Mycosis in the stomach compartments of cattle

During a period of 22 months, 9.7% (23 out of 238) of the cattle necropsied at the Department of Veterinary Pathology had mycotic affections in the stomach compartments. The various stomach compartments were affected in the following pattern: omasum: 15 cases, rumen: 10 cases, reticulum: 8 cases and abomasum: 6 cases. In 5 of the animals mycotic affection was also found in other organs of which the liver was most often involved. Out of the 23 cases described, a primary diagnosis of mycosis was only established in 5 cases. In the remaining 18 cases the mycotic infection was regarded as being of a minor importance in the total necropsy result. Macroscopically and histologically the mycotic processes could be grouped into acute, subacute or chronic affections. In 20 cases only one type of inflammation was present, in the remaining cases combinations were found. Identification of the infective agent was performed by immunological staining of hyphal structures in tissue sections. Members of the Zygomycetes were found to predominate as causative fungi. Aspergillus fumigatus was found to have a propensity for infecting the terminal gastric compartments, whereas the Zygomycetes were found regularly in all compartments. Candida spp. were only found in 1 case. Predisposing factors for developing systemic mycosis are discussed. Among these especially the use of antimicrobial drugs, other diseases, metabolic disturbances and stressors in the post parturient period seem to be important.     

IMAGING DIAGNOSIS—TRACHEOBRONCHIAL ZYGOMYCOSIS IN A CAT

Tracheobronchial zygomycosis is described in a cat with acute dyspnea. Zygomycetes are an uncommon opportunistic group of pathogens, and few examples have been described in feline patients. Radiographic, ultrasonographic, and computed tomography imaging allowed identification of tracheobronchial masses, with intraluminal and peribronchial involvement. Surgical removal was impossible and antifungal chemotherapy was ineffective. Feline zygomycosis is a serious condition that should be considered when tracheobronchial masses are identified.     

Beyond conidiobolomycosis – the other ‘zygomycoses’

Disease resulting from infection by Zygomycetes fungi (including two groups of coenocytic fungal pathogens: the Mucormycota and the Entomophthoramycota) has been collectively referred to as zygomycosis. Clinical disease associated with both the Mucormycota and the Entomophthoramycota is rarely encountered in horses. Potentially life-threatening, mucormycosis is an angioinvasive disease that principally affects immunocompromised individuals. The order of Entomophthorales include two genera: Conidiobolus and Basidiobolus. The most common of these, Conidiobolus coronatus, typically causes chronic necrohaemorrhagic tumefactions in the nostrils, nasal passages and nasopharyngeal walls of immunocompetent equine hosts, most commonly seen in the south-eastern USA and parts of Australia. Infection by Basidiobolus ranarum is reported less frequently and usually causes solitary ulcerative skin lesions with pruritus. This short commentary intends to complement the accompanying review of conidiobolomycosis by summarising reported cases of mucormycosis and basidiobolomycosis in horses. Moreover, some new information regarding taxonomic challenges to traditional ‘Zygomycosis’ classification is presented.     

Colorectal basidiobolomycosis in a dog

A 7-year-old castrated male French Bulldog was examined for chronic large intestinal enteropathy. A colonic mass and thickened rectal mucosa were identified, and histopathologic examination of endoscopic biopsy specimens disclosed eosinophilic proctitis with large (5-20 μm), irregularly shaped, pauciseptate hyphae that were Gomori methenamine silver and periodic acid-Schiff positive. Amplification and sequencing of ribosomal DNA extracted from paraffin-embedded tissues yielded a sequence with 97% identity to GenBank sequences for Basidiobolus ranarum. After itraconazole, terbinafine, and prednisone administration, clinical signs resolved rapidly, and sonographic lesions were largely absent after 6 weeks. Treatment was discontinued by the owner 15 weeks after diagnosis. Three weeks later, the dog collapsed acutely and was euthanized. Necropsy identified metastatic islet cell carcinoma and grossly unremarkable colorectal tissues. However, histopathology of the rectum disclosed multifocal submucosal granulomas with intralesional hyphae morphologically similar to those previously observed. This report is the first to describe medical treatment of gastrointestinal basidiobolomycosis in a dog.     

Gastrointestinal pythiosis with concurrent presumptive gastrointestinal basidiobolomycosis in a Boxer dog

A 2‐year‐old female spayed Boxer dog was presented for a 1‐month history of progressive hemorrhagic diarrhea with tenesmus and weight loss despite trial courses of antibiotics and diet change. Abdominal ultrasound revealed severe, focal thickening, and loss of normal architecture of the colonic wall with abdominal lymphadenomegaly. Dry‐mount fecal cytology, performed on several consecutive days, consistently revealed numerous, round, 16‐20 μm structures with basophilic, granular content, and a thin cell wall. Transmission electron microscopy identified these structures as fungi. Culture, polymerase chain reaction (PCR), and sequencing of the internal transcribed spacer, D1/D2 regions, and DNA‐directed RNA polymerase II core subunit (RPB2) confirmed the presence of Basidiobolus microsporus in the feces. Biopsies collected via ileocolonoscopy revealed marked, multifocal, chronic, neutrophilic, and eosinophilic ileitis and colitis with ulceration, granulation tissue, and intralesional hyphae (identified with Gomori methenamine silver stain). A Pythium enzyme‐linked immunosorbent assay and Pythium‐specific PCR performed on the formalin‐fixed paraffin‐embedded biopsy specimens were positive while Basidiobolus‐specific PCR was negative, thus confirming a diagnosis of pythiosis. This report describes a fatal case of colonic and intestinal pythiosis with the presence of fecal Basidiobolus sp. spores, suggestive of concurrent gastrointestinal basidiobolomycosis.     

Oral conidiobolomycosis in a dog

Conidiobolomycosis was diagnosed via culture from an oral lesion in a 1.5-year-old German Shepherd dog. Clinically, the lesion consisted of a large, irregularly shaped, ulcerative focus on the caudal hard palate. Microscopically, the lesion was characterized by an eosinophilic granulomatous stomatitis with hyphal organisms surrounded by eosinophilic sleeves (Splendore–Hoeppli material) suggestive of an entomophthoramycosis. The fungus was cultured and identified with features consistent with Conidiobolus sp. Treatment with itraconazole at 10 mg kg⁻¹ twice daily for 61 days resulted in clinical and radiographic resolution of the lesion.