Short-term Heart Rate Variability Analysis in Healthy Dogs of Different Ages

Background: The modulation of heart rate by autonomic nervous system may be evaluated by the heart rate variability (HRV), which illustrates the fluctuations between RR intervals. To evaluate this analysis, the intervals between 2 QRS complexes are measured. In general, high HRV values are expected in healthy individuals; otherwise, low values are indicative of organism dysfunction. Studies conducted in healthy humans show that HRV suffers reduction with ageing and that there is autonomic immaturity in neonates. The aim of this study was to describe the characteristic pattern of cardiac autonomic behavior in healthy dogs in different age groups through short-term HRV analysis.Materials, Methods & Results: A total of 87 healthy dogs were studied. HRV was analyzed in time and frequency domain, using Holter and heart rate monitor. It was observed that puppies (below one year old) presented a lower parasympathetic predominance and, consequently, lower HRV values on time domain (SDNN, PNN50% e RMSSD) compared to the other 2 groups and on frequency domain (LF, HF and LF/HF) compared to the adult animals group (between 1 and 7-year-old), which presented higher HRV values when compared to the other groups. Elderly dogs (over 8-year-old) exhibited a natural tendency to decrease cardiac parasympathetic HRV indexes.Discussion: The use of the HRV method as a prognostic index and as an arrhythmogenic marker for various canine heart diseases presents interesting perspectives. However, before it may be employed for these purposes, a better understanding should be established regarding the physiological behavior of autonomic cardiac modulation in different age groups to serve as a basis for future analyses. This study observed that puppies presented higher values for HR and, therefore, shorter RR intervals than the other groups (adult and elderly dogs), what was observed on Holter and heart rate monitor methods (HRM). There were significant differences between puppies and the other 2 groups (adults and elderly) for all time-domain variables using both methods (Holter and HRM methods). SDNN was significantly lower in puppies compared to adults and elderly dogs. In addition, both RMSSD and PNN50%, which were more reliable over shorter periods of time, also presented means and medians that were significantly lower in puppies. Regarding frequency-domain HRV parameters observed on Holter method, these indexes were decreased on the elderly group compared to adult dogs, which is a possible effect of aging. Also, puppies revealed lower frequency-domain HRV parameters on both methods when compared to adult dogs. The influence of age on HRV is possibly related to the stage of development of an individual, starting at conception up to the maturity in relation to the mechanisms that cause variations in HR. There are studies in humans that suggest a gradual increase in parasympathetic activity during childhood, followed by a steady decrease as aging occur. The present study observed the same pattern in dogs. The balance between sympathetic and parasympathetic systems is influenced by age in dogs, which alters HRV values in the short-term. The HRV method´s analysis is relatively simple and non-invasive for assessing cardiac autonomic function; also, it is widely used in human medicine as a risk measure for sudden cardiac death. The 24-hour HRV analysis is highly challenging, as it is time-consuming, expensive, delays diagnosis, and has a large number of artifacts; in this way, standards for its short-term analysis were developed. Keywords: cardiology, autonomic nervous system, heart rate monitor, Holter

Main risk factors of dogs with congestive heart failure diagnosed by doppler echocardiographic parameters

Nowadays, congestive heart failure is one of the major complications of heart disease in small animals, which is characterized by a clinical condition in which the heart is unable to eject the blood efficiently. At long term, some compensatory mechanisms it will eventually become detrimental and, mainly, due to the congestion caused by it. In dogs, the main cause of CHF is chronic mitral valve degeneration, it is responsible for the degeneration of collagen present in the mitral valve structure that will have detrimental consequences on the entire circulatory system. The aim of the present study was to perform a retrospective study of 498 echocardiographic reports collected at a veterinary cardiology service of the Bauru region, from January 2017 to June 2019. Two groups were formed according to the Doppler echocardiographic alterations found, one that included animals with characteristics of congestive heart failure (CHF), and the other formed by non-CHF patients. Of the total number of animals evaluated, 61 were classified as affected by congestive heart failure and after classification, it was considered the main epidemiological factors (race, sex and age) of animals belonging to this group. Small breed animals were overrepresented and also elderly animals, with no apparent sexual predisposition. In addition, animals with CHF presented higher values when compared to animals without CHF of LA/Ao ratio (2.31 ± 0.30 vs. 1.46 ± 0.35), E/IRTV ratio (2.96 ± 0.39 vs. 1.16 ± 0.43) and E-wave velocity (1.45 m/s ± 0.18 vs. 0.75 m/s ± 0.22) on echocardiographic examination

Hipotireoidismo em cães: revisão

Hypothyroidism is one of the most frequent endocrinopathies in dogs, affecting preferentially middle-aged, pure breed animals. Associated clinical signs are variable and often non-specific, including metabolic, dermatological or cardiovascular alterations. The main laboratorial findings are non-regenerative anemia and hypercholesterolemia. Hyponatremia and an increase in alanine transferase and alkaline phosphatase activities can also be observed with lower frequency. There are specific diagnostic tests that can be used to help diagnose hypothyroidism, and those should be interpreted in the light of the animal´s clinical symptoms. The levels of thyroxine stimulating hormone (TSH) and both free and total thyroxine (T4) are the most used hormonal tests. It is important to differentiate between hypothyroidism and the euthyroid sick syndrome, a condition that may be caused by severe diseases such as hyperadrenocorticism and lead to decreased TSH and T4 levels as well. Levothyroxine sodium is the standard treatment. The main objective of this paper is to review hypothyroidism in dogs, since this is a very common disease in small animal clinics, but with difficult diagnosis.El hipotiroidismo es la enfermedad endocrina más común en los perros, que afecta principalmente a animales de raza y de mediana edad. Los signos clínicos son muy variados e inespecíficos, incluyendo sintomas metabólicos, dermatológicos y cardiovasculares. Los hallazgos de laboratorio más comunes son la anemia arregenerativa y la hipercolesterolemia. La hiponatremia, aumento de la actividad de la fosfatasa alcalina y alanina aminotransferasa, también se observaron con menor frecuencia. Hay pruebas específicas utilizadas en el diagnóstico del hipotiroidismo, que deben ser interpretados conjuntamente con los signos clínicos del animal. Las concentraciones de tireotropina (TSH), tiroxina (T4) libre y total son las pruebas hormonales más utilizadas. Es importante diferenciar el hipotiroidismo del síndrome del eutiroideo enfermo, una condición que puede ser causada por enfermedades graves y, sobre todo el hiperadrenocorticismo, dando lugar a la disminución de los niveles de TSH y T4. El tratamiento de elección es la levotiroxina sódica. El objetivo de este trabajo es realizar una revisión bibliográfica sobre el hipotiroidismo en los perros, debido a que es una enfermedad difícil de diagnosticar y de ocurrencia común en la rutina de la clínica de animales pequeños.O hipotireoidismo é uma das endocrinopatias mais frequentes na espécie canina, que acomete preferencialmente animais de meia-idade de raça pura. Os sintomas clínicos são bastante variados e muitas vezes inespecíficos, incluindo alterações metabólicas, dermatológicas ou cardiovasculares. Os principais achados laboratoriais são anemia arregenerativa e hipercolesterolemia. Hiponatremia, aumento da atividade da fosfatase alcalina e da alanina aminotransferase também podem ser observados com menor frequência. Existem testes específicos, utilizados no auxílio ao diagnóstico do hipotireoidismo, que devem ser interpretados em conjunto com os sinais clínicos apresentados pelo animal. As concentrações de tireotopina (TSH), tiroxina (T4) livre e total são os testes hormonais mais utilizados. É importante diferenciar hipotireoidismo da síndrome do eutireoideo doente, condição que pode ser causada por doenças graves e, principalmente, o hiperadrenocorticismo, levando à diminuição dos níveis de TSH e T4. O tratamento de escolha é a levotiroxina sódica. O objetivo deste trabalho é realizar uma revisão sobre o hipotireoidismo em cães, por se tratar de uma doença de difícil diagnóstico e de ocorrência comum na rotina da clínica de pequenos animais

Eletrocardiograma em cães: revisão

The electrocardiogram (ECG) is an important tool used in the diagnosis of cardiac arrhythmias, since it gives the graphic representation of depolarization and repolarization processes of the cardiac muscle. This study allows recording the electrical activity of myocardial cells and the underlying differences in electric potential: the magnitude of this difference is measured in millivolts (mV), and its duration is measured in seconds. The ECG is indicated when an irregular rhythm is detected during physical examination, such as bradycardias, tachycardias or arrhythmias that are not secondary to breathing, in animals with a history of syncope or weakness, for monitoring the effectiveness of antiarrhythmic therapy, in cases of putative pleural or pericardial effusion, and also in systemic diseases that lead to arrhythmia. For a reliable assessment, the ECG must be evaluated in conjunction with findings from the physical examination and clinical signs of each patient.El electrocardiograma (ECG) es una importante herramienta utilizada en el diagnóstico de arritmias cardiacas, ya que proporciona la representación gráfica de los procesos de despolarización y repolarización del músculo cardiaco, permite el registro de la actividad eléctrica de las células del miocardio y registra las diferencias de los potenciales eléctricos, la magnitud de esta diferencia de potencial eléctrico se mide en milivoltios (mV) y su duración se mide en segundos. El electrocardiograma está indicado cuando un ritmo irregular se detecta durante un examen físico, incluyendo bradicardias, taquicardias o arritmias que no son secundarias a una arritmia respiratoria sinusal; en los animales con una historia de desmayo o debilidad; para el control de la eficiencia de la terapia antiarrítmica; ante la sospecha de derrame pleural o pericárdico, así como en las enfermedades sistémicas que conducen a una arritmia. Para obtener un resultado fiable, el ECG debe ser evaluado conjuntamente con el examen físico y los signos clínicos de cada paciente.O eletrocardiograma (ECG) é uma importante ferramenta utilizada no diagnóstico de arritmias cardíacas, já que fornece a representação gráfica dos processos de despolarização e repolarização do músculo cardíaco, um estudo que permite registrar a atividade elétrica das células miocárdicas e as diferenças de potenciais elétricos - a amplitude dessas diferenças de potencial elétrico é medida em milivoltes (mV), e sua duração, em segundos. O eletrocardiograma é indicado quando se detectam irregularidades do ritmo durante o exame físico, incluindo bradicardias, taquicardias ou arritmias que não sejam secundárias à respiração em animais com história de síncope ou fraqueza monitoração da eficácia de terapia antiarrítmica suspeita de efusão pleural ou pericárdica e doenças sistêmicas que levam a arritmia. Para uma avaliação fidedigna, o ECG deve ser avaliado em conjunto com o exame físico e os sinais clínicos de cada paciente

Hiperadrenocorticismo em cães: revisão

Hyperadrenocorticism is a relatively common endocrinopathy in dogs, which is associated to an excessive production or administration of cortisol. The most affected breeds are Poodles, Teckels, Boxers, Boston Terriers and Beagles. The clinical signs most commonly observed are polyuria, polydipsia, polyfagia, panting, distended abdomen, endocrine alopecia, muscular weakness and lethargy. Laboratorial abnormalities include stress leukogram, increase in alkaline phosphatase and alanine aminotransferase activities, hypercholesterolemia, lipemia, hyperglycemia and hyposthenuria. The preferred essay to evaluate adrenal gland function is the low-dose dexamethasone suppression test, whereas the most used treatments include mitotane and trilostane. The objective of this paper is to review hyperadrenocorticism in dogs, because this disease is relatively common in small animal clinics and has many long-term complications.El hiperadrenocorticismo es una endocrinopatía común en perros asociada con la producción o administración excesiva de cortisol. Las razas más comúnmente afectadas son Poodles, Teckels, Boxers, Boston Terriers y Beagles. Los signos clínicos observados son: poliuria, polidipsia, polifagia, respiración jadeante, distensión abdominal, alopecia endocrina, debilidad muscular y letargia. Los hallazgos de laboratorio se caracterizan por leucograma de estrés, aumento de la actividad de la fosfatasa alcalina y alanina aminotransferasa, hipercolesterolemia, hiperlipemia, hiperglucemia y hipostenuria. El examen de elección para evaluación de la función de la glándula adrenal es la supresión de la dexametasona en dosis bajas, y los tratamientos más comunes son las terapias con mitotano y trilostano. El objetivo de este trabajo es examinar el hiperadrenocorticismo en perros, porque es una enfermedad relativamente común en la clínica de pequeños animales que tiene muchas complicaciones a largo plazo.O hiperadrenocorticismo é uma endocrinopatia comum em cães, associada à produção ou à administração excessiva de cortisol. As raças mais comumente acometidas são poodle, teckel, boxer, boston terrier e beagle. Os sinais clínicos mais comumente observados são: poliúria, polidipsia, polifagia, respiração ofegante, abdômen distendido, alopecia endócrina, fraqueza muscular e letargia. Os achados laboratoriais caracterizam-se por leucograma de estresse, aumento da atividade da fosfatase alcalina e da alanina aminotransferase, hipercolesterolemia, lipemia, hiperglicemia e hipostenúria. O teste de escolha para avaliação da função da glândula adrenal é a supressão pela dexametasona em dose baixa, e os tratamentos mais utilizados são as terapias com o mitotano e o trilostano. O objetivo deste trabalho é fazer uma revisão sobre hiperadrenocorticismo em cães, por se tratar de enfermidade relativamente comum na clínica de pequenos animais e com diversas complicações a longo prazo