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Muscle stiffness with concurrent naturally occurring hypercortisolism

Naturally occurring or iatrogenic hypercortisolism can cause myopathic signs in addition to the more 'classical' signs of PuPd, polyphagia, bilateral symmetrical truncal hair loss, and excessive panting. Muscle atrophy and weakness are frequently seen contributing to the 'pot belly' appearance and exercise-induced weakness. Rarely, severe muscle stiffness (SMS) can develop with naturally occurring hypercortisolism. The pathophysiology is unclear. EMG in these dogs often reveals complex repetitive discharges which has led to this condition being labelled as a pseudomyotonia. Unlike myotonic discharges, there is no waxing and waning of these discharges. In this study, the authors evaluate signalment, presentation, treatments, and long-term outcomes of dogs with concurrent hypercortisolism and SMS. While muscle weakness usually resolves with hypercortisolism treatment, SMS does not. This was the case with the dog in the above video kindly provided by Drs Falzone, Gasparinetti, Della Camera from Diagnostica Piccoli Animali, Italy, showing you the severe SMS which can sometimes be associated with hypercortisolism.

Clinical features of muscle cramp in 14 dogs

Muscle cramps (MC) are defined as prolonged, involuntary, painful muscle contraction, having acute onset and short duration, lasting from seconds to minutes. MC are considered the clinical manifestation of nerve hyper excitability and characterised by repetitive motor unit action potentials from the simultaneous contraction of a large number of motor units. One of the main differentials for MC is paroxysmal dyskinesia (PD) which presents with similar characteristics helping to differentiate from epileptic seizures such as not being associated with autonomic signs, impaired consciousness and abnormal postictal behaviour. Although PD are considered painless, this criteria may be difficult to ascertain in a dog not showing overt pain manifestation. In this series, the authors described 3 clinical patterns of MC depending on whether or not the cramps migrate to other limbs. The most common cause of muscle cramps was hypocalcemia in 79% of dogs with primary hypoparathyroidism being most commonly encountered. In two third of dogs, MC were triggered by prompting the dog to move as shown in the attached video which shows one of our old patients with MC caused by primary hypoparathyroidism

Paradoxical pseudomyotonia in English Springer and Cocker Spaniels

The aim of this paper is to define and describe the clinical, diagnostic, and genetic features and disease course of paradoxical pseudomyotonia in 7 Spaniel dogs.

All dogs were <24 months of age at onset. The episodes of myotonic‐like generalized muscle stiffness always occurred with exercise, and spontaneously resolved with rest in <45 seconds in all but 1 dog - see video above. Extreme outside temperatures seemed to considerably worsen episode frequency and severity in most dogs. Complete blood count, serum biochemistry including electrolytes, urinalysis, brain magnetic resonance imaging, cerebrospinal fluid analysis, electromyography, motor nerve conduction velocity, ECG, and echocardiography were unremarkable. Muscle biopsy samples showed moderate but nonspecific muscle atrophy. The episodes seemed to remain stable or decrease in severity and frequency in 6/7 dogs, and often could be decreased or prevented by avoiding the episode triggers.

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Reversible positioning head tilt observed in 14 cats with hypokalaemic myopathy

Positioning head tilt (PHT) is a dynamic neurological sign in which the head tilts to the opposite side to which it is moving. This sign is triggered in response to head movement and is thought to be due to ineffective cerebellar nodulus and uvula function, most frequently believed to be due their congenital absence.

This study describe the acute onset of PHT in 14 cats. All the cats were diagnosed with hypokalaemic myopathy caused by a range of pathologies. The PHT resolved along with other signs related to myopathy, such as cervical flexion and generalised weakness, after electrolyte correction in all cats.

Access the paper for some fantastic videos of the affected cases and note the frequent ventroflexion that also affects these cats, as is more classically decribed.

Feline Arterial Thromboembolism

Feline arterial thromboembolism, sometimes referred to as 'saddle thrombus' is a potentially serious and emergent issue that can be responsible for severe neuromuscular dysfunction. Read the latest review on this subject in this great article that addresses each aspect of the disease with management options and outcomes described.

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Progressive increases in creatine kinase activity in an anorexic cat with necrotising myopathy


Cats with myopathy typically have generalised paresis with reduced segmental spinal reflexes and creatine kinase (CK) activity is variably increased. Increased CK activity does not always indicated primary myopathy and can be observed as a non-specific findings in unwell and anorexic cats who may experience moderate to marked increased in this enzyme activity. In anorexic cats, muscle catabolism has been postulated as the cause of the high serum CK activity. Beside the above, other causes of high CK activity include muscle trauma, seizure activity, prolonged recumbency, haemolysis or hyperbilirubinaemia. A recent case report documents increasing CK activity in a cat with anorexia, weight loss, hepatic lipidosis and muscle stiffness. Muscle biopsy shows myonecrosis which was postulated as the consequence of abnormal nutritional status and anorexia in this cat.

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Primary multifocal muscular T-cell lymphoma with cutaneous involvement in a dog: A case report and review of the literature

Canine lymphoma represents a heterogeneous group of lymphoid neoplasms, with multicentric nodal lymphoma being the most common presentation. Musculoskeletal involvement is uncommon, and primary muscular lymphoma is a very rare presentation.

A 5-year-old female neutered Beagle that presented with an intramuscular mass on the right shoulder and associated lameness and lethargy - Cytology, histopathology, immunohistochemistry, and PCR for antigen receptor rearrangements of one of the muscle masses and skin lesions supported a diagnosis of peripheral T-cell lymphoma.

Outcome and treatments of dogs with aortic thrombosis:100 cases (1997-2014)

Although uncommon, aortic thrombosis (ATh) is likely under diagnosed in dogs. In contrast to aortic thromboembolism (ATE) in cats, where thrombi form in the left atria or auricle embolize to the aorta, ATh is thought to be caused by a regional prothrombotic environment in the distal aorta. This retrospective study looks at risk factors, outcomes, and treatment in 100 dogs with ATh. In stark contrast, more than 2/3 of affected dogs have chronic signs with bilateral signs observed in only 39%, pain in 26%, and loss of ambulation in 25% within this category. 77% had one or more than one comorbidity thought to predispose to ATh with protein-losing nephropathy, neoplasia, and exogenous corticosteroids being the most commonly identified. Prognosis is generally considered poor, with non-ambulatory dogs at the time of diagnosis having the worst outcome.

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