Health

Health testing schemes recommended by the Kennel Club and The Japanese Shiba Inu Club of Great Britain are:

• Primary Glaucoma/PLA (gonioscopy)

• BVA Eye screening scheme

• GM1 Gangliosidosis

• GM2 Gangliosidosis

Primary Glaucoma/PLA (gonioscopy)

Gonioscopy assessment is to assess the drainage angle in breeds susceptible to primary closed angle/angle closure glaucoma and tonometry to measure the intraocular pressure in breeds susceptible to primary open angle glaucoma. This test should be repeated every three years per the BVA’s current advice. Each dog will be scored in the UK as per the below:

Grade 0: Normal iridocorneal angle (ICA) with no/minimal (0%-<1%) pectinate ligament abnormality. Unaffected, normal iridocorneal angle - highly unlikely to develop primary glaucoma. Suitable for breeding.

Grade 1:  1-25% of ICA affected by PLA. Mildly affected - unlikely to develop primary glaucoma. Suitable for breeding.

Grade 2: 26-75% of ICA affected by PLA. Moderately affected - low risk of developing primary glaucoma. Breed specific advice required if breeding considered.

 Grade 3:  >75% of ICA affected, and/or severe narrowing of ICA. Severely affected - highest risk of developing primary glaucoma. Not recommended for breeding. 

In addition to raised intraocular pressure the common clinical signs of acute closed angle glaucoma include pain, episcleral congestion, corneal oedema and a dilated non-responsive pupil. The age at which glaucoma presents will vary between breeds. The drainage channel in dogs cannot be viewed directly and therefore a goniolens is used to assess the eye.

BVA Eye Testing Scheme

The eye testing scheme as provided by the BVA is recommended to be completed annually by a BVA eye panelist. The conditions screened for during these examinations include:

Congenital/Neonatal eye conditions (inherited conditions present at birth):

• (CEA) Collie eye anomaly

• (MRD) Multifocal retinal dysplasia

• (TRD) Total retinal dysplasia

• (CHC) Congenital hereditary cataract

• (PHPV) Persistent hyperplastic primary vitreous

• (PLA) Pectinate ligament abnormality

Inherited conditions that develop later in life:

• (HC) Hereditary cataract

• (PLL) Primary lens luxation

• (POAG) Primary open angle glaucoma

• (PRA) Progressive retinal atrophy

• (RPED) Retinal pigment epithelial dystrophy

Other eye conditions which may be identified during the examination include:

• Distichiasis

• Ectopic cilia

• Trichiasis

• Entropion

• Ectropion

• Combined entropion/ectropion

• Corneal lipid deposition

• Ocular Melanosis

• Persistent pupillary membrane

• Various lens conditions

• Various retinal conditions

• Optic nerve hypoplasia

• Multi-ocular defects

Some signs of potential eye disease include:

• Redness

• Dilated pupil

• Discharge

• Cloudy appearance

Treatment for eye disease will depend on the specific eye disease the dog has.

GM1 Gangliosidosis

GM1 gangliosidosis is an inherited lysosomal storage disorder which affects Shiba Inu type dogs. Dogs with GM1 have a deficiency in the activity of the enzyme beta-galactosidase, which is responsible for breaking down specific carbohydrates in the cells. This results in an accumulation of the ganglioside carbohydrate GM1 in cells, especially in the cells of the brain and nervous system, causing damage to the central nervous system.  Signs of GM1 include:

• Vision loss

• Difficulty walking

• Loss of balance

• Head tremors

• Lethargy

• Weight loss

Affected dogs show signs of GM1 around 5/6 months of age, and the condition is progressive and lethal at around 15 months of age.

GM1 is inherited in an autosomal recessive manner which means that the dog must inherit two copies of the mutated gene (ie one from each parent) to develop the disease. Dogs who inherit a single copy of the mutated gene, from one parent, are not affected but are carriers who may have affected offspring if bred with another carrier.

In the UK, DNA tests can be completed with Laboklin for GM1 via a cheek swab which will be analysed. We would recommend that all results are submitted to the Shiba health survey at https://www.shibahealth.co.uk/gm-health-survey.php where all results will be treated with the strictest confidence. Results will tell you whether your dog is clear, carrier or affected.

GM2 Gangliosidosis (Sandhoff)

GM2 gangliosidos is similar to GM1 however, GM2 is where there is a deficiency in the beta-hexosaminidase enzyme. Beta-hexosaminidase is responsible for breaking down fatty substances called GM2 gangliosides and globosides. The disease pattern normally appears earlier and aggravates quicker compared to GM1. Even though both forms of gangliosidosis have similar symptoms, they are evoked by completely different defects of two specific lysosomal enzymes. These genetic mutations are due to a modification in the genetic code.

Signs of GM2 include:

• Incoordination

• Intention tremor (a tremor that is evident when an affected dog initiates a voluntary movement)

• Dysmetria (disturbance in the control in the range of muscular movement)

• Progressive inability to stand

• Corneal clouding

• Muscle rigidity

Affected dogs have a dramatically shortened expectancy and generally live for 15-16 months.

As with GM1, GM2 is also inherited in an autosomal recessive manner which means that the dog must inherit two copies of the mutated gene (ie one from each parent) to develop the disease. Dogs who inherit a single copy of the mutated gene, from one parent, are not affected but are carriers who may have affected offspring if bred with another carrier.

In the UK, DNA tests can be completed with Laboklin for GM2 via a cheek swab which will be analysed. We would recommend that all results are submitted to the Shiba health survey at https://www.shibahealth.co.uk/gm-health-survey.php where all results will be treated with the strictest confidence. Results will tell you whether your dog is clear, carrier or affected.

If your Shiba develops any other health condition(s) during it’s lifetime, please submit the details to the shiba inu health survey which can be found HERE.