November 2025
In this VETgirl online veterinary continuing education blog, we discuss a recent, cutting-edge study by Freeman et al entitled “Percutaneous enzymatic chemonucleolysis of intervertebral disks appears safe and effective in treatment of acute-onset paraparesis and paraplegia in small dogs,” published in JAVMA in March 2025. If you’re a general practitioner who sees a lot of down dogs—and especially if you practice in a Dachshund-heavy region—you’ll definitely want to read below! When in doubt, check out the VETgirl podcast interview with Dr. Jeffery HERE.

Intradiscal Injection of Chondroitinase ABC in Down Dogs with IVDD with Dr. Nicholas Jeffery

By Dr. Justine Lee, DACVECC, DABT, Director of Medicine / CEO, VETgirl  & Dr. Nick Jeffery, BVSc, PhD, MSc, DECVS, DECVN, Professor in Neurology and Neurosurgery from Texas A&M

Why This Study Matters

For decades, the prevailing wisdom has been that decompressive spinal surgery is the go-to standard of care for dogs that suddenly can’t walk due to thoracolumbar intervertebral disc herniation—especially those with intact deep pain. But that recommendation has always been based more on observational data than on randomized trials. We know many deep pain–positive dogs recover with conservative management alone. So what if there’s a middle-ground, nonsurgical approach that’s less invasive, more affordable, and still gets most dogs back on their feet?

That’s exactly what this new study aimed to explore. The authors hypothesized that intradiscal injection of chondroitinase ABC (often called “CHASE”) —an enzyme that breaks down chondroitin sulfate proteoglycans in the nucleus pulposus—would be both safe and effective in helping small dogs recover from acute, severe thoracolumbar intervertebral disc disease. Their goal? Offer a low-cost, minimally invasive alternative to decompressive surgery for pet owners who just can’t afford it.

Study design: A Pragmatic, Phase 1 Clinical Trial

This was a prospective, phase 1 clinical trial conducted across two academic neurology centers: Texas A&M University and the University of Cambridge. Dogs were enrolled between January 2023 and June 2024.

To be eligible, dogs had to meet the following inclusion criteria:

  • Acute-onset nonambulatory paraparesis or paraplegia occurring within 48 hours of presentation
  • Weight <15 kg
  • Age between 2 and 10 years
  • Owners unable to afford decompressive surgery

Importantly, dogs were not excluded based on their deep pain status—so this study included both deep pain–positive and deep pain–negative cases.

Diagnosis was made based on clinical and neurologic exams alone—no CT or MRI was performed. So this was a truly pragmatic, real-world design intended to replicate general practice scenarios where owners decline referral or imaging due to cost.

Materials and Methods: What Did They Do?

After informed owner consent and IACUC approval, dogs were sedated and positioned in lateral recumbency for fluoroscopic-guided disc injection. A total of 4 consecutive intervertebral discs centered on the suspected lesion site (determined by neuro exam and pain localization) were injected percutaneously with 1.25 units of chondroitinase ABC each (diluted in 0.2 mL saline). The needle was placed directly into the nucleus pulposus under fluoroscopic guidance.

Owners were instructed to restrict activity after discharge (ranging from 4-5 days at TAMU to 2-4 weeks at University of Cambridge) and received appropriate analgesics and, when needed, bladder care instructions. Likewise, at discharge, NSAIDs, corticosteroids and/or antineuropathic pain medications were given based on clinical signs, RDVM prescription, or owner observations. There was no standardized post-op rehab protocol.

Outcome was measured and defined as successful by the dog’s ability to walk 50 steps unassisted or defined as unsuccessful outcome if the dog was unable to walk 50 steps unaided within 4 months of injection. Follow-up was conducted via email or text, with video submission when possible.

Results: Let’s Talk Numbers

A total of 54 dogs were enrolled in the study. Here’s how things broke down:

  • Of the 54 dogs, 18 were female (14 spayed) and 36 were male (25 neutered)
  • Not surprisingly, Dachshunds made up 42 of the 54 dogs in the study. This aligns with their well-known predisposition to Hansen type I intervertebral disc disease. Other included breeds were Shih Tzus (n=3), French Bulldogs (n=3), mixed breeds (n=5), and one Beagle. Interestingly, the study notes that French Bulldogs were excluded early in the enrollment process due to frequent in-hospital respiratory complications—a good reminder of how this breed’s comorbidities (e.g., Brachycephalic Obstructive Airway Syndrome – or BOAS) can complicate otherwise routine procedures.

 

  • 41 dogs had intact pain perception in the hind limbs and/or tail at presentation, while 13 dogs had absent pain perception.

Of the 41 deep pain–positive chondroitinase treated dogs:

  • 38 out of 40 with appropriate follow-up recovered to walk 50 steps unassisted within 4 months. That’s a 95% recovery rate (95% CI: 83% to 100%), which is amazing! The median time to walking was 11 days (IQR: 8–20 days)
  • 2 dogs were euthanized due to clinical deterioration (1 developed myelomalacia)
  • 1 dog did not improve by 3 weeks and had decompressive surgery, at which point, was able to walk 50 steps within 3 weeks.

Of the 13 deep pain–negative chondroitinase treated dogs:

  • The recovery rate with sufficient follow-up was 40% (95% CI: 17% to 69%).
  • 4 dogs recovered to walking (by days 20, 30, 61, and 110)
  • 4 dogs developed progressive myelomalacia and were euthanized within 6 days
  • 2 dogs did not recover by 4 months
  • 3 dogs were lost to follow-up

No adverse events attributable to the injection procedure were observed. Fluoroscopic guidance was successful in all cases, and the injections were well tolerated. No dogs developed neurologic worsening or infections related to the chondroitinase injection. Long-term recurrence of clinical signs wasn’t reported over the 24-month follow-up period.

A Quick Word on Chondroitinase Availability in the U.S.

Chondroitinase ABC is not currently FDA-approved for use in veterinary patients in the United States. In this study, the enzyme was obtained under AMDUCA regulations and used with owner consent. The product is approved in Japan (under the trade name Condoliase) for use in human patients with lumbar disc herniation.

Because it’s not commercially available in the U.S., general practitioners currently cannot offer this therapy without specific institutional approval and sourcing under compassionate use or investigational drug protocols. However, its use in experimental and clinical trials has shown promising safety and efficacy profiles, and wider availability could eventually change treatment paradigms—especially in cost-sensitive settings.

Discussion: What Does This Mean for Your Patients?

Neurological examination in process for a paraplegic dog. (Photo curtesy of Amanda M. Shelby)

The results of this study are compelling. In deep pain–positive dogs, recovery after intradiscal chondroitinase injection was nearly identical to the reported outcomes for decompressive surgery, both in terms of proportion recovered and speed of recovery. That 11-day median to walking is actually faster than the 14-day median post-op recovery seen in some surgical cohorts.

For deep pain–negative dogs, the recovery rate was lower (40%) but not zero—and importantly, similar to the published rates for surgery in this more severe group. While the sample size is small, these findings suggest the procedure may still be worth considering in select cases.

For some dogs—especially those whose owners decline surgery—this minimally invasive, outpatient, low-cost alternative may offer a real, practical solution.

VETgirl Takeaways for General Practitioners

  • Intradiscal chondroitinase injection appears to be a safe, minimally invasive option for small dogs with acute nonambulatory paraparesis or paraplegia, especially when deep pain perception is intact.
  • Recovery rate in deep pain–positive dogs was 95%, with a median recovery time of just 11 days—very similar to decompressive surgery outcomes.
  • Even in deep pain–negative dogs, 40% recovered to walk again, although a higher rate of progressive myelomalacia was observed.
  • While you need fluoro and access to the non-FDA approved drug, this does give us hope for owners with financial limitations who cannot afford decompressive surgery!
  • While this procedure is not yet available for general use in the U.S., it paves the way for future clinical trials and potentially broader access.
  • And let’s not forget breed relevance—Dachshunds dominated this cohort, making these findings especially relevant for general practitioners seeing “the down Doxie.”


As always, we encourage you to read the full paper for the nitty-gritty details, but hopefully this gives you a clinically useful snapshot. Whether you’re counseling owners, triaging spinal emergencies, or just trying to keep your neurology knowledge sharp, studies like this challenge long-standing assumptions—and give us future hope to better help our canine down dogs!

References:

  1. Freeman P, Atiee G, Donoghue EM, Jeffery ND. Percutaneous enzymatic chemonucleolysis of intervertebral disks appears safe and effective in treatment of acute-onset paraparesis and paraplegia in small dogs. J Am Vet Med Assoc 2025;doi.org/10.2460/javma.24.12.0790.

  1. Justin Dutra says:

    Very promising. Hope to see wider availability for use in the future. Maybe another “GS” medication situation?

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