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The case of the stertorous kitty

“Alchemy,” a domestic shorthair, presented with labored breathing and, ultimately, had a nasopharyngeal polyp removed

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Figure 1: Tooth #204 is fractured with pulp exposure and there is a subtle ventral deviation of the soft palate due to a nasopharyngeal polyp.
Figure 1: Tooth #204 is fractured with pulp exposure and there is a subtle ventral deviation of the soft palate due to a nasopharyngeal polyp.
Photos courtesy John Lewis

Even though I specialize in dentistry and oral surgery, I am occasionally referred a patient that has multiple undiagnosed medical problems. Owned by an organic chemist, “Alchemy” is a four-year-old male domestic shorthair cat that was presented for treatment of a fractured left maxillary canine tooth (#204). In addition, the patient was assessed for chronic stertor, which is a low-pitched respiratory noise that sounds like snoring. In contrast, stridor is a high-pitched wheezing noise suggestive of airway obstruction.

Whenever a patient is presented with signs of nasal disease, a thorough oral examination should be performed to rule out a primary dental problem. Disease of the maxillary teeth can cause lymphocytic-plasmacytic rhinitis secondary to infection.1 This is particularly true of the maxillary canine tooth due to a very thin layer of bone on the palatal surface of its root apex, which, if disrupted by inflammation or infection, may result in extension of the inflammatory process into the nasal passage. Periodontal disease can extend along the periphery of a tooth and lead to an oronasal fistula. Endodontic disease can result in periapical bone loss that might erode into the nasal cavity.

It would have been nice to be able to explain all of Alchemy’s clinical signs with the known pathology of the fractured tooth, but the severity of his nasal stertor and the bilateral lack of nasal airflow at the nares made me suspect another etiology. Patients with small oronasal fistulae secondary to periodontal disease rarely show clinical signs except for the occasional sneeze and perhaps mild serous nasal discharge. Similarly, patients with endodontic disease rarely exhibit signs until the infection gets severe enough to cause facial swelling and/or a draining tract. Therefore, my suspicion for Alchemy’s nasal stertor was something other than dental disease, specifically a nasopharyngeal polyp.

The source of the sound

Cats aren’t obligated to breathe through their nose and can breathe through the mouth if necessary. However, their quality of life is much improved when nasal breathing is possible. This is especially true when eating, grooming, and sleeping. Although tooth #204 showed evidence of having potentially painful endodontic disease that was resolved by extracting it (Figure 1), it wasn’t the source of Alchemy’s noisy breathing.

Cats occasionally develop inflammatory nasopharyngeal polyps that block their caudal nasal passage. This interesting condition occurs due to inflammation within the middle ear, nasopharynx, or the tube that connects the two structures, called the Eustachian tube. Named after one of the founders of the science of human anatomy (Bartolomeo Eustachi), the Eustachian tube is a cartilaginous passageway connecting the middle ear with the nasopharynx. Its function is to equalize pressure on both sides of the tympanic membrane and drain the middle ear.

Figure 2: The nasopharyngeal polyp after removal.
Figure 2: The nasopharyngeal polyp after removal.

What causes nasopharyngeal polyps? Etiology is unknown, but exposure to certain respiratory viruses is thought to result in proliferation of the polyp. Once the polyp grows large enough to extend into the nasopharynx, it can occlude the entire caudal nasal passage. Signs may include sneezing, nasal discharge, gagging, voice change, decreased or nonexistent nasal airflow, and otitis externa.2

Diagnosis of a suspected polyp is often made by oropharyngeal examination and submission of removed mass for histopathology. Skull radiography and CT scan can be done to assess for middle ear involvement and to rule out other possible causes of nasal signs.

Treatment often involves manual removal of the polyp intraorally with slow, steady traction (see a video of a polyp removal below). However, since a portion of the polyp may still be retained within the middle ear, a bulla osteotomy surgery may be necessary to prevent recurrence. How likely is recurrence after removal of a polyp by traction alone? One study reviewed the case records of 37 cats treated for nasopharyngeal or aural inflammatory polyps. Thirty of them were managed conservatively, with the polyp being removed by traction alone. Long-term follow-up was available for 22 cats, of which 13 (i.e. 59 percent) showed no recurrence of clinical signs.3

Alchemy was placed in dorsal recumbency, and a Snook hook was used to pull the soft palate rostrally. Sanguinopurulent mucus was removed from the area with a cotton-tipped applicator. A circumscribed pink/white mass was identified and grasped with curved hemostats. Slow, steady traction was applied in a ventral direction until the polyp was dislodged. The polyp was inspected for evidence of a stalk (Figure 2). Significant bleeding could be seen immediately after polyp removal, so the throat was inspected and gauze was used to remove blood or mucus. After removal of a polyp, transient Horner’s syndrome may occur on the ipsilateral side. This was true for Alchemy, and it resolved within a few days.

There are few things in life more satisfying than removing a nasopharyngeal polyp in a cat that’s having trouble breathing. Nasopharyngeal polyps can recur and, therefore, a bulla osteotomy surgery may be in Alchemy’s future. But for now, he is “like a new cat,” according to his owners.

 

John Lewis, VMD, FAVD, DAVDC, practices dentistry and oral surgery at Veterinary Dentistry Specialists and is the founder of Silo Academy Education Center, both located in Chadds Ford, Pa.

References

  1. Stepaniuk KS, Gingerich W. Suspect Odontogenic Infection Etiology for Canine Lymphoplasmacytic Rhinitis. J Vet Dent. 2015; 32(1): 22–29.
  2. acvs.org/small-animal/nasopharyngeal-polyps. Accessed December 31, 2019.
  3. Anderson DM, Robinson RK, White RA. Management of inflammatory polyps in 37 cats. Vet Rec. 2000; 147(24): 684–687.
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