Unusual Lameness Cases in the Cat

Most lameness in cats can be attributed to traumatic fractures or abscesses. other more unusual causes can present more of a diagnostic challenge to the clinician and some of the conditions presented here are unique to the cat (1).

Myasthenia gravis
Cats with myasthenia gravis may present with generalised weakness or exercise intoler- ance, muscular weakness and apparent stiffness. other clinical signs indicative of neu- romuscular disease include neck ventroflexion, lack of palpebral reflexes, dysphonia and less commonly regurgitation (2). the abyssinian and Somali cat are predisposed breeds, and cats are usually older than three years (2).

Myasthenia gravis (MG) is a condition whereby muscles are unable to contract or main- tain contraction due to a deficiency or disorder of acetylcholine receptors (congenital form) or blockage of the receptors by immune complexes (acquired form). the acquired form is more common in the cat (2). the disease is confirmed by testing for acetylcho- line receptor (aChr) antibodies.

Many cats with myasthenia gravis will have a cranial mediastinal mass, most commonly a thymoma; (2). Myasthenic cats can be treated successfully with anticholinesterase drugs or immunosuppression.

Myositis ossificans
Generalised and localised forms of myositis ossificans have been reported in cats. the generalised form is known as progressive ossifying fibrodysplasia (3,4). the localised form tends to occur in specific muscles such as the biceps femoris or semitendinosus bellies (figure 1). its formation may be related to local or repetitive trauma. recurrence of the lesion in cats is likely after excision. [...]