Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Uppsala, Sweden
Information and instructions concerning home monitoring of dogs and cats diagnosed with heart disease should be provided to owners of animals in preclinical as well as clinical stages of heart disease. In both stages, the aim is to detect early (mild) signs of congestive heart disease (CHF), or other complications that can affect patients with heart disease. Pertinent owner information might improve the quality of life of diseased animals, as the owners observe and manage their animals on a daily basis, whereas clinicians only occasionally meet the animals.
Dogs and Cats in Preclinical Heart Disease
Many dogs and cats diagnosed with heart disease will never develop clinical signs related to their heart disease, and life expectancy might be minimally, if at all, affected. However, for selected patients, a high risk exists for future development of signs related to their heart disease. Accordingly, owners should be provided information about the current heart disease and the prognosis (if possible). Furthermore, owners should be informed about common signs of complications of heart disease in dogs and cats, such as tachypnea, dyspnea, cough (not commonly observed in cats), anorexia, abdominal distension, fatigue, exercise intolerance, alterations in sleeping behavior, and syncopal episode/collapse. However, these signs are not specific for heart disease, and diseases other than cardiac might precipitate similar signs.
The initial clinical signs of left- and right-sided CHF are often vague and mild, but may be aggravated within days or sometimes weeks. Should signs of significance be detected at home, the owner should be recommended to seek a veterinary consultation for their animal in order to evaluate if the signs could be explained by the heart disease diagnosed.
In cases of increased risk for future development of left-sided CHF, the owners should be instructed to count resting (RRR) or sleeping respiratory rates (SRR) at approximately 10 different occasions in the animal’s home environment in order to establish normal respiratory rates for the specific dog or cat. Although variation between individuals exists, RRR and SRR <30/min generally is seen in healthy dogs and cats as well as in dogs and cats with preclinical heart disease.
When a normal range for the individual dog or cat has been established, more infrequent measurements of SRR or RRR can be performed, as long as the animal appears healthy and alert at home. The owner should be instructed to contact their veterinarian if RRR and SRR >30/min are noted at repeated measurements in the future. It could be of value to also perform a follow-up examination on individuals demonstrating a steep increase in RRR or SRR, having measurements towards 30/min at repeated measurements, especially if the owner concurrently notes other signs of disease. The owner should be instructed to count RRR and/or SRR at multiple times. Preferably RRR/SRR should be <30/min during rest or sleep. The owner should contact the veterinarian if RRR and/or SRR >30 is noted frequently/at several occasions at home, as RRR/SRR <30 is to be expected in the majority of dogs and cats well stabilized by cardiac medications. However, the owner should not worry too much if RRR/SRR >30 is measured at some few occasions, as also other factors; such as REM sleep cycles, high environmental temperature or stress (if the animal is awake) can affect the respiratory rate.
Dogs and Cats in Clinical (Overt) Heart Disease
Regular contacts with the owner by phone or email should be maintained when the animals are managed on an outpatient basis in order to monitor therapeutic outcome and to establish a suitable maintenance dosage of diuretic. In addition, re-examinations should be scheduled.
The owner should be informed that the treatment protocol always needs to be optimized for the individual cardiac patients, and that the treatment protocol used is based on both the particular disease/disease stage affecting the animal, as well on the treatment response. Meticulous information about the various medicines should be given to the owner. It is important to use appropriate dosage of diuretics to relieve clinical signs, but unnecessary high maintenance dosages should be avoided. Overzealous use of diuretics may lead to weakness, hypotension, syncope, aggravation of prerenal azotemia and acid-base and electrolyte imbalances. Accordingly, the lowest dosage of diuretics possible, that can keep the animal free from clinical signs of CHF, should always be used. The maintenance dosage of diuretic in a patient that has developed CHF usually has to gradually be increased over weeks or years to prevent clinical signs of CHF to reoccur. Reasons for increasing the dosage often include recurrent dyspnea and tachypnea caused by pulmonary edema or, less commonly, development of ascites.
Dog owners should also be informed that the dog must be given the possibility to urinate approximately one to two hours after oral dosages of diuretics are given. Animals with symptomatic heart disease should avoid excessive intake of sodium.
Initially, in close proximity to the acute decompensated CHF event, the dog owner should be recommended to restrict the walking distances for the dog. Dogs that are stable on their heart failure therapy usually tolerate walks in their own pace, but strenuous exercise should be avoided. The owner should be instructed to avoid high ambient temperatures for the dog, if possible, for example by selecting early morning hours or late evenings for longer walks.
The owner should be informed about complications that may develop in the future, such as new signs of decompensated left- or right-sided CHF due to aggravation of congestion and edema (and accordingly a need for alteration in the treatment protocol) or syncopal episodes/collapse even at mild exercise.
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