A pedigree-based genetic appraisal of Boxer ARVC and the role of the Striatin mutation.

The objective of this paper was to investigate by pedigree-based genetic means the origins and inheritance of arrhythmogenic right ventricular cardiomyopathy (ARVC) in UK Boxers and assess the role of the proposed causal mutation in the gene, Striatin (STRN). All ARVC cases traced back to a small number of imported American dogs deriving from the group of Boxers studied by Harpster (1983) to define the disease, strongly suggesting that the disease is the same in the two countries. Dogs with and without the STRN mutation were found in both ARVC affected and normal Boxers showing that the mutation is not responsible for the disease. Evidence was found that the STRN mutation is, however, genetically linked with the gene responsible on the same chromosome. The linkage implies that the two genes can separate by meiotic recombination such that both ARVC-affected and ARVC-unaffected lines of dogs may carry either the STRN mutation or its wild-type allele. These have been found. Homozygotes for the STRN mutation tended to be severely affected at early ages, suggesting that there is an interaction between the known effects of the STRN mutation on the cardiomyocyte and ARVC.

Comparison of the effects of thiopentone and propofol on the electrocardiogram of dogs.

Sixty-four dogs were randomly assigned to receive either thiopentone or propofol and their electrocardiograms were recorded immediately before and shortly after they were anaesthetised. Thiopentone caused a marked increase in QT and JT intervals, a flattening of the T-wave and an increase in precordial QT dispersion. Propofol induced a less marked increase in QT and JT intervals, corrected for heart rate. Both agents induced an increase in heart rate and a decrease in heart rate variability, consistent with reduced vagal tone. Shortly after anaesthesia was induced, thiopentone affected ventricular repolarisation to a far greater extent than propofol, changes which suggest that it may be more likely to induce re-entrant ventricular arrhythmogenesis and could be associated with an increase in sympathetic tone. Propofol may therefore be more suitable than thiopentone for dogs with a susceptibility to ventricular arrhythmias or a long QT interval.

Thoracic high-resolution computed tomographic findings in dogs with canine idiopathic pulmonary fibrosis.

OBJECTIVES: To identify features of canine idiopathic pulmonary fibrosis (CIPF) using high-resolution computed tomography (HRCT), and to correlate these features with clinical stages of the disease. METHODS: Ten dogs with signalment, history and clinical signs highly suggestive of CIPF were investigated. Thoracic radiography, haematology and biochemistry profiles, bronchoscopy and bronchoalveolar lavage and HRCT were performed in each case. The dogs were classified as having mild, moderate or severe stages of the disease based on their clinical presentation and radiographic signs. Features identified by HRCT were correlated with these disease stages. RESULTS: HRCT showed a spectrum of pulmonary changes and it was possible to match some of these to the stage of CIPF. CLINICAL SIGNIFICANCE: HRCT is used extensively in humans in the diagnosis and treatment planning of idiopathic pulmonary fibrosis. This preliminary study identifies the high-resolution computed tomographic features of CIPF in a small group of dogs. With further work it may be possible to use HRCT as a non-invasive tool for diagnosing, staging and therapeutically monitoring CIPF.

Feline idiopathic cardiomyopathy: a retrospective study of 106 cats (1994-2001).

The case records of 106 cats with idiopathic cardiomyopathy that presented to the Feline Centre of the University of Bristol between September 1994 and September 2001 were reviewed retrospectively. Hypertrophic cardiomyopathy (HCM) was the most common form seen (57.5%), followed by restrictive cardiomyopathy (RCM) (20.7%), dilated cardiomyopathy (DCM) (10.4%) and unclassified cardiomyopathy (UCM) (10.4%). One cat showed echocardiographic changes compatible with a moderator band cardiomyopathy (MBCM). Most affected cats were domestic short hairs (DSH) (57.5%). The mean (+/-SD, range) age of cats with cardiomyopathy at presentation was 6.8 (4.3, 0.5-16) years, with an equal distribution of males and females. Clinical findings, electrocardiographic changes and radiographic abnormalities were also reviewed. The median survival time for 73 cats for which follow-up data was available was 300 days. A greater survival time was observed for cats with UCM (925 days) when compared with those with HCM (492 days), RCM (132 days) or DCM (11 days).

Aortic body chemodectoma causing pulmonary oedema in a cat.

A seven-year-old male domestic shorthaired cat was presented with persistent dyspnoea. Thoracic radiography and echocardiography revealed pulmonary oedema and a mass at the base of the heart. At necropsy the mass was found to be an aortic body chemodectoma that had metastasised to the sternal lymph node. This is a rare tumour in the cat, the third reported case where there was evidence of metastasis, and only the second reported case where there was evidence of lymphocytic infiltration of the primary tumour. Pulmonary oedema is an unusual presentation of this tumour in the cat.

Alterations in the organisation, ultrastructure and biochemistry of the myocardial collagen matrix in doberman pinschers with dilated cardiomyopathy.

Remodelling of the collagen matrix of the myocardium has been implicated in the pathogenesis of dilated cardiomyopathy, a major cause of heart failure in Doberman pinschers. The aim of this study was to characterise the myocardial collagen matrix of Dobermans. In clinically normal Dobermans there was evidence of focal fibrosis. Collagen cross-links were altered in both diseased and clinically normal Doberman myocardium as compared with myocardium from control dogs. Extensive remodelling, in the form of a loss of collagen tethers, increased collagen synthesis and alterations in the collagen cross-links, occurs in diseased Doberman myocardium. Changes in the collagenous matrix are also present in apparently normal Dobermans. These changes are likely to be involved in the progression of the disease and may explain the predisposition of this breed to dilated cardiomyopathy.

Everted laryngeal saccules: ultrasonographic findings in a young Lakeland terrier.

The ultrasonographic appearance of laryngeal eversion due to bilateral laryngeal paralysis is described in a young Lakeland terrier.

Tachyarrhythmia in a St Bernard dog.

SUMMARY: A young St Bernard dog was referred on three separate occasions for investigation of dyspnea and exercise intolerance. Electrocardiography was performed on each occasion and showed various forms of supraventricular tachycardia with aberrant conduction. Echocardiography showed a progressive decrease in systolic function and thoracic radiographs showed progressive cardiomegaly. The arrhythmia responded rapidly to treatment with propanolol.

Increased expression of promatrix metalloproteinase-9 and neutrophil elastase in canine dilated cardiomyopathy.

OBJECTIVE: Canine dilated cardiomyopathy, commonly affecting Doberman pinschers, results in extracellular matrix remodelling within the myocardium. The aim of this study was to examine the proteolytic activity in myocardium from Doberman pinschers with dilated cardiomyopathy. METHODS: Samples of myocardium, obtained rapidly post mortem from the left ventricular free wall of Dobermans with dilated cardiomyopathy, clinically normal Dobermans and control dogs (non-Dobermans), were examined for proteolytic activity using substrate gel zymography. Gels were analysed by scanning densitometry. RESULTS: Promatrix metalloproteinase-9 activity was significantly increased in all Doberman myocardium when compared to controls. A significant increase in an enzyme, identified to be neutrophil elastase by inhibition of its activity by Elastatinal and Western blotting, was also detected in all Dobermans when compared to controls. CONCLUSIONS: The results indicate that promatrix metalloproteinase-9 and neutrophil elastase, both of which are implicated in inflammatory responses, are present in significantly elevated levels in Doberman dilated cardiomyopathy and are raised in clinically normal Dobermans. Both proteolytic enzymes degrade a wide variety of connective tissue components and thus the increased levels found may play an important role in the structural remodelling seen in the myocardium and subsequent heart failure. Increased proteolytic enzyme levels in clinically normal Dobermans may be indicative of the predisposition of the breed to dilated cardiomyopathy.

Echocardiographic measurements of cardiac dimensions and indices of cardiac function in normal adult thoroughbred horses.

Cardiac dimensions and indices of cardiac function were measured in 29 clinically normal adult Thoroughbreds (TB) which performed minimal exercise using guided M-mode and two-dimensional (2-D) echocardiography, from a variety of image planes and measurement methods, and standardised imaging planes based on intracardiac anatomical landmarks. The different methods of measuring these variables were compared. The variables which were considered to be most valuable for quantitative echocardiography were measured in a further 9 horses. Comparable measurements of cardiac dimensions can be obtained from a variety of different imaging planes, using either 2-D or guided M-mode echocardiography from the left or right side of the chest, although differences in measurement methods must be taken into account. The results of this study give a useful range of dimensions and indices of cardiac function in normal adult TBs for comparison with those recorded from horses with suspected cardiac disease. Comparisons are only valid if there is meticulous attention to correct orientation of imaging planes with regard to internal landmarks and that comparable measurement locations and timing are used.

Effects of sedation with detomidine hydrochloride on echocardiographic measurements of cardiac dimensions and indices of cardiac function in horses.

Twenty-six horses were sedated with detomidine hydrochloride (Domosedan, SmithKline Beecham Animal Health, Tadworth, Surrey, UK) at a dose of 10 micrograms/kg bwt, administered i.v. Echocardiograms were recorded before and after sedation, measurements of cardiac dimensions were made and functional indices were calculated. The pre- and post sedation values were compared. No significant change was detected following sedation in the ejection time (ET), left ventricular dimension, left atrial diameter at the sinotubular junction at end-systole or end-diastole or at the sinus of Valsalva at end-diastole. Sedation was found to result in a statistically significant increase in end-systolic left ventricular diameter and internal area and aortic diameter measured at the sinus of Valsalva. Left ventricular free-wall thickness and interventricular septal thickness at end-systole, fractional shortening, fractional area change and heart rate were significantly reduced following sedation. A significant increase in pre-ejection period (PEP), duration of electromechanical systole (EMS) and PEP/ET (ejection time) was detected.

Assessment of dose and time responses to TRH and thyrotropin in healthy dogs.

Changes in total thyroxine (T4 [TT4]), free T4 (FT4) and total tri-iodothyronine (T3 [TT3]) in serum after the intravenous administration of different doses of thyrotropin (TSH) and thyrotropin-releasing hormone (TRH) were measured in six healthy beagles. Significant (P < 0.05) elevations in serum TT4, FT4 and TT3 were observed at each sampling time (two, four, five, six, seven, eight and 10 hours) after administration of 1, 3 or 5 iu (total dose) TSH and peak mean responses were observed six to eight hours after injection. At six hours after injection the mean TT4, FT4 and TT3 levels were approximately 2.6, 3.9, and 1.5 times basal levels, respectively, and there were no significant differences between the three doses of TSH, Significant (P < 0.05) elevations in serum TT4 and FT4 but not TT3 were observed at each sampling time (two, four, five, six, seven and eight hours) after the administration of TRH. Peak mean responses were observed at four hours after injection at which time TT4 and FT4 levels were approximately 1.7 and 1.9 times basal levels, respectively. No significant differences were observed between the four doses of TRH used (100, 200, 300, and 600 micrograms total dose). Concentrations of TT4, FT4 and TT3 were significantly (P < 0.05) higher following the administration of TSH compared with TRH, and the response to TRH showed greater individual variation.

Hamartomatous polyps in the intestine of two dogs.

Partly obstructing, proliferative mucosal masses in the small intestine of two dogs were shown histologically to be hamartomatous polyps. They were characterized by an extension of smooth muscle from the muscularis mucosae into the lamina propria of the lesion. This is the first report of such lesions in domestic animals. In one of the dogs the lesion had become malignant.

Angiostrongylus vasorum infection in seven dogs.

Angiostrongylus vasorum infection was diagnosed in six dogs by the identification of larvae in sputum or faeces, or by the identification of adult worms post mortem. In another dog strong evidence of the condition was obtained but no parasites were identified. In four cases the main clinical signs were coughing and dyspnoea, but one dog had exercise intolerance and no history of coughing. One dog in which larvae were found in the faeces had no clinical signs that were related to the infection. Another dog had flaccid hindlimb paralysis and forelimb hypermetria-clinical signs of the disease which have not been reported previously. Four of the cases came from south Wales, one of them being the first case of the infection to be reported from this area.

Atrial septal defect and atrial fibrillation in a foal.

Clinical examination of a four-and-a-half-month old foal revealed evidence of progressive heart failure associated with an atrial septal defect and atrial fibrillation. Atrial septal defects are rarely reported in foals and the foal's growth, development and demeanour were normal until a sudden onset of lethargic behaviour. The value of B-mode echocardiography in identifying the congenital lesion is indicated.