Ab Horse DECEMBER 2016 pages 1 to 23_Layout 1 22/11/2016 19:34 Page 23
A fibroblastic sarcoid
Weight loss can be sign of Lymphosarcoma
normally present cell, the lymphocyte. Normal lymphocytes play an important role in maintaining a healthy immune system. The vast majority of cases occur in horses aged 4-15 years, but it has been found in horses of all ages. There are 4 common forms of the disease: multi centric (present in multiple locations around the body), thymic (localised within the chest), alimentary (present in the gut) and cutaneous (in the skin). Signs of the disease can occur suddenly or insidiously over many months. The signs vary according to the type of the disease, the organ affected, physical obstruction caused by a tumour (such as an intestinal tumour causing colic), or from cancerous by-products. However depression, weight loss, subcutaneous oedema, fever, anaemia, and enlarged lymph nodes are commonly seen. Diagnosis is made on clinical signs and visualising cancerous lymphocytes in bodily fluids, aspirates and biopsies or from post-mortem examination. Unfortunately the majority of horses diagnosed with
lymphosarcoma either die or are euthanised within months of diagnosis (the cutaneous form carries a slightly longer survival time). Temporary improvement can occur following surgical excision, chemotherapy and steroid treatment, however the prognosis is still very poor. Sarcoids Sarcoids are not officially classed as a cancer, however they do mimic benign tumour growth and can be locally invasive and very problematic. Although they do spread to other areas of the skin, they do not however metastasise to other organs of the body. They're most common in horses of 1-4 years, and especially seen on the eyelids, limbs, underside of the belly and around the sheath in geldings. Sarcoids are classed into 6 different groups: Occult – areas of rough,
A mixed type of sarcoid
thickened skin. Typically slow growing they can undergo a rapid growth phase if interfered with or disturbed. Verrucous – dry, wart-like lesions typically like a 'cauliflower on a stalk' and hairless.
Reproductive Organ Tumours Mares can develop breast (or mammary) cancer, it is rare but usually malignant and carries a poor prognosis. Mares can also develop ovarian cancer, this can cause hormonal changes as abnormal amounts of hormones are produced (such as stallionlike behaviour in granulosa cell tumours due to excessive testosterone production). Stallions too can have tumours in their testicles and prostate glands, these are also rare as most horses are gelded early in life.
Fibroblastic – firm nodules, often with an ulcerated surface. Mixed – a combination of verrucous and fibroblastic. Nodular – found under the skin especially in areas of thin skin (such as the eyes). Malignant – these are very aggressive and grow rapidly in the skin. There are many treatments for sarcoids, around 40 at last count! Therefore there is not one single perfect solution. Also the treatment may depend on the type of sarcoid present. Treatment options include: topical cytotoxic treatments (such as The Liverpool Cream), immune-mediated therapy (using BCG vaccine), chemotherapeutic drugs, surgery or ligation (using a tight band), laser excision, cryosurgery (freezing), and use of radioactive sources.
Squamous cell carcinoma on the penis
Lipomas These are benign tumours of the fatty tissues, they can occur in the skin where they are unlikely to cause much issue unless very large or interfere with tack. However sometimes these tumours can develop internally in the abdomen, these are potentially life threatening as they can break off whilst attached to a stalk (or pedicle) and wrap around part of the gut causing a life threatening colic. Other cancers Other cancers have been reported in horses such as basal cell carcinoma, mast cell tumours and haemangio sarcoma. Luckily these are very rare.
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