Case report details SRT for rare canine intracranial granular cell tumor
Bottom line
A new case report in Veterinary Radiology & Ultrasound describes what the authors say is the first documented dog with a cytologically and histologically confirmed intracranial granular cell tumor treated with stereotactic radiotherapy. The patient, a 12-year-old Shih Tzu with a left cerebral mass, received 24 Gy in three consecutive 8 Gy fractions. The tumor volume decreased by 56.8%, and the dog initially improved clinically, but progressive cerebral microbleeds developed over time and neurologic decline was reported 18 months after treatment. Intracranial granular cell tumors are considered rare in dogs, with only a small number of prior canine CNS cases described in the literature. (onlinelibrary.wiley.com)
Why it matters: For veterinary professionals, this report adds a data point for managing an exceptionally uncommon brain tumor where treatment guidance is sparse. It suggests stereotactic radiotherapy can achieve meaningful short-term local response in a confirmed canine intracranial granular cell tumor, while also underscoring the need for long-term monitoring for delayed radiation-associated vascular injury, including cerebral microbleeds, which have been documented in dogs after brain radiotherapy. More broadly, the case fits with the growing use of hypofractionated stereotactic protocols in veterinary neuro-oncology for carefully selected patients. (pmc.ncbi.nlm.nih.gov)
What to watch: Watch for whether additional case reports or multi-center series clarify expected tumor control, late toxicities, and dose-planning considerations for rare canine intracranial tumor types treated with SRT. (pubmed.ncbi.nlm.nih.gov)
Key facts
- Article type
- Case report
- Journal
- Veterinary Radiology & Ultrasound
- Claimed first
- First documented dog with cytologically and histologically confirmed intracranial granular cell tumor treated with stereotactic radiotherapy
- Patient
- 12-year-old Shih Tzu
- Tumor location
- Left cerebrum
- Radiotherapy dose
- 24 Gy total, in three consecutive 8 Gy fractions
- Tumor response
- 56.8% reduction in tumor volume
- Late outcome
- Progressive cerebral microbleeds and neurologic decline 18 months after treatment
A newly published case report in Veterinary Radiology & Ultrasound details what appears to be the first reported use of stereotactic radiotherapy for a dog with a cytologically and histologically confirmed intracranial granular cell tumor. The patient, a 12-year-old Shih Tzu with a tumor in the left cerebrum, was treated with three consecutive 8 Gy fractions, for a total dose of 24 Gy. According to the report summary, the dog experienced initial clinical improvement and a 56.8% reduction in tumor volume, before later developing progressive cerebral microbleeds and neurologic deterioration 18 months after treatment. (onlinelibrary.wiley.com)
That matters in part because intracranial granular cell tumors are rare in dogs, and the published veterinary literature on them is thin. Earlier reports have described only scattered canine CNS cases, including pituitary and other intracranial presentations, plus a 2023 case series that emphasized how atypical MRI findings can complicate diagnosis. In other words, clinicians are often making decisions with very limited disease-specific evidence. (journals.sagepub.com)
The treatment approach in this case, stereotactic radiotherapy, reflects a broader shift in veterinary radiation oncology toward highly conformal, hypofractionated protocols for selected brain tumors. Reviews of canine and feline brain tumor radiotherapy note that stereotactic regimens commonly use three to five fractions, while retrospective reports in presumptive canine gliomas have used three fractions of 8 to 10 Gy. The appeal is practical as well as clinical: fewer anesthetic events, shorter treatment courses for pet parents, and the potential for meaningful tumor shrinkage and neurologic improvement. (pubmed.ncbi.nlm.nih.gov)
Still, the delayed course in this dog is just as important as the initial response. Radiation-associated cerebral microbleeds are increasingly recognized in canine neuro-oncology. A recent study found that cerebral microbleeds can occur after intracranial radiotherapy in dogs and may increase over time, supporting concern that late vascular injury is one mechanism of normal tissue toxicity. North Carolina State University’s veterinary hospital also notes that some pets can experience delayed worsening of neurologic signs in the months after brain radiotherapy because of effects on surrounding brain tissue. (pmc.ncbi.nlm.nih.gov)
No outside commentary specific to this case report was readily available, but the broader specialty view is consistent: stereotactic techniques are becoming a standard part of advanced veterinary cancer care, especially where precision matters and adjacent normal tissue is unforgiving. The American College of Veterinary Radiology describes radiation oncology as a specialized discipline focused on determining which diseases are most likely to respond and how to balance tumor control with risk to normal tissues. That tension is especially sharp in intracranial disease, where even successful local response may be limited by late toxicity. (acvr.org)
Why it matters: For veterinarians, this case is less about establishing a new standard of care than about expanding the map for rare-tumor decision-making. It shows that SRT may offer clinical benefit even in a highly unusual confirmed brain tumor, but it also reinforces the importance of setting expectations with pet parents around surveillance imaging, delayed adverse effects, and the uncertainty that comes with extrapolating from more common tumor types such as meningiomas and gliomas. As more referral centers adopt advanced planning and delivery systems, rare case reports like this can meaningfully shape how clinicians counsel, monitor, and select patients. (onlinelibrary.wiley.com)
What to watch: The next step is whether this remains an isolated proof-of-concept case or becomes part of a larger pattern. Future reports could help define whether granular cell tumors have distinctive imaging behavior, radiation sensitivity, or toxicity profiles compared with other canine brain tumors. Clinicians should also watch emerging work on canine brain dose-volume thresholds and other efforts to better predict late brain effects, since those data may eventually refine planning constraints for uncommon intracranial cases like this one. (onlinelibrary.wiley.com)