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Hypertrofische Cardiomypathy - HCM
Polycystic Kidney Disease - PKD
 Feline Hip Dysplasia - HD  and Patellar Luxation -PL

 

 

Hypertrofische Cardiomypathy - HCM :

•HCM is the most common heart disease of cats today
•Male cats are more often affected than females
•Many affected cats have no symptoms of heart disease when they are diagnosed
•Cats in heart failure at diagnosis may have difficulty breathing, lethargy, and a poor appetite
•Cats with blood clots blocking critical arteries may have difficulty walking or paralysis of the hind legs and may be in great pain
•The first breed identified with inherited HCM was the Maine Coon about 10 years ago (Dr. Mark Kittleson, University of California); mode of inheritance identified as autosomal dominant
•Since then, HCM known or strongly suspected to be inherited in several other breeds:
    American Shorthair, 
    Persian, 
    Rex breeds, 
    Ragdoll, 
    British Shorthair
•Several breeds appear to be at low risk, such as the Siamese and Abyssinian
•Characteristics of HCM vary among breeds:

o Maine Coons are best studied: usually no disease before one year of age; disease present by two years old, can become severe by age four; occasionally cats are not affected until much older
o American Shorthairs appear to have a milder form of HCM
o Persians appear to have a form involving asymmetrical septal hypertrophy
o Ragdolls appear to have a severe form with early onset

•HCM is a progressive disease that may progress slowly or quickly
•Characteristics of HCM:

o Hypertrophy or increase in size of heart muscle, especially of the left ventricle
o May be associated with enlargement of the left atrium
o An irregular heart rhythm may be present
o Heart murmurs are usually, but not always present – murmur can be variably present or absent in the same patient. A heart murmur that persists beyond 4-6 months of age in a kitten should be investigated.
o HCM is a common cause of heart failure
o Risk of blood clots that block blood flow to critical arteries
o Sometimes the first and only sign is sudden death

•Diagnosis is most reliable by echocardiogram (ultrasound of the heart)
•Treatment:

o Some patients are in heart failure and must have their immediate condition stabilized (oxygen, diuretics, treatment of clots if present)
o Diltiazem (Cardizem®): first line drug therapy
o Beta blockers (i.e. atenolol): may be best for cats with obstructive form of HCM 
o ACE inhibitors (enalapril – Enacard®, Vasotec®; benazepril –Fortekor®): may be useful in cats that do not respond to other medications
o Aspirin: commonly prescribed to prevent blood clots but does not work as well as expected; recent study showed that low dose works as well as higher doses

•Treatment of asymptomatic cats is controversial: some drugs such as diltiazem or ACE inhibitors may be able to reduce the muscle hypertrophy, so it might make sense to treat these cats if they are diagnosed at a young age while the hypertrophy is still developing; some cardiologists do not treat asymptomatic cats unless the left atrium is enlarged 
•Prognosis: highly variable; generally worse for cats that are in heart failure or for those with severe enlargement of the left atrium; poorest prognosis is for cats with thromboembolism (blood clots in critical arteries) 

o Some cat family lines have more malignant forms of HCM than others 
o A study published in 2002 on 260 cats with HCM: 
Well cats: survived up to 10 years 
Cats with heart failure: survived an average of 18 months 
Cats with blood clots: survived an average of 6 months, high risk of  clot happening again

•Advice for breeders:

o Screen breeding stock yearly with ultrasound 
o In general, we can assess males by age two, females by three to four years of age; occasionally affected cats may not be identified until later in life 
o Ragdolls: often have disease before one year of age, so can start screening earlier with ultrasound 

•Presents difficulties for breeders because cats have often produced offspring before they can be fully assessed 
•A genetic test is needed to identify affected cats earlier, but only  gene responsible for  feline HCM in Maine Coons has yet been identified
•Good website for HCM information: http://members.aol.com/jchinitz/hcm/index.htm

by Susan Little, DVM Diplomate, American Board of Veterinary Practitioners, Certified in Feline Practice

Do you have a Traditional Doll Face cattery who tests on HCM? Please let us know! Contact us by e-mail

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Polycystic Kidney Disease - PKD :

•PKD has been described in Persian-type cats since the 1960s; now found world-wide
•Some affected cats develop chronic kidney failure, usually in the middle years of their lives
•In the late 1980s, Dr. David Biller of the Ohio State University in the United States established a colony of PKD research cats after he acquired the offspring from a six year old Persian female with PKD
•Dr. Biller developed a pedigree database of 115 cats by crossing some of the offspring with unrelated, normal DSH cats
•Of the 115 cats in database, 102 were positive for PKD; analysis of the data proved autosomal dominant inheritance of PKD in cats
•Starting in the late 1990s, breeders in the United States and around the world have been testing their cats for PKD with ultrasound screening
•Breeds most at risk are: Persian and its related breeds, Himalayan and Exotic SH
•Data from some recently published studies on PKD:

o In 2000, in the United States: 745 Persian/Himalayan cats ultrasounded for PKD at specially arranged clinics, over 42% of cats were positive for PKD
o In 2001, in Australia: 45% of a group of 250 Persians were positive for PKD
o In 2001, United Kingdom: almost 50% of a group of 132 Persian cats examined at the University of Bristol were positive for PKD
o In 2003, France: 42% of 220 Persians and 39% of 64 Exotics were positive for PKD

•In most studies, the majority of cats did not have signs of kidney failure at the time of their diagnosis
•Age at which kidney failure develops in PKD patients ranges from three to 10 years of age, average is seven years of age
•But the high prevalence of PKD in Persians, Himalayans and Exotic Shorthairs makes this an important cause of kidney failure in cats, especially when we consider that over 40,000 Persians are produced by breeders every year in the United States alone
•So far, only very low rates of PKD have been reported in other breeds at risk, which include: Scottish Folds, British Shorthairs, and Birmans. In the past, Persians were allowable outcrosses for these breeds and so the PKD gene may have been introduced into some bloodlines. 
•Criteria for diagnosis of PKD with ultrasound:

o Experienced ultrasonographer with good quality machine, transducers of 7.5 to 10 MHz (7.5 MHz for adults, 10 MHz for kittens)
o Minimum 9-10 months of age; each kidney scanned carefully in two planes 
o Multiple cysts in both kidneys; presence of cysts in one kidney only, especially in a high risk breed, is strongly suspicious for PKD and the cat should be re-scanned when older

•On an x-ray, it may be possible able to see the enlarged kidneys in some patients 
•At post mortem, the kidney can be markedly misshapen, variable in size, and contains multiple cysts; the cysts may not be visible on the surface of the kidney, so examination must be done carefully, the pathologist must make several slices through the kidney to identify milder cases
•The laboratory of Dr. Leslie Lyons, University of California-Davis, found the mutation responsible for feline PKD in 2004; a genetic test performed on cheek swabs or by blood is available since 2005.
•A genetic test will make it possible for breeders to identify affected cats very accurately and at a very young age 
•Advice for breeders: 

o PKD genetic test: test breeding stock of unknown status and test any new cats being added to a breeding program
o Ultrasound: scan all breeding stock by 10 months of age; may be wise to re-scan at 2 years of age or older because a few cats with mild PKD will not be detected at 10 months 
o To eliminate PKD from bloodlines, it is best to breed only normal cats

•A good website for PKD information: www.felinepkd.com

by Susan Little, DVM Diplomate, American Board of Veterinary Practitioners, Certified in Feline Practice

Do you have a Traditional Doll Face cattery who tests on PKD by  DNA? Please let us know! Contact us by e-mail

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Feline Hip Dysplasia (HD) and Patellar Luxation (PL)

•Although little information is known about feline HD compared to canine HD, reports of HD in cats date back to at least the 1960s
•Recent research shows feline HD is more common than once thought
•Feline HD is similar to canine HD in some ways:

o It is a developmental malformation of the hip joint
o It is not congenital (not apparent at birth)

•Most cats with HD are asymptomatic, and are often diagnosed incidentally when x-rays are taken for other reasons
•One study showed a potential link between HD and patellar luxation (dislocating kneecaps) in cats
•Males and females are equally affected 
•Studies done in the United States show some breed predispositions:

o Devon Rex (about 40% affected)
o Persian/Himalayan (about 20% affected)
o Maine Coon (about 23%)
o Non-pedigreed cats (about 5.8% affected)

•HD is assumed to be an inherited trait in cats, likely polygenic; the role of environmental factors (ie. breed, size, diet, growth rate, etc) is unknown
•Clinical Signs of hip dysplasia:

•Physical findings and x-ray findings do not necessarily correlate: cats with severe HD on x-ray may not have any clinical abnormalities or pain 
•Conservative therapy for HD and degenerative joint disease (DJD): 

o Weight reduction if obese 
o Avoidance of activities that worsen pain and lameness
o NSAIDs: aspirin, ketoprofen, meloxicam; used with caution in cats and only under veterinary supervision
o Neutraceuticals: (Adequan, Cosequin, Glycoflex) have become popular with pet owners, perceived to have low risk of adverse effects, no controlled trials have evaluated their use for treatment of chronic DJD 
o Corticosteroids: such as prednisone are controversial for treatment of DJD since they have negative effects on cartilage metabolism; may be best to leave to last resort 

•Surgical therapy for HD and degenerative joint disease (DJD): considered when conservative management fails, or when owner perceives quality of life is unacceptable 


o Goal is to relieve pain and restore mobility 
o Best surgical technique is femoral head and neck ostectomy (FHO); also called excision arthroplasty 
o Cats do very well post-operatively; experience pain relief and return to normal function


•Good website for feline HD information: www.winnfelinehealth.org/health/hip-dysplasia.html

by Susan Little, DVM Diplomate, American Board of Veterinary Practitioners, Certified in Feline Practice

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