Clinical Presentation, Consecutive Measurements of Serum Butyryl-Cholinesterase Activity and Treatment of a Dog Intoxicated by Anticholinesterase and Presented Acute Cholinergic Crisis Followed by Intermediate Syndrome. Case Report and Review of the Literature

The article describes the clinical signs, laboratory findings, including consecutive serum butyryl-cholinesterase (sBuChE) activity measurements, treatment and outcome of a dog diagnosed with intermediate syndrome (IMS) of organophosphate intoxication. A 2-year old neutered female mixed-breed dog was presented with acute cholinergic crisis (ACC) due to anticholinesterase intoxication. sBuChE activity upon admission was markedly low [382 U/L; reference interval, (RI) 2,660-11,00 U/L]. The dog was treated with atropine sulfate, diphenhydramine, 2-pyridine aldoxime-methyl-chloride and supportive care. The muscarinic signs resolved, but 24 hrs post-admission the dog sustained a grand-mal seizure and developed quadriparalysis and severe weakness, including respiratory muscle weakness, necessitating positive pressure mechanical ventilation (PPMV). The dog recovered slowly, presenting signs of ventroflexion, front limb muscle weakness and absent swallow reflex of several days, which gradually improved. During ventilation sBuChE activity was 2735 U/L, and later on during hospitalization, remained mildly less than the RI. The dog was discharged on day 8 of hospitalization. IMS has previously been diagnosed based on the history of a previous case of ACC, with deterioration to classic IMS clinical signs, requiring PPMV. Interestingly, sBuChE was within or mildly below RI during the course of the IMS, which highlighted the possibility of a diagnosis of IMS in face of normal sBuChE activity. The authors conclude that IMS should be suspected in dogs showing cranial nerve, respiratory, neck and proximal limb muscle weakness or paralysis, especially in face of prior ACC, but even in the absence of preceding ACC signs.