Clinical features of muscle stiffness in 37 dogs with concurrent naturally occurring hypercortisolism

Abstract

Background Severe muscle stiffness (SMS) in dogs with hypercortisolism (HC) is uncommon. Objectives To evaluate signalment, presentation, treatments, and long‐term outcomes of dogs with concurrent HC and SMS. Animals Thirty‐seven dogs. Methods Medical records of dogs with HC and concurrent SMS were recruited from 10 institutions. Clinical information, test results, therapeutic responses, and survival times were reviewed. Results All 37 dogs with HC and SMS had pituitary‐dependent hypercortisolism (PDH); 36/37 weighed <20 kg. Signs and test results were typical of PDH aside from SMS, initially diagnosed in all 4 limbs in 9, pelvic limbs of 22, and thoracic limbs of 6 dogs. Hypercortisolism and SMS were diagnosed together in 3 dogs; HC 1‐36 months before SMS in 23; SMS 1‐12 months before HC in 11. Mitotane or trilostane, given to control HC in 36/37 dogs, improved or resolved HC signs in 28; SMS did not resolve, remaining static or worsening in 31/36 dogs, mildly improving in 5/19 dogs given additional therapies. Progression of SMS included additional limbs in 10 dogs and the masticatory muscles of 2. The median survival time from diagnosis of SMS was 965 days (range, 8‐1188). Conclusions and Clinical Importance Concurrent SMS and HC is uncommon, possibly affecting only dogs with PDH. Development of SMS might occur before or after diagnosis of HC. Apart from SMS, the clinical picture and survival time of these dogs seem indistinguishable from those of dogs with HC in general. However, while muscle weakness usually resolves with HC treatment SMS does not.

Trismus due to myotonia associated with hyperadrenocorticism in a dog

“…On the other hand, some cases in past studies indicated that remission of myotonia symptoms, especially those of the temporalis muscle, tends to be difficult. In a few past case reports, myotonia of the limbs did not improve despite trilostane treatment [ 9 , 13 , 15 , 19 ]; in this case, as well as in previous cases, no sufficient therapeutic effects were observed on myotonia. The reason for different treatment responses between trismus and myotonia of the extremities is not clear.…”

“…Decreased mandibular range of motion has been reported in myotonia congenita [ 8 ]. There has been a report that the canine case with muscle stiffness with concurrent hypercortisolism exhibited difficulty in chewing and swallowing, but the details of the case are not available [ 9 ]. In the present case, the diagnosis of hyperadrenocorticism was based on clinical presentation, bilateral adrenal enlargement, and the cortisol level of the ACTH stimulation test.…”