cancer issue 18.qxd:Jerkins feature.qxd
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CANCER
be carried to other parts of the body. Diagnosis If a tumor starts to form near the surface of the body then the cancer can be picked up quite early on because it is visible and therefore easily detectable. However, if the cancer is deep within the body – in the chest or abdomen, for example – then it is not usually detected until the tumor starts to impede the horse’s vital functions. In both circumstances, lumps and associated lymph nodes are either biopsied or removed for examination under the microscope to search for abnormal cancer cells which identify the individual cancer. Treatment Although the treatment options for equine cancer are similar to that of human medicine – surgery, chemotherapy, and radiotherapy – the frontline therapy for cancer in horses is surgery. However, the treatment of specific cancers often depends upon the type and location of the cancer. For example, a skin tumor can be removed surgically or have substances applied to it or injected into it whereas tumors deep within the chest or abdomen are hard to access and treat. Hopefully, all the cancer research that is being undertaken in human medicine will eventually be carried across into the treatment of cancer in horses as regrettably, unless the tumor is benign or detected at a very early stage, the long-term prognosis for most horses with a serious cancer is poor. Papillomas or ‘warts’ Perhaps the least significant benign tumor the racehorse can get is the papilloma, which is more commonly referred to as a ‘wart.’ These are usually found in horses aged two years or less and are thought to be caused by the Equine Papillomavirus. They appear quickly and can look quite unsightly but they are harmless and usually disappear in a relatively short period of time, so if they persist then the strength of the horse’s immune system should be questioned. They are most frequently found around the horse’s face and muzzle but can also appear in other locations such as the lower leg. Sarcoids The most common skin tumor in the horse is the sarcoid. Sarcoids are rather strange skin growths that can occur in all ages, breeds, and colors of horses and mainly affect the head and legs. The exact cause is unknown but research strongly suggests that Bovine Papillomavirus has some involvement. Due to the fact that sarcoids often grow at sites where the horse had previously suffered a wound, it has been suggested that flies may play a part in spreading the disease, probably by passing
A young horse with ‘papillomas’ or ‘warts’ around its muzzle
the virus from one horse to another. As a result, work is currently being carried out to try to produce a commercial vaccine. There are several types of sarcoid and some are more serious than others. Horses can have one inconspicuous, small sarcoid on the inside of a back leg or can be affected by several malignant sarcoids that spread quickly and eventually result in death. A small, settled sarcoid in a place where it is not causing a problem should be left alone; however, if a sarcoid is in an important place, or if it is particularly active
and growing, then treatment may be attempted. There are many treatment options which include a rubber ring to kill the root of a round nodular sarcoid, chemotherapy, radiation therapy, cryotherapy, the injection of BCG, surgery to remove the sarcoid, or the application of sarcoid cream. Fortunately, the majority of sarcoids are manageable but they are very important when it comes to pre-purchase veterinary examinations – it is impossible to predict which sarcoids will end up causing problems and so no horse with a
On the left is a horse with a single, settled sarcoid just behind its right ear which was treated successfully using sarcoid cream. On the right is a horse that is severely affected by several active, growing sarcoids on the inside of its left stifle
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