Epidemiology of necrotizing meningoencephalitis in Pug dogs

BACKGROUND: Although the histopathologic features of necrotizing meningoencephalitis (NME) have been described previously, little information is available concerning the signalment, geographic distribution, seasonal onset, treatment, and survival of affected dogs. ANIMALS: Sixty Pugs with NME and 14 contemporaneous control Pugs with other intracranial diseases (non-NME group). METHODS: Pugs that were euthanized or died because of intracranial disease were prospectively obtained. All dogs had necropsy, histopathology, and testing for various infectious diseases and were subsequently divided into NME and non-NME groups. Signalment, geographic distribution, seasonal onset, treatment, and survival were compared between groups. RESULTS: In Pugs with NME, median age at onset of clinical signs was 18 months (range, 4-113 months). A greater proportion of female dogs were present in the NME group (40/60) compared with the control group (6/14). Pugs with NME had a significantly lower mean weight (7.81 kg) than control Pugs (9.79 kg) (P= .012). Mean survival in Pugs with NME was 93 days (range, 1-680 days), with dogs receiving any form of treatment living significantly longer than those that were not treated (P= .003). Anticonvulsive drugs were the only treatment significantly associated with longer survival (P= .003). CONCLUSIONS AND CLINICAL IMPORTANCE: NME appears to be a common cause of intracranial signs in Pugs, based on the high proportion of NME dogs reported in this population. Pugs with NME are most commonly young adult female dogs. Although further investigation is needed to determine the optimal treatment of NME, anticonvulsive drugs appear to beneficially affect duration of survival.     

Necrotizing meningoencephalitis associated with cortical hippocampal hamartia in a Pekingese dog

A 4-year-old male Pekingese dog was referred to the clinic with a history of recurrent seizures and progressive abnormal gait and behavior, which did not respond to treatment. At necropsy, a large cortical defect in the right temporo-parietal cortex, malacia of subcortical white matter, right basal nuclei, and capsula interna, as well as abnormalities of the right hippocampus were observed. Histological examination of the brain revealed moderate to severe nonsuppurative meningoencephalitis in the left cerebral hemisphere and extensive infarction-like lesions with milder inflammation in the right hemisphere. In the right hippocampus, the pyramidal cells were arranged in a gyrus-like pattern and intermingled with gemistocytic and fibrillary astrocytes. The histopathological features of the inflammatory lesions were consistent with necrotizing meningoencephalitis and resembled those described in so-called Pug dog encephalitis. The hippocampal changes were interpreted as dysplasia (monolateral hippocampal cortical hamartia), unrelated to clinical signs and necrotizing inflammatory lesions.     

A necrotizing meningoencephalitis of pug dogs

Clinical and pathologic features of a sporadic, necrotizing meningoencephalitis affecting adolescent and mature pug dogs are described. Many of the affected animals were closely related. Acute and chronic forms occur, with clinical signs reflecting the pathologic affinity of the disease for the cerebral hemispheres. No etiologic agent has been identified. The extensive necrosis and affinity for the cerebral hemispheres are similar to alphatype herpesvirus encephalitides of other species.     

Keratomycosis in five dogs

Five cases of canine keratomycosis were diagnosed and treated at a private Veterinary Ophthalmology Practice in Melbourne, Australia. Clinical presentations varied between dogs. Predisposing factors were identified in 4 of 5 cases. Diagnostic modalities utilized were corneal cytology and fungal culture. Corneal cytology confirmed the presence of fungal organisms in all five cases. Aspergillus, Scedosporium, and Candida were cultured from three cases, respectively. Specific antifungal treatment included 1% voriconazole solution or 1% itraconazole ointment. Keratectomy and conjunctival grafting surgery was performed in two patients. Resolution of infection and preservation of vision were achieved in 4 of 5 patients.     

Synovial chondrometaplasia in five dogs

Synovial chondrometaplasia was diagnosed in 5 dogs. Four dogs improved dramatically after surgical removal of subsynovial nodules, but the fifth improved only slightly. This potentially treatable condition is recognized in human beings, and has been described in dogs in the German scientific literature. Synovial chondrometaplasia should be suspected if numerous joint mice are visualized radiographically, without an obvious inciting cause. It also should be suspected when periarticular osteophytes are found radiographically in unusual locations.     

Necrotizing meningoencephalitis and pneumonitis in a simian immunodeficiency virus-infected rhesus macaque due to Acanthamoeba

Free-living amoebae of the genus Acanthamoeba can cause a fatal disease of the brain in humans called granulomatous amoebic encephalitis. We present a case of meningoencephalitis and pneumonitis in a simian immunodeficiency virus (SIV)-infected rhesus macaque caused by Acanthamoeba sp. The animal became ill 176 days after intravenous inoculation with SIVmac251 after a short history of weight loss and a sudden onset of hind limb paresis and abnormal head movements. Histopathologic examination of hematoxylin and eosin-stained tissues revealed multifocal to coalescing necrotizing neutrophilic meningoencephalitis and pneumonitis. Immunofluorescence and polymerase chain reaction were used to identify the genus of amoeba as Acanthamoeba. Immunohistochemistry of immune cell markers was used to characterize the animal's immune response to the opportunistic amoebic infection with features of both innate and adaptive cell-mediated immunity. Although not previously reported, the potential transmission to humans, either through environmental contamination or contact with an infected animal, makes this disease a threat to laboratory animal care staff and pathologists.     

Immune-mediated vasculitis in five dogs

Vasculitis was diagnosed in 5 dogs. Clinical signs varied, but all 5 dogs had signs of systemic illness. Inflammation and fibrinoid necrosis of small blood vessels were consistent findings. The skin and mucous membranes were the main tissues involved in 3 dogs; polyarthropathy and myopathy were diagnosed in 1 dog and myopathy in 1 dog. Good response to corticosteroid therapy was achieved in 3 dogs; in 2 dogs, immunosuppressive therapy with cyclophosphamide was necessary and the dogs responded well.     

Transcranial Doppler sonographic findings in granulomatous meningoencephalitis in small breed dogs

Granulomatous meningoencephalitis (GME) is an acute, progressive, and often fatal inflammatory disease of the central nervous system, affecting mainly small and toy dog breeds. A definitive diagnosis of GME can only be achieved through histopathologic examination of samples collected after death. This retrospective study describes transcranial Doppler ultrasonography (TDS) findings in dogs with confirmed clinical histopathology of GME. Eleven dogs were selected for this study. Sonographic findings in B-mode demonstrated diffuse decreased brain parenchyma echogenicity in 9 dogs, ventriculomegaly in 8 dogs, brain atrophy in 4 dogs, and hyperechoic focal lesions in 6 dogs. Color Doppler imaging revealed more obvious vessels of the arterial circle in 10 dogs. Spectral Doppler examination was performed in 10 dogs to detect the 6 major cerebral arteries of interest. The examination showed normal and high resistive index (RI) values in the outlined arteries. The TDS findings were consistent with pathology found on postmortem examination.     

Use of cyclosporine to treat granulomatous meningoencephalitis in three dogs

Use of cyclosporine to treat granulomatous meningoencephalitis in three dogs Three dogs with a presumptive diagnosis of granulomatous meningoencephalitis were treated with orally administered cyclosporine. In 2 dogs, cyclosporine administration replaced initial corticosteroid administration, and in 1 dog, cyclosporine was the only treatment used. One dog had the focal form of the disease in the brainstem, 1 dog had the focal form in the forebrain associated with a concurrent ocular form, and 1 dog had the disseminated form of disease. At 12-month follow-up, the 2 dogs with the focal form of the disease had no clinical signs. The dog with the disseminated form improved only partially, and euthanasia was performed 3 weeks after initial evaluation. Cyclosporine was considered effective at an initial dosage of 6 mg/kg (2.7 mg/lb) every 12 hours. Adverse effects associated with cyclosporine administration included transient lymphopenia, excessive shedding, and focal symmetric hair discoloration.     

Necrotizing enterotyphlocolitis in dogs treated with a potent antimuscarinic

To assess the safety of a potent muscarinic receptor antagonist (antimuscarinic) for human clinical testing, repeat-dose oral toxicity studies were conducted in the Beagle dog. Treatment resulted in unexpected gastrointestinal system effects that were likely mediated by the exaggerated pharmacologic effects of the antimuscarinic on intestinal motility. Dogs developed profound anorexia followed by severe bloody diarrhea, and at necropsy, the intestinal tract was distended, filled with red-tinged fluid, and the mucosa was reddened. Histologically, intestinal lesions consisted of severe epithelial necrosis and mucosal atrophy localized predominantly to the ileum and large intestine. Feces from dogs with diarrhea were culture-positive for Clostridium perfringens (CP), suggesting that CP might be the etiologic agent; however, the intestinal lesions were not consistent with histologic findings reported in dogs with hemorrhagic canine enteritis.     

Immune-mediated neutropenia suspected in five dogs

Five cases of suspected immune-mediated neutropenia in dogs are described. Clinical signs varied depending on whether the animals had a systemic infection or concurrent immune-mediated disease. Patients were diagnosed by excluding other causes of neutropenia, supportive bone marrow aspirate findings, an initial favourable response to corticosteroid administration in four of the cases, and concurrent immune-mediated disease. Four of the dogs were receiving medications at the time of diagnosis, and immune-mediated neutropenia secondary to drug therapy cannot be excluded. This study shows that appropriate immunosuppressive treatment can lead to a favourable outcome, however, care is required to avoid adverse effects associated with corticosteroid use. It is also imperative that medications are not withdrawn abruptly as a second remission may not always be achievable.     

Cerebral vascular hamartomas in five dogs

Vascular hamartomas are considered developmental lesions rather than true neoplasms. Reports of such anomalies in the canine brain are scarce, and their classification is confusing. This case series of vascular hamartomas from the brains of five dogs was characterized using histochemistry and immunohistochemistry, in addition to gross and microscopic findings. All five hamartomas were located in the telencephalon, three in the pyriform lobe, without any predilection for the left or right side. Each hamartoma consisted of a proliferation of thin-walled vessels which varied in caliber. These vessels were elastin-negative, with varying amounts of collagen and no muscular component. In four of the five hamartomas, lining cells were actin- and factor VIII-positive. All five hamartomas contained glial fibrillary acid protein (GFAP)-positive parenchyma at moderate to high frequency, and four contained neurofilament-positive axons between component vessels. This report shows that vascular hamartomas in the canine brain are structural malformations for which immunohistochemistry is useful for accurate classification.     

Atrial septal defect in five dogs

The clinical, electrocardiographic, radiographic, and two-dimensional, M-mode and Doppler echocardiographic findings of five cases of canine ostium secundum type atrial septal defect (ASD) are described. The atrial septal anomaly was associated with other congenital cardiac abnormalities in two dogs: ventricular septal defect in one case and tricuspid dysplasia in the other. ASD was found in addition to dilated cardiomyopathy and suspected atrial thrombosis in one geriatric dog, but was the only cardiac abnormality detected in the remaining two dogs. Colour Doppler imaging facilitated the diagnosis of ASD in all subjects. The long-term prognosis for dogs with isolated and small-sized ASD is usually good, but can be compromised by the presence of concurrent congenital or acquired cardiac diseases.     

The T wave in the V10 precordial electrocardiographic lead is negative in healthy Chihuahua dogs

Objectives

The T wave polarity in the V10 precordial electrocardiographic (ECG) lead in Chihuahuas is described as positive in the veterinary literature. The aim of this study was to investigate the polarity of the T wave in the V10 precordial ECG lead in clinically healthy Chihuahuas. Our null hypothesis was that healthy Chihuahuas have a negative T wave in V10.

Animals, materials and methods

In this prospective study, 67 healthy breeder-owned Chihuahuas were used. A physical examination, 10-lead ECG and an echocardiogram were performed on each dog.

Results

No cardio-respiratory abnormalities were revealed in any of the otherwise healthy dogs. Three out of 67 ECGs were of insufficient quality because of baseline artifacts due to movement of the animal. Two other ECGs showed a nearly iso-electric T wave in the V10 lead. The remaining 62 ECGs showed negative T waves in the V10 lead. Right ventricular hypertrophy was excluded with echocardiography in all dogs.

Conclusion

In contrast to previous reports, we found that healthy Chihuahuas have negative T wave in the V10 precordial ECG lead.     

Nasca classification of hemivertebra in five dogs

: Five dogs, four small mixed breed and a Doberman Pinscher, presented in our clinic with hemivertebra. Complete physical, radiological and neurological examinations were done and the spinal deformities were characterized in accord with the Nasca classification used in human medicine. Two dogs had multiple hemivertebrae (round, oval or wedge-shaped: Type 3) in the thoracic region; one dog had an individual surplus half vertebral body (Type 1) plus a wedge-shaped hemivertebra (Type 2b) in the lumbar region; one dog had multiple hemivertebrae which were fused on one side (Type 4a) in the thoracic region; and one dog had a wedge-shaped hemivertebra (Type 2a) in the cervical region.     

Chronic idiopathic pulmonary fibrosis in five dogs

Five dogs presented with chronic and progressive pulmonary illness characterized by progressive dyspnea, exercise intolerance, and significant inspiratory crackles on auscultation. Radiographically, there was a widespread and diffuse interstitial lung pattern with varying degrees of bronchial involvement. Histopathological changes included thickened alveolar septa, interstitial fibrosis, and pneumocyte hyperplasia. Based on the clinical, radiographic, and histopathological changes, a diagnosis of idiopathic pulmonary fibrosis was made. Idiopathic pulmonary fibrosis is a chronic disease characterized by inflammation and fibrosis of the pulmonary interstitium and peripheral airspaces, which has been poorly characterized in the dog.