Glycogen storage disease type IV in cats (GSD IV): symptoms, treatment and prevention

Glycogen storage disease type IV in cats (GSD IV): symptoms, treatment and prevention

Glycogen storage disease type IV is a extremely serious genetic disease, fortunately rare, which leads to the death of most affected kittens in just a few hours after birth, the other victims of GSD IV also eventually dying following the progressive deterioration of their condition. This pathology exclusively affects Norwegian cats, one of the most robust feline breeds. Spotlight on the GSD IV for which there is no no treatmentits symptoms, its mode of transmission, its diagnosis, and see if it is possible to eradicate this disease through prevention.

Feline glycogen storage disease type IV: symptoms

A Norwegian cat affected by this genetic disease presents the following different symptoms:

    • Hyperthermia that persists despite taking an antibiotic or a corticosteroid,
    • Tremors of the whole body and limbs,
    • contractions,
    • A discontinuous apathy,
    • A gait made difficult and unsafe due to the rapid atrophy of the kitten’s muscles,
    • Paralysis of the front and rear limbs, none being spared,
    • cardiac decompensation,
    • A comatose stage.

Kittens affected by glycogen storage disease type IV die very quickly after they are born, except for a few. But these are doomed to certain death at most within a few months.

GSD IV (glycogen storage disease type IV): transmission

The mode of transmission of this genetic disease depends on the status of the breeding cats (male and female). So :

    • The cat born of parents both non carriers of a mutated gene copy cannot strictly not be a carrier. Consequently, there is no risk that he will transmit GSD IV to his offspring.
    • The cat has a 1 in 2 chance of being a carrier and of transmitting GSD IV if it is from a non-carrier cat and a carrier cat of a mutated gene copy. The disease does not develop but can be transmitted to its offspring.
    • The cat born of two parents each of which carries a copy of the mutated gene a:
        • 1 in 4 chance of not being a carrier,

       

        • 1 out of 2 chance of being a healthy carrier, note that two healthy carrier parents statistically generate 1 healthy kitten out of 4, or 25% of their offspring.

       

        • 1 in 4 chance of carrying both copies of the mutated gene, thus being able to fall ill. Either the disease progresses gradually and death occurs between 8 and 14 months

       

Every owner of a Norway cat should know that the dead East inevitable if the animal is mutated homozygote that is, if it is carrier of two mutated genes. It occurs within hours or at the latest within days following birth in most mutated homozygotes. In the others, up to a maximum of 7 months of age, the phenotype is normal, but the disease evolves gradually thereafter, these kittens then all without exception show the revealing symptoms. Death inevitably occurs between 8 and 14 months, but very often these cats are euthanized before this age.

At present, we do not know the frequency of healthy carrier Norwegian cats at European level. On the other hand, it is established that in the United States, it is 15%.

Feline glycogen storage disease type IV: diagnosis

GSD IV was first described in the United States in 1992 by the Professor Fyfe who, in 1996, developed screening tests after having sequenced the mutation in question. Today, with some hindsight, it is presumed that in France, Norwegian cats who died of an unidentified disease were probably suffering from glycogen storage disease type IV.

In France, the availability of this genetic test is very recent. It is carried out thanks to the removal with the brush of buccal cells. It is very quick to perform and causes no discomfort or pain. It allows to search in the cat for the presence of the GBE1 mutation (GBE is a deficient enzyme in glycogen storage disease type IV). It is also essential to detect a healthy carrier. This is very important since these cats reach adulthood and therefore can reproduce, which represents a great danger for this feline breed.

Of the Additional tests are done. The veterinarian is looking for a noticeable increase in creatine kinase level (CK) in the blood, which confirms muscle involvement. Indeed, CK is a specific enzyme that plays a role in muscle contraction.

Currently, it doesn’t exist no treatment which can treat cats suffering from glycogen storage disease Type IV.

Glycogen storage disease type IV: prevention

To prevent transmission of GSD IV from generation to generation, Norwegian cat breeders have a responsibility to get tested each of their cats as well as the offspring that are intended for breeding. Similarly, it is necessary to test a newly arrived Norwegian cat in a breeding and to ensure that it has been sterilized. Otherwise, do not wait to regularize the situation. Necessarily, any cat detected and then recognized as a carrier must imperatively be sterilized. Finally, if you want to organize a mating between one of your cats and a cat outside your own breeding, it is crucial to find out beforehand about the status of the latter.

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