PRESENTING SIGNS

Entropion is an in-rolling of the lid margin such that hairs rub against the cornea. Cases typically present young, 4–12 months of age, and although sometimes unilateral the potential for both eyes to become affected is high. Normally the patient will have a painful watering eye and this is why the owner will come to see you. Signs of irritation are usually present with attempts at rubbing and sometimes the animal will be head shy. Pedigree dogs are most commonly affected and a wide variety of types of entropion is encountered depending on the anatomical weakness with each particular conformation. Thus, in sporting breeds such as the Labrador retriever, Weimaraner and other gundogs, the lateral half of the lower lids is typically affected. In giant breeds such as the Great Dane and St Bernard a combination of upper lid entropion laterally plus medial and lateral entropion with central ectropion of the lower lid is common – so-called diamond eye. The Shar Pei often has 360 degree entropion and can present with problems at 2–3 weeks of age, immediately after the eyelids have opened. Older cocker spaniels suffer from facial droop with an upper lid entropion and trichiasis (atonic entropion). Brachycephalic breeds, including Persian cats, suffer from a medial entropion of the lower lid. The list could go on and on! Secondary entropion should not be overlooked – any trigeminal pain can result in blepharospasm which can progress to entropion.

CASE HISTORY

Typically the history is of mild ocular discomfort and wetness for several weeks, possibly intermittently initially (worse when the animal is tired) but with progression to quite obvious blepharospasm such that the dog does not hold the eye fully open at any time. Occasionally owners will have already tried treating the dog which might have become very head shy and resent any further intervention.

CLINICAL EXAMINATION

No abnormalities are present on general clinical examination but before doing this, and prior to handling the patient at all, it is important to assess the eyes from a distance. This will reveal the true degree of blepharospasm and discomfort before it is exacerbated by the hands-on examination. Evidence of bilaterality, the nature of any discharge and self-trauma should be visible before holding the animal for examination. The discharge is typically serous in nature and present both at the classic medial canthal area but also extending along the area of eyelid in-turning. During the ophthalmic examination care must be taken not to pull the facial skin out of position too much as eyelid position can be dramatically altered, especially in breeds with loose skin on their faces.

Menace responses should be normal providing the dog is able to open its eyes sufficiently to be assessed! However, they might trigger an intense blepharospasm such that further examination is difficult. Providing there is no evidence of keratoconjunctivitis sicca (in which case a Schirmer tear test should be performed first), a drop of topical anaesthetic can be applied to the cornea to relieve the trigeminal pain and ease further examination. This will also remove any spastic component to the entropion such that the degree of anatomical entropion can be assessed. The lid margin will typically be wet, and is often slightly depigmented along the area of inversion (Figures 5.1 and 5.2). It can be gently rolled out but will immediately start to roll inwards again. Many dogs will have elevation of their nictitans membranes and possibly some degree of enophthalmos as a result of chronic corneal pain and this should also be reduced following the application of topical anaesthesia. Conjunctival hyperaemia will be present and varying degrees of corneal damage will be noted. This can range from very slight irregularity of the corneal epithelium, fine superficial vascularization, overt ulceration of differing depths and scarring and granulation tissue. In very severe cases of entropion, particularly in young Shar Pei puppies, the rubbing from the eyelid hair can have been so severe as to cause almost total corneal granulation or sometimes corneal rupture (see Case example 5.1).

Figure 5.1 Ten-month-old Rhodesian ridgeback with typical lower lid entropion.

Figure 5.2 Same dog having gently pulled down the lower lid. Note the wetness along the hairs and the depigmentation of the lid margin.

In addition to assessing the position of the eyelids it is important to consider the canthi, especially in large breed dogs. Normally the medial and the lateral canthus should be in the same horizontal plane, but with laxity at the lateral canthus – for example, in giant breeds with ‘diamond eye’ – this can slip ventrally giving a sloping appearance to the palpebral fissure (Figure 5.3). The skin at the lateral canthus can be rolled in (lateral canthal involution) which is common in breeds with large skulls such as Rottweilers and retrievers, especially male dogs, and is due to a tight and abnormally positioned lateral canthal ligament. This sometimes needs addressing along with the entropion, discussed in the case below (see Case example 5.2).

Figure 5.3 Eight-month-old Neapolitan mastiff with severe ‘diamond eye’.

Other ocular abnormalities such as distichia might accompany the entropion and it is essential to determine whether they are significant in the pathogenesis. Similarly, if a corneal ulcer is present this might have been the primary problem, with entropion developing secondary to the trigeminal pain. Secondary entropion can follow from corneal sequestrum formation in cats (Figure 5.4). A mild reflex uveitis might be noted on intraocular examination but often the rest of the examination is unremarkable.

Figure 5.4 Large corneal sequestrum with lower lid entropion in an 8-year-old domestic short haired cat. Did the sequestrum cause the entropion or vice versa?

CASE WORK-UP

Minimal work-up is required since the entropion can be easily diagnosed on clinical examination and the use of topical anaesthesia will assist in determining the degree of spastic versus anatomical entropion. If the lid inversion is purely due to trigeminal pain, then this will be resolved fully following the application of two drops of topical anaesthetic 30 seconds apart. If it is still not clear how significant the entropion is, then temporary everting sutures can be placed under general anaesthesia (see below).

EPIDEMIOLOGY

Most cases of primary entropion are breed related, with an inherited component. It is not uncommon for several related animals to be affected with entropion and breeding from such individuals is to be discouraged. Unfortunately some breeders, particularly those of the Shar Pei, seem to consider it ‘normal’ for puppies to require eyelid tacking at only a few weeks of age followed by sharp surgery when only a few months old. This attitude – that the condition is not severe and easily managed by surgery with few long-term sequelae, such that it is not really important – is a worrying trend among some breeders who deliberately choose animals with poor eyelid anatomy for breeding simply because that is the way they like the animals to look. Although the specific inherited factors contributing to entropion have not been identified, and a multifactorial aetiology is likely (as with hip dysplasia), the strong breed predisposition justifies advising against breeding from affected individuals and breed clubs should be encouraged to try to reduce the incidence of the condition in their particular breed.

The wide variation in skull shape, eye size, skin thickness and actual globe positioning all contribute to the development of entropion. There is a complex relationship between the relatively weak tarsal plate (which should provide support and eyelid rigidity), pressure on the lids from the globe, tone within the orbicularis oculi muscle and the length of the palpebral fissure, all of which interact and result in eyelid involution. Some patients have a very mild, borderline entropion, which is only intermittent and causes minimal clinical signs until they develop ocular pain for another reason such as a corneal ulcer, which then causes blepharospasm and ‘tips the balance’, such that the entropion then becomes more severe and needs addressing as well as the ulcer.

Secondary entropion due to spasm in the orbicularis oculi muscle results from many painful ocular conditions, particularly if chronic or not correctly treated. In such cases surgical repair of the entropion will only result in temporary improvement and careful re-examination will be necessary to elucidate the underlying problem.

TREATMENT OPTIONS – MEDICAL

Medical management alone is not sufficient in cases of primary entropion, and unfortunately many cases of secondary entropion (such as due to corneal ulceration) also require surgery, since once the blepharospasm–trigeminal pain cycle has been established the entropion rapidly becomes permanent and not just spastic secondary to the pain.

The use of topical medication in complicated cases of entropion should be undertaken with caution. As mentioned above, many patients are extremely head shy and resent any attempts at examination, cleaning or medication of their sore eyes. If medicating is becoming a fight each time the owner attempts to do so, then most patients are better off with minimal intervention. Although systemic antibiotics are not usually required following entropion surgery, in complicated cases their judicious use can be beneficial over topical preparations. Systemic NSAIDs are often used as well.

TREATMENT OPTIONS – SURGICAL

For uncomplicated cases of entropion a simple Hotz-Celsus procedure under general anaesthesia, removing an ellipse of skin parallel to the in-turning, is very successful. The steps for how to do this are detailed in Table 5.1. However, we will concentrate on the more complicated cases – and only the more commonly encountered types of these. Some very complex lid abnormalities, such as diamond eye with lateral canthal laxity, might be better referred to an experienced ophthalmic surgeon.

Table 5.1 Steps for performing a Hotz-Celsus procedure

Rottweiler type (Case example 5.1)

Entropion in large-headed breeds, such as the Rottweiler, can be challenging to treat – although on initial examination it might appear as a straightforward lower lid entropion. Unfortunately, this breed, and others with similar anatomy, frequently develops very intense blepharospasm resulting in corneal ulceration in the ventrolateral quadrant (Figure 5.5). This can develop prior to your intervention, or sometimes a few days following a simple Hotz-Celsus surgery. It is not uncommon for the patient to look fine on a 2-day post-surgery check-up, only to return 48 hours later with a very sore eye with ulceration, marked blepharospasm and further entropion – even with the sutures from the initial surgery now rubbing and exacerbating things. Obviously owners are never happy if this situation develops!

Figure 5.5 Fifteen-month-old male Rottweiler. Severe lower lid entropion with marked lateral canthal involution and large ventrolateral corneal ulcer. This photograph was taken after the application of topical anaesthesia. See Case example 5.1.

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