Page 694 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Respir atory system: 3.2 Surgical conditions of the respir atory tr act 669

VetBooks.ir is not as easy as might be anticipated. Endoscopic 3.126
examination may dislodge a blood clot and precipi-
tate a fatal haemorrhage. It is the author’s policy to
admit a horse to a surgical facility following tenta-
tive diagnosis by a large blood clot in the guttural
pouch. The horse is then prepared for surgery and
examined endoscopically in anaesthetic induction.
Any haemorrhage at this point can be controlled
by proceeding with surgery. If the guttural pouch
is examined endoscopically the information gained
can be limited. Visibility is frequently obscured by
blood. The principal aim of the examination is to
localise where the fungal plaque is. Dorsomedial
mycosis is usually associated with internal carotid
haemorrhage while lateral mycosis is often associ- Fig. 3.126 A large blood clot from the right guttural
ated with external maxillary haemorrhage. pouch ostia, typical of haemorrhage due to guttural
In all patients it is important to assess laryngeal pouch mycosis.
motility as this is frequently affected in horses with
mycosis. Guttural pouch mycosis often results in total
paralysis of the larynx (Grade IV) and lesser grades nostril the catheter is passed via the ipsilateral nostril
of hemiparesis are more likely to be idiopathic RLN. with the bend downwards. Once in the pharynx
Dysphagic patients usually exhibit permanent the catheter is rotated outwards and advanced, so the
DDSP. Repeated attempts at swallowing should be bend is upwards. This usually opens the ostia of the
observed – usually by flushing water into the naso- guttural pouch and the catheter is advanced easily
pharynx. This should result in active contraction of and the balloon inflated. The pouch is then irrigated
the pharynx and bilateral opening of the guttural daily with an antifungal solution. Some clinicians
pouch ostia, followed by replacement of the soft pal- use antifungal powders (nystatin) to insufflate into
ate in a subepiglottic position. the pouch to improve contact of the medication with
Radiography can also be used in diagnosis. the fungal lesion.
A lateral radiograph of the parotid region may reveal Surgical management as a matter of urgency is
fluid lines in the guttural pouch, or more irregular advised for all haemorrhaging cases. Simple ligation
blood clots forming soft-tissue densities. of the internal carotid and occipital arteries has been
advised. However, the collateral circulation in both
Management the internal and external carotid arteries is substantial
Medical management can be pursued in all patients. and proximal and distal vascular occlusion is preferred.
Generally, surgery is recommended for all haemor- Occlusion of the internal carotid proximally (closer to
rhaging patients – fatal haemorrhage usually results the heart) results in no change in blood pressure and
before antifungal medication has been successful. only a 19% reduction in flow in the internal carotid
In dysphagic patients, medical management is more artery in the guttural pouch, while occlusion of the
appropriate, but consideration should be given to common carotid artery results in an increase in flow.
prophylactic vascular occlusion. Currently two methods of proximal and distal
Medical management is topical administration of vascular occlusion are in widespread clinical use.
antifungal agents such as enilconazole. A Foley cath- The use of embolisation coils under fluoroscopic
eter is implanted in the guttural pouch. The catheter control is a very elegant system, with minimal sur-
is passed using a wire stiffener down the centre of gical morbidity. A simpler technique is catheterisa-
the catheter, which has a slight bend in the distal tion of the selected vessels using embolectomy or
1–2 cm. With an endoscope in the contralateral Foley catheters (Fig. 3.127). The external carotid