murmur may be heard by your vet when he or she listens to your kitten's heart. A
heart murmur is caused by turbulent blood flow within the heart or the large
vessels exiting from the heart. This results in an abnormal noise which can be
heard by your vet when listening with a stethoscope. Kittens that might have a
heart murmur should not be put under anesthesia, and surgery to spay and neuter
should be put off until they are 5-6 months of age.
One type of innocent
heart murmur is often found in young growing kittens, particularly kittens that
are growing rapidly. The murmur may first appear at 6-8 weeks of age, and a
kitten with an innocent heart murmur will usually outgrow it by about 4-5
months of age. This type of murmur is benign. Some normal adult cats may have
an intermittent heart murmur that shows up when their heart rate is increased
due to stress. This type of physiologic murmur disappears when the heart rate
is normal, and has no impact on the cat's health.
In general, a
physiologic or innocent heart murmur will have a low intensity (usually Grade
I-II out of VI), and does not cause any symptoms or clinical signs. The
symptoms associated with murmurs depend on a variety of characteristics,
including their grade, configuration, and location. If, however, the murmur is
associated with structural heart disease, your cat may display signs of
congestive heart failure such as coughing, weakness, or exercise intolerance.
Grading Scale for Murmurs
II—soft, but easily heard with a stethoscope
III—intermediate loudness; most murmurs which are related to the mechanics
of blood circulation are at least grade III
IV—loud murmur that radiates widely, often including opposite side of
V—very loud, audible with stethoscope barely touching the chest; the
vibration is also strong enough to be felt through the animal's chest wall
VI—very loud, audible with stethoscope barely touching the chest; the
vibration is also strong enough to be felt through the animal's chest wall.
Heart murmurs are assessed and graded according to
certain criteria. Grades I-VI are recognized, with Grade I being the most mild,
and Grade VI 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.
The grade of the heart murmur does not necessarily
relate to the degree severity of the underlying heart problem. Some severe
heart conditions may not be associated with any heart murmur at all, and some
quite loud murmurs may occur with relatively small defects.
Although the presence of a murmur usually implies an
underlying heart condition, murmurs can sometimes have other causes. In young
kittens, so-called 'innocent' heart murmurs may be heard as an incidental
finding. These are usually no longer present when the kitten is older. An
innocent or physiologic heart murmur is a heart murmur that has no impact on
the cat's health.
Hypertrophic Cardiomyopathy (HCM) is the
most common cause of heart disease and the most frequent cause of spontaneous
death in indoor adult cats. In cats with this condition, the walls of the
ventricles become thick. However, because the muscle fibers are replaced by
fibrous connective tissue (scar tissue), the thicker heart walls do not
translate into increased pumping power. In fact, the heart is actually weakened
as the affected wall of the heart becomes less elastic and the heart chambers
Early signs of hypertrophic cardiomyopathy
are vague and indefinite. Increased heart rate and a murmur are common signs.
Decreased appetite, weight loss, and an increase in respiratory rate may all be
noted. Loss of pep and appetite and reduced exercise tolerance may go
unnoticed, because cats are able to recognize their own physical limitations
and restrict their activities accordingly. Other than possibly hearing a heart
murmur, it is unusual to detect heart disease before signs of congestive heart
failure. The first and only sign may be sudden death. (WebMD for cats)
The breed-specific mutation for HCM in
Ragdoll cats produces early onset of the disease with average age at
diagnosis of 15 months. It also appears that homozygotes (2 copies) for
the mutation have an earlier age of onset of disease than heterozygotes (1
copy). The mutation, known as R820W, is a single base pair change in MYBPC3 that
is thought to alter the shape and function of this essential protein for normal heart
muscle development. The same R820W mutation has been recently found to be
associated with HCM and left ventricular non-compaction in humans (see
reference below, Ripoll et al. 2010. Veterinary Genetics Laboratory UC Davis)
MPS VI & VII
Mucopolysaccharidosis VI severe (MPS VIs) and mild (MPS VIm) are lysosomal storage diseases resulting from two
independent mutations in the gene for enzyme N-acetylgalactosamine 4-sulfatase
(4S). Both are inherited as autosomal recessives, thus males and females
can be equally affected if they carry 2 copies of the defective gene. Cats with
2 copies of the severe form show signs at 6-8 weeks of age that include wide
faces, shortened noses, small ears, reduced flexibility and retarded growth
compared to unaffected littermates. By 8 months of age, problems of
severe hind-limb mobility or paralysis, and signs of degenerative joint disease
can be observed. Clinically, urine samples show increased levels of dermatan
sulfate (DS) and an increase in white blood cell granules. Organs and
tissues can also be compromised by accumulation of intercellular DS. Additional
effects of the disease include corneal clouding and heart valve thickening.
Cats with two copies of the mild form disease (MPSVIm) have less 4S enzyme and
form granules in the white blood cells but otherwise appear healthy. The
same is true of cats with one copy of the mild form and one copy of the severe
form. Cats with only one copy (carrier) of either mutation and one copy of the
normal gene appear healthy. Breeding two carriers together is predicted
to produce 25% affected offspring and 50% carriers of the disease. Breeds
at risk for MPSVIs and MPSVIm are Birman, Ragdoll, Siamese and related breeds,
Mucopolysaccharidosis VII (MPS VII) is a progressive, autosomal recessive disorder resulting
from a single mutation in the GUSB gene that produces lysosomal enzyme
B-glucuronidase. Disruption of this enzyme results in dermatan sulfate,
heperan sulfate and chondroitin sulfate accumulation. By three
months of age affected cats show clinical signs that include gait
abnormalities, possibly due to muscle weakness, as well as bone abnormalities,
disproportionate skull to body ratio, plump paws and corneal clouding, among
other defects. Most affected animals must be euthanized by 6 months. Males
and females are equally affected and carriers are normal and without sign of
the disease. MPS VII has been reported in random bred cats (Veterinary Genetics Laboratory UC Davis).
Polycystic Kidney Disease (PKD) is
an inherited disease
Primarily found in Persian cats,
related breeds, and cats with Persian
ancestry. Other forms of PKD occur in
other animals, and in humans. Feline polycystic kidney disease has been
reported occasionally in the scientific literature since 1967, but actual
study into this disease did not begin until 1990. In 2004, the mutation
responsible for PKD in Persians and cats with Persian ancestry was
identified. Multiple cysts develop in both kidneys, sometimes leading to
chronic kidney insufficiency or failure. Rarely, cysts are also seen in
other organs such as the liver and uterus. Problems occur when these cysts start to grow and
progressively enlarge the kidney, reducing the kidney's ability to
function properly. Some of the signs of kidney insufficiency are increased
thirst, increased urination, decreased appetite, weight loss, vomiting,
and lethargy. Cats affected by kidney insufficiency due to PKD are usually
identified when they are between three and ten years of age. They are treated
as for any other cause of chronic kidney disease as no specific treatment
for PKD is available. PKD can be diagnosed by ultrasound of the kidneys.
There is also a genetic test for PKD in Persian cats and cats with Persian ancestry (Winn Feline
Retinal Atrophy (PRA) in Abyssinian, Somali and
some Ocicat breeds, is an inherited late-onset blindness condition has been
identified and is characterized by progressive degeneration of the
photoreceptors (rods and cones) in the retina. This disease has been designated
"rdAc". Cats affected with this form of blindness have normal
vision at birth, with degeneration first detected by electroretinographic (ERG)
exam at about seven months of age. Vision loss progresses slowly and is
variable, with most cats becoming blind by usually 3-5 years of age.
There is no treatment available for the condition. This is an autosomal
recessive condition, thus the disease is not associated with gender and two
copies of the mutation are required for the cats to lose their vision.
Carriers, cats that have one copy of the mutation, are not affected and have
normal vision (Veterinary Genetics Laboratory UC Davis).
FELINE BLOOD GROUPS
There are three feline blood types: A, B and AB. The A type is the most common in cats. The prevalence of type B blood differs by breed. There is a high occurrence of Type AB in the Ragdoll Breed. Cats have naturally occurring antibodies ( a protein made by the body's immune system that latches onto foreign particles, such as viruses, bacteria, other proteins, to make them ineffective by destroying them) to antigens (foreign proteins) not on their erythrocytes. Erythrocytes are Red blood cells (RBCs). In medical terminology, erythro- means red, while -cyte means cell. Erythrocytes are red and consist of a protein called hemoglobin, which contains red iron. This is why our blood is red in color. Erythrocytes are round and perform two functions of gas exchange: transport oxygen and remove carbon dioxide.
Cats with type A blood have antibodies to type B antigens, and cats with type B blood have antibodies to type A antigens. Cats with type AB blood have both A and B antigens on the erythrocyte membrane and do not have naturally occurring antibodies to either type A or B blood. Cats with the rare "AB" type do not have anti-A or anti-B antibodies and are thus universal recipients for blood transfusion.
Cats that are transfused, even once, with an incompatible blood type, are at risk for a transfusion reaction. Cats with B erythrocytes exhibit an immediate and catastrophic systemic reaction when transfused with type A blood, because of their natural high anti-A antibody Death is extremely likely.
Cats with A erythrocytes and natural low anti-B antibody will exhibit only a mild reaction when transfused with type B blood, but the transfused cells will have a shortened life span. The recipient will develop moderate concentration of anti-B antibody that will result in a serious reaction if a subsequent incompatible transfusion is administered. If there is a need to treat a blood disorder or trauma, knowing the patient’s blood type can help prevent an emergency.
Serious problems can result from accidental or mismatched mating.
A mating of a type B queen with a type A tom will result in their type A kittens being at risk for neonatal isoerythrolysis (“NI”), commonly known as “fading kitten syndrome”. The maternal naturally occurring, highly concentrated anti-A antibody occurs in the colostrum (mother's milk) where it can be absorbed by the newborn kittens. The absorbed antibody attacks the kittens’ type A erythrocytes. Although the kittens can seem normal at birth, they develop signs after nursing, fade and die within the first days of life. Determining the blood type of the queen and the tom prior to mating,can minimize the risk of NI. Furthermore, immediate blood type determination of the newborn kittens will alert the breeder to remove the kittens and to begin surrogate nursing where necessary.
• All cats should be blood typed.
• No cats should be mated before blood typing.
• All kittens resulting from incompatible matings should be blood typed at birth so that surrogate nursing can be started where necessary and the kittens allowed to thrive.
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