“Francois” is a 7 year-old Dachshund. Francois presents with a two month history of minimal jumping and over the past 3 days has become very painful and cries when touched. Patient continues to eat and drink, etc. There are no neurologic deficits and no ataxia. Collapse of the L3-4 intervertebral disc is seen. A disc herniation is suspected.
Sequences include T2-weighted sequences, STIR sequences, and T1-weighted images before and after contrast. T1-weighted images are performed post-contrast with fat-saturation to reduce the bright signal from the fat and allow better visualization of the contrast enhancement.
The abnormality at L3-4 is readily visualized. On figure 1, a sclerotic reaction can be seen involving the caudal endplate of L3 and the cranial endplate of L4. On figure 2, the STIR sequence reveals a bright increased signal intensity at the intervertebral disc space. This is atypical for a dachshund that tends to desiccated intervertebral discs, as seen in the other sites. Also, notice that this animal has an enlarged prostate gland.
Figure 3 is a sagittal image following the administration of gadolinium contrast agent. Contrast enhancement can be seen in the intervertebral disc space. Notice how the fat has turned dark (fat saturation technique) allowing better visualization of the contrast enhancement.
On figure 4, the contrast enhancement of the disc space, as well as in some of the paraspinal musculature, can be readily seen.
This animal has evidence of discospondylitis, an infectious condition of the disc space and intervertebral endplates. This was not detected on a radiographic examination. Only the narrowness of the disc space was detected. This condition can often be confirmed via culture of the blood, CSF, or urine. Most clinicians opt for urine culture. Most common cause of this condition is from a staphylococcus infection from the genitourinary tract. Other conditions, including Brucella sp., have been found. This should always be considered due to the potential for a zoonotic spread to the owner. In this case, Staphylococcus aureus was cultured from the urine.
MR allowed for the definitive diagnosis of discospondylitis in this case. The case went from the typical dachshund with presumed intervertebral disc disease to an animal having an infectious condition. The study prevented this animal from having an unwarranted surgery of the spine and allowed for the condition to be properly treated with antimicrobial therapy. While discospondylitis can cause erosion of the vertebral endplates, that takes time. It takes a 30-50% decrease in bone density in order to be seen radiographically. MR is must more sensitive for the detection of the soft tissue as well as osseous abnormalities. Just because it’s a dachshund with back pain does not mean it is a disc herniation. Dachshunds, unfortunately, are subjected to all the other diseases known to affect the spine, spinal canal, and spinal cord.