EQUINE | CPD
EQUINE | CPD
with vestibular and facial nerve dysfunction and nasal discharge . SCC at this location are characterised by locally infiltrative growth patterns . Neoplasia may extend into the oropharynx , into the tympanic cavity , invade through the temporal bone to the calvaria as well as through the mandible into the regional lymph node . Distal metastatic spread to the lung is rarely reported .
Treatment Surgery remains the only viable treatment modality at this location , although locally infiltrative growth patterns complicate surgical options .
Oral Cavity
SCC of the gums and hard palate develop as a consequence of chronically irritated alveolar epithelium in cases of periodontitis . At these locations , these tumours exhibit destructive locally infiltrative growth patterns and are prone to metastasis to the regional lymph nodes . Invasion of tooth roots , with tooth loss , and maxillary / mandibular bone is common . Maxillary tumours often extend into the adjacent sinuses plus nasal , orbital and cranial cavities . Glossal SCC is an uncommon form of oral SCC in the horse .
Treatment Combinations of surgery and metronomic chemotherapy have been attempted with varying outcomes .
Stomach
Gastric SCC are the most common tumour of the stomach of horses . They arise from the pars esophagea and are most commonly documented in middle aged to older animals . Clinical signs are non-specific including unexplained anorexia , in some instances dysphagia , and weight loss ; but symptoms usually only become evident when the neoplasia is in an advanced state . Invasion through the stomach wall with peritonitis is common ; while extension up the distal oesophagus with occlusion is less frequently documented .
Treatment Treatment of gastric SCC is generally not attempted as the disease is usually advanced at presentation with the prognosis being grave .
Urinary Bladder
Although urinary bladder tumours are rare in the horse , SCC are the most common bladder tumour of horses .
Treatment Radical surgical resection with urinary diversion is the only realistic therapy option available and so rarely performed .
Diagnostics
Cytological preparations ( FNA , impression smears , scrapings ) are hampered by the fact that cells are interpreted in isolation with no correlation to architecture at the site sampled . Therefore , cytology at best can suggest a diagnosis of SCC . However , biopsy of affected tissue into formalin for histopathology remains the gold standard for the diagnosis of SCC .
Histopathology allows for critical evaluation of cellular atypia , architectural changes , mitotic index , invasive growth patterns and completeness of local excision . All of this information is critical to accurate prognostication and the development of effective and relevant treatment modalities .
REFERENCES
1 . Hewes C A & Sullins K E 2009 . Review of the treatment of equine cutaneous neoplasia . Proceeding of the American Association of Equine Practitioners .
32 • Equine Health Update •