Feline HCM and the Role of Nutrition
HCM in cats and the role of nutrition
Feline Hypertrophic Cardiomyopathy and the Role of Nutrition (youtube.com)
This article provides a summary of the webinar Feline Hypertrophic Cardiomyopathy and the Role of Nutrition by veterinary technician and veterinary nutrition consultant Kara M. Burns, MS, MEd, LVT, VTS. The webinar is part of the Every Cat Health Foundation webinar series.
When we talk about hypertrophic carydydomyopathy in cats, we are referring to the thickening of the left heart wall and ventricle, resulting in a reduced ability of the heart to contract while also reducing the volume of the left ventricle. The lesion may affect all or part of the left half of the heart.
Early recognition of health problems in the cat is very important. The problem, however, may be that cats are very good at hiding pain, a mechanism that has served them well in evolution for survival. In our households, this feline ability can mean that early symptoms of HCM and other ailments can escape attention for quite a long time.
The most common manifestations of disease associated with HCM in cats include:
- congestive heart failure.
- feline arterial thromboembolism - this often results in hind limb paralysis. With embolism, it is crucial to seek veterinary help immediately (48 - 72 hours is crucial). The condition is very painful.
- Sudden cardiac death (sudden cardiac death)
Kara M. Burns states that basically we can distinguish two basic forms of HCM.
- The first form is characterized by an early onset and can be encountered in certain lines of breeds (Ragdoll, Maine Coon, Devon Rex, Cornish, Selkirk), Sphynx, Norwegian Forest Cat, Birman, British Cat, Siberian Cat, and Neva Masquerade, Scottish Fold, and others. Only in Maine Coon cats and Ragdolls has one of the possible causative mutations in the myosin binding protein been discovered. The mutation is specific to each breed - RAG (C820T), MCO (A31P). Another mutation has been discovered and is under further investigation - the Nyberg and Koch mutation in MCO (A74T). Thus, only in MCO and RAG are there genetic tests. The gold standard for all breeds remains a repeated sonographic examination from approximately one year of age and additional examinations such as X-ray or ECG, and in some cases biochemical examination (BNP).
- The second form of HCM tends to be sporadic, appears at an older age and may again be due to genetics or developmental abnormalities.
The treatment of HCM consists not only of medication, but also of a balanced diet that is optimised according to the degree of HCM the cat is currently experiencing. The sooner we start dietary modification, the better. The diet must not only be balanced, but must also be appropriate to the age of the cat.
The risk of disease outbreak is:
- obesity
- belonging to a particular breed
- other diseases the cat suffers from, such as chronic kidney disease
- other medications
- endocrine disorders
In obese cats we observe:
- increased heart activity
- increased plasma and extracellular fluid volume
- increased neurohumoral activation (relationship to the nervous system and hormones, improper sympathetic and parasympathetic function)
- reduced urinary sodium excretion
- reduced water excretion
- increased heart rate/heart works faster
- abnormal systolic and diastolic function
- decreased willingness to move
- fluctuating blood pressure
As mentioned, chronic kidney disease is an additional risk in HCM. This is because it causes increased blood pressure and the kidneys are unable to adequately remove waste products from myocardial metabolism. Heart disease exacerbates chronic kidney disease.
Another problem can be excessive thyroid activity - hyperthyroidism.
Kara M. Burns gives an example of a questionnaire for cat owners in her presentation. It contains the following questions:
1. How does your cat interact with you?
2. Can you tell me how your cat behaves during play? Is your cat interested in playing or not? Does she play with people or other animals in your home?
3. Has your cat's enjoyment of joint activities, such as playing together, changed? There may be other additional questions - for example : Why doesn't your cat interact with you? Does your cat seem to tire easily when playing? Does your cat lie down more after playing together than before?
4. What is your cat's appetite like? Have you noticed any changes in your cat's eating habits? Can your cat eat all of its food?
5. Can you tell me about your cat's sleeping habits? Does your cat regularly adjust his/her sleeping position to make him/her feel more comfortable?
6. What behavioral changes have you observed in your cat? When and under what circumstances did or do these changes occur?
7. How much does your cat weigh?
8. What is the physical condition of your cat?
9. What muscle condition does your cat have?
Of course, other questionnaires follow, such as the standardized dietary history questionnaire
(WSAVA Short Diet History Forum).
Cats with heart disease usually experience physical weakness, weight loss and muscle loss. This condition is referred to as cachexia. It is a manifestation of destructive metabolism. Anorexia and inappetence are encountered.
It should be emphasized that cachexia is not the same as starvation.
In starvation, fat stores are lost first, while muscle mass is preserved. There is also a reduction in liver size, reduced glucose metabolism, and reduced protein breakdown. When the nutrient supply is restored, the destructive changes stop and return to their original state.
In cachexia, there is both loss of fat stores and loss of muscle mass. Resting energy expenditure is normal or increased. The liver is enlarged. Glucose metabolism is normal or increased. There is increased protein breakdown. Resumption of supply alone does not lead to improvement.
Nutrition in cats with HCM
The composition of the diet of cats with HCM depends on the stage of HCM the cat is in.
Designation of stages/stages of HCM in cats
A - predisposition
B1 - subclinical stage - low risk
B2 - subclinical stage - higher risk ( slight thickening of the left heart wall and ventricle is already evident)
C - status prior to congestive heart failure or arterial thromboembolism
D - congestive heart failure unresponsive to treatment
Cat with a predisposition for HCM, without clinical signs
- Diet aimed at achieving ideal body weight and condition
- Moderate sodium restriction - no more than 50 mg and less than 100 mg /kcal (this should not be a major restriction)
Cats with mild HCM
- Moderate sodium restriction - less than 80 mg /kcal
- medication is no longer required
- anorexia may occur (anorexia can be a side effect of medication, so careful monitoring of medication dosage is necessary)
- serum biochemical values are monitored - creatine and electrolyte levels, BUN - blood urea nitrogen
- digestive system and kidney function are monitored
- an appetite-enhancing diet should be given (see below)
Key nutrients
- sodium (Na)/chlorine (Cl) - as HCM heart disease worsens, the individual's ability to excrete sodium from the body decreases, so dietary sodium intake must be regulated; dietary sodium content depends on the degree of disability and ranges from 0.07% to 0.3% on a dry weight basis, and chloride content should be 1.5 times sodium
- taurine - inactivates free radicals, controls osmoregulation and influences calcium modification and muscle contraction proteins (contractile proteins), the taurine content in dry matter should be greater than or equal to 0.3%
- phosphorus (P) - excess phosphorus in the diet should be avoided, the content should be between 0.3 and 0.7% in dry matter
- potassium (K)/magnesium (Mg) - deficiency or excess can cause arrhythmia, affects the heart's ability to contract, causes severe muscle weakness, enhances the adverse effect of drugs containing glycosides (e.g. thimbleberry drugs), optimal values should be K = 0.52% in dry matter and Mg 0.04% in dry matter
- water - cats must have fresh water available throughout the day. Water is a source of sodium, chlorine and other minerals. The composition of the water is therefore a major influence on the health of cats with HCM. The quality of water can change continuously, so we should regularly check the composition of the drinking water where we live and if the water is not suitable, an alternative source should be provided.
- protein - the protein in the diet for cats with HCM should be high quality and easily digestible. Again, we should prefer to choose veterinary food brands such as Hills, Royal Canin or Purina Proplan. Kara M. Burns recommends these brands because the manufacturers invest in their own research. Each manufacturer should disclose the parameters of the food and its composition on request.
- fatty Amino Acids - this is particularly fish oil, which can positively affect the health of cats with congestive heart failure and a tendency to arterial thromboembolism. Omega 3 fatty acids have an anti-inflammatory effect, are given to prevent cachexia, improve the taste of the food and have an anti-arrhythmic effect. Fatty amino acids are the primary substrate used by the mitochondria (energy-producing organelles in the cell). They improve myocardial metabolism and mitochondrial function. The most important omega-3 fatty acids are EPA - eicosapentaenoic fatty acid and DHA - docosahexaenoic fatty acid. The EPA content should be 80 mg per 100 kcal and the DHA content 150 mg per 100 kcal
