Probably one of the more unusual-sounding conditions that can be seen in cats, Chediak-Higashi syndrome is a rare genetic disorder that was first described in humans in the early 1940s, causing albinism, easy bruising and recurrent infections. It is so rare that to date, there are thought to have been fewer than 500 cases worldwide. The discovery was first made in cats in the 1970s but there is no data on the number of cases so far.
In cats, Chediak-Higashi syndrome only affects the Persian breed. And of these, only those with the ‘blue-smoke’ hair colour and yellow eyes. The cause is a defect in a gene that deals with how the body’s cells dispose of waste products. In order to be affected, cats must inherit the faulty gene from both parents. But as the fault is recessive and less likely to be passed on than the dominant allele, the odds of this happening are very low.
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What are the symptoms of Chediak-Higashi Syndrome?
Chediak-Higashi syndrome in cats will cause albinism just like in humans; which manifests as a lighter than normal coat colour and a paler iris. Retinal reflection will appear red as opposed to green. And they are prone to developing cataracts at a younger age than is usually seen, sometimes as young as three months old. They tend to show a sensitivity to bright light because of all these ocular changes.
The disease will also affect both red and white blood cells. In probably the most significant symptom of the condition, the faulty gene will mean that the platelets in the blood do not function properly. Platelets are responsible for the initial clotting of the blood at a site of injury and if they do not do this, affected cats are at risk of excessive bleeding. Even something as benign as a nose bleed or skin graze can end in complications.
In affecting a cat’s white blood cells, the immune system can also be compromised and leave them prone to recurrent and potentially severe infections.
How is Chediak-Higashi Syndrome in cats diagnosed?
Because of the non-specific symptoms of Chediak-Higashi syndrome, it can be difficult to pin-point a diagnosis. However if there are suspicions, a blood sample can be checked to look for abnormal white blood cells with large granules in; a sign of the failure of the waste product removal system of the cells. The number of white blood cells will also be reduced. Skin or muscle samples can also be examined to look for these granules to aid diagnosis. There is currently no DNA test to identify either carriers or affected animals.
How is Chediak-Higashi syndrome treated?
Unfortunately, because it is a genetic disorder, there is no prevention or treatment for Chediak-Higashi syndrome. The main way to help these cats is to look at methods to minimise the impact of the clinical signs. Because of the ocular effects and the lack of pigment in the skin, it can help to keep affected cats indoors to minimise exposure to bright UV light. Keeping them inside can also minimise the risk of injury and exposure to infections. The effect on the cat’s mental health by keeping them inside must be taken into account but indoor enrichment can help alleviate some of the negative impact.
From a veterinary point of view, it is vital that if a cat is known to have Chediak-Higashi syndrome, any interventions such as injections, blood samples and especially surgery must be meticulously planned and in the case of surgery, blood products given beforehand or at least be on standby for use should problems arise. Affected cats ought to be considered immune-suppressed and antibiotics and antiviral medications used in the face of infections where necessary.
Ultimately, cats that have Chediak-Higashi syndrome can potentially live a relatively normal life, particularly if they are not too severely affected. In some cases, the clinical effects could be life threatening but it remains, however, an incredibly rare condition.
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