By Vet Freya Wood
Chronic progressive lymphoedema (CPL) is a condition that is becoming much more widely acknowledged.
There is a wide variation of awareness of the condition and the issues it can cause. It is a common concern with owners of cob and draft horses who present with thick skin folds, nodules and cone shaped legs.
CPL is a condition caused by build-up of lymphatic fluid in the lower legs and has been described in Shires, Clydesdales, Friesians, English cobs, Gypsy Vanners, Belgian and German draft horses and Percherons.
The lymphatic system is a network of vessels and tissues that move fluid around the body and compliments the blood circulatory system, collecting excess fluid from the body to return it to the circulatory system, helping the body absorb fats and also is part of the immune system.
Movement of fluid relies on the elasticity of the lymphatic vessels to help push fluid around the system of vessels. In CPL, this elasticity is lost. It is thought that there are many factors involved in this condition and research is ongoing to attempt to identify these.
Early signs are more subtle and often missed as these horses are often heavily feathered, with just a mild thickening of the lower limbs. When clipped the cone shaped appearance of the legs can be more apparent rather than the cannon, fetlock and pastern being defined structures. Initially the swelling is soft and pits when pressed with a finger.
As the name suggests this is a progressive condition. The combined effects of heavy feathering and lack of lymphatic flow provide the perfect environment for bacterial and parasitic infection to take hold and often these horses struggle repeatedly with feather mites. Bacterial infections can develop into painful sores causing lameness and it is not until the legs are clipped that the true extent of these sores is evident.
Recurrent infections lead to further swelling and the legs becoming more firm. Skin folds and nodules develop providing further environments for these infections to develop allowing the cycle to continue. Eventually the swelling and lesions associated with CPL can affect the skin up to the knees and the hocks.
Diagnosis is primarily based on the predisposition of the breed, the clinical presentation and clipping of the feathers to identify the extent of the lesions. Skin biopsies can sometimes be helpful to demonstrate changes in the elastic fibres within the skin, however the characteristic lesions are often too deep to be seen on a regular skin biopsy. Imaging techniques involving the use of contrast agents can identify distortions in the lymphatic system and the impaired drainage.
There is no permanent treatment for CPL but with careful management these horses can have an acceptable quality of life. In severe cases sadly euthanasia is the kindest option.
The primary management of these horses involve:
* Promoting good skin health. Colloidal oatmeal shampoos can be helpful to maintain skin health and use of emollients to improve skin suppleness. Legs must be dried thoroughly with either paper towel or a hairdryer when becoming wet
* Managing feather mites. Feathers must be clipped short and steps taken to prevent recurrence of feather mites, including use of antiparasiticides and use of sulphur-based shampoos.
* Treating secondary bacterial infections if these occur.
Horses should have daily exercise to encourage the lymphatic flow and feet must be cleaned daily and regularly trimmed. Compression bandaging can be helpful but if done incorrectly can cause more harm than good so it is advised this is only performed by professionals.
For any concerns about your horse, your vet should always be your first port of call for advice.
For more information about CPL there are resources available through UC Davis School of Veterinary Medicine Center for Equine Health.