An Unusual Case of Nasal Mucormycosis Caused by Rhizopus Oryzae in a German Shepherd Dog
M. Selk Ghaffari1; D. Shirani2; A. Khosravi3; A. Vajhi2; T. Zahraei Salehi4; N. Khorami2; M. Abarkar2; M. Marjani1
A 1-year-old, male German shepherd dog was presented because of unilateral epistaxis, mucopurulent nasal discharge, sneezing and nose pawing with 10 days duration. In general observation there was no ulceration, depigmentation or crusting of the external nares, just stertorous breathing was noticeable.
On referral, the animal was in good condition. The dog vaccinated in routine vaccination program the owner reported that there was history of head trauma 2 months ago which was associated with mild self limited epistaxis. Nasal discharge initially was serous and later becomes purulent and hemorrhagic. Oral examination revealed no significant abnormality but pain and discomfort in the nasal region was remarkable during palpation. And the rest of physical examination was normal. First at all, general aesthesia was induced by combination of ketamine+diazepam, then for diagnostic assessment of intranasal diseases nasal radiography was obtained. Open- mouth ventrodorsal radiograph marked typical turbinate destruction and increased in radiolucency in the left nasal chamber was present the vomer bone remains intact. Thoracic radiography revealed no significant abnormality.
Initial nasal rhinos copy, suggested severe, turbinate destruction (black necrotic turbinate), endotracheal intubations was preformed and by nasal flush technique fluid collected and submitted to cytological examination, fungal and bacteriocidal culture. Unfortunately sever haemorrhage during nasal biopsy developed and cold saline infusion used to control haemorrhage. It was decided to do biopsy procedure in the next time.
All haematological, biochemistry and urinalysis values were normal. Antibiotic treatment was initiated and 5 mg/kg enrofloxacin parenterally every 24 hours was given for first week.
Direct microscopic examination KOH /dimethyl sulphoxide wet mount smear revealed the fragments of septate hyphae. The specimen was cultured on Sabouraud glucose agar with chloramphenicol, which resulted in the isolation of Rhizopus oryzae. On bacterial culture proteus isolated in the culture media. Unfortunately the owner did not bring the dog for more diagnostic clinical studies and following therapeutic management.
Mucormycosis is a severe fungal disease. It can present in two clinical forms: localized or disseminated (Neri G and others 2002). The most frequent form begins in the nose and the Para nasal sinus and can rich the brain. It is a fulminant and often fatal disease, not well known by many specialists (Sanabria Gomez F and others 1992).
Rhinocerebral mucormycosis is a rare complication which was mainly seen in patients with diabetic ketoacidosis. The lesion invaded nose, eyes and brain with a high mortality (Guo H and others). It is characterized by aggressive necrotizing infection originating from nose and spreading to paranasal sinuses, orbit and central nervous system. Although Fungi and spores of mucorales show minimal intrinsic pathogen city towards normal persons, they can initiate fulminant infections in patients with underlying debilitating conditions (Trivedi TH and others 2002).
The clinical course of patients with mucormycosis of the Para nasal sinuses can be unpredictable and is often determined by intrinsic host factors. The degree to and mechanism(s) by which these factors influence a patient's ability to survive the disease is poorly understood. (Anand VK and others 1992).
Some investigators believed that nasal fungal infections in German shepherd is related to genetic factors so, It is known that genetic base of reduced serum IgA in German shepherds act as a predisposing factor for development of aspergillosis (Ettinger 2000).
Furthermore "mucormycoses," usually occur in immunocompromised hosts, trauma or burn victims. (Chaney S and others 2004).
Breed predisposition and history of past trauma, in our case are considerable predisposing factors for development of nasal Rhizopus infection. There is also a close relationship between diabetes mellitus and Mucormycosis in human patients but results of biochemistry and urinalysis values in the presented case was normal which is remained that such factors have not been identified in most instances. (Muller and Kriks 2001). And our case classified as healthy normoglycemic dog. Isolation of proteous in bacterial culture highlights Heavy growths of entero bacteriacea in the necrotic turbinate of nasal cavity as it is common in canine nasal aspergillosis and penicilliosis (pp421 Muller). There are many reports in the medical literature in which Mucormycosis presented as a cause of destructive nasal fungal disease but to the author's knowledge, this is the first reported case in the German shepherd dog, because the most common clinical form which is reported in dogs and cattle affects the lymph nodes of respiratory and intestinal tracts characterize by caseous necrosis. The involvement of internal organs can be occurred (Quinn P.J. 1994). Localized nasal Mucormycosis is clinically indistinguishable from other pathologic.