2.5-year-old, Male, Neutered, Shiba Inu, Canine

This case was presented in our monthly virtual Abdominal Rounds with Donald E. Thrall DVM, PhD, DACVR in April 2021. If you’d like to join us in these sessions. please click this link.

History: This dog was in a tussle with his housemate and tore off his collar and ate part of it.  Over the next 12 hours the dog developed diarrhea and experienced tremors and ataxia.  Abdominal radiographs were made because of the diarrhea.

Radiographs: Left lateral (1A), Right lateral (1B) and Ventrodorsal (1C) views were made.


  • The stomach is mildly to moderately gas distended and contains multiple square to broad linear mildly mineralized structures measuring up to approximately 2 x 1 cm. A mild amount of amorphous homogenous soft tissue opaque material is also present in the lumen.
  • A few small intestinal segments are moderately distended and contain additional broad linear and squared mildly mineralized structures.
  • The remaining small intestinal segments are within normal limits for diameter, characterizing two populations of small intestine.
  • The remaining abdominal organs are unremarkable.
  • The abdominal serosal detail is adequate.
  • There is Incidental bilateral coxofemoral osteoarthritis.


  • There is gastric and small intestinal luminal foreign material, consistent with the reported collar ingestion.
  • There is evidence of a secondary mechanical ileus and a partial pyloric outflow obstruction cannot be excluded.
  • The reported tremors and ataxia are most likely a manifestation of a toxicity associated with the collar being antiparasitic.  The size and shape of the foreign material are typical of fragments of an antiparasitic collar.


Endoscopy or induced emesis could be considered for removal of the gastric foreign material.  However, with the signs of an intestinal obstruction, a laparotomy would be justified.  With some obstructions careful observation could be considered to allow the obstruction an opportunity to resolve spontaneously but, as in this patient, when the source of the obstruction is toxic this is not a recommended approach.  The specific outcome of this patient is not known.


The key to the correct diagnosis in this patient is recognizing that the size and shape of the foreign material are typical of fragments from an antiparasitic collar.  Fortunately, most flea and tick collars are radio-opaque (Stilabower, 2021).

According to the Animal Poison Control Center, flea and tick collars vary in their active ingredient.  This site states, “Often, these collars contain amitraz (a chemical that is an alpha2-adrenergic agonist and monoamine oxidase inhibitor), organophosphates or carbamates, or pyrethrins/pyrethroids. Please see each individual active ingredient for more information. When flea and tick collars are accidentally ingested or applied to pets inappropriately, they can result in severe clinical signs of the central nervous system (e.g., lethargy, walking drunk, dilated pupils, seizures, coma), gastrointestinal system (e.g., drooling, vomiting, diarrhea, bloating), and cardiac system (e.g., slowed heart rate, low or high blood pressure). Depending on what the active ingredient is, treatment must be initiated promptly” (Anon, 2021).

If possible, collar segments present in the stomach should be considered for removal by induced emesis, endoscopy or gastrotomy.  Any small intestinal obstruction should be treated appropriately.  Clinical signs will persist until all collar fragments are removed and/or eliminated.


Anon. (2021, April 24). Flea Collar. Retrieved from 24/7 Animal Poison Control Center: (855) 764-7661: flea collar info

Stilabower, A. (2021, April 24). Common Flea and Tick Toxicity Questions and Answers. Retrieved from 24/4 Animal Poison Control Center (855) 764-7661: Flea and Tick Toxicity Q/A

Photo by Christal Yuen on Unsplash

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