Why is a lame dog lame? The obvious, but incorrect, answer to the question is 'because it has a sore leg'. The correct answer is more complicated, but also quite obvious when you think about it. Firstly, what is a lameness? Everybody knows what a lame animal looks like - they 'walk wrongly'. But what is happening to make them walk wrongly? There are three main reasons why lameness may occur. Pain is the most common and most important cause of lameness. If an animal damages a limb, any further pressure causes more pain, and so the instinctive response is to rest the limb, by carrying it, or at least by not putting full weight on it. The type of damage can vary widely from a bruise to a laceration. 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. Long term diseases such as arthritis can also involve considerable pain. The second cause of lameness is instability. It is common for dogs to rupture the ligaments of the knee, and when this happens, the knee becomes unstable. If the dog tried to put weight on the leg, the knee would collapse. So the dog refuses to put weight on the leg. Any other joint can be affected in the same way by damage to the supporting ligaments. The third cause of lameness is stiffness. When a dog develops arthritis, the affected joint becomes swollen and gnarled - like many older people's arthritic finger joints. The swelling of the joint is due partly to new bone which grows around the arthritic joint as part of the disease process. This new bone acts like rust seizing up a metal hinge - it stops full normal movement of the joint. An elbow joint may only be able to move through half of its normal range of movement. 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. Hips, shoulders and knees are also commonly affected in this way. So lameness can be caused by pain, instability and stiffness. What can be done to help lame animals? Weight control, controlled exercise and physical therapy are all important aspects: this always has to be individualised, and the best answer is to ask your vet what your pet needs in these areas. The new generation of painkillers provide excellent relief from pain. Immediately after an injury, dogs can be given drugs which prevent short term suffering until the injury is treated. In addition, if a disease involves long term pain (such as arthritis), this can be dealt with very effectively by continual daily medication, as advised by a vet. Instability of joints can often be well treated using new surgical techniques which may involve inserting artificial ligaments, using metal implants or by other methods. The stiffness of arthritis can be helped by using regular anti-inflammatory medication, similar to that used for arthritis in humans. There is also an animal-only anti-arthritic drug, given by injection, which can help considerably in some cases. Other therapies including hydrotherapy and acupuncture can also play a role, as can daily food supplements such as glucosamine chondroitin sulphate, and even special high fish-oil diets designed for pets with joint disease. Owners should be warned that it can be very dangerous to give human drugs to their pets, unless their vet has given them permission to do so. Toxic reactions are common, especially when some of the more modern human painkillers and anti-arthritic drugs are given to dogs. If you have a lame dog, you should ask your vet for advice on the best way to relieve the problem.