Pimobendan is a veterinary medication used to treat congestive heart failure (CHF) in dogs. It belongs to the class of drugs known as indicators, which enhance the contractility of the heart and dilate blood vessels, resulting in increased cardiac output and decreased systemic vascular resistance.
Pimobendan was first introduced in Europe in the 1990s and subsequently approved for use in the United States in 2007. It is now widely used in veterinary medicine for the treatment of CHF due to its efficacy, safety profile, and ease of administration. The use of pimobendan has been shown to improve both the quality and length of life in dogs with CHF, particularly those with dilated cardiomyopathy[1] or mitral valve disease.
It has also been found to delay the onset of CHF in dogs with preclinical cardiac disease. Some potential adverse effects of pimobendan include gastrointestinal disturbances, such as vomiting and diarrhea, as well as decreased appetite and lethargy. However, these side effects are generally mild and self-limiting.
The signs of pimobendan poisoning include:
- Allergic reaction (impaired breathing, hives)
- Diarrhea
- Dark stool (melena)
- Loss of appetite
- Weight loss
- Dehydration
- Depression
- Loss of movement coordination (ataxia)
- Gagging
- Coughing
- Increased breathing rate
- Increased thirst and urination frequency
- Urinary accidents
- Elevated heart rate
- Irregular pulse or weak pulse
- Heart murmur
- Low blood pressure
- Fainting
- Accumulation of fluids in the chest and abdomen
- Restlessness
- Staggering
- Shaking and trembling
- Seizures
Why not for Cats?
Pimobendan is primarily used to treat congestive heart failure (CHF) in dogs and is not currently approved for use in cats in most countries, including the United States. While some studies have investigated the use of pimobendan in cats with heart disease, the results have been mixed and the safety and efficacy of the drug in feline patients have not been firmly established.
One reason for the limited use of pimobendan in cats is that feline heart disease is typically different from the types of heart disease seen in dogs. The most common type of feline heart disease is hypertrophic cardiomyopathy (HCM)[2], which involves the thickening of the heart muscle rather than the dilation of the heart chambers as seen in many cases of canine heart disease. The pathophysiology of HCM is complex and not fully understood, which makes it difficult to predict how cats will respond to treatments like pimobendan.
Another reason for the limited use of pimobendan in cats is the potential for adverse effects. Cats are known to be more sensitive to certain medications than dogs, and pimobendan has been associated with an increased risk of side effects such as vomiting and decreased appetite in some feline patients. Overall, while there is ongoing research into the use of pimobendan in cats with heart disease, the drug is not currently considered a first-line treatment option for feline patients. Veterinarians may consider other medications or treatment strategies, such as diuretics, ACE inhibitors, or beta-blockers, depending on the individual cat’s condition and response to therapy.
It is important to note that pimobendan should only be used under the guidance of a veterinarian, as dosage and administration may vary depending on the individual patient’s condition and response to treatment.
Footnotes
- Dilated cardiomyopathy (DCM) is a condition in which the heart becomes enlarged and weakened, affecting its ability to pump blood effectively. DCM is a type of cardiomyopathy, which is a broad term used to describe diseases of the heart muscle. In DCM, the walls of the heart become thin and stretched, which can lead to problems with the heart’s electrical system and impair its ability to contract properly. This can cause a variety of symptoms, such as shortness of breath, fatigue, swelling of the legs and abdomen, and irregular heartbeats. In severe cases, DCM can lead to heart failure or sudden death. DCM can be caused by a variety of factors, including genetic predisposition, nutritional deficiencies, infections, or exposure to toxins or drugs. In many cases, the exact cause of DCM is unknown. DCM can affect both humans and animals, including dogs, cats, and other mammals. In dogs, DCM is most commonly seen in large and giant breeds, such as Great Danes, Doberman Pinschers, and Irish Wolfhounds. In cats, DCM is most commonly seen in middle-aged male cats, particularly those with a history of heart disease. [Back]
- Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats and is characterized by the thickening of the heart muscle, particularly the left ventricle. This thickening can lead to problems with the heart’s ability to contract and relax, which can cause a variety of clinical signs, including heart murmurs, arrhythmias, difficulty breathing, and sudden death. HCM can be caused by genetic mutations, and certain breeds, such as Maine Coons and Ragdolls, are known to be predisposed to the disease. Diagnosis of HCM typically involves a thorough physical examination, electrocardiography, and echocardiography. Treatment for HCM aims to manage clinical signs and prevent complications and may include medications such as beta-blockers, calcium channel blockers, or anti-arrhythmic drugs. Some cats with severe HCM may require surgical intervention, such as pacemaker implantation or septal myectomy. While there is no cure for HCM, early diagnosis and management can help improve the prognosis for affected cats. [Back]
Further Reading
Sources
- Dog Discoveries
- Atkins CE, Keene BW, Brown WA, et al. Results of the veterinary enalapril trial to prove reduction in onset of heart failure in dogs chronically treated with enalapril alone for compensated, naturally occurring mitral valve insufficiency. J Am Vet Med Assoc. 2007;231(7):1061-1069.
- Oyama MA, Boswood A, Connolly DJ, et al. Clinical efficacy and safety of pimobendan in dogs with preclinical myxomatous mitral valve disease: the EPIC study–a randomized clinical trial. J Vet Intern Med. 2016;30(6):1765-1779.
- Häggström J, Boswood A, O’Grady M, et al. Effect of pimobendan or benazepril hydrochloride on survival times in dogs with congestive heart failure caused by naturally occurring myxomatous mitral valve disease: the QUEST study. J Vet Intern Med. 2008;22(5):1124-1135.
- Fuentes VL, Corcoran B. Pimobendan in heart failure—dogs and beyond. J Vet Cardiol. 2012;14(1):161-172.
- Atkins CE, Snyder PS, Keene BW, et al. A retrospective study of hypertrophic cardiomyopathy in 50 cats: 1994-2001. J Vet Intern Med. 2003;17(2): 304-314.
- Littman MP, Dambach DM, Vaden SL, et al. Efficacy of enalapril for prevention of congestive heart failure in dogs with myxomatous valve disease and asymptomatic mitral regurgitation. J Vet Intern Med. 2010;24(3):613-621.
- Singh MK, Kittleson MD, Kass PH, et al. Pimobendan in cats with hypertrophic cardiomyopathy: A retrospective study of 35 cases. J Feline Med Surg. 2013;15(9):810-816.
- Maron BJ, Towbin JA, Thiene G, et al. Contemporary definitions and classification of the cardiomyopathies: an American Heart Association Scientific Statement from the Council on Clinical Cardiology, Heart Failure and Transplantation Committee; Quality of Care and Outcomes Research and Functional Genomics and Translational Biology Interdisciplinary Working Groups; and Council on Epidemiology and Prevention. Circulation. 2006;113(14):1807-1816.
- Meurs KM, Miller MW, Wright NA. Clinical features of dilated cardiomyopathy. In: Ettinger SJ, Feldman EC, eds. Textbook of Veterinary Internal Medicine. 8th ed. Elsevier; 2017:1037-1043.
- Kittleson MD, Kienle RD. Dilated cardiomyopathy. In: Ettinger SJ, Feldman EC, eds. Textbook of Veterinary Internal Medicine. 8th ed. Elsevier; 2017:1009-1036.
- Payne JR, Brodbelt DC, Luis Fuentes V. Cardiomyopathy prevalence in 780 apparently healthy cats in rehoming centres (the CatScan study). J Vet Cardiol. 2015;17(Suppl 1):S244-S257.
- Meurs KM, Norgard MM, Ederer MM. Feline hypertrophic cardiomyopathy: genetics and pathogenesis. J Vet Cardiol. 2015;17(Suppl 1):S10-S19.
- Fox PR, Keene BW, Lamb K, et al. Long-term incidence and risk of noncardiovascular and all-cause mortality in apparently healthy cats and cats with preclinical hypertrophic cardiomyopathy. J Vet Intern Med. 2018;32(1):379-390.
