30 May 2019 | Animal health
Why should we check the eyes of older dogs?
It would be very surprising if we humans did not get our eyes checked regularly over our lifetime, so there is no reason why our dogs should be treated any differently, especially as many of the ageing changes are common to both dogs and humans
It would be very surprising if we humans did not get our eyes checked regularly over our lifetime, so there is no reason why our dogs should be treated any differently, especially as many of the ageing changes are common to both dogs and humans and the eye can be a useful indicator of systemic disease.
The Eye Scheme, run by BVA, the Kennel Club (KC) and the International Sheep Dog Society (ISDS), is a screening programme for identifying inherited and non-inherited ocular conditions in dogs. The majority of dogs presented for examination under the Eye Scheme are pedigree dogs with known inherited diseases of the eye, but it is important to emphasise that all dogs, including crossbreds, can be examined under the scheme.
The Eye Scheme
The Eye Scheme includes examination and certification of older dogs (over 8 years of age). This is an excellent means of checking that:
- the dog remains free of the inherited eye diseases listed for the breed being examined under Schedule A of the Eye Scheme (127 KB PDF)
- no late onset potentially inherited conditions are emerging in older animals
- age-related ocular and generalised disease of potential or actual significance is absent
As an extra incentive, older dogs are examined and certified at a reduced fee of £32 including VAT.
All the non-congenital conditions listed under Schedule A have a variable age of onset. For example, some forms of generalised progressive retinal atrophy and hereditary cataract may first be identified in older dogs that have already been used for breeding. In order to provide the longitudinal information that owners and breeders need it is particularly important to examine these dogs under the Eye Scheme, as this will help to establish lines that are genuinely free of inherited eye disease and enable breeding programmes to be better informed.
Ocular changes in older dogs
Normal ageing changes in dogs include senile nuclear sclerosis of the lens because the lens continues to grow throughout life and its central portion, the nucleus, becomes denser and greyish over time. Although the grey appearance is of concern to some owners, senile nuclear sclerosis has little apparent effect on vision.
Some age-related retinal changes accompanied by deterioration of vision do occur, but such age-related retinal changes in dogs cannot be compared with age-related macular degeneration in humans. Dogs do not have a macula and their retina is dominated by rods (concerned with night vision), rather than the cones (colour vision and visual acuity) that populate the macular area in human eyes.
Local ocular changes in older dogs that are of actual, or potential, clinical significance include:
- Adnexal changes (for example, eyelid tumours)
- Cataract formation (many causes other than hereditary cataract, simple ageing being the most common)
- Glaucoma (a damaging rise in intraocular pressure) – see the Canine Health Schemes primary glaucoma and goniodysgenesis leaflet (28 KB PDF)
- Neoplasia (for example, melanomas in a variety of ocular sites)
- Inflammatory changes (for example, active and inactive lesions of the ocular fundus caused by the common roundworm Toxocara canis)
Generalised disease with ocular manifestations
Generalised problems in older dogs, which may present with ocular manifestations, include:
- Systemic hypertension (raised blood pressure), commonly as a consequence of kidney disease (usually chronic renal failure), but also associated with hyperadrenocorticism (Cushing’s syndrome), diabetes mellitus and pheochromocytoma (a rare tumour of the adrenal gland)
- Haematological abnormalities (for example, anaemia, defective clotting)
- Various metabolic diseases, for example, hyperadrenocorticism, diabetes mellitus and hypothyroidism, all of which may be associated with ocular manifestations of hyperlipidaemia (raised circulating fat levels) in addition to the hypertensive changes already mentioned for hyperadrenocorticism and diabetes mellitus
- Disseminated infection (for example, associated with bacteraemia and sepsis)
- Neoplasia (for example, multicentric lymphoma and other malignant metastatic tumours)
Clearly, quite apart from the benefits of obtaining a more accurate picture of breed-related and inherited disease in older dogs, it is very helpful to identify ocular and generalised problems that may require treatment, because early diagnosis is a crucial part of successful management.
You can also download the following CHS leaflets:
- Hereditary eye disease in dogs (1.5 MB PDF)
- DNA testing for inherited eye diseases in dogs – FAQ’s (106 KB PDF)
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