Variation in the MRI appearance of the canine pituitary gland.

A recent publication described pathological findings in the pituitary gland incidentally discovered during routine necropsies of the brain of dogs and cats; however, imaging characteristics of these lesions were not reported. Aims of this retrospective, observational study were to characterize MRI variants and incidental lesions in pituitary glands of dogs with no clinical signs of pituitary disease. Cranial MRIs from dogs with no suspicion of pituitary disease, based on history and presenting clinical signs, were retrieved from a veterinary teleradiology database during the period of January 2014 to January 2016. Images were reinterpreted by two observers and pituitary lesions were described based on consensus. A total of 580 scans were evaluated and pituitary lesions were detected in 78 dogs (13.44%). Pituitary cystic lesions were the most common finding and occurred in 31 dogs (5.34%). Of these 31 dogs, the majority (74%) were of toy or brachycephalic breed. Partial or total empty sella lesions were detected in 14 dogs (2.41%), and all of these were small or toy breeds. A significantly increased incidence of the partial empty sella lesion was found in male dogs (P = .034). Pituitary lesions greater than 1 cm occurred rarely (0.69%). There was a significant association between low-field (LF) MRI strength and detection of a partial or total empty sella lesion (P = .0112), and detection of a pituitary lesion greater than 1 cm (P = .0125). A significant difference was present between the MRI field strength (FS) that identified pituitary cysts and the FS that detected an empty sella (P = .0068), with the former being a high FS and the latter a LF strength. The findings from this study indicated that up to 13% of dogs with no presenting clinical signs of pituitary disease may have MRI pituitary lesions.

Estimation of the prevalence of idiopathic epilepsy and structural epilepsy in a general population of 900 dogs undergoing MRI for epileptic seizures.

Due to variation in study designs the prevalence of idiopathic epilepsy (IE) and structural epilepsy (SE) in dogs is largely unknown. The objective was to provide estimates of the prevalence of IE and SE in a large population of dogs undergoing MRI for epileptic seizures. A retrospective study on 900 dogs undergoing MRI for seizures was performed. MRI scans, summary clinical history and neurological examination from the VetCT database were reviewed and a diagnosis assigned by board-certified radiologists. Structural lesions were identified as a cause of seizures in 45.1 per cent (n=406) of cases. No structural lesions were identified in 54.9 per cent (n=494) of cases with presumed IE diagnosed in 53.8 per cent (n=484) of dogs. Dogs between six months and six years were more often associated with IE (P<0.001), small breeds were overrepresented with suspected inflammatory brain disease (P=0.001) and large entire dogs more often diagnosed with extra-axial neoplasms (P=0.001). Over 31.0 per cent of dogs with suspected IE were six years or older. This study is the largest of its kind in dogs and provides accurate estimates of underlying causes of epilepsy. MRI findings should be considered in the context of a detailed clinical history and neurological examination.

Hepatic fibrosarcoma incarcerated in a peritoneopericardial diaphragmatic hernia in a cat.

CASE SUMMARY: A 14-year-old, female neutered domestic shorthair presented for dyspnoea. Thoracic ultrasonography and radiography showed that a heterogeneous mass was present within the pericardial sac, and the mass continued caudally with the mesenteric fat. On CT, the outline of the diaphragm was not continuous and there was an obvious defect with diaphragmatic thickening present at the mid-level of the liver. A pleural effusion and a small-volume pericardial effusion were also present. A ventral midline coeliotomy and median sternotomy revealed a 5 × 6 × 7 cm firm, irregular, tan-coloured soft tissue mass within the pericardial sac attached to both the diaphragmatic defect and liver. The mass was carefully dissected away from the heart and the diaphragmatic defect was repaired with primary closure. Postoperatively, the cat had a persistent pneumothorax that required continuous pleural suction for 41 h. The cat died 44 h postoperatively. Histopathology and immunohistochemistry confirmed the mass to be a hepatic fibrosarcoma incarcerated in a peritoneopericardial diaphragmatic hernia (PPDH). RELEVANCE AND NOVEL INFORMATION: This is the first reported case of metaplastic transformation of liver into a sarcoma in a cat with PPDH. In addition, hepatic fibrosarcoma is a rarely reported location for fibrosarcoma in this species.

Marked cytoreduction of a lymphocyte-rich mediastinal thymoma with neoadjuvant chemotherapy in a cat.

CASE SUMMARY: A 15-year-old neutered female domestic shorthair cat presented with lethargy and acute-onset dyspnoea. Thoracic computed tomography (CT) revealed a large, cranial mediastinal mass with an estimated volume of 180.7 cm3. Chemotherapy consisting of dexamethasone followed by L-asparaginase, prednisolone, vincristine and doxorubicin was commenced owing to the severity of disease and initial possibility of lymphoma. A diagnosis of lymphocyte-rich thymoma was made based upon histological examination, positive pancytokeratin staining, variable lymphocyte CD3 expression and T cell receptor gamma polyclonality. Thoracic CT performed 35 days after the commencement of chemotherapy showed a marked reduction in the size of the mass, with an estimated volume of 9.4 cm3. A median sternotomy and thymectomy were performed. No clinical signs have recurred 34 months after surgery. CONCLUSIONS AND RELEVANCE: The response to chemotherapy in this case was unusual, and is likely associated with the high non-neoplastic lymphoid component of the mass. The case demonstrates that preoperative chemotherapy can be used to reduce thymoma volume prior to surgery, potentially decreasing anaesthetic risk.

Electrophysiological features in dogs with peripheral nerve sheath tumors: 51 cases (1993-2010).

OBJECTIVE: To determine the electrophysiological changes in dogs with peripheral nerve sheath tumors (PNSTs), evaluate the prevalence of these changes, assess the correlation between spontaneous activity in epaxial muscles and proximal invasion by the tumor, and evaluate whether knowledge of electrophysiological changes could be helpful in the imaging diagnosis via CT or MRI. DESIGN: Retrospective case series. ANIMALS: 51 dogs with a histologic (n = 18) or a suspected (33) diagnosis of PNST. PROCEDURES: Clinical, postmortem, and histologic reports and details of electrodiagnostic procedures and CT or MRI reports were studied. Twenty-four CT and 6 MRI reports for dogs with PNSTs were reviewed by a single observer blinded to the diagnosis. RESULTS: Only 2 of the 51 dogs had no electrophysiological changes. The most commonly affected muscles were those innervated by the radial, ulnar, median, tibial-sciatic, and peroneal nerves. Abnormal spontaneous epaxial muscle activity was significantly more frequent in the group with foraminal or spinal invasion by the tumors. Knowledge of the electrophysiological changes increased diagnostic accuracy of CT. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that electrophysiological studies may be sensitive for the detection of PNST and helpful in the imaging diagnosis. Epaxial electromyographic abnormalities appeared to be predictive for intervertebral or vertebral canal invasion by PNSTs in dogs.

Age-related thoracic radiographic changes in golden and labrador retriever muscular dystrophy.

Golden retriever and Labrador retriever muscular dystrophy are inherited progressive degenerative myopathies that are used as models of Duchenne muscular dystrophy in man. Thoracic lesions were reported to be the most consistent radiographic finding in golden retriever dogs in a study where radiographs were performed at a single-time point. Muscular dystrophy worsens clinically over time and longitudinal studies in dogs are lacking. Thus our goal was to describe the thoracic abnormalities of golden retriever and Labrador retriever dogs, to determine the timing of first expression and their evolution with time. To this purpose, we retrospectively reviewed 390 monthly radiographic studies of 38 golden retrievers and six Labrador retrievers with muscular dystrophy. The same thoracic lesions were found in both golden and Labrador retrievers. They included, in decreasing frequency, flattened and/or scalloped diaphragmatic shape (43/44), pulmonary hyperinflation (34/44), hiatal hernia (34/44), cranial pectus excavatum (23/44), bronchopneumonia (22/44), and megaesophagus (14/44). The last three lesions were not reported in a previous radiographic study in golden retriever dogs. In all but two dogs the thoracic changes were detected between 4 and 10 months and were persistent or worsened over time. Clinically, muscular dystrophy should be included in the differential diagnosis of dogs with a combination of these thoracic radiographic findings.

Effect of breed, age, weight and gender on radiographic renal size in the dog.

In the adult dog, kidney length has been reported as 2.98 ± 0.44 times the length of L2 on ventrodorsal views and 2.79 ± 0.46 times the length of L2 on lateral radiographs. Our aim was to test the hypothesis that the suggested maximum normal left kidney size is too high, and to evaluate the effect of breed type, gender, weight and age of the dog on kidney size. Abdominal radiographs of 200 dogs with no evidence of concurrent disease that might have an effect on renal size were included in the study. The mean ratio of kidney length to the second lumbar vertebra length was similar to previous reports. For the right lateral view it measured 2.98 ± 0.60 and for the ventrodorsal view 3.02 ± 0.66. Significant differences of this ratio between skull type were present, especially between brachycephalic and dolichocephalic dogs. On the right lateral view brachycephalic dogs had the highest median LK/L2 ratio of 3.1 (3.20 ± 0.40), whereas for dolichocephalic dogs it was 2.8 (2.82 ± 0.50), and for mesaticephalic dogs it was 2.97 (3.01 ± 0.6). A ratio >3.5 was found only in mesaticephalic dogs on the ventrodorsal view. There was a significant difference in the LK/L2 ratio between small (≤10kg) and large breed dogs (>30kg) where small dogs had a significantly higher LK/L2 ratio. There was no statistically significant relation between this ratio and age or gender. The previously reported ratios for kidney size seem valid, but because skull type has an impact on the LK/L2 ratio, a single normal ratio should not be used for all dogs.

Penetrating ocular gunshot injury in a Labrador Retriever.

A 3½-year-old, female (spayed) working black Labrador Retriever was referred to the Unit of Comparative Ophthalmology at the Animal Health Trust after a penetrating lead gunshot injury to the right eye. Clinical examination revealed penetrating injuries to the right cornea, left lateral canthus, and left forelimb. Radiography revealed the presence of multiple metallic foreign bodies in the head and one in the left forelimb. B-mode ocular ultrasonography confirmed the presence of an intraocular metallic foreign body within the posterior tunics of the right eye. Medical treatment of the right eye over a period of 1 month resulted in a comfortable, visual eye. Long-term follow-up over 4½ years revealed a slow deterioration in vision because of progressive lens opacification and the presence of a localized area of chorioretinopathy.

Ultrasonographic evaluation of vitreous degeneration in normal dogs.

Vitreous degeneration is common in dogs and may be associated with cataract formation. Vitreous degeneration may be identified using B-mode ultrasonography and appears as multiple, small, motile, point-like echoes within the vitreous cavity. In humans, vitreous degeneration has also been observed in normal aging eyes but the incidence of vitreous degeneration in dogs without cataract has not previously been documented. The purpose of this study was to describe the ultrasonographic appearance of vitreous degeneration and to investigate its incidence in a population of dogs without cataract or other apparent eye disease. The eyes of 62 dogs were evaluated as part of a prospective study. All dogs underwent ophthalmological and ultrasonographic examinations and vitreal changes were graded on ultrasonography using a predetermined grading scheme. Vitreous degeneration was found in 20% (23/114) of the eyes on ultrasonographic examination but in only 8% (9/114) of eyes on direct ophthalmoscopy. Sensitivity and specificity of ophthalmoscopy using ultrasonography as a gold standard were respectively, 39% and 100%. Vitreal syneresis and asteroid hyalosis could be distinguished according to their ultrasonographic characteristics. The probability of having vitreous degeneration increased with the age of the dog (odds ratio = 6.7 for dogs of 7 + years compared with 0-6 years) and also increased in females compared with males (odds ratio = 3.6). Vitreous degeneration, especially mild vitreal syneresis, is not uncommon in normal dogs; it was shown to be an age-related condition and its significance should not be overinterpreted on ocular ultrasonography.