Lameness in Pets

Lameness is common in pets. Dogs, in particular, are prone to obvious long term lameness, and in recent years, vets have also been becoming more aware about lameness in cats. 

Long Term Prognosis For Lameness

Everyone knows how a normal animal should walk, with a steady, even gait, with equal pressure on all four legs. When a pet is limping, it’s obvious that there’s something wrong, but it can be more difficult to specify precisely what is going on. Where, exactly, is the lameness, and what’s causing it.  And equally importantly, what can be done to help the lame animal, and what’s the long term prognosis?

Some vets have chosen to specialise in lameness – technically known as “orthopaedics” – but all vets have been trained in understanding how to assess and treat the common causes of the problem. A referral to a specialist is only needed for the rarer, more complex cases.

Severity Of Lameness

Vets use a simple scale to classify the severity of lameness. One-out-of-five describes an animal whose lameness can barely be noticed, whereas five-out-of-five means that the animal is not weight-bearing at all on the affected leg.

Causes Of Lameness

There are four main reasons for a dog or cat to be lame.

1. Pain

If an animal injures a limb, any further pressure causes more pain, and so the instinctive response of the animal is to rest the limb, by holding it up, or by not putting full weight on it. The damage can be anywhere in the limb, from the toe to the shoulder or hip, and the result is the same – a lame animal because of pain. One-off injuries are not the only cause of pain in the limbs: many long term conditions can cause considerable pain.

It can be difficult for vets to assess pain in their patients. We need to use the primitive approach of poking and prodding, and gently flexing and extending joints, watching our patients all the time so that we can see when they flinch because of pain. Sometimes we need to do this several times, to ensure that we have definitely found the sore bit.

2. Instability

The second cause of lameness in pets is less well known to owners: instability. A limb needs to be stable and solid, like the leg of a chair, to carry weight. If the leg loses this stability, the animal cannot put full weight on the limb. If the animal tries to put weight on the leg, the knee collapses, so the pet learns not to put any weight on the leg.

3. Stiffness

The third cause of lameness is stiffness. When a dog develops arthritis, the affected joint becomes swollen and gnarled-like an older person’s arthritic finger joint. The swelling of the joint is due partly to the new bone which grows around the arthritic joint as part of the disease process. The result of this new bone is that the joint is stiffer and less mobile than it should be – and this means that the animal is unable to use the limb in the normal way.

Arthritis in dogs has been well recognised for many years: the classic example would be the elderly, creaky Labrador. In recent years, it’s been discovered that older cats can also suffer from pain and stiffness due to arthritis, and there are now effective ways of treating this.

4. Nerve Damage

The final cause of lameness can be neurological: if the nerve supply to a leg is damaged, the animal cannot control the muscles properly, and lameness results.

Treating Lame Animals

So lameness can be caused by pain, instability, stiffness and nerve damage. What can be done to help lame animals?

The answer depends on the precise cause of the lameness: a broken leg or a torn ligament needs surgical repair to remove the instability, a leg that’s painful due to arthritis needs daily pain relieving medication, a joint that’s stiff may need medication as well as physiotherapy, and if nerve damage is causing the lameness,  there are various ways of helping.

Investigating Lameness

There’s a standard approach to investigating lameness to reach that precise diagnosis of the cause. The first stage is to stand back and watch the animal moving. This is easier for dogs than for cats. A vet will often take a dog out of the consulting room, and ask the owner to get the dog to walk, then trot, up and down the car park. Observation of the precise nature of the gait can give a great deal of information. Sometimes the use of a video can help, allowing the gait to be examined in slow motion.

With cats, it’s a case of letting them walk around the consulting room, perhaps jumping up and down from a chair. Again, a video can help if the lameness is subtle.

The next stage is the physical examination, palpating each part of the limb, and moving each joint in turn. 

Many cases then need some sort of diagnostic imaging: x-rays provide useful information about the bones and joints, and nowadays, more detailed and expensive techniques such as CAT or MRI scans may be recommended.  More recently, the use of arthroscopy, where a fibreoptic scope is inserted directly into the affected joint, has become widely used: this allows the joint to be visually inspected internally, and a sample of joint fluid can be harvested at the same time, for laboratory analysis.

It can take several weeks for the process of investigation to be completed, but once this has been done, an appropriate treatment plan can be put into place.