve fracture, and abdominal skin necrosis. Three of these dogs had 1 or more successful revision surgeries and 1 dog was successfully treated with antibiotics. All, but 1 dog, were discharged within 1 week of surgery, and had substantial neurologic improvement. Median survival time for all dogs was 320 days (1–2340 days), for dogs with idiopathic hydrocephalus, 274 (60–420) days and for dogs with secondary hydrocephalus, 365 (1–2340) days. Conclusions: VP shunting was successful in relieving neurologic signs in most dogs and postoperative complications occurred in 29%, but were resolved medically or surgically.     

Pituitary tumor size, neurologic signs, and relation to endocrine test results in dogs with pituitary-dependent hyperadrenocorticism: 43 cases (1980-1990).

Pituitary neoplasm was identified in 43 dogs with pituitary-dependent hyperadrenocorticism via necropsy (n = 33), diagnostic imaging with computerized tomography or magnetic resonance imaging (n = 5), or diagnostic imaging and necropsy (n = 5). All dogs had clinical signs and clinicopathologic test results typical of hyperadrenocorticism. Thirty-seven dogs had grossly visible pituitary tumors, and 6 dogs had microscopic pituitary tumors. Fifteen dogs had developed neurologic signs typical of those resulting from an enlarging pituitary mass. Twenty-three dogs had pituitary tumors greater than or equal to 1 cm in diameter. Provocative testing of the pituitary-adrenocortical axis was performed on all dogs. Dogs with grossly visible pituitary tumors and dogs with neurologic signs had significantly (P less than 0.05) higher mean plasma endogenous ACTH concentrations, compared with values from dogs with microscopic tumors and dogs without neurologic signs, respectively. Dogs with grossly visible pituitary tumors and dogs with tumors greater than or equal to 1 cm in diameter had significantly (P less than 0.05) lower adrenocortical responsiveness to exogenous ACTH, compared with dogs with microscopic pituitary tumors and dogs with tumors less than 1 cm in diameter, respectively. Despite these differences, there was overlap between test results among dogs. On the basis of endocrine test results, it would appear difficult to distinguish dogs with pituitary-dependent hyperadrenocorticism and large pituitary tumors from those with pituitary-dependent hyperadrenocorticism and microscopic pituitary tumors prior to onset of neurologic signs.     

Immunohistochemical and clinical evaluation of p53 in canine cutaneous mast cell tumors

One hundred twenty-six cutaneous mast cell tumors obtained by excisional biopsy from 106 dogs were evaluated using immunohistochemical staining for the presence of p53 protein. A standard avidin-biotin immunohistochemical protocol was used incorporating a polyclonal antibody of rabbit origin (CM-1) as the primary antibody. Histopathologic grading of tumors was performed on hemotoxylin and eosin-stained samples. There was a significant difference in the percentage of cells staining positive for p53 for the histopathologic grades (P = 0.0005). Grade III tumors had a significantly greater p53 content than did grade I or II tumors (P < 0.05). Clinical data obtained retrospectively was available for 54 dogs. Tumor recurred in 19 of 54 (35.2%) dogs. Twenty-nine dogs died by the end of the study; 9 of 29 (31.0%) died of mast cell tumor disease. Histopathologic grade showed a significant negative association with survival time. Both clinical stage and histopathologic grade showed a significant negative association with time to recurrence. The percentage of cells staining positive for p53 did not significantly improve the forward analysis. Immunohistochemical detection of p53 did not appear useful in characterizing the clinical association between cutaneous mast cell tumor cellular features and survival time or time to tumor recurrence in dogs.     

POSTOPERATIVE IRRADIATION OF SPINAL CORD TUMORS IN 9 DOGS

Between 1985 and 1993, nine dogs with spinal cord tumors were treated postoperatively with cobaltradiation at North Carolina State University-Veterinary Teaching Hospital. Total doses ranged between 33.3–48.0 Gy given in 10–12 fractions of 3–4 Gy over a four week period. Five dogs were euthanized due to recurrence of the tumor or neurologic signs and two dogs were euthanized due tounrelated problems. Two dogs were alive but lost to follow-up at 12 and 25 months. Survival time ranged from 6.5–70.0 months. Median survival time (95% confidence interval) was 17 (12–70) months. Results of this study suggest decompressive surgery followed by irradiation can be an effective treatment for dogs with spinal cord tumors.     

Clinical signs associated with brain tumors in dogs: 97 cases (1992-1997).

OBJECTIVE: To determine the prevalence of various clinical signs in dogs with brain tumors. DESIGN: Retrospective study. ANIMALS: 97 dogs with brain tumors. PROCEDURE: Medical records were reviewed for signalment, tumor type and location, and clinical signs. RESULTS: 33 breeds were represented; Golden Retrievers were most commonly affected. Most dogs were older (median age, 9 years); 95% of dogs were > or = 5 years old. Seventy-six percent of dogs had tumors in the supratentorial region. Seizures were the most common clinical sign at initial examination, with lower prevalence for circling, ataxia, and head tilt. Meningioma was the most common tumor. CONCLUSIONS AND CLINICAL RELEVANCE: Brain tumors develop most often in dogs > or = 5 years old and are uncommon in dogs < 5 years old. Seizures are a common clinical sign, and a brain tumor should be considered in dogs that have their first seizure after they are 4 years old.     

Neurologic, endocrinologic, and pathologic findings associated with large pituitary tumors in dogs: eight cases (1976-1984)

Invasive tumors of the pituitary gland were diagnosed in 8 dogs. Seven of the dogs had been treated for pituitary-dependent hyperadrenocorticism before the onset of neurologic signs. All 8 dogs had behavior abnormalities and similar neurologic signs: 6 dogs had rotary nystagmus and 7 dogs had symmetric tetraparesis. Once neurologic signs developed, the clinical course in all 8 dogs had a mean duration of 4.7 +/- 2.0 months before death or euthanasia; 5 dogs had a clinical course of less than or equal to 2 months. Necropsy was performed in 7 dogs. The histologic diagnosis was malignant pituitary adenocarcinoma in 2 dogs and pituitary adenoma in 5 dogs.     

Clinical Signs of Tumors Affecting the Rostral Cerebrum in 43 Dogs

The clinical and pathologic features of 43 dogs with neoplasia of the rostral cerebrum were reviewed. Primary brain tumors included meningioma, astrocytoma, neuroblastoma, oligodendroglioma, and ependymoma. Other tumors that secondarily affected these areas included solitary hemangiosarcoma, nasal neuroendocrine carcinoma, nasal cell adenocarcinoma, nasal squamous cell carcinoma, and nasal neurofibrosarcoma. Older dogs were usually affected (mean, 10 years), and meningioma was the most frequent tumor type. Thirty-one dogs (72% of total) had a late-onset (greater than 5 years of age) of either generalized seizures or behavior abnormalities, or both, with an initially normal neurologic examination. In these 31 dogs, a mean time of 78 days (range, 2 to 400 days) elapsed from the onset of seizures or behavior change to the detection of a persistently abnormal neurologic examination. In all 43 dogs, the time from the detection of neurologic deficits to death or euthanasia and necropsy ranged from 1 to 63 days (mean, 13 days). On the basis of this review, it appears that dogs with late-onset seizures or behavior change, or both, should be suspected of having tumors involving the rostral cerebrum, despite the absence of persistent neurologic deficits commonly associated with cerebral tumors. Further, the onset of abnormalities in the neurologic examination and the time of death seem to occur within predictable time periods.     

PRIMARY IRRADIATION OF CANINE INTRACRANIAL MASSES

Twenty-nine dogs received primary radiation therapy for intracranial lesions and clinical signs suggestive of neoplasia. Presumptive diagnosis and tumor categorization was based on computed tomographic or magnetic resonance images. Meningioma was the most likely tumor type in 22 dogs and glioma or choroid plexus tumors were tentatively identified in 4 and 3 dogs, respectively. Cobalt-60 radiation was delivered in 3 Gy fractions on a daily, Monday-through-Friday basis for a total dose of 48 Gy (16 fractions) in 28 dogs; one dog received 54 Gy. Two of 29 dogs died during treatment of signs suggestive of progressive tumor growth but were included in the overall evaluation of response to treatment. Median overall survival was 250 days (range 21-804). Mild acute radiation effects on normal tissue developed and did not influence outcome in any dog. Late radiation effects could not be evaluated in this study. No significant predictive indicators were identified from the clinical or imaging data. Radiation therapy is superior to medical treatment of brain tumors in dogs with steroids, is useful for tumors that are not currently operable and may be preferable to surgical resection in dogs if the mass appears infiltrative. However, 22/29 (76%) dogs died of recurrent progressive neuropathy suggestive of tumor regrowth or progression. Thus, alternative methods for delivery of radiation to dogs with brain tumors or novel combinations of therapy should continue to undergo evaluation.     

Electrophoretic determination of albumin and gamma globulin concentrations in the cerebrospinal fluid of dogs with encephalomyelitis attributable to canine distemper virus infection: 13 cases (1980-1987)

Thirteen dogs with encephalomyelitis attributable to canine distemper virus infection were classified into 3 groups on the basis of histopathologic evidence of virus-induced lesions in CNS tissue. Analysis of data indicated a similarity within groups when arranged by age, clinical neurologic signs, and alterations in the CSF electrophoretic protein values. Comparison with results in dogs with experimentally induced canine distemper encephalomyelitis suggested that when grouped by age, CSF electrophoretic values are helpful in predicting the CNS histopathologic changes in dogs with naturally acquired canine distemper encephalomyelitis.     

Oncologic outcome after curative-intent treatment in 39 dogs with primary chest wall tumors (1992-2005)

Objective— To describe the clinical features and determine oncologic outcome and prognostic factors for dogs with primary tumors of the osseous chest wall. Study Design— Historical cohort. Animals— Dogs (n=39) with spontaneous tumors involving the chest wall. Methods— Medical records were reviewed for dogs with rib and/or sternal tumors treated by chest wall resection and reconstruction. Signalment, preoperative clinical features, reconstruction technique, and oncologic outcome (local tumor recurrence, metastasis, and survival time) were determined from medical records and by telephone contact with owners and referring veterinarians. Oncologic outcome and prognostic factors were determined using Kaplan–Meier survival analysis and Cox proportional hazards. Logistic regression was used to determine if increased serum alkaline phosphatase (ALP) concentration was associated with tumor type. Results— Of the 39 dogs with tumors arising from the chest wall, 25 had osteosarcoma, 12 had chondrosarcoma, and 2 dogs had hemangiosarcoma. Median survival time (MST) for dogs with rib osteosarcoma was 290 days. Increased activity of total ALP significantly decreased survival in dogs with osteosarcoma (210 days versus 675 days, P=.0035). MST for dogs with rib chondrosarcoma was not reached (mean 1301 days) and survival was significantly greater than all other types of rib tumors (P=.0321). Conclusion— Rib tumors should be resected with wide margins to decrease the risk of incomplete excision, because local tumor recurrence has a significant impact on the survival time. The prognosis for dogs with rib chondrosarcoma is very good, but guarded for other types of tumors. Clinical Relevance— Osteosarcoma and chondrosarcoma are the most common primary tumors of the chest wall. Prognosis for dogs with primary rib chondrosarcoma is very good with surgery alone, but surgery and adjunctive chemotherapy is recommended for dogs with primary rib osteosarcoma and the prognosis remains guarded.