Journal Articles

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    Longitudinal assessment of systolic anterior motion of the mitral valve in cats with hypertrophic cardiomyopathy.
    (Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine, 2024-09-26) Seo J; Novo Matos J; Munday JS; Hunt H; Connolly DJ; Luis Fuentes V
    BACKGROUND: The proportion of cats with hypertrophic cardiomyopathy (HCM) that lose systolic anterior motion of the mitral valve (SAM) in the long term is unknown. HYPOTHESIS/OBJECTIVES: Cats with HCM will lose SAM in the long term. Loss of SAM will be associated with greater age, longer scan-interval, and altered left ventricular (LV) dimensions. ANIMALS: Sixty unsedated cats with HCM, not receiving beta blockers or pimobendan. METHODS: A retrospective cohort study from 2 referral centers. Cats were eligible if they had been diagnosed with HCM and had a repeat echocardiogram ≥1 year later. Clinical and echocardiographic data of the left heart variables were collected. RESULTS: Thirty-eight cats had SAM at the initial scan. After a median follow-up time of 2.1 years (range: 1.0-5.9), 7 cats had lost SAM (18%) and 5 cats (23%) gained SAM. On follow-up, cats with SAM at the initial scan had a larger left atrium (P = .037), lower left atrial fractional shortening (P = .014), greater LV internal diameter in end-systole (P = .002), and lower LV fractional shortening (P < .001). Four cats with SAM developed congestive heart failure. There were no new cases of congestive heart failure or change in left heart variables in cats without SAM at the initial scan. The gain or loss of SAM was not associated with age or time between scans. CONCLUSIONS AND CLINICAL IMPORTANCE: Similar proportions of cats gained or lost SAM. Cats with SAM at baseline had more evidence of disease progression than cats without SAM.
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    Prevalence of cardiomyopathy and cardiac mortality in a colony of non-purebred cats in New Zealand.
    (Taylor and Francis Group, 2024-09-29) Seo J; Owen R; Hunt H; Luis Fuentes V; Connolly DJ; Munday JS
    Aims To evaluate the prevalence of subclinical cardiomyopathy and cardiac mortality in a research colony of non-purebred cats, established as a model of the wider cat population in New Zealand. Methods All apparently healthy, compliant, non-pregnant, non-neonatal cats in the colony at the Centre for Feline Nutrition (Massey University, Palmerston North, NZ) underwent physical examination and echocardiography using a 4.4–6.2-MHz probe by a board-certified veterinary cardiologist. Cardiac phenotype was classified following current guidelines. Hypertrophic cardiomyopathy (HCM) phenotype was defined as an end-diastolic left ventricular wall thickness ≥ 6 mm. Colony mortality data from February 2012 to February 2022 was reviewed to determine cardiac mortality. Results Cats (n = 132; 65 females and 67 males) included in the study had a median age of 4.1 (IQR 3.0–8.0) years. Thirty-two (24%) cats had a heart murmur, and three (2%) cats had an arrhythmia. Echocardiography revealed heart disease in 24 (18.2%) cats, including 23 with an HCM phenotype and one with a restrictive cardiomyopathy phenotype. Of the cats with the HCM phenotype, 3/23 had systemic hypertension or hyperthyroidism or both, and these cats were excluded from the final diagnosis of HCM (20/132; 15.2 (95% CI = 9.5–22.4)%). Between 2012 and 2022, 168 colony cats died, with 132 undergoing post-mortem examination. Heart disease was considered the cause of death in 7/132 (5.3%; 95% CI = 2.2–10.6%) cats; five had HCM, one a congenital heart defect, and one myocarditis. The overall prevalence of death related to HCM in the colony during this period was 3.8% (95% CI = 1.2–8.6%). Three cats with HCM and the cat with a congenital heart defect died unexpectedly without prior clinical signs, while congestive heart failure was observed prior to death in two cats with HCM and the cat with myocarditis. Additionally, 30/132 (22.7%) cats had cardiac abnormalities but died for non-cardiac reasons. Conclusions Subclinical cardiomyopathy, specifically HCM, was common in cats in the colony. Given that the colony originated as a convenience selection of non-purebred cats in New Zealand, the true prevalence of HCM in the wider New Zealand population is likely to fall within the 95% CI (9.5–22%). The proportion of deaths of colony cats due to HCM was lower (3.8%) supporting the conclusion that subclinical cardiomyopathy may not progress to clinical disease causing death. Clinical relevance Veterinarians should be aware of the high prevalence of subclinical HCM when treating cats. Abbreviations CAM: Systolic anterior motion of the chordae tendineae; CFN: Centre for Feline Nutrition; HCM: Hypertrophic cardiomyopathy; LA/Ao: Left atrial to aortic ratio; LV FS: Left ventricular fractional shortening; LVIDd: Left ventricular internal diameters in end-diastole; LVIDs: Left ventricular internal diameter in end-systole; LVWT: Max Maximum left ventricular wall thickness; SAM: Systolic anterior motion of the mitral valve; 2D: Two-dimensional
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    Prevalence of Hypertrophic Cardiomyopathy and ALMS1 Variant in Sphynx Cats in New Zealand
    (MDPI (Basel, Switzerland), 2024-09-10) Seo J; Loh Y; Connolly DJ; Luis Fuentes V; Dutton E; Hunt H; Munday JS; Montoya-Alonso JA
    Recently, hypertrophic cardiomyopathy (HCM) in Sphynx cats has been associated with a variant in the gene encoding Alström syndrome protein 1 (ALMS1). The primary aims of this study were to describe the prevalence of HCM in Sphynx cats in New Zealand, and to assess the association between HCM and the ALMS1 variant in this population. In this prospective study, 55 apparently healthy Sphynx cats from registered Sphynx breeders and pet owners in New Zealand were screened by a cardiologist. A total of 42 of these cats had a repeat cardiac examination after median 1.8 years (range: 1.6-2.2). The frequency of the ALMS1 variant was 70.9% (11 homozygous and 28 heterozygous). At the median age of 5.8 years (range: 2.4-13.1), the prevalence of HCM was 40% (20 out of 55 cats). Three cats with HCM died during the study with congestive heart failure. All three cats had focal but extensive myocardial ischemia or infarction at necropsy. The ALMS1 variant was not associated with the HCM diagnosis. In summary, HCM was common in the studied cohort, suggesting Sphynx cats are predisposed to this disease. While the ALMS1 variant was also frequently detected, it was not associated with HCM in this population.
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    Rapid Patient-Side Evaluation of Endothelial Glycocalyx Thickness in Healthy Sedated Cats Using GlycoCheck® Software.
    (2021) Yozova ID; Londoño LA; Millar KK; Sano H; Weidgraaf K; Thomson NA; Munday JS
    The endothelial glycocalyx (EG) determines transvascular fluid fluxes, and influences inflammation, coagulation, and capillary blood flow. The GlycoCheck® software calculates EG thickness using sidestream dark field videomicroscopy recordings. This method has not been evaluated for use in cats. The aim of the present study was to evaluate the use of GlycoCheck® for estimating EG thickness in healthy cats, and to investigate the variability of EG thickness in this population. One hundred and one healthy research-purposed cats were included in the study. The cats were sedated, and a handheld videomicroscope, connected to GlycoCheck® software, was used to evaluate the sublingual microvasculature. The parameters measured included perfused boundary region (PBR, an indirect measurement of EG thickness) in vessels between 5 and 25 μm in diameter, valid vessel density, percentage red blood cell filling, and median red blood cell column width. Heart rate, respiratory rate, pulse oximetry and oscillometric blood pressure readings were also recorded. There were 35 neutered male cats, 11 intact males, 38 neutered females, and 17 intact females. The average age was 63 months (range, 11-160 months). Tolerance intervals for PBR (vessel diameter 5-25 μm) were 1.89-3.00 μm (95% CI, lower limit 1.76-2.04, upper limit 2.83-3.13 μm); for valid vessel density were 73.33-333.33 μm/mm2 (95% CI, lower limit 77.00-99.33, upper limit 312.67-350.33 μm/mm2); for percentage red blood cell filling were 59.85-85.07% (95% CI, lower limit 58.97-63.33, upper limit 83.07-88.20 %); and for median red blood cell column width were 5.63-8.59 μm (95% CI, lower limit 5.28-6.07, upper limit 8.14-9.51 μm). There was a negative association between median red blood cell column width and body weight (p = 0.007). The median red blood cell column was significantly wider in intact females when compared to spayed females (p = 0.033). The GlycoCheck® analysis was easily performed in healthy sedated cats. Clinical variables did not have an effect on the EG thickness. These results suggest that this technique could be valuable for evaluation of the EG and microvascular parameters in cats.