Bilateral microphthalmos with cyst in a neonatal foal.

A 1-day-old miniature horse filly was presented to the University of Florida Veterinary Ophthalmology service for evaluation of multiple ocular anomalies which were present from birth. Protruding from the right orbit was a large, fluctuant, red, dry and variably ulcerated mass. A globe could not be appreciated clinically in the left orbit. Ocular ultrasound of both orbits was performed. This revealed a lobular, hypo-echoic structure filling the right orbit, with multiple hyperechoic septations; normal ocular structures were not identified. Ultrasound of the left orbit revealed a microphthalmic eye, with a well-defined, hyperechoic structure in the vitreous that was thought to be the lens. Due to irreversible blindness, the foal was humanely euthanized. Histopathology and immunohistochemistry of the orbital contents revealed bilateral microphthalmos with cyst, a congenital defect rarely reported in the veterinary literature.

Dynamic exophthalmos and lateral strabismus in a dog caused by masticatory muscle myositis.

CASE DESCRIPTION: A 5.5-year-old neutered male mixed-breed dog was presented for evaluation of a 5-month history of deviation of the right globe upon opening the mouth and a 1-month history of conjunctivitis in the same eye. Clinical findings, diagnostic imaging results, treatment and follow-up are described. CLINICAL FINDINGS: When the mouth was opened, the right globe deviated rostrally and laterally. There was no pain or resistance to opening the mouth, or resistance to retropulsion of the globe. No other abnormalities were observed. Computed tomography was performed, revealing a contrast-enhancing region associated with the right masseter muscle impinging into the right orbit; this was more pronounced with the mouth open. Cytology revealed a small number of mildly to moderately atypical mesenchymal cells. Histopathology was consistent with polyphasic myositis, with a predominance of lymphocytes and plasma cells. No infectious agents were identified. Serum antibody titers for Toxoplasma gondii and Neospora caninum were negative. Serum titers for 2 M antibody were positive at 1:500, consistent with a diagnosis of masticatory muscle myositis. TREATMENT AND OUTCOME: Therapy with prednisone was initiated. During a follow-up period of 5 months, there was no recurrence of clinical signs, and the dose of prednisone was reduced by 25%. CLINICAL SIGNIFICANCE: To the authors' knowledge, this is the first reported case of masticatory muscle myositis causing dynamic exophthalmos and strabismus in a dog.

MRI findings in a dog with kernicterus.

A severe increase in total bilirubin coincided with a decline in neurologic status to comatose in a 9 yr old spayed female mixed-breed dog being treated for immune-mediated hemolytic anemia. MRI of the brain was performed to investigate potential causes for the neurologic signs. MRI revealed bilaterally symmetrical hyperintensities within the caudate nuclei, globus pallidus, thalamus, deep cerebellar nuclei, and cortical gray matter on T2-weighted and fluid-attenuated inversion recovery (FLAIR) sequences, which coincided with areas of bilirubin deposition and neuronal necrosis (kernicterus) identified on necropsy examination. This is the second case report of an adult dog exhibiting kernicterus, and the first report to document MRI findings associated with that condition. Kernicterus is an uncommonly reported complication of hyperbilirubinemia in dogs, but is potentially underreported due to difficulties in recognizing subtle lesions and distinguishing kernicterus from other potential causes of neurologic abnormalities with readily available antemortem tests. MRI may be helpful in supporting the diagnosis of kernicterus.

Gastrointestinal leiomyosarcoma in a pygmy sperm whale (Kogia breviceps).

An adult male pygmy sperm whale (Kogia breviceps) was stranded within a tidal pool on Fernandina Beach on the north Florida Atlantic coast (USA) and expired soon after discovery. Necropsy findings included a small intestinal mass markedly expanding the intestinal wall and partially obstructing the lumen. This finding likely led to the malnutrition and ultimately the stranding of this whale. The differential diagnoses for the mass based on gross evaluation included a duodenal adenocarcinoma, leiomyoma/sarcoma, gastrointestinal stroma tumor, and benign/malignant peripheral nerve sheath tumor, previously referred to as neurofibromas or schwannomas. The mass was presumptively diagnosed as a leiomyosarcoma via routine histopathology and confirmed by immunoreactivity for desmin and smooth actin (SMA). KIT, a gene name for CD 117, was negative, excluding a gastrointestinal stromal tumor (GIST). Leiomyosarcomas have been reported within numerous wild and domestic species, although this is the first reported case of any neoplasm in a pygmy sperm whale (K. breviceps).

Third eyelid dermoid in a horse.

An 8-year-old Gypsy Vanner gelding presented to the University of Florida Ophthalmology service for the evaluation of chronic, recurrent corneal ulcers behind the third eyelid of the right eye. On ophthalmic examination, a cluster of aberrant hairs was identified growing along the margin of the third eyelid. This portion of third eyelid was surgically excised, and histopathology identified the haired tissue as a dermoid. Chronic keratitis secondary to a third eyelid dermoid was diagnosed, and excision appeared curative at 6 months post-operative follow-up.

Surgical management of a subepiglottic thyroglossal duct cyst in a dog.

A 2 yr old dog presented for dysphagia and coughing secondary to a 4 cm × 4 cm turgid subepiglottic mass. Cervical radiographs, an esophagram, and computed tomography confirmed the presence of a cystic mass that was not intimately associated with any surrounding structures. An incisional biopsy confirmed the cystic nature of the mass and helped to rule out a malignancy. A marginal surgical excision was performed via a ventral approach. Histopathology of the mass was consistent with a thyroglossal duct cyst. This is the first report of a thyroglossal duct cyst in this location in a dog. There was no recurrence of clinical signs 14 mo after surgery.

Spontaneous external biliary fistula in a dog.

CASE DESCRIPTION: A 10-year-old sexually intact female dog was examined because of a static, well-circumscribed subcutaneous mass and associated fistulous draining tract located along the right ventrolateral aspect of the thoracic body wall of 15 months' duration. CLINICAL FINDINGS: Results of computed tomography and fistulography confirmed the presence of the fistulous tract. Computed tomography also revealed a focal, hypodense region in the right ventral portion of the liver that was adjacent to but not clearly associated with the fistulous tract. TREATMENT AND OUTCOME: Surgical exploration of the tract revealed that it passed into the right hemithorax to the diaphragm; entered the right medial lobe of the liver; and terminated in a well-encapsulated, cystic liver lesion. The right medial liver lobe and all affected tissues were removed. Histologically, the liver lesion consisted of a fibrotic, dilated bile duct. The dilated bile duct and fistula were lined with biliary epithelium. On the basis of these findings, a diagnosis of spontaneous external biliary fistula was made. Five months after surgery, the dog was clinically normal. CLINICAL RELEVANCE: To the authors' knowledge, spontaneous external biliary fistula in a dog has not been reported in the veterinary medical literature. Despite the rarity of this condition, it should be considered in a dog with similar clinical findings. Clinical findings and results of appropriate diagnostic imaging procedures may provide valuable information in making this diagnosis and in planning surgical treatment.

A retrospective study of the prevalence of calcium oxalate crystals in veterinary Aspergillus cases.

Fungi in the genus Aspergillus are some of the most common fungal pathogens in veterinary species, primarily affecting the respiratory tract. In both human and veterinary cases, calcium oxalate crystals have been documented in sites of Aspergillus infection. Cases in multiple species (16 birds, 15 horses, 5 dogs, 1 ox, and 1 dolphin) were identified that had either positive cultures for Aspergillus sp., or had conidiophores present that could be identified as belonging to the genus Aspergillus. Histologic slides were examined to confirm the presence of oxalate crystals and how often they were identified on the original report. Calcium oxalate deposition was detected in 14 of 38 cases examined, including A. fumigatus, A. versicolor, A. niger, and unspecified Aspergillus sp. infections. Calcium oxalate crystals were identified in 11 of 16 avian cases, as well as in 1 of 1 bovine, 1 of 15 equine, and 1 of 5 canine cases. Crystals were described in only 3 of the 14 original pathology reports of these cases, indicating that identification and reporting of crystals in histologic specimens could be improved. All the tissues with crystals were respiratory tissues with air interfaces, including nasal sinus, trachea, syrinx, lung, and air sac. In cases with crystals identified on H&E-stained sections, crystals were frequently not present or were fewer in number in tissue sections stained with Gomori methenamine silver and periodic acid-Schiff. Routine polarization of slides of fungal infections, especially in the respiratory tract, should be considered to check for calcium oxalate crystals.

Comparison of histomorphology and DNA preservation produced by fixatives in the veterinary diagnostic laboratory setting.

Histopathology is the most useful tool for diagnosis of a number of diseases, especially cancer. To be effective, histopathology requires that tissues be fixed prior to processing. Formalin is currently the most common histologic fixative, offering many advantages: it is cheap, readily available, and pathologists are routinely trained to examine tissues fixed in formalin. However, formalin fixation substantially degrades tissue DNA, hindering subsequent use in diagnostics and research. We therefore evaluated three alternative fixatives, TissueTek(®) Xpress(®) Molecular Fixative, modified methacarn, and PAXgene(®), all of which have been proposed as formalin alternatives, to determine their suitability for routine use in a veterinary diagnostic laboratory. This was accomplished by examining the histomorphology of sections produced from fixed tissues as well as the ability to amplify fragments from extracted DNA. Tissues were sampled from two dogs and four cats, fixed for 24-48 h, and processed routinely. While all fixatives produced acceptable histomorphology, formalin had significantly better morphologic characteristics than the other three fixatives. Alternative fixatives generally had better DNA amplification than formalin, although results varied somewhat depending on the tissue examined. While no fixative is yet ready to replace formalin, the alternative fixatives examined may be useful as adjuncts to formalin in diagnostic practices.

Compartment syndrome associated with expansile antebrachial tumors in two dogs.

CASE DESCRIPTION: A 10-year-old spayed female Jack Russell Terrier and a 7-year-old neutered male mixed-breed dog were evaluated because of acute, progressive, unilateral forelimb lameness associated with signs of pain and turgid antebrachial swelling. CLINICAL FINDINGS: For either dog, there were no salient pathological or diagnostic imaging abnormalities. A diagnosis of compartment syndrome was confirmed on the basis of high caudal antebrachial compartmental pressure in the affected forelimb. TREATMENT AND OUTCOME: Both dogs underwent surgical exploration of the affected forelimb. In each case, an intramuscular tumor (mast cell tumor in the Jack Russell Terrier and suspected sarcoma in the mixed-breed dog) was detected and presumed to be the cause of the high compartmental pressure. At 6 months following tumor excision, the dog with the mast cell tumor did not have any clinical signs of disease. The dog with a suspected sarcoma underwent tumor excision and forelimb amputation at the proximal portion of the humerus followed by chemotherapy; the dog was euthanized approximately 1 year following treatment because of pulmonary metastasis. CLINICAL RELEVANCE: Compartment syndrome is a serious but rarely reported condition in dogs and is typically ascribed to intracompartmental hemorrhage. These 2 cases illustrate the potential for expansile intramuscular antebrachial tumors to cause compartment syndrome in dogs.

A novel gammaherpesvirus in a large flying fox (Pteropus vampyrus) with blepharitis.

A novel gammaherpesvirus was identified in a large flying fox (Pteropus vampyrus) with conjunctivitis, blepharitis, and meibomianitis by nested polymerase chain reaction and sequencing. Polymerase chain reaction amplification and sequencing of 472 base pairs of the DNA-dependent DNA polymerase gene were used to identify a novel herpesvirus. Bayesian and maximum likelihood phylogenetic analyses indicated that the virus is a member of the genus Percavirus in the subfamily Gammaherpesvirinae. Additional research is needed regarding the association of this virus with conjunctivitis and other ocular pathology. This virus may be useful as a biomarker of stress and may be a useful model of virus recrudescence in Pteropus spp.

Ocular and olfactory forebrain abnormalities within a neonatal alpaca (Vicugna pacos).

A 5-day-old Huacaya alpaca cria (Vicugna pacos) was euthanized due to deteriorating health. At birth, the cria had ophthalmologic abnormalities, but had appropriate mentation. At 2 days of age, the cria gradually stopped suckling and began to circle. At 5 days old, the owner elected euthanasia due to declining clinical condition. Grossly, the right iris had a scalloped pupillary margin, and the right olfactory bulb was malformed. Histopathology revealed persistent hyperplastic primary vitreous bilaterally and iridal abnormalities, as well as aplasia of the olfactory ventricle, olfactory tract, and olfactory foramen on the right side.