Origin of the cat breed: Siam (Thailand)

Cats Coat: Short and tight coat

Color of cat: Body pale milky or beige with mask ears, tail, and feet another color

The color is always restricted to points: seal, chocolate, blue or lilac mask, ears, tail and feet. The body is of medium size with a long, tapering, wedge shaped head. The eyes are almond shaped. These are muscular but slender cats with a whiplike tail. The Siamese is usually a noisy and demanding cat that does not like to be left alone. A very popular cat, it is totally unpredictable.


Cardiovascular conditions

Dilated cardiomyopathy

• Less common than in the past

• Genetic factors may influence susceptibility to disease

• Males predisposed

Endocardial fibroelastosis

• Age of onset: <6 months

• May be familial in this breed

Patent ductus arteriosus

• A possible slightly increased predisposition for this condition in this breed has been suggested

• Familial

• No sex predisposition in cats

Persistent atrial standstill

• Uncommon disease

• Marked predisposition in this breed

Dermatological conditions

Cutaneous tuberculosis

• Rare unless there is a high degree of exposure


• See under Infectious conditions


• See under Infectious conditions


• Rare

Generalised demodicosis

• Rare in cats

• Usually less severe in cats than in dogs

Food hypersensitivity

• Siameses and Siamese crosses accounted for 30% of cases in two studies

• Odds ratio 5.0

Systemic lupus erythematosus

• Rare in cats

• No age or sex predisposition

Feline pinnal alopecia

• Cause unknown

Junctional epidermolysis bullosa

• Claw shedding noted

• Autosomal recessive inheritance likely

Congenital hypotrichosis

• Familial

Feline acromelanism

• Temperature-dependent enzyme involved in pathogenesis


• Presumed to be hereditary

Periocular leukotrichia

• Bilateral

• No age predilection

Aguirre syndrome

• Unilateral periocular depigmentation

• May be associated with Horner’s syndrome, corneal necrosis and upper respiratory tract infection

Psychogenic alopecia

• Thought to be a result of anxiety


• Uncommon

• Entire males predisposed

• Mainly affects cats <4 years old

Eyelid coloboma

• Congenital

Skin tumours

• See under Neoplastic conditions

Drug reactions


• Anecdotal reports suggest a predisposition to side effects with this drug in this breed

Endocrine conditions

Parathyroid tumours (resulting in primary hyperparathyroidism)

• Rare

• In a report of seven feline cases, five were Siamese

• Older cats affected


• Rare disease

• In three reported cases where signalment was included, all were male Siamese and the average age was 14 years

Gastrointestinal conditions

Cleft palate

• Congenital disorder; familial occurrence in this breed

Congenital idiopathic megaoesophagus

• Breed predisposition

Pyloric dysfunction

• Breed predisposition

Small intestinal adenocarcinoma

• Possible breed predisposition

• Seen in older cats

Tail sucking

• Psychogenic disorder

Congenital portosystemic shunt

• Usually extrahepatic shunts


• Familial

• Age of onset: 1-4 years

• Amyloid deposits are found mainly in the liver and thyroid glands, resulting in clinical signs of cachexia, jaundice and occasionally liver rupture. This may be another example of systemic amyloidosis.

Haematological conditions

Haemophilia B

• Factor IX deficiency

• Also known as Christmas disease

• Inherited as a sex-linked trait

• Less common than haemophilia A

Hereditary porphyria

• May be anaemia with renal failure in this breed

Infectious conditions

Mycobacterium avium

• Rare condition

• Possible breed predisposition


• Rare condition in cats. Most reported cases have been in this breed

• Geographic distribution: around the Mississippi, Ohio, Missouri, Tennessee, and St Lawrence Rivers, the southern Great Lakes, and the southern mid-Atlantic states. Not reported in the UK


• Uncommon


• Rare

Infectious skin disease

• See under Dermatological conditions

Musculoskeletal conditions

Cleft palate/lip

• See under Gastrointestinal conditions

Hip dysplasia

• Case reports suggest an over-representation of Siamese with hip dysplasia

• Heritability in cats poorly understood

Congenital myasthenia gravis

• See under Neurological conditions

Mucopolysaccharidosis VI

• Lysosomal storage disease

• Inherited as an autosomal recessive trait

• Causes dwarfism and multiple skeletal, neurological and retinal deficits

Neoplastic conditions

Mast cell tumours

• Possible breed predisposition

• Usually seen in cats > 4 years

• There are reports of two litters of Siamese kittens with cutaneous mast cell tumours. One litter was 6 weeks and the other 8 weeks at diagnosis. In all kittens the lesions had disappeared at 4 months


• Usually occurs in animals older than 8 years

Basal cell tumour

• Reported to be at increased risk

• Average age is 7-10 years

Sweat gland tumour

• Reported to be at increased risk

• Average age reported as 11.6 years

Nasal cavity tumours

• Reported to be at increased risk

• Average age reported as 8-10 years

• A predisposition for neutered males has been suggested

Parathyroid tumours (resulting in primary hyperparathyroidism)

• See under Endocrine conditions


• See under Endocrine conditions

Small intestinal adenocarcinoma

• See under Gastrointestinal conditions

Mammary tumours

• Possible breed predisposition

• Seen in older cats (mean age 10-12 years)

Neurological conditions

Congenital vestibular disease

• Signs seen < 3 months

Congenital deafness

• Signs seen from birth


• Congenital; inherited as an autosomal recessive trait

Lysosomal storage disease – GM1 gangliosidosis

• Autosomal recessive inheritance

• Rare

• Signs seen at 3-6 months

Lysosomal storage disease – ceroid lipofuscinosis

• Inheritance suspected

• Rare

• Signs seen at 6-12 months

Lysosomal storage disease -sphingomyelinosis (Niemann-Pick disease)

• Autosomal recessive inheritance

• Rare

• Signs seen at 3-6 months

Lysosomal storage disease -mucopolysaccharidosis type VI

• Autosomal recessive inheritance

• Rare

• Signs seen at 2-3 months

Hyperaesthesia syndrome

• Breed predisposition

Congenital myasthenia gravis

• Has been reported

• Age of clinical onset: 5 months

Ocular conditions

Convergent strabismus and nystagmus

• Congenital condition found in this breed

• Results from abnormal visual pathway development

Corneal sequestration

• Breed predisposition


• Breed predisposition

Congenital cataract

• Has been reported in this breed


• Rare condition; reported in this breed

Retinal degeneration

• Inheritance suspected

• Seen in older cats (10 years) in the UK

Lysosomal storage diseases

• Autosomal recessive inheritance

• Rare

• Types affecting ocular tissues: GMj gangliosidosis, mucopolysaccharidosis VI

• See under Neurological conditions

Physiological conditions

Blood group

• In the USA 100% of Siamese reported to be group A

Respiratory conditions

Feline asthma

• Common

• Affects all ages


• No sex predisposition

• This breed over-represented in one study

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