Case report highlights plasma exchange for PANS in a dog

A newly published case report in the Journal of Veterinary Emergency and Critical Care details the successful use of modified manual therapeutic plasma exchange, or MTPE, in a dog with postattenuation neurological signs after portosystemic shunt surgery, marking what the authors describe as the first documented use of this technique for PANS in dogs. The patient was a 4-year-old Yorkshire Terrier that developed neurologic signs after surgical correction of a congenital portosystemic shunt and recovered after treatment with the modified manual exchange approach. (pubmed.ncbi.nlm.nih.gov)

That matters because PANS remains one of the most feared complications after surgical attenuation of congenital portosystemic shunts. A 2022 review of 50 publications found that PANS most commonly appears within seven days of surgery and can include depression, behavioral change, tremors, twitching, and seizures. The same review reported a wide incidence range, 1.6% to 27.3% for PANS overall, reflecting differences in case definitions and reporting, and noted that mortality is often tied to generalized seizure activity. (pubmed.ncbi.nlm.nih.gov)

The syndrome’s underlying mechanism is still unsettled. Historically, clinicians have ruled out more familiar postoperative causes such as persistent hyperammonemia, hypoglycemia, and electrolyte derangements, and the literature suggests those abnormalities often do not explain the neurologic decline. More recent work has explored metabolic explanations, including altered tryptophan pathway metabolites. A pilot study published in 2025 found that dogs developing PANS had lower postoperative serum 3-hydroxykynurenine concentrations, suggesting the pathogenesis may involve more complex neurochemical shifts than ammonia alone. (pubmed.ncbi.nlm.nih.gov)

Against that backdrop, plasma exchange is an interesting addition. Therapeutic plasma exchange has been reported only sporadically in veterinary medicine, including prior cases involving hepatic encephalopathy, kernicterus, toxin exposure, immune-mediated disease, and myasthenia gravis. In a 2020 report, manual therapeutic plasma exchange was used successfully in a dog with hepatic encephalopathy secondary to a portosystemic shunt, and the dog was discharged three days later without neurologic signs. More recent canine reports also suggest TPE can be performed with acceptable procedural safety in specialty settings, though monitoring for hemodynamic changes, hypocalcemia, and protein loss remains important. (pubmed.ncbi.nlm.nih.gov)

There does not yet appear to be broad published expert commentary on this specific new case, but the surrounding literature helps frame the likely reaction: cautious interest rather than immediate practice change. Reviews of PANS emphasize that evidence for prevention and treatment remains thin, and even prophylactic antiepileptic strategies have not consistently reduced incidence. That makes any plausible rescue therapy noteworthy, but this remains a single case report, not proof of efficacy across the wider shunt population. (pubmed.ncbi.nlm.nih.gov)

Why it matters: For veterinary professionals, especially surgeons, neurologists, and ECC teams managing congenital shunt cases, this report expands the conversation about salvage options when postoperative neurologic deterioration escalates. If MTPE can reduce circulating neuroactive or inflammatory mediators involved in PANS, it could offer a practical bridge in selected referral cases, particularly where fully automated or membrane-based extracorporeal platforms are unavailable. At the same time, implementation would require blood-product access, intensive monitoring, procedural expertise, and careful case selection, all of which limit immediate generalizability to primary care practice. That likely places MTPE, for now, in the category of emerging specialty intervention rather than standard postoperative protocol. This is an inference based on the case report and the broader TPE literature. (pubmed.ncbi.nlm.nih.gov)

What to watch: The next important step is replication. Additional case reports, small series, or multicenter retrospective data will be needed to show whether MTPE improves outcomes in refractory PANS, whether it works best in seizure-dominant versus nonseizure cases, and how its risk-benefit profile compares with intensive medical management alone. Longer term, emerging mechanistic work on PANS may also help clarify whether plasma exchange is targeting the right biology, or simply buying time while the postoperative brain stabilizes. (pubmed.ncbi.nlm.nih.gov)