Barbara J. Watrous

Coccidioidomycosis in dogs and cats: A review

The dimorphic fungi Coccidioides immitis and Coccidioides posadasii are the causative agents of coccidioidomycosis. Dogs and cats residing in and visiting endemic areas are at risk of exposure to infectious arthrospores. The primary infection is pulmonary and frequently results in chronic cough. Disseminated disease is common and causes cutaneous, osseous, cardiac, ocular, nervous system, or other organ disease. Radiographic changes include a variable degree of interstitial pulmonary infiltration, hilar lymphadenopathy, and osseous lesions. Serological titers support the diagnosis, but definitive diagnosis relies on identification of Coccidioides in cytological or tissue samples. Coccidioidomycosis should be considered in any dog or cat that has been potentially exposed during the previous 3 years and is presented with chronic illness, respiratory signs, lameness, lymphadenopathy, nonhealing cutaneous lesions, or neurological, ocular, or cardiac abnormalities.

Gastrointestinal Transit of Nondisintegrating, Nonerodible Oral Dosage Forms in Pigs

Gastrointestinal (GI) transit data necessary as “baseline” or “control” information were collected using pigs as animal models preliminary to bioavailability studies of new sustained action formulations. Density and size effects of nondisintegrating dosage forms on GI transit were investigated. Initially, enteric-coated nondisintegrating magnesium hydroxide caplets (density, 1.5 g/ml; size, 19.6 × 9.5 mm; weight, 1.2 g) were utilized in seven pigs. Prolonged gastric residence (>5 days) occurred in every case for this dosage form. Therefore, nondisintegrating caplets of three densities (1.25, 1.45, and 2.3 g/ml) and three different sizes (large, 20 × 10 mm; medium, 10 × 10 mm; small, 5 × 10 mm) were studied in two more pigs. Roentgenography was used to visualize passage of caplets through the GI tract. Heidelberg pH capsules (size, 8 × 20 mm; density, 1.61 g/ml) were also used in this study. Total GI transit times range from 2 to 33 days for 22 administrations of these nondisintegrating dosage forms. Pigs are found to not be an appropriate model for evaluating bioavailability of nondisintegrating controlled-release dosage forms because total GI transit time (especially gastric transit) is much too long.

Prophylactic partial stylohyoidostectomy for horses with osteoarthropathy of the temporohyoid joint

Summary A technique of partial, unilateral, stylohyoidostectomy was developed for use in horses with chronic proliferative temporohyoid osteoarthrosis and ankylosis to prevent stress fractures of the skull. Partial stylohyoidostectomy may prevent fracture by eliminating forces on the skull resulting from movement of the tongue and larynx. Clinical, radiographic and histologic effects of unilateral (n=4) and bilateral (n=1) partial ostectomy performed in 5 horses were evaluated. Dysphagia was present for 1 week following unilateral, partial ostectomy but the horse that had a bilateral, partial ostectomy had residual prehension and mastication deficits when it was euthanatized 5 weeks after surgery. A pseudoarthrosis occurred between the cut ends of the stylohyoid bone. Unilateral, partial stylohyoidostectomy was easily performed and caused no permanent complications.

Head tilt in horses.

Head tilt in the horse is commonly a sign of either central or peripheral vestibular disease. The confirmation of vestibular disease is based on physical findings, including results of cranial-nerve function evaluation and observation of stance, posture, and gait. Further localization is made by ancillary tests such as cerebral spinal fluid analysis, electrodiagnostic testing, and radiography. The normal anatomy and physiology of the vestibular system, the abnormal clinical signs demonstrated during physical examination, and the various etiologies are discussed.

Immunogenicity of a soluble antigen against Pasteurella haemolytica-associated pneumonia in calves

Three experiments were performed to evaluate the immunogenic potency of a soluble fraction ofPasteurellahaemolytica against pneumonic pasteurellosis in calves. A soluble antigen was extracted by a 2.5% saline solution fromP.haemolytica. Weaned Holstein bull calves, seronegative for infectious bovine rhinotracheitis virus (IBRV) and the pasteurella antigen, were vaccinated either by repeated subcutaneous (SC) vaccination, or by exposure 3 times to the aerosol ofP.haemolytica antigen. Challenge exposure to aerosol ofP.haemolytica was preceded by infection with IBRV, or in experiments 2 and 3, the virus exposures were combined with a stress treatment. The lung lesions were examined at necropsy 3 to 8 days post infection. In the first experiment, all the vaccinated calves produced specific antibody response to the pasteurella antigen, and none of the calves including controls showed significant lesions in the lung. In the second experiment 2 aerogenically vaccinated calves had no lesions. One of the two SC-vaccinated calves had mild consolidated lesions. Two control calves, one of which died 3 days following the challenge, developed severe fibrinous pneumonia with consolidation of 50% or more of the lung surfaces.P.haemolytica was isolated only from the 2 control animals. In the third experiment, 2 of the 3 control calves developed moderate to severe consolidation, butP.haemolytica was isolated only from one of them. Two of the three aerosol-vaccinated calves also developed significant lesions and one of them yielded the bacteria from the lung. Three SC-vaccinated calves had slight lesions and the organism was not isolated from their lungs. The results did not consistently indicate an immunogenic potential of the soluble antigen againstP.haemolytica-related pneumonia. The effect of stress on the pathogenesis of bovine viral penumonia and correlation between pneumonic lesions and antibacterial resistanceinsitu are discussed.

Keratinizing Ameloblastoma in a 9-Month-Old Llama (Lama Glama)

A 9-month-old male llama (Lama glama) was presented because of a rapidly growing mass on the right side of the face. Radiographs revealed a marked expansion of the right caudal face region with bone lysis involving the maxilla and the nasal, lacrimal, zygomatic, and palatine bones. Cytologically, the mass consisted of atypical round to polygonal cells with round nuclei and basophilic cytoplasms that formed acini and rows. Histologically, the mass consisted of anastomosing cords and sheets of neoplastic odontogenic epithelial cells embedded in a loose fibrovascular connective tissue. Single layers of peripheral, polarized, palisading, columnar epithelial cells were seen at the edges of some cords. Within the centers of the cords, epithelial cells showed rapid progression to keratin production. The histologic diagnosis was keratinizing ameloblastoma. Ameloblastomas are neoplasms of odontogenic epithelium that tend to be locally aggressive and can cause substantial destruction of bony structures. Because ameloblastomas do not tend to metastasize, they can be successfully treated by complete surgical excision, performed before extensive bony destruction occurs. Ameloblastoma, although expected to be rare, should be on the list of differential diagnoses for facial swelling in llamas.

Cervical dorsal spondylosis with spinal cord compression in a black swan (Cygnus atratus).

Cervical dorsal spondylosis with spinal cord compression in a black swan (Cygnus atratus) was confirmed radiographically and morphologically. Clinically ataxia was associated. Noninflammatory, degenerative changes of the synovial joint cartilage were associated with the spondylosis.