“He’s been limping all week, but he doesn’t seem painful” is something I hear on a regular basis! So what’s going on?
A limp is an interruption in the normal rhythm of a gait- whether that’s in walk, trot, canter or gallop. A good rule of thumb is that for forelimb lameness they have a head dip or nod on the good leg, and for hindlimb there is generally a greater range of up/down movement of the hip on the bad leg. So why do they do this?
- Pain. The vast majority of lamenesses are down to pain. When someone tells me their pet is lame and doesn’t seem painful, I have to be very careful that we’re not dealing with a very stoic, pain resistant animal. Signs of pain in cats can sometimes be very subtle, and some dog breeds, especially bull breeds, seem to be able to tolerate very high levels of pain with few outward signs.
Your pet is trying to avoid bearing full weight on the injured limb, and is doing this by altering their centre of gravity, and hence interrupting the normal gait.
You can get a good idea of the source of the pain by watching the gait – if it’s better on a soft surface then it may be in the foot, whilst if they’re better on pavement then that can indicate upper limb pain. Hindlimb lameness with toe touching at rest can indicate cruciate disease. A lameness that improves with exercise can indicate joint pain e.g. arthritis, whereas one that worsens with exercise is more likely soft tissue (ligament, muscle tendon) in origin.
- Neurological. If your pet can’t feel where their foot is in space via a sense called proprioception (via stretch receptors in muscles and tendons) then they will become malcoordinated and look lame. This will look similar to a pain lameness, but is often more “staggery”, and is commonly caused by spinal disc problems. If the neurological lesion is worse they may become weak in the leg (think sciatica), and look like they are collapsing when during the weight bearing phase of the stride.
- Functional. If your pet’s leg is slightly long, or more often short, then this imbalance will manifest as a lameness. Commonly dislocation of a joint can cause this. A lump in the groin or in the armpit might also be getting in the way of a swinging leg and cause lameness.
A careful examination of the lameness by observing your pet at walk and trot can give a huge amount of information when we’re working out what actually is going on. Lameness that doesn’t get better after a couple of days needs a check up, as the vast majority are down to pain, or are accompanied by pain.