by Michael

The Siamese cat has a long list of genetic diseases; longer than any other purebred cat. This is a shame. It is still in the top three most popular cat breeds probably because the Siamese is loyal and vocal. There is plenty of interaction between cat and person. One of the diseases reported more commonly in Siamese cats than other cat breeds is congenital heart disease:

• Aortic stenosis – aortic valve of the heart does not open fully causing reduces blood flow, which can lead to shortness of  breath and difficulties in breathing.
• PDA – Patent ductus arteriosus – the word “patent” in this instance means “open”. The condition is an open  blood vessel that should have closed after birth.
• Endocardial fibroelastosis – thickening of the heart muscle and replacement with fibrous tissue.
• Atrioventricular valve malformation – malformed heart valve

Signs in kittens with heart defects are:

• kittens are small for their age
• kittens are in poor condition
• they don’t play as much as normal
• kitten tires quickly
• difficulty breathing
• throbbing heartbeat

Left -sided heart failure causes:

• dyspnea – shortness of breath
• rales – crackling noise when inhaling air
• hydrothorax – serous fluid accumulating in the pleural cavity. “Serous” means watery. The pleural cavity is the space between two membranes that line the lungs.

Right-sided heart failure causes:

• distended pulsating jugular veins
• ascites – excess fluid build up in the space between the tissues that line the abdomen and abdominal organs.
• hepatomegaly – enlarged liver.

Briefly, although not a congenital heart condition, a disease called Mucopolysaccharidosis VI is found in Siamese cats. This is a deficiency of arylsulfate B activity resulting in storage of glycosaminoglycan dermatan sulfate. This has serious development consequences:

• skeletal abnormalities such as eyes spaced too far apart, small ears, flattened face, depressed sternum,  flattened chest.
• Kittens are smaller than average with larger forepaws than normal. At five months there are gait abnormalities taking short steps while keeping the head low. These kittens cannot jump normally. A quarter of these kittens have hind legs weakness or paralysis at ten months.

I mention this disease because a visitor asked if there was a sex-linked genetic disease that affects Siamese cats (the male) which causes growth retardation, distended abdomen, paraparesis (partial paralysis of the lower limbs). The disease that I have referred to may be the cause. It appears not to be sex-linked however.

Source: Medical, Genetic & Behavioral Aspects of Purebred Cats – ISBN0-9634124-0-X – pages 155 and 156. Edited by Dr Ross D Clark DVM.

Michael