The mere mention of a brain tumor sends shivers down the spine, especially when it involves our cherished four-legged companions. The possibility of a meningioma, a rather frequent cause of concern, might seem daunting, yet understanding this adversary is paramount. Meningiomas emerge as a leading culprit behind seizures in dogs aged six and older. Delving into the depths of knowledge, we uncover the enigma surrounding this tumor, which accounts for a staggering 50% of canine and up to 85% of feline brain tumors.
The meninges, those delicate membranes enveloping the skull and spine, stand as sentinels guarding the central nervous system, comprising the brain and spinal cord. Dispelling the notion of deep-seated brain growths, meningiomas arise from the outer membranes, their growth trajectory directed from the skull inward. This unique positioning renders them more accessible for surgical intervention, contingent upon their size.
While the term "tumor" often evokes fears of malignancy, meningiomas predominantly lean toward the benign spectrum, exhibiting a lack of cancerous tendencies. These growths abstain from metastasizing or inflicting local tissue havoc. The crux of the issue arises from limited intracranial space, where the burgeoning tumor encroaches upon brain tissue, sparking inflammation and swelling, ultimately impinging on crucial brain functions.
Decoding the Signs
In dogs, seizures and epilepsy take center stage as telltale signs, whereas feline manifestations veer toward the subtle, encompassing listlessness and behavioral shifts. The symptoms of meningiomas exhibit variation, contingent upon the brain area impacted:
- Circular ambulation
- Visual impairment
- Dragging of paws
- Unsteady gait
Illuminating Insights: What We Know
While meninges encapsulate both the brain and spinal cord, meningeal tumors predominantly sprout from the cranial meninges. (Notably, approximately 14% of canine and 4% of feline meningiomas involve the spinal cord.)
Meningiomas undergo classification based on the distinct cell types they involve, each exerting diverse growth rates.
The benign nature of meningiomas precludes the ominous specter of widespread dissemination.
Remarkably, these growths harbor a high density of progesterone receptors. In dogs, the number of these receptors correlates with a more aggressive tumor course, potentially inviting the aid of anti-progesterone medications. Curiously, feline counterparts exhibit no such relationship, leaving anti-progesterone therapy in a state of ongoing exploration.
Around 95% of canine meningiomas manifest in dogs aged seven and above, whereas most affected cats fall within the 10-year age bracket.
Certain breeds, such as those with elongated snouts (notably collies), appear predisposed to meningiomas.
In cats, the texture of meningiomas tends to be more pliable than their canine counterparts, easing surgical removal.
Notably, most canine meningiomas are situated in the frontal skull region, encompassing the olfactory lobes responsible for the sense of smell. An altered sense of smell could potentially trigger shifts in behavior or appetite.
Cracking the Diagnostic Code
Diagnostic pursuits commence with a fundamental blood panel and urinalysis, providing an overview of the patient's overall health. While invaluable in identifying concurrent issues, routine blood work cannot definitively diagnose a brain tumor.
Chest radiographs play a pivotal role in screening for metastatic cancer, revealing instances where brain tumors originated from malignancies elsewhere. Strikingly, a study unveiled that 55% of brain tumors had metastasized to the brain from distant sites.
Peering into the Mind: Imaging Techniques
Crucially, advanced imaging techniques, namely CT (Computed Tomography) scans or MRI (Magnetic Resonance Imaging), form the cornerstone of brain tumor diagnosis. These modalities unveil precise tumor location, distinguishing it from hemorrhagic foci or inflammation. These technologies revolutionize brain imaging, offering unprecedented insight into intracranial landscapes. The MRI, wielding superior capabilities in detecting fluid accumulation, cysts, bleeding, and subtle soft tissue alterations, emerges as the preferred choice.
Plotting a Path Forward: Treatment Odyssey Medicinal Measures
For palliative care aimed at enhancing comfort and curbing seizures, prednisone, an anti-inflammatory steroid, may be employed to alleviate brain tissue swelling. Concurrently, anti-seizure medications like phenobarbital or potassium bromide can be administered. Remarkably, prednisone exhibits an unexpected facet, facilitating meningioma shrinkage by reducing tumor blood flow. A study showcased a remarkable 21% reduction in tumor blood volume within 24 hours of commencing prednisone. Although this approach proves effective for a period, its efficacy wanes as the tumor outgrows these strategies (with survival extending 3-6 months on average).
Surgical Symphony
In the realm of feline companions, surgical removal of meningiomas emerges as a feasible option, buoyed by a favorable prognosis owing to the benign nature of these growths. Survival statistics from one study highlight a promising landscape, with 71% of cats surviving six months post-surgery, 66% enduring a year, and 50% persisting for two years. However, recurrence punctuates the narrative, affecting approximately one in five cats within 27 months.
For their canine counterparts, surgical challenges surface, primarily due to the infiltrative nature of canine meningiomas. A groundbreaking study by A.K. Forward et al., published in 2022, unveils compelling outcomes from meningioma surgery in dogs. A staggering 94% of surgical patients survived, with a median survival time of 386 days. (Approximately 50% lived through the first year, 25% persevered for 1-2 years, and 15% endured 2-3 years). Pioneering technology, the ultrasonic aspirator, revolutionizes surgical outcomes, minimizing bleeding and swelling. Meningiomas excised using this device exhibited a remarkable 42-month median survival period.
Radiation
Radiation treatment strategies vary in frequency, with combinations of surgery and radiation yielding optimal results. Radiosurgery, an innovative technique, deploys focused radiation beams to obliterate the tumor's core. This approach proves effective for compact tumors (<1 inch in diameter), notably in the confines of stereotactic radiosurgery.
Radiation therapy is more cautiously considered in feline patients, given the efficacy of surgical intervention.
The Dawn of Chemotherapy
Chemotherapeutic endeavors demand drugs capable of traversing the blood-brain barrier, the brain's formidable defense mechanism against systemic metabolic changes. Limited options curtail the success of chemotherapy against brain tumors. Despite promising outcomes in dogs and relatively subdued results in cats, this landscape evolves rapidly, with veterinary oncologists best equipped to offer tailored guidance.
Meningiomas, an intricate labyrinth of science and care, usher us into an era where advanced diagnostics and multifaceted treatments illuminate a path of hope. While the journey may be daunting, our dedicated veterinary teams stand poised to navigate this voyage alongside you, championing the health and vitality of our treasured companions.
Don't have a vet in your area yet? We can help you find a local veterinarian.
If you have more questions, the GeniusVets Telehealth platform will give you unlimited access to text and/or video calls with board-certified veterinarians! To learn more click here.