Hypertrophic Cardiomyopathy in Cats (HCM)

There is an enormous amount of information out there regarding HCM - Hypertrophic Cardiomyopathy. It can be overwhelming  and exhausting  trying to figure out the basic information you need to know to keep your kitten safe.  There's also conflicting information in the world of breeding both online and off that can cause confusion. We have put together a snapshot containing the basics of HCM below. As a potential/ current owner of a Canadian Sphynx, its imperative you know what HCM is and understand the basics as Canadian Sphynx are prone to the disease.

In 2021, The copies of mutations for HCM associated specifically in the Sphynx Breed were identified by researchers at North Carolina Research University. An amazing finding for those who breed Sphynx cats and for those who have them as pets! 

It's  essential as a screening test and monitoring tool and paves the way for ethical preservation breeders to test (PRIOR TO BREEDING) and remove cats from their breeding pool who test Positive Homozygous thereby, significantly reducing the risk of passing the genes to their kittens and producing kittens at high risk for HCM.

In addition, it provides an invaluable tool to monitor a cat who test Positive Heterogeneous for symptoms/signs ensuring they are seeing a veterinarian for a Health & Wellness Exam annually along with NT-proBNP blood test that can determine the possible presence of heart disease. (North Carolina Research University 2021)

More and more ethical preservation breeders are adopting genetic testing into their breeding program. Veterinarians are now recommending pet owners, not just breeders, have their kittens tested as a marker for monitoring should your cat test positive with copies of 1 or more mutations.

There are 5 types of testing for HCM that ethical breeders & pet owners of sphynx cats can and should utilize to test for HCM. 

1. Genetic testing-  breeders are beginning to recognize how critical HCM genetic testing is and advising those who adopt kittens from them to have their kitten tested.
2.  Auscultation (listening with a stethoscope) 
3. NT-proBNP blood Test 
4. Echo Cardiogram scan 
5. EKG Testing

What you need to know about HCM to understand the importance of utilizing both genetic testing and cardiograms scan: 

Causes of HCM:

1. Inherited (passed down from a parent) - common in certain breeds including the Canadian Sphynx.

2. Idiopathic (meaning the cause is unknown).

3. Caused by another condition such as hyperthyroidism or high blood pressure.

4. Taurine is an essential amino acid for cats.  Its important . A deficiency of Taurine will also lead to a weakening of the muscle cells in the heart, causing a condition called dilated cardiomyopathy (DCM). Ensure you have a discussion with your vet about what food/diet you are feeding your Canadian Sphynx, they may recommend to add Taurine (supplement powder) to your kitten/cat's food. (VCA Canada)

HCM is a rapidly progressive cardiac disease in felines. 'Age of presentation varies from cat to cat. Development of the disease typically occurs around 2-3 years of age or older and between 8-10 years of age.'  (NC State Veterinary Hospital)    

'A cat's heart has four distinct sections, each with a unique and vital role to play. The bottom left section of the heart is called the left ventricle. This section is responsible for receiving oxygenated blood from the lungs and pumping it out to all parts of your cat's body that require oxygenated blood.

While the left ventricle is naturally thicker than the other 3 sections of the heart due to its immense workload, hypertrophic cardiomyopathy occurs when there is an abnormal thickening of the muscles of the left ventricle which then negatively impacts the heart's ability to pump the blood out into the body.' (animeRGe 2023)

HCM makes it difficult for the heart to pump blood properly and often leads to:

• An irregular heartbeat
• High blood pressure
• Blood clots (aortic thromboembolism/saddle thrombus)  a very common complication of HCM
• Problems with the heart valves
• Heart failure (when the heart can’t compensate anymore)
• Sudden death (pdsa 2021)

Symptoms:

• lethargy  
• difficulty breathing
• shortness of breath (snapping or crackling sound when breathing) 
• Abnormal hearts sounds (galloping,muffled,rhythm,murmurs) 
• Inability to tolerate exercise
• sudden hind limb paralysis
• syncopal episodes (fainting spells)
• sudden discoloration of the feet pads & nails bed
• Collapse, Sudden heart failure (pdsa 2021)

It's important to note that HCM can be asymptomatic (many cats don't show symptoms) and  idiopathic in nature (Cause unknown)  It can strike any cat randomly, at any age over the course of their lifetime for no known reason; much like lung cancer can strike a human whose never smoked and lives a super healthy lifestyle. 

 5 HCM TESTING TOOLS

1. Genetic testing- Provides health markers analysis (test results) that are critically essential to the health & wellness of a Canadian Sphynx cat.

• Your cats analysis (test results) provides you and your vet with specific information on whether or not they inherited 1 or more copies of the specific gene mutations. 

Genetic Test results are classified as: 

• 1-Negative -no copies of gene mutations
• 2-Positive Heterogeneous - 1 copy of normal gene one copy of mutated gene 
• 3- Positive Homozygous - 2 copies of genes mutations 

2.  Auscultation (listening with a stethoscope)  Physical exam performed by veterinarian and/ or Vet technician. Categorized in  grades 1, 2, 3, 4, 5, and 6 heart murmurs in cats. 

Grade 1 is the mildest and Grade 6 the most severe. The grading system is based largely on how loud the murmur is, but other factors are also considered, such as the area over which the murmur is audible. 

3. NT-proBNP blood test: An elevated NTproBNP suggests that heart failure may be present.  The blood test measures the NT-proBNP hormone levels that is released by stretched or stressed muscle cells in the heart. The rise in the level of this hormone is proportional to the abnormal stretching and stress of heart muscles. Low NT-proBNP levels can be used as rule-out test for heart failure.  (Today's Veterinary Practice)

The blood test is useful if vet has concerns after a physical examination. It's also recommended that NT-proBNP blood levels are submitted annually by primary care veterinarians in all (including healthy) middle to older-aged cats as part of their routine annual Health & Wellness examinations.This test has an 85% sensitivity for detecting heart disease in cats.  (Today's Veterinary Practice)

4. Echo Cardiogram Ultrasound: An echo cardiogram is the gold standard today in scanning & diagnoses for HCM in cats. The test uses sound waves  (ultrasound)  to see if the hearts muscles are unusually thick. It also shows how well the hearts chambers and valves are pumping blood. 

4.  Electrocardiogram (ECG or EKG): Examines the electrical currents in the heart muscles and may reveal possible abnormalities in the hearts electrical conduction.

Prevention & Diagnoses is the difference between genetic testing and scans.  Both equally critical to your future kittens/cats health and from a breeders standpoint.

 Genetic testing allows us to monitor, screen and prevent breeding high risk cats while  NT-proBNP blood test, echo cardiograms and EKG testing allows your veterinarian to diagnose the disease, determine progression and formulate a treatment plan.

Always ask what type of scan a breeder performs.

It's also important to ask what type of 'scan' your breeder uses, EKG or Echo Cardiogram. Echo cardiograms, as mentioned are the gold standard or "go to' for detecting HCM today. Some clinics offer scans completed by professionals with various credentials.

Ensure you understand if a Board Certified Cardiologist, Licensed GP Veterinarian or a Trained Technician is performing the scan and what the differences in qualifications are.

Never not have a scan done because a "Board Certified Cardiologist" is difficult to find in your area or involves expensive travel cost at the expense of your pets health. If a Licensed GP Veterinarian or Trained technician is the only option near you, trust their professional qualifications. It's more important to have a scan completed then decide not to based on veterinary credentials.

These are all highly trained & skilled professionals. If all else fails have your veterinarian perform a physical examination,  request a NTprobBNP blood test.... use the tools available so that your vet has some degree of knowledge re: your beloved sphynxs' heart health. Some knowledge is better then no knowledge. Research local HCM Clinics that may be held in your area.

Prices for scan

 An EKG tends to be much less expensive then an echo cardiogram but provide less information compared to an Echo cardiogram scan. 

While Echo cardiogram scanning can be costly, they are priceless in diagnosing HCM. Prices vary pending where you live. Anywhere from 500.00+ to 2000.00+. Each vet clinic/specialist  charges vastly different prices.  Some clinics require a referral  for a Echo cardiogram from your primary vet.  In most cases the professional performing the scan is a cardiomyopathy specialist  who travels from clinic to clinic and  determines the price and clinic where they prefer to perform the scans.  

 What do we do at Soul Valley Cattery to screen detect, diagnose & prevent the passing down of HCM down to our kittens.

We believe Genetic testing/screening and NT-proBNP blood tests & Echo cardiogram scans are critical tools and vitally important to the health & wellness of our Sire & Dams.  

1.We genetically test all our Sire & Dams PRIOR to breeding them. 

2. Immediately remove a cat who has tested Positive Homozygous from our very small breeding pool,  despite the significant investment made in the cat.

3. Monitor cats who test Positive Heterogeneous closely for symptoms.

4. Ensure all our cats have annual Health & Wellness exams.

5. Follow our vets recommendations, i.e. blood test and/or Echo cardiograms for further testing if concerns arise.