3. Leipziger Tierärztekongress und 1st scientific Symposium of the ECEIM, Januar 2005
A practical approach to treat guttural pouch mycosis in horses
W. Scheidemann1, N. H. Huskamp1, A. Kirchhoff2
1 Tierklinik Hochmoor, D – 48712 Gescher, Germany
2 Praxis für Tierpathologie, D – 45840 Gelsenkirchen, Germany
Introduction
Guttural pouch mycosis (GPM) is the most common and probably the most dramatic fungal infection of the respiratory tract. Hemorrhage caused by this disease can be fatal: more than 60% of horses with hemorrhage will die without surgical occlusion of the affected artery (1).
1) Fatal bleeding due to internal carotid artery arrosion
The fungal plaques of the GPM are usually found in one or two characteristic sites: the dorsal roof of the guttural pouch – especially the medial compartment – is the most common location. The clinical features vary according to location and extent of the infection. The most common clinical sign is spontaneous recurrent, bright red epistaxis. The infection often damages the internal carotid artery sometimes the external carotid or maxillary artery. Predilection side is also close to important cranial nerves: 9th to 12th, the sympathetic trunc and sympathetic ganglion or the facial nerve. Therefore it is not unusual to have different neurological disorders: i.e. dysphagia, laryngeal or pharyngeal paralysis, Horner’s syndrome or abnormal head posture, etc.
2) Photomicrograph (H & E stain): mycelium in a biopsy preparation
Diagnosis of GPM is based on history, clinical signs and endoscopy of the guttural pouch (GP). It is necessary to perform endoscopy of both pouches to preclude a bilateral problem. Mostly blood can be seen draining from the guttural pouch orifice. The typical diphtheric membranes can be identified in the infected segment of the GP.
3) Fungal lesions in the medial compartment of the guttural pouch
Once the diagnosis is made, the patient should be treated as emergency. If untreated this infection may result in most cases in a fatal hemorrhage, therefore medical and / or surgical treatment should be initiated immediately.
Local or parenteral medication is discussed controversial because of doubtful results. Therefore the affected artery should be occluded by an appropriate surgical technique. The techniques require general anaesthesia and lateral recumbency, a well equipped clinic and experienced surgeons (2).
With successful occlusion of all involved vessels, fungal plaques resolve without any other treatment within 4 to 9 weeks.
On the other hand only medical antifungal therapy requires prolonged treatment and places the horse at risk of hemorrhage.
Material and Methods
The following study describes own experience of a practical technique to treat GPM: it concerns a combination of surgical and local medical treatment.
In the period of 2000 to 2004 three German Warmblood horses (2 mares - 7 and 9 years old – and 1 gelding – 8 years old) were referred to the Animal Hospital Hochmoor because of recurrent, unilateral epistaxis since 2 to 14 days. One horse had also neurological disorders: it shows from time to time head trembling; in this horse a hemiplegia laryngis dextra was also diagnosed.
In all 3 horses we diagnosed a unilateral GPM (twice in the right and once in the left GP), Aspergillus spp. (2x) and Candida spp. (1x) were cultured. In all horses the medial compartment of the GP was infected in a different extent, in one horse the stylohyoid bone was also markedly involved. In all cases the bleeding came from damage of the internal carotid artery.
Two horses were hospitalized, one received ambulatory treatment in the clinic. Because of economic reasons we treated all 3 horses in a medical and minimal invasive surgical way: The route was
- to ventilate and to change the microclimate of the affected humid GP with fresh air or oxygen. Therefore a permanent balloon catheter (Foley, Size CH 24) was placed in 2 horses with wide extent of fungal plaques under general anaesthesia via a hyovertebrotomy approach into the medial compartment of the GP.
- In the second step necrotic debris and diphtheric membranes were detached by gently swabbing with a biopsy forceps through endoscopic guidance in the standing, sedated horse. Afterwards detached masses were flushed with NaCl 0.9% and the fungal lesions irrigated with antifungal shampoo (Epi-pevaryl® Econazol, Janssen-Cilag Comp.) with a high quality of topical contact. The procedure b) was repeated every four to six days. The Foley catheters were withdrawn after 4 weeks of treatment. No bleeding or different neurological disorders were seen during the time of therapy.
Results
Four weeks after treatment all three horses were free of diphtheric membranes. After another rest of 2 to 4 weeks in their homestable they returned to their previous activities. Control endoscopies of the GP were performed 1, 2 and 6 months after treatment showing no recurrence of fungus. The horses were fine.
Conclusion
- Treatment of GPM is guided by its clinical features and presentation. Horses without a history of significant hemorrhage can be treated medically and / or surgically.
- If the diphtheric fungal plaques are well extended we think that it is necessary to change the humid, necrotic environment by ventilation the GP, i.e. by a temporary balloon catheter via a hyovertebrotomy approach.
- A medical treatment of GPM is possible however it is necessary to observe the patient and the way of treatment very critically. The owner must be informed in advance about possible fatal complication.
- Treatment of GPM is often frustrating because of high cost, demanding technical equipment and duration of treatment. In our 3 cases the period of local, medical treatment was - in comparison to the literature (2) - very short and the outlay for medication very low.
Literature
- Freeman DE. Diagnosis and Treatment of Guttural Pouch Hemorrhage. 4th Geneva Congress of Equine Medicine and Surgery, 1995; Proceedings pp 49-51
- Hardy J, Léveillé R. Diseases of the guttural pouches. Vet Clin North Am - Equine Pract 2003; 19:123- 58
Dr. Wolfgang Scheidemann, Dipl ECEIM
Tierklinik Hochmoor
D – 48712 Gescher