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October 4, 2014

Normally abnormal: the Mastino Eye

Most people are familiar with the eye as we often peer into them as our dogs beg, train or peer about. But most of what we look at every day in our furry friends, is actually more appropriately classified as the external supporting structures of the eye, or ocular adnexa. These include the eyelids, eyelashes, tear glands, and finally all of the eye muscles.

DogEyeThe eyelids, including the 3rd eyelid or nictitating membrane (a common structure in many animals but missing in the person), function to wipe debris from the surface of the eye and to spread lubrication across the globe. The upper and lower eyelid should close to protect the eye and to shut out light to allow the dog to sleep, the 3rd eyelid  provides an added layer of protection. The third eyelid is also called the haw by many in the dog fancy, a term I have grown to hate since so many appear to confuse the structure of the 3rd eyelid with the inner portion of the eyelid, or conjunctiva, which is also visible in some droopy-eyed breeds. 

3rdEyelid

The eyelashes are located along the outer surface of the external rim of the upper eyelids but not present on the lower or 3rd eyelid or on any other structure of the eye. When the eyelashes are present in abnormal locations or when the eyelids abnormally curl problems can occur.

Which brings me to the Neapolitan Mastiff. The eye of the Neapolitan Mastiff has been the focus of much criticism within the last few years especially in the UK with more than a few kennel clubs around the world changing the standard of the breed.

AKC Standard

Eyes: Set deep and almost hidden beneath drooping upper lids. Lower lids droop to reveal the haw. Eye color: Shades of amber or brown, in accordance with coat color. Pigmentation of the eye rims same as the coat color. Severe Faults: Whitish-blue eyes: incomplete pigmentation of the eye rims

Kennel Club Standard

Eyes: Clean eyes, set forward, well apart, rather rounded. Rims tight without haw. Rim pigmentation to tone with nose colour. Free from obvious eye problems.

Modern ENCI Standard

Eyes: Set on an equal frontal level, well apart one from the other; rather round, slightly deep set. Compared with the coat colour, the colour of the iris is darker. The eye may nevertheless be lighter in coats of diluted shades.

ENCI (1971) – this redrafted standard is very close to the original 1949 standard

The eyelids should normally adhere to the eyeball (neither ectropic, nor entropic). The eyes, situated sub-frontally, are well distanced from one another. The eyelid (palpebral) slit tends to be round nut because of abundant eyebrow skin, it appears to be oval. The eyeball is slightly sunken. Pigmentation of the eyelid edge is black, blue or brown according to the colour of the coat. The colour of the iris blends with the darkest colour of the coat. Faults: Small or prominent, iris (shading) too light in colour in relationship to the coat; eyelids not in subfrontal position, ectropion, entropion; eyes too close – strabism. Partial depigmentation of the eyelids.

These modern standards are a far cry from the ENCI standard of the 1980’s as described by Mario Zacchi’s book, The Neapolitan Mastiff. The move away from this original 1949 standard (re-drafted in 1971 by prof. Fabio Cajelli), represents the move away from more appropriate ocular health and the above Kennel Club standard that was recently revised for health does little to realign the current standards with the more reasonable original standard.

Historically The Neapolitan Mastiff has had consistent ocular anatomical abnormalities since its creation (re-creation) in the 1940’s and 1950’s. Due to the quality of photographs and acuteness of the memory it is hard to get the full scope of the ocular anatomy or tell just how prominent the 3rd eyelid was in these early specimens or the exact conformation of the upper and lower lids.

What is obvious is that even with minimal wrinkle compared to modern Neapolitans, these historical dogs still suffered from the typical abnormalities such as ectropion and macroblepheron, even though their standard called for an eye free of ectropion. Their eye openings ranged from ovoid to rounded, and even with some degree of upper lid wrinkle their eyes remained prominent and clearly visible. What is also different is that even with some obvious eyelid abnormalities, there is no visible corneal scarring, and there is no question if these dogs can actually see.

1960's Neapolitan Mastiff

1960’s Neapolitan Mastiff

Entropion is the condition where the eyelid turns in and the eyelashes or fur can rub against the cornea (outer part of the eyeball) resulting in pain, corneal ulcers or corneal erosions. This corneal damage can also result in corneal scarring, that can interfere with vision.

Ectropion is the condition in which the eyelid, typically the lower eyelid turns out. This leaves the inner surface, the conjunctiva exposed and prone to irritation. Entropion is where the eyelid turns in towards the surface of the eye. This can, but doesn’t always cause irritation and scratching of the surface of the eye.

Macroblepharon is an abnormally large eyelid opening that can leave the inner surface of the lower eyelid, the 3rd eyelid and the surface of the eye exposed and prone to irritation.

The macroblepharon, ectropion and even some versions of entropion do not necessarily cause disease in the dog but by exposing all of the internal tissue of the eye they absolutely can predispose the animal to conjuntivitis. Eyelids that are so significantly abnormal that the eye cannot be closed sufficiently and debris cannot be appropriately wiped away can also predispose an animal to conjunctivitis. And it’s this chronic conjunctivitis that can lead to more serious and painful eye conditions such as keratoconjunctivitis sicca (KCS), corneal ulcerations and corneal erosions.

In the modern Neapolitan Mastiff the weight of the supraorbital wrinkle can lead to excessive heaviness in the upper lid which can predispose a dog to entropion and can occlude the vision. The AKC even promotes this phenotype with their eye description “…almost hidden beneath drooping upper eyelids.” This can be additionally compromised if the frontal anatomy, the stop, is shallow or the skin is thin or the globe is significantly sunken into the skull. The supraorbital heaviness and lower lid weakness is a common eye phenotype in many modern Neapolitan Mastiffs and is often described as a ‘diamond eye’. This diamond shape is a far cry from the more normal round to oval conformation of a dog eye, or the type of conformation described in the original Neapolitan Mastiff standard.

Diamond eye

Diamond eye

While this phenotype is not wrong as per the current breed standards this conformation is far from ideal. This phenotype, especially when found in excess, can predispose the Mastino to eye disease and can ultimately disrupt or impair vision. First and foremost the Neapolitan Mastiff is a guard dog and acute vision throughout the entire life of the dog is critical to achieving this function.

While I will not debate the importance of a healthy functional eye, I do admit that there are other, more pressing, health issues that have more significantly impacted the morbidity and mortality of the breed. The good news is that these conditions are currently being addressed by many breeders around the world. Perhaps now it is time to also address the health and functionality of the eye in the Mastino as it’s long overdue for the breed to get back to the basics.

What can be done right now to start the process towards a better eye? Ophthalmic exams through OFA, BVA or AVA…