Contributors: David Godfrey, Sorrel Langley-Hobbs

 Species: Feline   |   Classification: Miscellaneous

Lameness and feline musculoskeletal disease

  • It is particularly important in cats that when considering lameness - the inability to move normally - that we do not get too focused on limping, as many cats show lameness in more subtle ways. This is less so when an acute-onset problem affects a single limb but certainly is the case when considering conditions with an insidious onset and when multiple limbs are affected.
  • There is a daunting list of possible causes of lameness in cats (see below) but many cases will be readily diagnosed just using history and examination. Trial treatment to allow some time for natural healing, often with analgesia being supplied, will allow many more cases to resolve, perhaps without a definitive diagnosis being made. Rest may also be helpful in some of these cases but this is usually impossible to impose on a cat without restriction to a cage - and this probably should be left for those cases with a definitive diagnosis where strict rest is known to be required.

History

  • Presentation: this article assumes that lameness is present but it should be pointed out that many cats with musculoskeletal disease may not actually show lameness as a sign to their owner. These cats might be presented for other problems - reduced ability or willingness to jump, apparent weakness, toileting issues (inability to use a litter tray that was previously used with no problem), inability or unwillingness to groom or simply that the cat is quiet, withdrawn, and is generally not itself.  Cats presenting with these histories should all have an examination of the musculoskeletal system.
  • Many cats with musculoskeletal disease, especially chronic conditions with an insidious onset such as osteoarthritis Arthritis: osteoarthritis, will not be presented for a perceived musculoskeletal problem and a proactive attitude is required on behalf of the practice to help these cats. Older cats will often be presented for routine examination, vaccinations or because of internal medicine issues, dental disease, etc but a large proportion of cats over about 12 years old will have significant arthritis that can be alleviated with environmental modifications and medical intervention. It is most useful to ask the owner about things the cat used to do when younger but now does not do at all, or less often. Note that just because the cat can jump on to the work top it does not mean that it is pain free when doing so; if the cat's food bowl is on the work top then the cat will continue to try to get to it while it is physically possible - there is a large incentive. Ask about any decrease in locomotion - walking, running, jumping up and jumping down (jumping up is more limited by back leg problems and jumping down by the front legs), playing with people and other pets, hunting, grooming and ability to use the litter tray.
  • Signalment: hunting and fighting injuries are more likely in younger and male animals (but not in kittens below the age of sexual maturity). Degenerative diseases and neoplasia are more likely in older individuals. It is unusual for cats to be injured by a cat they live with - even though their altercations sometimes sound furious.
    There are a number of unusual developmental and idiopathic conditions that are confined to a particular breed (see below) and these usually have a particular age of onset.
  • Roaming, fighting, hunting: whether the cat is indoors only or has access to the outside is crucial information for forming a differential diagnosis list. Most owners will know whether their cat is a regular hunter and thus prone to rodent bites and subsequent infections. They may know whether there is a new cat in the area that could be fighting with their pet. They may have been told by a neighbour that the cat has been involved in an incident - cat fight, dog attack, vehicle trauma, deliberate assault, eg shooting or kicking. Major trauma is not expected to occur in indoor-only cats unless they have escaped. Falling from an injurious height then might be a consideration.
  • Recent vaccination: calicivirus-associated polyarthritis is seen with natural infection but is also reported after vaccination.
  • Concurrent disease: cat flu - this can be taken as circumstantial evidence of calicivirus-associated disease Feline calicivirus disease.
  • Recent drug treatments: an association with drugs is rare but a recent badly placed intramuscular injection could cause sciatic nerve damage. Whether any response has been seen to analgesics or anti-inflammatory drugs may guide as to the severity of the condition, eg if improvement has been seen and whether further investigations should be pursued at this time.
  • Any response to previous treatments: a lack of response should prompt re-evaluation and further diagnostic procedures, improvement on therapy, eg an antimicrobial could indicate a causative infection.

Examination

  • Much can be gained from watching the cat move about the consultation room. The room must be secure and safe. Attention should be paid to the possibility of escape from windows and if anyone should unexpectedly open the door from outside.
  • The cat should be given the opportunity to exit the carrier by itself, time permitting. If reluctant to do so then it may be possible to deconstruct the box. The last alternative is to haul the cat out but this gets the consultation off to a poor start.
  • It is often most useful for the veterinary surgeon to get down on the floor to cat level in order to see the cat's gait while it walks around the room. Allow jumping up and down but do not force the cat to perform these activities if it is reluctant.
  • It is not uncommon in first-opinion practice for a cat presented with acute-onset single limb lameness to show no problem at the practice. Presumably the stress of the situation overrides pain felt at home by the cat. But this does suggest that the problem is less serious than otherwise.
  • It may be possible to get the cat moving by offering toys to play with. An alternative for the more nervous cat is just releasing it from the end of the room and observing the scuttling across to the "safety" of the carrier or whatever bolt-hole it has identified. This procedure may be repeated.
  • Gait abnormalities may show as holding up a leg, a head bob - the head being dropped when the sound thoracic limb is weight bearing and being raised when the painful limb is down, a similar movement may be seen with the tail and the pelvic limbs, or a plantigrade or palmigrade stance.
  • If there is an obviously affected area the rest of the cat should be examined before paying gentle attention to the affected area. It is possible to miss an important second lesion while being distracted by an obvious problem.
  • The claws should be examined for evidence of "scuffing" - often associated with vehicle impacts the claws can also be damaged during other events. Cat fights can sometimes be evidenced by finding the other cat's fur snagged around claws. The color and capillary refill of the claws and the skin of the pads should be examined as evidence of the blood supply to each limb and digit.
  • The coat of the cat should be examined for oil stains; sometimes these will be initially smelt rather than seen. These are evidence of vehicle trauma. Saliva may be found in the case of dog attacks.
  • Cat bite wounds are often felt rather than being seen. A small firm mat of fur is found stuck in the coat. If small this can often be plucked off to reveal a small area of alopecia with an open wound. Sedation and clipping will be required for larger areas. 
  • The muscles and joints of each leg should be examined visually and by palpation, comparison with the other leg is often useful but it should be borne in mind that osteoarthritis is often symmetrical so, for example, an older cat may have thickened elbows with reduced ability to extend and flex the joint on both sides. Any difference from normal may be significant. Pain may also be elicited by palpation or manipulation. It can be difficult, with the smaller legs of a cat, to be sure which area is actually painful. The shoulder, elbow, carpus, hips, stifle and tarsus should all be flexed and extended and the hips should also have their abduction and rotation examined.
  • The cranial draw test can be performed to check cranial cruciate ligament integrity Stifle: cranial draw test. Patellar luxation Patella: luxation can be tested but cats normally have somewhat looser patellae than dogs.
  • The spine should be included in the examination so the head and neck, the thoracic, lumbar and lumbosacral area and the tail are manipulated
  • The digits should be included in the examination.
  • Neurological tests may be appropriate Neurological examination - placing, knuckling and hopping tests can be performed as part of the examination of each limb. Individual tests of peripheral nerve function are explained elsewhere Neuroanatomical diagnosis Peripheral neuropathies, eg Garosi (2012).

Differential diagnosis

  • There is a wide range of differential diagnoses. Conditions considered by the author to be common are in bold.
Pathological type
(some conditions could
be described
or included in
multiple categories)
Examples
DegenerativeForaminal stenosis
Intervertebral disk protrusion Intervertebral disk disease
Osteoarthritis (this may be associated with developmental joint conditions or
trauma - for example, but is often idiopathic)
Synovial cyst
DevelopmentalCongenital elbow dysplasia
Congenital elbow luxation Elbow: congenital luxation
Congenital hip dysplasia Hip: dysplasia
Congenital myotoniaMyopathies
Congenital shoulder dysplasia
Devon Rex myopathy Devon Rex myopathy
Dysostoses - amelia, apodia, ectrodactyly, hemimelia, micromelia, phocomelia
Dystrophin-deficient muscular dystrophy Muscular dystrophy
Familial hypothyroidism
Femoral neck metaphyseal osteopathy
Laminin Alpha 2-deficient muscular dystrophy
Mannosidosis
Mucolipidosis
Mucopolysaccharidosis type IStorage disease Mucopolysaccharidosis type VI
Mucopolysaccharidosis type VII
Nemaline myopathy
Osteochondroplasia of the Scottish Fold cat
Osteogenesis imperfecta
Patellar luxation Patella: luxation
Spontaneous slipped;capital physeal fracture;Slipped capital epiphyses;
Stifle osteochondrosis
Vitamin D-dependant rickets (types I, II and other)
AutoimmuneImmune-mediate non-erosive polyarthritisArthritis: polyarthritis - idiopathic
Immune-mediated polymyositis Idiopathic polymyositis
Myasthenia gravisMyasthenia gravis
Systemic lupus erythematosusSystemic lupus erythematosus
MetabolicCalcinosis
Hypoadrenocorticism associated muscle weakness
Hyperthyroid neuromuscular weakness
Hypokalemic polymyopathy Hypokalemic myopathy (Burmese)
Neuropathy associated with diabetes mellitus Diabetes:neuropathy
Renal secondary hyperparathyroidism Renal secondary hyperparathyroidism
 
NeoplasticAneurysmal bone cyst
Hypertrophic osteopathy (Maries);Hypertrophic osteopathy;
Paraneoplastic polymyopathy (eg associated with thymoma)
Primary musculoskeletal neoplasia Bone tumor: overview-
osteosarcoma Osteosarcoma
,
juxtacortical osteosarcoma, chondrosarcoma Chondrosarcoma , ossifying fibroma,
chondroma, osteochondroma,
reticulum cell tumour, osteoid osteoma, osteoma, osteocarcinoma, giant cell tumour.
Primary neoplasia from non-musculoskeletal tissues of the limb-
squamous cell carcinoma Squamous cell carcinoma
,
melanoma Melanoma , adenocarcinoma Adenoma / adenocarcinoma ,
fibrosarcoma Fibrosarcoma,
lymphosarcoma, rhabdomyosarcoma, hemangiosarcoma Hemangiosarcoma .
Metastatic neoplasia (eg lung-digit syndrome)
Peripheral nerve sheath neoplasia Nerve sheath: neoplasia
NutritionalHypernatremia-associated polymyositis
Hypervitaminosis A Hypervitaminosis A
Nutritional hyperparathyroidism Nutritional secondary hyperparathyroidism
Vitamin E deficiency
Infectious/inflammatoryBacterial arthritis Arthritis: infective
Bacterial discospondylitis
Cat bite abscess
Cat bite cellulitis
Calicivirus-associated polyarthritis
Fungal arthritis
Hypertrophic neuritis
L-form arthritis Arthritis: bacterial L-form
Lyme disease
Mycobacterial granuloma
Mycoplasma arthritis
Neosporosis
Osteomyelitis Osteomyelitis
Plexus neuritis
Pox virus infection Cat pox disease
Sarcocystosis
Septic polyarthritis Arthritis: septic
Toxoplasmosis Toxoplasmosis
IdiopathicChronic progressive polyarthritis
Feline hyperesthetic syndrome (Burmese) Feline hyperesthesia
Fibrodysplasia
Fibrodysplasia ossificans;- generalized or myositis ossificans
Meniscal ossification
Myopathy with tubulin-reactive inclusions
Osteocartilaginous exostoses
Osteochondromatosis
Patella fractures Patella: fracture , and other stress fractures -
often seen in cats with retained decidous teeth
Plasma cell pododermatitis Plasma cell pododermatitis
Synovial osteochondromatosisArthritis: synovial osteochondromatosis
TraumaticCat bite
Claw trauma
Limb bone fracture
Axial bone fracture
Foreign body in muscle - air-gun pellet, claw, tooth
Ligament rupture eg cranial or caudal cruciate
Lux
ations;
Peripheral nerve injuryPeripheral nerve: trauma
Plexus avulsion
Rodent bite
Soft tissue contusion
Tendon rupture
Tenosynovitis
ToxicDrug-induced non-erosive polyarthritis Arthritis: non-erosive
Tetanus
VascularFibrocartilagenous embolus Fibrocartilaginous embolism
Ischemic neuropathy due to thromboembolism

Diagnostic tests

  • As can be seen from the list of differential diagnoses a wide range of diagnostic tests might be pursued in a cat presenting as lame. Only those of special interest are discussed here.
  • Most cases can be readily diagnosed from the history and examination in the consultation room.
  • More challenging cases will require greater thought. A logical approach will help to sort out these cats. Start with using a system such as the DAMNIT V list used here so that conditions are not forgotten. Then create a differential diagnosis list with an indication as to which conditions are more likely. The appropriate diagnostic tests and the order which they should be performed will then be apparent.
  • Sedation for full examination of the musculoskeletal system is often helpful. This may be essential for any reasonable examination of a fractious cat. For other cats as full an examination as possible should be made on the conscious cat as neurological function and pain responses will be altered by chemical restraint. Certainly if the cat is sedated for, eg radiography then this opportunity should be taken for repeated examination, eg to check carefully for a cat bite.
  • Radiography may usefully be expanded for the traumatized cat. It is common for there to be a second injury that may be missed if only the immediate area is focused on.
  • For cats with acute-onset single limb lameness when no cause is found on physical examination a trial treatment with a licensed non-steroidal anti-inflammatory drug (NSAID) may be appropriate Analgesia: NSAID. The potential side effects of these drugs must be considered and it may be appropriate for some routine blood and urine tests to be performed prior to this trial. This may be particularly important when treating cats with possible risk factors for kidney disease, liver disease, dehydration and sepsis as will often be the case in cats with a recent trauma or infected bite. Checking hematology, biochemistry and urine concentration will reduce the chance of causing significant side effects by prescribing a NSAID.
  • The older cat with osteoarthritis is in a similar position. A suspicion for the presence of osteoarthritis should arise when an older cat has either a history of behavior changes associated with the condition or lameness, or has physical findings of thickened/painful joints with reduced motility even when the owner has not noticed changes at home. Ideally these cats would have radiology to confirm their disease but this may be resisted by owners. You may recommend a trial treatment with a licensed NSAID, at a time when the owner is in a position to judge the response - perhaps to a set limited number of parameters. But, again, these cats may well have risk factors for NSAID side effects, perhaps particularly renal disease and chronic dehydration. Checking routine hematology, biochemistry and urinalysis should be recommended.