Puffer Fish Toxicity in Dogs

Philip R Judge BVSc MVS PG Cert Vet Stud MACVSc (Vet Emergency and Critical Care; Medicine of Dogs)

Introduction

Puffer fish ingestion is a well-documented cause of poisoning in both humans and animals. For dogs, which are often exposed during off-lead walks along beaches, the risk can be life-threatening due to the presence of tetrodotoxin (TTX) – a potent neurotoxin that is concentrated in the skin, liver, ovaries and sometimes muscle of puffer fish¹.

Tetrodotoxin: A Lethal Neurotoxin

TTX is a heterocyclic guanidine compound that binds selectively to voltage-gated sodium channels in nerves and muscles, blocking sodium influx and halting action potential generation in post-synaptic nerves and muscles¹.

This blockade leads to the development of acute neurological impairment, paralysis and, in severe cases, respiratory arres1t.

Toxicity levels vary considerably by Puffer fish species, geographical location, and season. Within Puffer fish, the highest concentration of TTX usually found in the liver and ovaries, though muscle tissue in some species (e.g. Lagocephalus lunaris) can also be dangerously toxic. Importantly, the toxin is heat stable, with cooking, drying, or decomposition not reliably reducing its potency¹.

Clinical signs in dogs

Dogs show a similar clinical picture to humans when suffering TTX toxicity¹. 

Early clinical signs may include¹:

• Vomiting and hypersalivation
• Lethargy, weakness and ataxia
• Tremors, seizures and progressive paralysis
• In severe cases, cardiac arrhythmias, respiratory failure and death may occur 

Case documentation from Honduras described two dogs that ingested multiple juvenile puffer fish. One dog developed gastrointestinal and neurological signs for 4–6 hours, but recovered within 6–12 hours following decontamination therapy². 

A case series in New Zealand, described 15 dogs poisoned after contact with TTX-containing sea slugs, with vomiting, ataxia, lethargy, and neurological symptoms as described above (seizures, respiratory failure etc.). Five died despite veterinary intervention³.

Management of intoxication

There is no specific antidote for TTX¹. Treatment, therefore, is directed to providing decontamination, and supportive and symptomatic care, including^14,5:

1. Decontamination:
   1. Induction of emesis for patients with recent ingestion, who are neurologically stable.
   2. Administration of activated charcoal may be considered @ 1–2 g/kg PO; repeat every 4–6 h if appropriate, to reduce toxin absorption.
2. Supportive therapy:
   1. Intravenous fluids to treat hypovolaemia, and to provide for maintenance 
   2. Thermoregulation
   3. Monitoring
   4. Control of tremors and seizures when indicated
3. Respiratory support:
   1. Dogs with respiratory muscle paralysis require oxygen supplementation, but may require intermittent positive pressure ventilation (manual or mechanical ventilation)
4. Recovery is possible with prompt intervention, as toxin effects generally resolve within 24 hours if the animal survives the initial crisis.

Epidemiological context

While puffer fish poisoning is most frequently reported in humans in East Asia, where consumption is a cultural practice, accidental canine intoxications are increasingly recognised worldwide. 

Veterinarians in coastal communities, therefore, should maintain a high index of suspicion when presented with acute onset neurological collapse in dogs with beach access.

Prevention and client education

Prevention is a key component in reducing risk to animals¹. Owners should be advised to:

1. Keep dogs on leads when walking near beaches where puffer fish or other toxic marine animals may wash ashore.
2. Avoid allowing pets to scavenge or mouth unknown fish or sea slugs.
3. Seek veterinary attention immediately if ingestion is suspected, bringing any remains of ingested materials into the clinic for identification.

Conclusion

Puffer fish intoxication in dogs is a potentially fatal condition, that necessitates a thorough patient assessment, adherence to the principles of providing basic and advanced life support, decontamination, and supportive care to optimise patient outcome. Understanding the toxicology of TTX, recognising the rapid onset of signs, and instituting aggressive supportive care are critical for survival. 

References 

1. Nagashima Y, Arakawa O. Pufferfish poisoning and tetrodotoxin. In: Gopalakrishnakone P, et al., editors. Marine and Freshwater Toxins, Toxinology. Dordrecht: Springer; 2016. p. 259–284
2. Brown TW, Lacqua AJ, Maryon DF, Sansur AD. Caribbean Sharp-nosed Pufferfish (Canthigaster rostrata) Tetrodotoxin Poisoning in Two Dogs in Honduras. Caribb J Sci. 2020;50(2):219-224.
3. McNabb P, Selwood AI, Munday R, Wood SA, Taylor DI, MacKenzie LA, et al. Detection of tetrodotoxin from the grey side-gilled sea slug (Pleurobranchaea maculata), and associated dog neurotoxicosis on beaches adjacent to the Hauraki Gulf, Auckland, New Zealand. Toxicon. 2010;56(3):466-73.
4. Nikolaidis G, Katikou P, Panagiotopoulos I, Zacharaki T, Fotaras T, Botana LM, et al. An Updated Review of Tetrodotoxin and Its Peculiarities. Mar Drugs. 2022;20(1):47.
5. Schmid RD, Brutlag A. Principles of Toxicosis Treatment in Animals. In: MSD Veterinary Manual (Professional Version). Revised June 2024.