Proximal aortic dissection (dissecting aortic aneurysm) in a mature ostrich

The gross and histopathologic lesions observed in a case of spontaneous proximal aortic dissection (dissecting aortic aneurysm) in a mature ostrich are reported. At necropsy, a dissecting intramural hematoma was seen in the proximal aorta, extended about 12 cm distally from the aortic valves. Histopathologic changes in aortic dissection included fragmentation and disruption of elastic laminae, presence of cystic extracellular spaces, and pooling of ground substance in the tunica media. Hepatic copper levels were measured, and the low concentration found suggested that a copper deficiency together with other risk factors such as the elevation of blood pressure may have been implicated in the development of the aortic dissection seen in this ostrich.     

Annuloaortic ectasia in a four-month-old male Newfoundland dog: long-term follow-up and immunofluorescent study

A 4 month-old, 14.8 kg, male Newfoundland dog was presented for cardiovascular evaluation following detection of a heart murmur. Echocardiography revealed enlargement of the sinuses of Valsalva and marked, diffuse dilation of the ascending aorta (annuloaortic ectasia, AAE), with mild/equivocal subaortic stenosis (SAS). The dog was monitored over the duration of its lifetime, with serial echocardiograms performed at 5, 6, and 8 months and 1, 2, 3, 4, 8, and 10 years demonstrating persistent, diffuse dilation of the ascending aorta. The dog lived until it was 10 years old and died of metastatic carcinoma. Postmortem examination confirmed AAE and mild SAS. Hematoxylin and eosin and Weigert van Gieson stains were used to compare the ascending aorta to the descending aorta and left subclavian artery, and to compare aortic samples to those of three control dogs. Histopathologic evaluation revealed mild medial degeneration in the ascending aorta of all four dogs. Immunofluorescent microscopy was used for determining the deposition of proteins known to play a role in aortic aneurysms in humans: fibrillin-1 (FBN1), latent transforming growth factor beta binding protein 4 (LTBP4) and fibronectin. The ascending aorta of the AAE case demonstrated reduced deposition of FBN1, indicating that its loss may have contributed to aortic dilation. Diffuse, primary ascending aortic dilation is uncommonly reported in dogs; when it is, it carries a poor prognosis. This case provides an important example of marked dilation of the ascending aorta in a dog that lived with no associated adverse effects for 10 years.     

Aortopulmonary fistula in a Warmblood mare associated with an aortic aneurysm and supravalvular aortic stenosis

This case report describes the clinical presentation, the necropsy findings, and genetic results of a 13-year-old Warmblood mare presented with colic and a bilaterally loud, holosystolic murmur. Echocardiographic examination revealed the presence of a thoracic aortic aneurysm, an aortic pseudoaneurysm, a periaortic hematoma (circumferential cuffing by perivascular hemorrhage), and aortopulmonary fistulation. A supravalvular aortic stenosis (SVAS) was visible during echocardiography. Necropsy confirmed that the thoracic aortic aneurysm had ruptured and connected to the pseudoaneurysm, which fistulated into the pulmonary artery. Histologically, the aneurysm wall revealed chronic lesions such as fibrosis, mucin depositions, mineralizations, and elastin fragmentation. The mid abdominal aorta showed lesions suggestive of a systemic elastin arteriopathy. Molecular analysis, however, could not attribute this disease to a variant in the elastin gene, the most common causative gene for SVAS. To the authors' knowledge, this case report describes a case of aortopulmonary fistulation in a Warmblood horse associated with the presence of SVAS and an aortic aneurysm.     

Hematomas in the thymus in dogs

Twenty dogs with a hematoma of the thymus are described. In four dogs the cause of the hematoma was a ruptured dissecting aneurysm of the aorta and in three cases the dogs had been hit by cars. In seven dogs the necks were overstretched by different factors. One dog was hit by a stone. In two dogs no anamnestic data were available, and in the last three cases, according to owner's statements, no trauma had occurred before the first signs. Thymic hemorrhages in the dog should not be considered to be a circumscribed pathogenetic entity. Indications are offered that trauma, or even commonly occurring microtrauma, can be involved in the pathogenesis of the hematomas in the thymus.     

Vesicular cutaneous lupus erythematosus in a Border Collie in New Zealand

A 3-year-old Border Collie was initially presented for a small ulcerative lesion on the left axilla. The lesion failed to respond to conservative treatment with antibiotics, and the dog was re-presented one week later with ulcerative lesions involving the inguinal and axillary areas bilaterally. Histology of a biopsy of these lesions revealed a lymphocytic ulcerative interface dermatitis. Apoptosis and degeneration of basaloid cells was evident, with clefting along the dermo–epidermal junction. Vesicular cutaneous lupus erythematosus was diagnosed. The dog was treated with prednisone and azathioprine, resulting in complete remission of signs. However, recurrence occurred when drugs were tapered, necessitating ongoing treatment. Vesicular cutaneous lupus erythematosus has been described in North America in Rough-coated Collies and Shetland Sheepdogs. However, in Australasia, it is most commonly observed in Border Collies.     

Nemaline Rods in Canine Myopathies: 4 Case Reports and Literature Review

The diagnosis of nemaline rod myopathy (NM) is based on the presence of numerous pathognomonic rods within a fresh frozen muscle biopsy specimen. Three forms of congenital NM have been described in humans, and rods have been found to occur in various other conditions. A similar myopathy was described in 1986 in a family of cats. In this report, we describe a case of congenital NM in a 10-month-old Border Collie, an adult-onset NM in an 11-year-old Schipperke, and 2 acquired myopathies with nemaline rods in adult dogs associated with hypothyroidism and Cushing's syndrome. Common clinical features included exercise intolerance, abnormal electromyography, and the presence of nemaline rods in fresh, frozen, and glutaraldehyde-fixed biopsies from proximal appendicular limb muscles. Staining of cryostat sections of muscle biopsy specimens by the modified Gomori trichrome technique disclosed numerous rod bodies that were localized to type 1 fibers by the histochemical adenosine triphosphatase reaction. Accumulation of rods also was demonstrated by electron microscopy in 2 of the cases with localized enlargement and streaming of Z lines. Documentation of NM in a young Border Collie and the adult-onset form in the Schipperke alerts clinicians to the existence of this disorder in these breeds.     

Novel insertion mutation of ABCB1 gene in an ivermectin-sensitive Border Collie

P-glycoprotein (P-gp) is encoded by the ABCB1 gene and acts as an efflux pump for xenobiotics. In the Border Collie, a nonsense mutation caused by a 4-base pair deletion in the ABCB1 gene is associated with a premature stop to P-gp synthesis. In this study, we examined the full-length coding sequence of the ABCB1 gene in an ivermectin-sensitive Border Collie that lacked the aforementioned deletion mutation. The sequence was compared to the corresponding sequences of a wild-type Beagle and seven ivermectin-tolerant family members of the Border Collie. When compared to the wild-type Beagle sequence, that of the ivermectin-sensitive Border Collie was found to have one insertion mutation and eight single nucleotide polymorphisms (SNPs) in the coding sequence of the ABCB1 gene. While the eight SNPs were also found in the family members'' sequences, the insertion mutation was found only in the ivermectin-sensitive dog. These results suggest the possibility that the SNPs are species-specific features of the ABCB1 gene in Border Collies, and that the insertion mutation may be related to ivermectin intolerance.     

Trapped neutrophil syndrome in a Border Collie dog: clinical, clinico-pathologic, and molecular findings

Trapped neutrophil syndrome (TNS) is an autosomal recessive inherited neutropenia known in Border Collies since the 1990's. Recently, the causative mutation has been identified in the canine VPS13B gene and a DNA-based diagnosis has now become available. The present paper describes clinical and clinico-pathologic findings in a Border Collie with TNS that was molecularly diagnosed for the first time in Japan. In a 10-week-old male Border Collie with microgenesis and symptoms related to recurrent infections, a hematological examination revealed severe leukopenia due to neutropenia, suggesting the dog to be affected by inherited neutropenic immunodeficiency. Direct DNA sequencing demonstrated that the dog was homozygous for the causative mutation of TNS and both its parents were heterozygous carriers. In addition, a simple and rapid polymerase chain reaction-based length polymorphism analysis coupled with microchip electrophoresis was developed for the genotyping of TNS. This assay could discriminate clearly all genotypes, suggesting that it was suitable for both individual diagnosis and large-scale surveys for prevention.     

Radicular cyst of the premaxilla in a dog

A 13-year-old, male/neutered Border Collie dog was diagnosed with a radicular cyst of the left premaxilla. Tooth extraction and curettage of the lesion resulted in a positive clinical outcome 6-months following treatment.     

Familial aortic aneurysm in Leonberg dogs

A thoracic aortic aneurysm was diagnosed in a 6-month-old male Leonberg dog by use of radiography, transthoracic and transesophageal echocardiography, and magnetic resonance imaging. The aneurysm was associated with a twisted ascending aorta and dilatation of several other thoracic arteries (pulmonary trunk, brachiocephalic trunk, and left subclavian artery). Histologic examination of the aorta revealed cystic medial necrosis, with disruption of the elastic network, collagen fibers, and the muscle glycoprotein fibrillin-1. The dam and sire of the dog and 8 littermates were examined by use of transthoracic echocardiography. The sire and 1 male littermate also had an aneurysm of the ascending aorta. To the authors' knowledge, this is the first report of familial aortic aneurysm in dogs.     

Chronic intestinal pseudo-obstruction in a dog

SUMMARY A three-year-old neutered female Border Collie was presented with in-appetence, vomiting and diarrhoea. Abdominal radiographs revealed an obstructive pattern but no physical obstruction was evident at laparotomy. A diagnosis of chronic intestinal pseudo-obstruction was made based on histopathological changes in intestinal biopsies. Treatment was unsuccessful and the dog deteriorated progressively until euthanased five weeks after presentation.     

Aortic interruption in a dog.

A 3-month-old English Bulldog was found to have a discontinuity between the ascending and descending aorta. There were no signs of illness associated with the interruption. The descending aorta was supplied with blood by collateral circulation. An aortic graft of woven synthetic material was surgically implanted to connect the ascending and descending aorta. Without any restrictions on the dog's activity, the dog has lived for over 1 year and continues to do well.     

Idiopathic arterial medial calcification of the thoracic arteries in an adult horse

A 6-year-old, gelded, Paint horse displayed clinical signs of muscle wasting and limb stiffness for a 6-month period. The horse's clinical signs abated with corticosteroid therapy, but returned upon cessation of treatment. Upon necropsy, severe lesions of aortic thickening and aortic valve rigidity were observed. Histologically, the tunica media of the aorta, coronary arteries, and pulmonary arteries were expanded by foci of elastin fiber calcification and extracellular matrix with lacunae formation. The vascular lesions are comparative to what has been described as medial arterial calcification, seen in humans suffering from chronic renal failure or diabetes mellitus. No exposure to vitamin D-containing plants or feedstuff could be documented at the time of onset or during the period of clinical signs. The current case describes dramatic lesions of arterial medial calcification of the aorta, coronary, and pulmonary arteries of undetermined cause.     

Coma and respiratory failure due to moxidectin intoxication in a dog

Objective: To describe the clinical consequences following ingestion by a dog of a moxidectin‐containing equine deworming product. Few reports exist concerning the treatment and outcome of severe moxidectin toxicity. Treatment, known factors influencing intoxication, and prognosis are reviewed. Case summary: A 10‐month‐old female Border Collie ingested an unknown quantity of a moxidectin‐containing equine deworming product several hours before presentation. Severe neurological signs subsequently developed and included: ataxia, seizures, coma, and respiratory failure. The dog was treated with supportive care including intravenous fluids, activated charcoal, and positive pressure ventilation. Normal spontaneous respiration returned in 34 hours and the patient was discharged 58 hours after ingestion. Full recovery occurred within 1 week of intoxication. New information provided: This report describes moxidectin intoxication and associated respiratory failure in a dog that required mechanical ventilation. The dog's recovery was rapid. Despite severity of signs, the prognosis for patients with moxidectin intoxication is good with appropriate supportive care.     

Reactive histiocytosis of the orbit and posterior segment in a dog

We present a case of reactive histiocytic disease involving the orbit, optic nerve, retina, and choroid in a Border Collie dog initially presenting for vision loss. Long-term partial return of vision has been achieved with systemic immunosuppression. Anterior segment and ocular surface manifestations of reactive histiocytic disease in dogs are relatively common. Posterior segment and orbital involvement, however, are minimally documented in the existing literature. To the authors' knowledge, this is the first report of disease confined to the orbit and posterior segment as well as the first report of vision loss as a presenting complaint for reactive histiocytic disease. Clinical, magnetic resonance imaging, cytologic, and histopathologic findings are reviewed.     

AORTIC AND CARDIAC MINERALIZATION IN THE DOG

Aortic and cardiac mineralization was found in 21 of 3443 (0.61%) canine thoracic radiographs. In none of 786 feline thoracic radiographs reviewed were such lesions present. Mineralizations were superimposed on the ascending aorta (19 dogs) or on the caudal cardiac silhouette (2 dogs). In 2 of 4 dogs mineralization was identified echocardiographically dorsal to the aortic valve in close proximity to coronary arteries. Computed tomography confirmed mineralization of the aortic arch and root in 2 of 2 dogs. Necropsy and histopathologic examination in 1 dog revealed multiple nodular aortic tunica media calcifications with adjacent areas of degeneration. Lesions were significantly overrepresented in older dogs and in Rottweilers, and regarded as dystrophic calcification, caused either by age-related degenerative changes or chronic disease-related processes. There was no evidence of clinical significance attributed to the mineralization in any dog. Aortic and cardiac mineralization should be recognized as an incidental, non-significant finding in dogs of advanced age and differentiated from pleural and pulmonary structures.     

Use of a point-of-care urine drug test in a dog to assist in diagnosing barbiturate toxicosis secondary to ingestion of a euthanized carcass

Objective – To describe a case of barbiturate toxicosis in a dog secondary to ingestion of a previously buried euthanized goat carcass and to discuss the utility of urine drug testing in diagnosing barbiturate toxicosis.
Case Summary – A 6-year-old neutered male Border Collie was presented to a university veterinary teaching hospital for evaluation of ataxia and acute collapse. Past pertinent history included Addison's disease that had been managed for 1 year. A companion dog was seen 12 hours earlier chewing on the partially decomposed head of a goat that had been euthanized 47 days previously and buried on the owner's property. The dog was laterally recumbent, unresponsive to stimuli, and hypothermic on physical examination. Initial blood work revealed hyponatremia and hyperkalemia, with a Na/K ratio of 18.5. The dog was volume resuscitated and received an injection of dexamethasone sodium phosphate due to a suspected Addisonian crisis. Despite this treatment, the dog remained laterally recumbent and unresponsive to stimuli. A urine drug screen was performed and was positive for barbiturates. A diagnosis of barbiturate toxicosis secondary to ingestion of a euthanized goat carcass was made. The dog was treated supportively over 12 hours with IV fluids and activated charcoal. The dog was able to walk 11 hours after presentation and was subsequently discharged from the hospital.
New or Unique Information Provided – Urine drug testing is a fast, easy, and point-of-care test that may be useful in dogs to assist in the diagnosis of barbiturate intoxication. Proper disposal of euthanized animals is necessary to prevent toxicosis and possible death of companion animals and wildlife.     

Calcium phosphate urolithiasis and renal dysplasia in a young dog.

Calcium phosphate urolithiasis and bilateral renal dysplasia was diagnosed in an 8-week-old Border Terrier with a history of urine dribbling, which had been observed from the time of birth. Most reported cases of calcium phosphate urolithiasis are secondary to hypercalcemic disorders, but this was not detected. In addition, despite renal dysplasia, there was no evidence of renal failure. After cystotomy and calculus removal, the dog has remained clinically normal.     

Some segmental features on the structure of the aortic wall of the dog

Structural features of segmental parts of the aorta of the dog were studied by light microscopy (LM) and scanning electron microscopy (SEM). The variability in the wall architecture composition and vascular thickness of the ascending (T2-3 level), thoracic (T7-8 level) and abdominal (L6-7 infrarenal level) segments of the aorta was analysed. Morphological features such as presence of intimal folds, pattern of the medial myoconnective components with segmental variations in the number of elastic lamellae, whose relative number was higher in the thoracic aorta (ascending and descending parts), compared with the abdominal aorta, and a network of connective (stromal) elements formed by elastic and collagen lamellae and fibres in the adventitia were observed. The results were discussed on a histophysiological basis, because small but significant segmental differences had been characterized in the aortic wall structure of the dog.     

Beating heart mitral valve replacement with a bovine pericardial bioprosthesis for treatment of mitral valve dysplasia in a Bull Terrier

OBJECTIVES: To describe an open, beating heart surgical technique and use of a bovine pericardial prosthetic valve for mitral valve replacement (MVR) in the dog. STUDY DESIGN: Clinical case report. ANIMALS: Male Bull Terrier (17-month-old, 26 kg) with mitral valve dysplasia and severe regurgitation. METHODS: A bovine pericardial bioprosthesis was used to replace the mitral valve using an open beating heart surgical technique and cardiopulmonary bypass. RESULTS: Successful MVR was achieved using a beating heart technique. Mitral regurgitation resolved and cardiac performances improved (left ventricular end-diastolic diameter decreased from 57.6 to 48.7 mm, and left atrium/aorta ratio returned to almost normal, from 1.62 to 1.19). Cardiopulmonary by-pass time and total surgical duration were decreased compared with standard cardioplegic techniques. Surgical recovery was uneventful and on echocardiography 6 months later valve function was excellent. CONCLUSION: Considering the technique advantages (no cardiac arrest, ischemic reperfusion injury, and hypothermia, or the need for aortic dissection and cannulation for administration of cardioplegic solution), short-term mortality and morbidity may be reduced compared with standard cardioplegic techniques. CLINICAL RELEVANCE: Based on experience in this dog, beating heart mitral valvular replacement is a seemingly safe and viable option for the dog and bovine pericardial prosthesis may provide better long-term survival than mechanical prostheses.