Juvenile onset masticatory muscle myositis diagnosed in a 16-week-old Cavalier King Charles Spaniel puppy

Authors: Lu HY
Publication: Australian Veterinary Practitioner, Volume 49, Issue 4, pp 105-109, Dec 2019
Publisher: Australian Veterinary Association

Animal type: Dog
Subject Terms: Animal remedies/veterinary medicines, Clinical examination, Genetics, Pain
Article class: Clinical Report

---

Abstract:

CASE REPORT: A 16-week-old female spayed Cavalier King Charles Spaniel (CKCS) was referred with a 3-day history of dysphagia, hypersalivation, lip-smacking and unwillingness to open the mouth. The puppy’s mouth was held slightly open at rest and saliva staining of the fur around the mouth was observed. Pain was elicited on manipulation of the jaw and trismus was exhibited. A mild increase in creatine kinase was present (1190 IU/L; RI 0-385 IU/L) and 2M fibre antibody testing was positive, with a titre of 1:500 mg/dL, confirming the diagnosis of masticatory muscle myositis (MMM).

CONCLUSION: This is the first reported case of MMM in a juvenile CKCS puppy in New Zealand. Together with a previous publication of atypical MMM in three 12-week-old CKCS puppies from the same litter in the UK, and 11 juvenile CKCS identified with MMM in the USA, it reinforces the prevalence of MMM in young CKCS puppies and again raises the hypothesis of MMM being a genetically predisposed disease in the breed.

KEYWORDS: masticatory muscle myositis, Cavalier King Charles Spaniel, 2M fibre antibody test, juvenile

---