News In Feline Hypertrophic Cardiomyopathy Treatment
Feline hypertrophic cardiomyopathy (HCM) is the most commonly diagnosed cardiac disease in cats, affecting approximately one in seven cats worldwide. Proper treatment and diagnosis can decrease the chance that HCM-affected cats will experience certain symptoms, and can improve their quality of life. Researchers have discovered interesting information concerning a commonly used HCM medication, and an animal health research and development company has recently been granted consent to pursue the expanded conditional approval pathway for their HCM therapeutic candidate.
Feline hypertrophic cardiomyopathy
HCM causes a cat’s heart walls to thicken, decreasing the heart’s ability to effectively pump blood throughout the body. The cause has not clearly been identified, but genetics likely play a role, since certain breeds, including Maine Coon, Ragdoll, British shorthair, Sphynx, Chartreux, and Persian cats, are predisposed. When a cat is affected by HCM, their ventricular wall thickens (i.e. hypertrophies). If the hypertrophy is mild, the cat may remain symptom free throughout their entire life, but if the hypertrophy is severe, the heart muscle will be unable to relax completely, leading to increased intracardiac pressure, and congestive heart failure (CHF). Other HCM complications include:
- Dynamic obstruction of the left ventricular outflow tract (DOLVOT) — This occurs when the mitral valve’s abnormal movement against the inner ventricle wall disrupts blood ejection from the left ventricle, partially obstructing blood from exiting the aorta.
- Cardiac arrhythmias — The ventricle hypertrophy can cause abnormal heart rhythms.
- Clot formation — The heart’s inefficient pumping may cause clot formation in the left atrium. If a clot breaks apart and travels to a major artery, a phenomenon known as feline arterial thromboembolism (FATE), the cat will need immediate emergency veterinary care.
Feline hypertrophic cardiomyopathy signs and diagnosis
Many cats affected by HCM are asymptomatic, especially in the early stages. The disease may be discovered during a wellness exam when the family veterinarian ausculates heart abnormalities, including murmurs, arrhythmias, or extra heart sounds. When the disease progresses to CHF, fluid accumulates in and around the lungs. Signs include increased respiratory rate and respiratory effort, vomiting, decreased appetite, and hiding. If a FATE occurs, the cat will experience sudden onset paralysis that affects one or several limbs. HCM is diagnosed using echocardiography to measure the ventricular walls. Other diagnostics may include chest radiographs, electrocardiogram, and blood pressure measurements. HCM screening tests are also available.
- Genetic testing — A specific genetic anomaly in Ragdolls and Maine Coons has allowed development of a blood test that evaluates the two copies of the affected gene. If the copies are normal, HCM risk is low. If one copy is abnormal, risk is moderate. If both copies are abnormal, risk is high, and the disease is likely severe. This test is accurate only for Ragdolls and Maine Coons, and can be useful to those breeders.
- Periodic echocardiography — This approach is used in at-risk breeds who have no genetic testing available.
- N-terminal pro B-type natriuretic peptide (NT-proBNP) testing — This blood test can help identify asymptomatic cats who have moderate to severe HCM, but false positives are possible.
Feline hypertrophic cardiomyopathy treatment
HCM has no known cure, but proper management can improve the affected cat’s quality of life. Treatment goals include controlling the heart rate, alleviating lung congestion, and preventing blood clot formation. In cats at risk for FATE, blood thinners, such as clopidogrel, can help decrease their risk. Cats in CHF are treated with medications that include diuretics, ACE-inhibitors, and drugs stimulating the heart’s contractility. In asymptomatic cats, no treatment has been shown to change the natural disease progression.
Genetic makeup influences response to clopidogrel
In June 2021, a study by the University of California, Davis, veterinarians was published in the Nature Portfolio Journal, Scientific Reports. The study showed that a cat’s DNA alters their response to clopidogrel, a commonly prescribed medication to prevent blood clots in HCM cats. Many cats still form blood clots when on clopidogrel, which led the research team to investigate mutations in the drug pathway. Their data showed that nearly 20 percent of cats were resistant to clopidogrel therapy. They began a clinical trial on HCM cats, first testing their ability to form blood clots. Then, the cats’ owners gave them clopidogrel for 14 days, and the cats were tested again. Researchers were able to test if the genetic mutations they identified in the drug pathway were responsible for reducing the drug’s effectiveness, and they found a gene variant in cats who had clopidogrel resistance. This finding provides the ability to use a simple genetic test to determine the best drug therapy for preventing blood clots in HCM cats.
Expanded conditional approval pathway for Felycin
The Food and Drug Administration’s (FDA) Center for Veterinary Medicine (CVM) decided in September 2021 that TriviumVet, an Ireland-based animal health research and development company, could pursue the expanded conditional approval pathway for their feline HCM therapeutic candidate, Felycin. Conditional approval allows drug sponsors to legally market a product before the critical clinical studies are completed, as long as they prove the drug is safe, they meet the FDA’s rigorous manufacturing standards, and the drug’s effectiveness can reasonably be expected. CVM’s approval acknowledges no approved veterinary drug exists in the United States for treating feline HCM.
Felycin is a patented, delayed release rapamycin formulation. Rapamycin is a fermentation product derived from soil samples, and the drug has immunosuppressive and anti-proliferation effects. TriviumVet is conducting a clinical study in client-owned cats, to evaluate the drug's effectiveness in treating HCM. Previous laboratory animal study results and effects observed in human organ transplant patients suggest Felycin has the potential to slow or reverse the damaging cardiac remodeling that underlies the HCM disease process. TriviumVet conducted preclinical investigations showing that healthy cats tolerated Felycin well when given multiple times the intended dose.
New strides in treatment approaches for feline HCM will hopefully result in better management options for this problematic condition. These advances could greatly improve many cats’ quality of life.
Comments
Related Articles
Copyright © 2025 - All Rights Reserved
ISSN 2768-198X
List
Add
Please enter a comment