Clip, a 9 year-old male Golden Retriever presented to Southeast Veterinary Neurology for a 4-month history of progressive behavior change and confusion. The signs were initially quite subtle, but gradually progressed to him constantly pacing around the house, walking in circles, staring at walls and getting stuck in corners.
On initial examination, Clip was dull and distant. He did not respond to his name being called or sounds. He tended to constantly pace until he ran into a wall or other obstacle. At that point, he would stop and press his head against the wall or obstacle. This is called ‘head pressing’. He had a slight tendency to turn more towards the left. He would occasionally stumble on the right side of his body. He acted blind in both eyes. His spinal reflexes were normal. He did not seem painful. The goal of the neurological examination is to determine if the patient’s problem is a neurological one and where in the neurological system the problem is (e.g. what is the neuroanatomical localization).
Based on Clip’s examination of walking in circles, tendency to turn left, central blindness, head pressing, and being mentally dull a problem in the cerebral cortex (‘forebrain’) was suspected.
Differential diagnoses included a primary brain tumor such as a meningioma or glioma, a secondary tumor (such as a nasal tumor, a skull tumor, a pituitary tumor), or a metastatic tumor. Encephalitis, malformation (such as a cyst), or brain infection were considered possible but less likely. Older dogs do get strokes which can cause the exact same signs, however, strokes typically do not worsen over a 4-month period, so this was considered unlikely. Metabolic problems such as severe liver disease, electrolyte abnormalities or low blood sugar can cause patients to be dull and confused, but typically do not cause asymmetric signs (e.g. circling in one direction).
His blood tests were normal. Chest X-rays did not show any evidence of metastatic cancer in the lungs. An MRI of the head was recommended to further evaluate Clip’s abnormal behavior.
Note the large, contrast-enhancing mass that arises from the skull and pushes the brain down. Differential diagnoses for this skull-based tumor included a multilobular osteochondroma, osteosarcoma, chondrosarcoma or other soft-tissue sarcoma.
After discussion with the owners about the pros and cons of surgery, it was decided to remove the tumor. The neurosurgeons at Southeast Veterinary Neurology performed surgery to remove the abnormal tumor tissue and leave only normal skull. Clearly, removing this large amount of skull required that a new protective ‘skull’ be made for Clip. A titanium mesh (similar to a wire screen) was used to reconstruct the natural shape, size and contour of Clip’s head.
Compare the MRI to the radiograph. First, the tumor is more obvious on the MRI. Secondly, the MRI gives information about the brain, which is not visible on a radiograph. Third, the MRI images are able to be made in various planes, allowing the neurologist to accurately create a ‘three-dimensional view’ of the head. In addition to the MRI sequences shown (sagittal and axial T1 post-contrast images), other sequences are routinely performed that give additional information. Lastly, there is much more detail as there is no ‘superimposition’ of structures since the MRI creates ‘slices’.
The tumor was removed successfully and the biopsy confirmed the diagnosis of multilobular osteochondroma (MLO). MLO’s tend to be slow-growing tumors and if removed carry a good prognosis with extended survivals (2 years +).
The day after surgery, Clip was already improving. He was more playful and animated and was found carrying his food bowl around in his mouth (something he had not done for months).
Within a week, the owners reported that it was as if he was 4 years younger. We are happy to report that Clip is doing amazingly well. Thanks Clip for being such a trooper and thanks to your family and Dr. Sanchez of the Animal Health and Rehabilitation Center for allowing us to be part of your care.