A 5-year-old 30-kg (66-lb) spayed female Labrador Retriever was referred to the emergency service at a veterinary teaching hospital because of a 2-week history of progressive lethargy and hyporexia. On initial evaluation, the dog was quiet but responsive, with a rectal temperature of 40°C (104°F) and a respiratory rate of 45 breaths/min. The mucous membranes were pale pink, and the dog's capillary refill time was 2 seconds. Muffled heart sounds were ausculted bilaterally, and there was bilateral jugular venous distension. There was no pertinent previous medical history, and the dog was not currently receiving any medications.
A 6-year-old 4.2-kg (9.2-lb) castrated male Yorkshire Terrier mix was evaluated because of a suspected anaphylactic reaction secondary to a bee sting on the right pelvic limb. Shortly after being stung, the dog vomited and became tachypneic, which prompted the dog's owner to seek veterinary medical attention. The dog was not receiving any medication at the time of the evaluation, and no previous medical problems were reported. At the evaluation, the dog appeared anxious and aggressive. Physical examination findings were unremarkable except for an irregular heart rhythm and a heart rate of 66 beats/min. A single lead II ECG was
A 14-year-old castrated male domestic medium-hair cat was evaluated by the cardiology service of a veterinary teaching hospital because of episodes of collapse. The collapse episodes became evident to the owner 1 week prior to the evaluation and were reported to occur multiple times each day. The collapse episodes were variable in intensity from hind limb weakness to complete loss of consciousness and postural tone.
On physical examination, the cat was bright, alert, and responsive. It weighed 3.7 kg (8.14 lb) and had a body condition score of 2.5 (on a scale of 1 to 5). Rectal temperature was 38.1°C
A 7-year-old 5.78-kg (12.7-lb) spayed female domestic shorthair cat was evaluated by the Emergency Service at a veterinary teaching hospital because of sudden onset vomiting of 1 day's duration. Two weeks previously, the cat had developed a subcutaneous swelling between the shoulder blades at the site of vaccine administration. Meloxicam (0.1 mg/kg [0.045 mg/lb], PO, q 24 h) was prescribed at that time, and the owner had been administering the drug for 1.5 weeks. The owner reported that the cat had no previous health problems.
On initial physical examination, the cat was bright, alert, and responsive. Rectal temperature was 36.2°C
Objective—To sequence the exonic and splice site regions of the 4 desmosomal genes associated with the human form of familial arrhythmogenic right ventricular cardiomyopathy (ARVC) in Boxers with ARVC and identify a causative mutation.
Animals—10 unrelated Boxers with ARVC and 2 unaffected Labrador Retrievers (control dogs).
Procedures—Exonic and splice site regions of the 4 genes encoding the desmosomal proteins plakophilin-2, plakoglobin, desmoplakin, and desmoglein-2 were sequenced. Sequences were compared for nucleotide sequence changes between affected dogs and the published sequences for clinically normal dogs and between affected dogs and the control dogs. Base-pair changes were considered to be causative for ARVC if they were detected in an affected dog but not in unaffected dogs, and if they involved a conserved amino acid and changed that amino acid to one of a different polarity, acid-base status, or structure.
Results—A causative mutation for ARVC in Boxers was not identified, although single nucleotide polymorphisms were detected in some affected dogs within exon 3 of the plakophilin-2 gene; exon 3 of the plakoglobin gene; exons 3 and 7 of the desmoglein-2 gene; and exons 6, 14, 15, and 24 of the desmoplakin gene. None of these changed the amino acid of the respective protein.
Conclusions and Clinical Relevance—Mutations within the desmosomal genes associated with the development of ARVC in humans do not appear to be causative for ARVC in Boxers. Genomewide scanning for genetic loci of interest in dogs should be pursued.
Objective—To identify Doppler echocardiographic (DE) variables that correlate with left ventricular filling pressure (LVFP).
Animals—7 healthy dogs (1 to 3 years old).
Procedures—Dogs were anesthetized and instrumented to measure left atrial pressure (LAP), left ventricular pressures, and cardiac output. Nine DE variables of LVFP derived from diastolic time intervals, transmitral and pulmonary venous flow, and tissue Doppler images were measured over a range of hemodynamic states induced by volume loading and right atrial pacing. Associations between simultaneous invasive measures of LVFP and DE measures of LVFP were determined by use of regression analysis. Receiver operating characteristic analysis was used to predict increases in mean LAP on the basis of DE variables.
Results—Mean LAP was correlated with several DE variables: the ratio between peak velocity during early diastolic transmitral flow and left ventricular isovolumic relaxation time (peak E:IVRT) during sinus rhythm and during right atrial pacing, IVRT, the ratio between late diastolic transmitral flow velocity and pulmonary venous flow duration, and the interval between onset of early diastolic mitral annulus motion and onset of early diastolic transmitral flow. Cutoff values of 2.20 and 2.17, for peak E:IVRT in dogs with sinus rhythm and atrial pacing predicted increases in mean LAP (≥ 15 mm Hg) with sensitivities of 90% and 100% and specificities of 92% and 100%, respectively.
Conclusions and Clinical Relevance—Doppler echocardiography can be used to predict an increase in LVFP in healthy anesthetized dogs subjected to volume loading.
Objective—To determine the prevalence of ventricular arrhythmias in clinically normal adult Boxers.
Design—Prospective cross-sectional study.
Animals—301 Boxers (181 females and 120 males) > 1 year old with echocardiographically normal systolic function and no history of syncope or congestive heart failure.
Procedures—Physical examination, which included echocardiography, was performed on all dogs. A 24-hour ambulatory ECG was performed on each dog, and results were evaluated to assess ventricular arrhythmias. Statistical evaluation was performed to determine correlations between the total number of ventricular premature complexes (VPCs)/24 h, grade of ventricular arrhythmia, and age of the dogs.
Results—Age of dogs ranged from 1 to 16 years (median, 4 years). Number of VPCs/24 h in each dog ranged from 0 to 62,622 (median, 6 VPCs/24 h). Grade of arrhythmias ranged from 0 to 3 (median, 1). Age was correlated significantly with number of VPCs/24 h (r = 0.43) and with grade of arrhythmia (r = 0.37). Number of VPCs/24 h was significantly correlated with grade of arrhythmia (r = 0.82).
Conclusions and Clinical Relevance—Clinically normal adult Boxers generally had < 91 VPCs/24 h and an arrhythmia grade < 2. Boxers with > 91 VPCs/24 h were uncommon and may have represented dogs with arrhythmogenic right ventricular cardiomyopathy or other disease processes that could have resulted in the development of ventricular arrhythmias.
Diet-associated DCM first came to light in cats in the late 1980s1 and in dogs in the mid-1990s.2 The association between diet and DCM in dogs has generally not been much in the news since the early 2000s, but over the past few years, an increasing number of DCM cases involving dogs appear to have been related to diet. The extent of this issue is not clear, not all cases have been confirmed to be linked to diet, and a true association has not been proven to exist. However, when one of the authors (RF) recently
A14-year-old 7.3-kg (16.1-lb) spayed female West Highland White Terrier was evaluated at a veterinary medical teaching hospital for possible pacemaker implantation to treat suspected sick sinus syndrome (SSS). Three days earlier, the dog had multiple collapse episodes; periods of sinus arrest were detected during an ECG examination. At that time, results of a CBC and serum biochemical analysis were within reference intervals. Transthoracic echocardiography revealed mild myxomatous mitral and tricuspid valve degeneration without cardiac chamber enlargement (American College of Veterinary Internal Medicine classification1 stage B1) as well as mild pulmonary hypertension. The dog's history included chronic cough (presumed
To evaluate the frequency of variants in the pyruvate kinase dehydrogenase 4 (PDK4) and titin (TTN) genes in a group of Doberman Pinschers with dilated cardiomyopathy (DCM) and to determine whether there were unique clinical attributes to each variant.
48 Doberman Pinschers with DCM.
Doberman Pinschers with recently diagnosed DCM were identified, and genomic DNA from each was genotyped with a PCR assay for detection of PDK4 and TTN genetic variants. Dogs were grouped on the basis of whether they had the TTN variant alone, PDK4 variant alone, both variants, or neither variant. Descriptive statistics were compiled for dog age, body weight, and left ventricular dimensions and fractional shortening and for the presence of ventricular and supraventricular arrhythmias and heart failure. Results were compared across groups.
Of the 48 dogs, 28 had the TTN variant alone, 10 had both variants, 6 had neither variant, and 4 had the PDK4 variant alone. The mean age was younger for dogs with the PDK4 variant alone, compared with other dogs. However, the number of dogs with the PDK4 variant alone was very small, and there was an overlap in age across groups. No other meaningful differences were detected across groups, and independent genotype-phenotype relationships were not identified.
CONCLUSIONS AND CLINICAL RELEVANCE
Although findings indicated that the TTN variant was most common, 6 dogs had neither variant, and this fact supported the concept of ≥ 1 other genetic contributor to DCM in Doberman Pinschers. Future studies are warranted to evaluate genotype-phenotype relationships in Doberman Pinschers with DCM.