Quiz: Brain Tumors in Dogs & Cats

The correct answer is C. The cat in the video is pacing in the examination room for an unusual amount of time as compared with healthy cats. Given the history of pacing and circling at home and observation of pacing in the examination room, this is likely a true abnormal finding. Pacing occurs most commonly with forebrain (ie, prosencephalic) dysfunction. Compulsive circling occurs with either forebrain or vestibular (both peripheral and central) dysfunction and is usually toward the side of the lesion. Because there is no evidence of significant weakness or ataxia, a right forebrain disorder is more likely.

Cranial nerve examination reveals an absent menace response in the left eye, which could be caused by a lesion in the visual pathway (eg, left retina, left optic nerve, optic chiasm, right optic tract, right lateral geniculate nucleus/thalamus, right optic radiations [connections between thalamus and occipital lobe], right occipital lobe), a lesion in the right forebrain (the cat was unable to process the hand gesture as a threat), a lesion in the left facial nerve (which controls the ability to blink), or a lesion in the left cerebellum (the cerebellum has some influence over the menace response). Because the cat has an intact palpebral reflex (not shown), it can be concluded that the motor arm of the reflex (facial nerve, VII) is intact. Because there are no other cerebellar signs (eg, dysmetria/hypermetria, intention tremors), a cerebellar lesion is unlikely. Therefore, a sensory or processing abnormality is likely. The patient’s pupillary light reflex is normal. The patient appears visual when cotton balls are thrown through visual field (not shown); thus, the sensory arm of the menace response is intact. Therefore, a right forebrain disorder is the most likely cause of the absent menace response.

The patient also demonstrates delayed to absent postural reactions in the left thoracic and pelvic limbs. Forebrain dysfunction typically causes postural reaction deficits without ataxia or significant weakness, whereas vestibular dysfunction typically causes both weakness and ataxia. The lack of weakness/ataxia makes vestibular dysfunction unlikely. Possible lesion locations for this include the left C6-T2 spinal cord, left C1-C5 spinal cord, left brainstem, or right forebrain. 

When each of these abnormalities and possible lesion locations are considered, the lesion is likely located in the right forebrain.

The correct answer is C. The cat in the video is pacing in the examination room for an unusual amount of time as compared with healthy cats. Given the history of pacing and circling at home and observation of pacing in the examination room, this is likely a true abnormal finding. Pacing occurs most commonly with forebrain (ie, prosencephalic) dysfunction. Compulsive circling occurs with either forebrain or vestibular (both peripheral and central) dysfunction and is usually toward the side of the lesion. Because there is no evidence of significant weakness or ataxia, a right forebrain disorder is more likely.

Cranial nerve examination reveals an absent menace response in the left eye, which could be caused by a lesion in the visual pathway (eg, left retina, left optic nerve, optic chiasm, right optic tract, right lateral geniculate nucleus/thalamus, right optic radiations [connections between thalamus and occipital lobe], right occipital lobe), a lesion in the right forebrain (the cat was unable to process the hand gesture as a threat), a lesion in the left facial nerve (which controls the ability to blink), or a lesion in the left cerebellum (the cerebellum has some influence over the menace response). Because the cat has an intact palpebral reflex (not shown), it can be concluded that the motor arm of the reflex (facial nerve, VII) is intact. Because there are no other cerebellar signs (eg, dysmetria/hypermetria, intention tremors), a cerebellar lesion is unlikely. Therefore, a sensory or processing abnormality is likely. The patient’s pupillary light reflex is normal. The patient appears visual when cotton balls are thrown through visual field (not shown); thus, the sensory arm of the menace response is intact. Therefore, a right forebrain disorder is the most likely cause of the absent menace response.

The patient also demonstrates delayed to absent postural reactions in the left thoracic and pelvic limbs. Forebrain dysfunction typically causes postural reaction deficits without ataxia or significant weakness, whereas vestibular dysfunction typically causes both weakness and ataxia. The lack of weakness/ataxia makes vestibular dysfunction unlikely. Possible lesion locations for this include the left C6-T2 spinal cord, left C1-C5 spinal cord, left brainstem, or right forebrain. 

When each of these abnormalities and possible lesion locations are considered, the lesion is likely located in the right forebrain.

The correct answer is C. The cat in the video is pacing in the examination room for an unusual amount of time as compared with healthy cats. Given the history of pacing and circling at home and observation of pacing in the examination room, this is likely a true abnormal finding. Pacing occurs most commonly with forebrain (ie, prosencephalic) dysfunction. Compulsive circling occurs with either forebrain or vestibular (both peripheral and central) dysfunction and is usually toward the side of the lesion. Because there is no evidence of significant weakness or ataxia, a right forebrain disorder is more likely.

Cranial nerve examination reveals an absent menace response in the left eye, which could be caused by a lesion in the visual pathway (eg, left retina, left optic nerve, optic chiasm, right optic tract, right lateral geniculate nucleus/thalamus, right optic radiations [connections between thalamus and occipital lobe], right occipital lobe), a lesion in the right forebrain (the cat was unable to process the hand gesture as a threat), a lesion in the left facial nerve (which controls the ability to blink), or a lesion in the left cerebellum (the cerebellum has some influence over the menace response). Because the cat has an intact palpebral reflex (not shown), it can be concluded that the motor arm of the reflex (facial nerve, VII) is intact. Because there are no other cerebellar signs (eg, dysmetria/hypermetria, intention tremors), a cerebellar lesion is unlikely. Therefore, a sensory or processing abnormality is likely. The patient’s pupillary light reflex is normal. The patient appears visual when cotton balls are thrown through visual field (not shown); thus, the sensory arm of the menace response is intact. Therefore, a right forebrain disorder is the most likely cause of the absent menace response.

The patient also demonstrates delayed to absent postural reactions in the left thoracic and pelvic limbs. Forebrain dysfunction typically causes postural reaction deficits without ataxia or significant weakness, whereas vestibular dysfunction typically causes both weakness and ataxia. The lack of weakness/ataxia makes vestibular dysfunction unlikely. Possible lesion locations for this include the left C6-T2 spinal cord, left C1-C5 spinal cord, left brainstem, or right forebrain. 

When each of these abnormalities and possible lesion locations are considered, the lesion is likely located in the right forebrain.

The correct answer is C. The cat in the video is pacing in the examination room for an unusual amount of time as compared with healthy cats. Given the history of pacing and circling at home and observation of pacing in the examination room, this is likely a true abnormal finding. Pacing occurs most commonly with forebrain (ie, prosencephalic) dysfunction. Compulsive circling occurs with either forebrain or vestibular (both peripheral and central) dysfunction and is usually toward the side of the lesion. Because there is no evidence of significant weakness or ataxia, a right forebrain disorder is more likely.

Cranial nerve examination reveals an absent menace response in the left eye, which could be caused by a lesion in the visual pathway (eg, left retina, left optic nerve, optic chiasm, right optic tract, right lateral geniculate nucleus/thalamus, right optic radiations [connections between thalamus and occipital lobe], right occipital lobe), a lesion in the right forebrain (the cat was unable to process the hand gesture as a threat), a lesion in the left facial nerve (which controls the ability to blink), or a lesion in the left cerebellum (the cerebellum has some influence over the menace response). Because the cat has an intact palpebral reflex (not shown), it can be concluded that the motor arm of the reflex (facial nerve, VII) is intact. Because there are no other cerebellar signs (eg, dysmetria/hypermetria, intention tremors), a cerebellar lesion is unlikely. Therefore, a sensory or processing abnormality is likely. The patient’s pupillary light reflex is normal. The patient appears visual when cotton balls are thrown through visual field (not shown); thus, the sensory arm of the menace response is intact. Therefore, a right forebrain disorder is the most likely cause of the absent menace response.

The patient also demonstrates delayed to absent postural reactions in the left thoracic and pelvic limbs. Forebrain dysfunction typically causes postural reaction deficits without ataxia or significant weakness, whereas vestibular dysfunction typically causes both weakness and ataxia. The lack of weakness/ataxia makes vestibular dysfunction unlikely. Possible lesion locations for this include the left C6-T2 spinal cord, left C1-C5 spinal cord, left brainstem, or right forebrain. 

When each of these abnormalities and possible lesion locations are considered, the lesion is likely located in the right forebrain.

The correct answer is D. Studies have reported an average survival time of 2 years following surgical excision of meningiomas^1-4; however, in the author’s experience, many cats have experienced long-term survival (eg, 5-10 years) after surgical excision. The median survival time for cats treated palliatively (eg, corticosteroids, anticonvulsants) was only 18 days as compared with 685 days for cats treated surgically,¹ making surgery the treatment of choice for feline meningioma. These tumors are usually slow-growing and benign and can be easily removed if surgically accessible. They typically do not infiltrate the brain in cats as in dogs. Advanced imaging is required to confirm diagnosis; MRI is preferable to CT. Radiation therapy for meningiomas that are not surgically accessible is recommended, but data are insufficient to provide accurate median survival times.

The correct answer is D. Studies have reported an average survival time of 2 years following surgical excision of meningiomas^1-4; however, in the author’s experience, many cats have experienced long-term survival (eg, 5-10 years) after surgical excision. The median survival time for cats treated palliatively (eg, corticosteroids, anticonvulsants) was only 18 days as compared with 685 days for cats treated surgically,¹ making surgery the treatment of choice for feline meningioma. These tumors are usually slow-growing and benign and can be easily removed if surgically accessible. They typically do not infiltrate the brain in cats as in dogs. Advanced imaging is required to confirm diagnosis; MRI is preferable to CT. Radiation therapy for meningiomas that are not surgically accessible is recommended, but data are insufficient to provide accurate median survival times.

The correct answer is D. Studies have reported an average survival time of 2 years following surgical excision of meningiomas^1-4; however, in the author’s experience, many cats have experienced long-term survival (eg, 5-10 years) after surgical excision. The median survival time for cats treated palliatively (eg, corticosteroids, anticonvulsants) was only 18 days as compared with 685 days for cats treated surgically,¹ making surgery the treatment of choice for feline meningioma. These tumors are usually slow-growing and benign and can be easily removed if surgically accessible. They typically do not infiltrate the brain in cats as in dogs. Advanced imaging is required to confirm diagnosis; MRI is preferable to CT. Radiation therapy for meningiomas that are not surgically accessible is recommended, but data are insufficient to provide accurate median survival times.

The correct answer is D. Studies have reported an average survival time of 2 years following surgical excision of meningiomas^1-4; however, in the author’s experience, many cats have experienced long-term survival (eg, 5-10 years) after surgical excision. The median survival time for cats treated palliatively (eg, corticosteroids, anticonvulsants) was only 18 days as compared with 685 days for cats treated surgically,¹ making surgery the treatment of choice for feline meningioma. These tumors are usually slow-growing and benign and can be easily removed if surgically accessible. They typically do not infiltrate the brain in cats as in dogs. Advanced imaging is required to confirm diagnosis; MRI is preferable to CT. Radiation therapy for meningiomas that are not surgically accessible is recommended, but data are insufficient to provide accurate median survival times.

The correct answer is B. Overall, meningioma is the most common primary brain tumor in dogs, but glioma is the most common brain tumor in brachycephalic breeds.^5-9

The correct answer is B. Overall, meningioma is the most common primary brain tumor in dogs, but glioma is the most common brain tumor in brachycephalic breeds.^5-9

The correct answer is B. Overall, meningioma is the most common primary brain tumor in dogs, but glioma is the most common brain tumor in brachycephalic breeds.^5-9

The correct answer is B. Overall, meningioma is the most common primary brain tumor in dogs, but glioma is the most common brain tumor in brachycephalic breeds.^5-9

The correct answer is B. Overall, meningioma is the most common primary brain tumor in dogs, but glioma is the most common brain tumor in brachycephalic breeds.^5-9

The correct answer is B. Although a wide range of survival times has been reported with palliative treatment of brain tumors in dogs, the median survival time is 3 to 4 months.^9,10-12 Survival time is generally longer for patients with cerebral tumors but shorter for tumors in the caudal fossa (ie, cerebellum, brainstem).

The correct answer is B. Although a wide range of survival times has been reported with palliative treatment of brain tumors in dogs, the median survival time is 3 to 4 months.^9,10-12 Survival time is generally longer for patients with cerebral tumors but shorter for tumors in the caudal fossa (ie, cerebellum, brainstem).

The correct answer is B. Although a wide range of survival times has been reported with palliative treatment of brain tumors in dogs, the median survival time is 3 to 4 months.^9,10-12 Survival time is generally longer for patients with cerebral tumors but shorter for tumors in the caudal fossa (ie, cerebellum, brainstem).

The correct answer is B. Although a wide range of survival times has been reported with palliative treatment of brain tumors in dogs, the median survival time is 3 to 4 months.^9,10-12 Survival time is generally longer for patients with cerebral tumors but shorter for tumors in the caudal fossa (ie, cerebellum, brainstem).

The correct answer is B. Although a wide range of survival times has been reported with palliative treatment of brain tumors in dogs, the median survival time is 3 to 4 months.^9,10-12 Survival time is generally longer for patients with cerebral tumors but shorter for tumors in the caudal fossa (ie, cerebellum, brainstem).

The correct answer is C. Up to 17% of cats with meningioma have multiple meningiomas at the time of diagnosis^1,13-14; 10% of cats have meningioma and another tumor type. Meningiomas in cats are usually firm, well circumscribed masses that are easily removed, whereas approximately 33% of meningiomas in dogs invade the adjacent parenchyma.^15,16 Cats have a significantly longer postoperative survival time as compared with dogs. Although cats can be expected to survive for up to 2 years, the postoperative survival time for dogs is 9 to 12 months.^1-4,17-18 Because of the invasive nature of meningioma in dogs, radiation therapy should ideally be performed in all dogs following surgical excision.

The correct answer is C. Up to 17% of cats with meningioma have multiple meningiomas at the time of diagnosis^1,13-14; 10% of cats have meningioma and another tumor type. Meningiomas in cats are usually firm, well circumscribed masses that are easily removed, whereas approximately 33% of meningiomas in dogs invade the adjacent parenchyma.^15,16 Cats have a significantly longer postoperative survival time as compared with dogs. Although cats can be expected to survive for up to 2 years, the postoperative survival time for dogs is 9 to 12 months.^1-4,17-18 Because of the invasive nature of meningioma in dogs, radiation therapy should ideally be performed in all dogs following surgical excision.

The correct answer is C. Up to 17% of cats with meningioma have multiple meningiomas at the time of diagnosis^1,13-14; 10% of cats have meningioma and another tumor type. Meningiomas in cats are usually firm, well circumscribed masses that are easily removed, whereas approximately 33% of meningiomas in dogs invade the adjacent parenchyma.^15,16 Cats have a significantly longer postoperative survival time as compared with dogs. Although cats can be expected to survive for up to 2 years, the postoperative survival time for dogs is 9 to 12 months.^1-4,17-18 Because of the invasive nature of meningioma in dogs, radiation therapy should ideally be performed in all dogs following surgical excision.

The correct answer is C. Up to 17% of cats with meningioma have multiple meningiomas at the time of diagnosis^1,13-14; 10% of cats have meningioma and another tumor type. Meningiomas in cats are usually firm, well circumscribed masses that are easily removed, whereas approximately 33% of meningiomas in dogs invade the adjacent parenchyma.^15,16 Cats have a significantly longer postoperative survival time as compared with dogs. Although cats can be expected to survive for up to 2 years, the postoperative survival time for dogs is 9 to 12 months.^1-4,17-18 Because of the invasive nature of meningioma in dogs, radiation therapy should ideally be performed in all dogs following surgical excision.

The correct answer is C. Up to 17% of cats with meningioma have multiple meningiomas at the time of diagnosis^1,13-14; 10% of cats have meningioma and another tumor type. Meningiomas in cats are usually firm, well circumscribed masses that are easily removed, whereas approximately 33% of meningiomas in dogs invade the adjacent parenchyma.^15,16 Cats have a significantly longer postoperative survival time as compared with dogs. Although cats can be expected to survive for up to 2 years, the postoperative survival time for dogs is 9 to 12 months.^1-4,17-18 Because of the invasive nature of meningioma in dogs, radiation therapy should ideally be performed in all dogs following surgical excision.

The correct answer is B. Hydroxyurea is a conventional oral chemotherapy drug used most commonly in veterinary medicine to treat polycythemia vera and chronic lymphocytic leukemia. It has also been used in both human and veterinary medicine for treatment of meningioma.^19-21 In a small retrospective study, dogs treated with hydroxyurea and glucocorticoids lived 2.97 times longer (median, 28 weeks) than dogs treated with glucocorticoids alone (median, 14 weeks).¹⁹ Hydroxyurea is inexpensive and side effects are generally mild. The standard dose is 20-30 mg/kg/day. A CBC should be obtained prior to initiation of treatment and every 1 to 2 weeks until the patient is stable. Obtaining a CBC and serum chemistry profile every 3 to 4 months is recommended. Side effects are uncommon but may include GI signs (eg, anorexia, vomiting, diarrhea), stomatitis, sloughing of nails, dysuria, alopecia, bone marrow suppression (eg, anemia, leukopenia, thrombocytopenia), and pulmonary fibrosis.

The correct answer is B. Hydroxyurea is a conventional oral chemotherapy drug used most commonly in veterinary medicine to treat polycythemia vera and chronic lymphocytic leukemia. It has also been used in both human and veterinary medicine for treatment of meningioma.^19-21 In a small retrospective study, dogs treated with hydroxyurea and glucocorticoids lived 2.97 times longer (median, 28 weeks) than dogs treated with glucocorticoids alone (median, 14 weeks).¹⁹ Hydroxyurea is inexpensive and side effects are generally mild. The standard dose is 20-30 mg/kg/day. A CBC should be obtained prior to initiation of treatment and every 1 to 2 weeks until the patient is stable. Obtaining a CBC and serum chemistry profile every 3 to 4 months is recommended. Side effects are uncommon but may include GI signs (eg, anorexia, vomiting, diarrhea), stomatitis, sloughing of nails, dysuria, alopecia, bone marrow suppression (eg, anemia, leukopenia, thrombocytopenia), and pulmonary fibrosis.

The correct answer is B. Hydroxyurea is a conventional oral chemotherapy drug used most commonly in veterinary medicine to treat polycythemia vera and chronic lymphocytic leukemia. It has also been used in both human and veterinary medicine for treatment of meningioma.^19-21 In a small retrospective study, dogs treated with hydroxyurea and glucocorticoids lived 2.97 times longer (median, 28 weeks) than dogs treated with glucocorticoids alone (median, 14 weeks).¹⁹ Hydroxyurea is inexpensive and side effects are generally mild. The standard dose is 20-30 mg/kg/day. A CBC should be obtained prior to initiation of treatment and every 1 to 2 weeks until the patient is stable. Obtaining a CBC and serum chemistry profile every 3 to 4 months is recommended. Side effects are uncommon but may include GI signs (eg, anorexia, vomiting, diarrhea), stomatitis, sloughing of nails, dysuria, alopecia, bone marrow suppression (eg, anemia, leukopenia, thrombocytopenia), and pulmonary fibrosis.

The correct answer is B. Hydroxyurea is a conventional oral chemotherapy drug used most commonly in veterinary medicine to treat polycythemia vera and chronic lymphocytic leukemia. It has also been used in both human and veterinary medicine for treatment of meningioma.^19-21 In a small retrospective study, dogs treated with hydroxyurea and glucocorticoids lived 2.97 times longer (median, 28 weeks) than dogs treated with glucocorticoids alone (median, 14 weeks).¹⁹ Hydroxyurea is inexpensive and side effects are generally mild. The standard dose is 20-30 mg/kg/day. A CBC should be obtained prior to initiation of treatment and every 1 to 2 weeks until the patient is stable. Obtaining a CBC and serum chemistry profile every 3 to 4 months is recommended. Side effects are uncommon but may include GI signs (eg, anorexia, vomiting, diarrhea), stomatitis, sloughing of nails, dysuria, alopecia, bone marrow suppression (eg, anemia, leukopenia, thrombocytopenia), and pulmonary fibrosis.

The correct answer is B. Hydroxyurea is a conventional oral chemotherapy drug used most commonly in veterinary medicine to treat polycythemia vera and chronic lymphocytic leukemia. It has also been used in both human and veterinary medicine for treatment of meningioma.^19-21 In a small retrospective study, dogs treated with hydroxyurea and glucocorticoids lived 2.97 times longer (median, 28 weeks) than dogs treated with glucocorticoids alone (median, 14 weeks).¹⁹ Hydroxyurea is inexpensive and side effects are generally mild. The standard dose is 20-30 mg/kg/day. A CBC should be obtained prior to initiation of treatment and every 1 to 2 weeks until the patient is stable. Obtaining a CBC and serum chemistry profile every 3 to 4 months is recommended. Side effects are uncommon but may include GI signs (eg, anorexia, vomiting, diarrhea), stomatitis, sloughing of nails, dysuria, alopecia, bone marrow suppression (eg, anemia, leukopenia, thrombocytopenia), and pulmonary fibrosis.

The correct answer is D. This boxer is diagnosed with right-sided unilateral atrophy of the muscles of mastication. Unilateral atrophy is most often the result of an ipsilateral trigeminal nerve disorder, with a trigeminal nerve sheath tumor being most common.²² 

Masticatory muscle myositis, an immune-mediated inflammatory disease of the muscles of mastication, typically causes bilateral atrophy.²³ Trigeminal neuritis typically causes a dropped jaw and inability to close the mouth with minimal muscle atrophy.²⁴ Head trauma and hypothyroidism are rare causes of unilateral atrophy.

The correct answer is D. This boxer is diagnosed with right-sided unilateral atrophy of the muscles of mastication. Unilateral atrophy is most often the result of an ipsilateral trigeminal nerve disorder, with a trigeminal nerve sheath tumor being most common.²² 

Masticatory muscle myositis, an immune-mediated inflammatory disease of the muscles of mastication, typically causes bilateral atrophy.²³ Trigeminal neuritis typically causes a dropped jaw and inability to close the mouth with minimal muscle atrophy.²⁴ Head trauma and hypothyroidism are rare causes of unilateral atrophy.

The correct answer is D. This boxer is diagnosed with right-sided unilateral atrophy of the muscles of mastication. Unilateral atrophy is most often the result of an ipsilateral trigeminal nerve disorder, with a trigeminal nerve sheath tumor being most common.²² 

Masticatory muscle myositis, an immune-mediated inflammatory disease of the muscles of mastication, typically causes bilateral atrophy.²³ Trigeminal neuritis typically causes a dropped jaw and inability to close the mouth with minimal muscle atrophy.²⁴ Head trauma and hypothyroidism are rare causes of unilateral atrophy.

The correct answer is D. This boxer is diagnosed with right-sided unilateral atrophy of the muscles of mastication. Unilateral atrophy is most often the result of an ipsilateral trigeminal nerve disorder, with a trigeminal nerve sheath tumor being most common.²² 

Masticatory muscle myositis, an immune-mediated inflammatory disease of the muscles of mastication, typically causes bilateral atrophy.²³ Trigeminal neuritis typically causes a dropped jaw and inability to close the mouth with minimal muscle atrophy.²⁴ Head trauma and hypothyroidism are rare causes of unilateral atrophy.

The correct answer is D. This boxer is diagnosed with right-sided unilateral atrophy of the muscles of mastication. Unilateral atrophy is most often the result of an ipsilateral trigeminal nerve disorder, with a trigeminal nerve sheath tumor being most common.²² 

Masticatory muscle myositis, an immune-mediated inflammatory disease of the muscles of mastication, typically causes bilateral atrophy.²³ Trigeminal neuritis typically causes a dropped jaw and inability to close the mouth with minimal muscle atrophy.²⁴ Head trauma and hypothyroidism are rare causes of unilateral atrophy.

The correct answer is B. The reported median survival time ranges between 6 and 12 months in dogs.^5,17,18 Survival time may be significantly increased by postoperative radiation therapy. In one study of canine meningioma, patients that underwent surgery alone had a median survival time of 7 months (range, 0.5-22 months), whereas dogs that underwent surgery followed by radiation therapy had a median survival time of 16.5 months (range, 3-58 months).¹⁷

The correct answer is B. The reported median survival time ranges between 6 and 12 months in dogs.^5,17,18 Survival time may be significantly increased by postoperative radiation therapy. In one study of canine meningioma, patients that underwent surgery alone had a median survival time of 7 months (range, 0.5-22 months), whereas dogs that underwent surgery followed by radiation therapy had a median survival time of 16.5 months (range, 3-58 months).¹⁷

The correct answer is B. The reported median survival time ranges between 6 and 12 months in dogs.^5,17,18 Survival time may be significantly increased by postoperative radiation therapy. In one study of canine meningioma, patients that underwent surgery alone had a median survival time of 7 months (range, 0.5-22 months), whereas dogs that underwent surgery followed by radiation therapy had a median survival time of 16.5 months (range, 3-58 months).¹⁷

The correct answer is B. The reported median survival time ranges between 6 and 12 months in dogs.^5,17,18 Survival time may be significantly increased by postoperative radiation therapy. In one study of canine meningioma, patients that underwent surgery alone had a median survival time of 7 months (range, 0.5-22 months), whereas dogs that underwent surgery followed by radiation therapy had a median survival time of 16.5 months (range, 3-58 months).¹⁷

The correct answer is E. The MRI reveals a large, contrast-enhancing mass extending dorsally out of the sella turcica. The most likely histologic diagnosis for this large mass is a pituitary macroadenoma; other tumors that occur in this location include suprasellar germ cell tumor, meningioma, and lymphoma.

The correct answer is E. The MRI reveals a large, contrast-enhancing mass extending dorsally out of the sella turcica. The most likely histologic diagnosis for this large mass is a pituitary macroadenoma; other tumors that occur in this location include suprasellar germ cell tumor, meningioma, and lymphoma.

The correct answer is E. The MRI reveals a large, contrast-enhancing mass extending dorsally out of the sella turcica. The most likely histologic diagnosis for this large mass is a pituitary macroadenoma; other tumors that occur in this location include suprasellar germ cell tumor, meningioma, and lymphoma.

The correct answer is E. The MRI reveals a large, contrast-enhancing mass extending dorsally out of the sella turcica. The most likely histologic diagnosis for this large mass is a pituitary macroadenoma; other tumors that occur in this location include suprasellar germ cell tumor, meningioma, and lymphoma.

The correct answer is E. The MRI reveals a large, contrast-enhancing mass extending dorsally out of the sella turcica. The most likely histologic diagnosis for this large mass is a pituitary macroadenoma; other tumors that occur in this location include suprasellar germ cell tumor, meningioma, and lymphoma.

The correct answer is B. Following transsphenoidal hypophysectomy, postoperative IGF-1 level appears to be correlated to glycemic control and resolution of diabetes in cats. A complete (83%) or partial (17%) remission of diabetes has been reported in cats;²⁵ normalization of IGF-1 occurred by 4 weeks after surgery, whereas cats with elevated postoperative IGF-1 (>1000 ng/mL) remained diabetic.²⁵

The median survival time with radiation therapy is approximately 1 to 2 years.^26-27 ACTH levels often remain elevated following full-course radiation therapy.²⁸ Unlike in humans, blindness is uncommon in dogs with pituitary macroadenoma. It has been suggested that anatomic differences in dogs, including incomplete dural adhesion to the pituitary gland and the frequent involvement of the pars distalis, can lead to dorsal expansion of the tumor rather than rostral impingement of the optic chiasm.²⁹

The correct answer is B. Following transsphenoidal hypophysectomy, postoperative IGF-1 level appears to be correlated to glycemic control and resolution of diabetes in cats. A complete (83%) or partial (17%) remission of diabetes has been reported in cats;²⁵ normalization of IGF-1 occurred by 4 weeks after surgery, whereas cats with elevated postoperative IGF-1 (>1000 ng/mL) remained diabetic.²⁵

The median survival time with radiation therapy is approximately 1 to 2 years.^26-27 ACTH levels often remain elevated following full-course radiation therapy.²⁸ Unlike in humans, blindness is uncommon in dogs with pituitary macroadenoma. It has been suggested that anatomic differences in dogs, including incomplete dural adhesion to the pituitary gland and the frequent involvement of the pars distalis, can lead to dorsal expansion of the tumor rather than rostral impingement of the optic chiasm.²⁹

The correct answer is B. Following transsphenoidal hypophysectomy, postoperative IGF-1 level appears to be correlated to glycemic control and resolution of diabetes in cats. A complete (83%) or partial (17%) remission of diabetes has been reported in cats;²⁵ normalization of IGF-1 occurred by 4 weeks after surgery, whereas cats with elevated postoperative IGF-1 (>1000 ng/mL) remained diabetic.²⁵

The median survival time with radiation therapy is approximately 1 to 2 years.^26-27 ACTH levels often remain elevated following full-course radiation therapy.²⁸ Unlike in humans, blindness is uncommon in dogs with pituitary macroadenoma. It has been suggested that anatomic differences in dogs, including incomplete dural adhesion to the pituitary gland and the frequent involvement of the pars distalis, can lead to dorsal expansion of the tumor rather than rostral impingement of the optic chiasm.²⁹

The correct answer is B. Following transsphenoidal hypophysectomy, postoperative IGF-1 level appears to be correlated to glycemic control and resolution of diabetes in cats. A complete (83%) or partial (17%) remission of diabetes has been reported in cats;²⁵ normalization of IGF-1 occurred by 4 weeks after surgery, whereas cats with elevated postoperative IGF-1 (>1000 ng/mL) remained diabetic.²⁵

The median survival time with radiation therapy is approximately 1 to 2 years.^26-27 ACTH levels often remain elevated following full-course radiation therapy.²⁸ Unlike in humans, blindness is uncommon in dogs with pituitary macroadenoma. It has been suggested that anatomic differences in dogs, including incomplete dural adhesion to the pituitary gland and the frequent involvement of the pars distalis, can lead to dorsal expansion of the tumor rather than rostral impingement of the optic chiasm.²⁹