PRESENTING SIGNS

Blepharitis, inflammation of the eyelids, is seen relatively commonly in general practice but is not always immediately diagnosed as such. Patients are more commonly dogs than cats and the condition is more frequently bilateral than unilateral. Owners report that the dog is irritated by its eyes with frequent attempts at rubbing. Some mucoid or mucopurulent discharge is likely and the owner is also likely to mention that the eyes look red. This can be due to a combination of conjunctival hyperaemia, eyelid hyperaemia and eyelid erosions or areas of ulceration. The condition is most likely to be insidious and gradually progressive in onset, although occasionally acute presentations do occur. Although focal forms, such as chalazia and styes, do occur, we will concentrate on the diffuse cases since the former are typically straightforward to diagnose and treat.

CASE HISTORY

The history will vary somewhat according to the underlying aetiology for the blepharitis. Thus there might be a history of slight conjunctivitis for a few days followed by a marked eyelid reddening and swelling together with a purulent ocular discharge in the case of a staphylococcal blepharitis. There might be a young puppy, less than 3–4 months old, or more than one in a litter, which has swollen eyelids then develops ulceration and crusting around the lids and nose, together with general malaise, pyrexia, inappetance and clearly has developed a juvenile pyoderma. A young Labrador retriever might present seasonally with itchy eyes and foot-chewing associated with atopy. A dog which has recently travelled to Mediterranean countries could present with blepharitis and eyelid crusting together with uveitis, and Leishmania would be strongly suspected in such an example. In these instances the definitive diagnosis can be reached from the history and clinical examination, with perhaps response to treatment, or just a single diagnostic test to confirm the diagnosis. However, other, often more chronic presentations are less straightforward, perhaps with a several week history of bilateral swelling and redness with intermittent rubbing, or simply a change in appearance of the periorbital area. Clearly further work-up is required in these cases.

CLINICAL EXAMINATION

Since many forms of blepharitis are part of a generalized dermatological condition, careful general clinical examination with specific concentration on the skin is required. The causes of blepharitis can be as varied as those for generalized dermatitis and sometimes the ocular symptoms can be the first signs of a more general involvement. Secondary bacterial infection is common and can mask the underlying aetiology. Careful examination of the feet, external ear canals and all mucocutaneous junctions is advised.

Ophthalmic examination will reveal eyelid swelling and hyperaemia, possibly with crusting or exudative erosions close to the eyelid margins (Figure 4.1). Some lesions are erosive and a serosanguinous discharge can be present (Figure 4.2). Periorbital hyperaemia or alopecia could be signs of self-trauma. Close examination of the eyelids themselves might reveal multiple swellings along the lid margin in the location of the meibomian glands – suggestive of a meibomianitis (Figure 4.3). Schirmer tear test readings should be checked in all cases.

Figure 4.1 Six-year-old male spaniel with severe blepharitis. Note the lid swelling, hyperaemia and exudative lesions but marked lack of actual ocular involvement. This was due to a staphylococcal infection and responded well to systemic cefalexin.

Figure 4.2 Five-year-old rough collie with ulcerative blepharitis at the medial canthus. The condition was bilateral and similar lesions were noted at the lip commissures. Skin biopsy confirmed immune-mediated disease.

Figure 4.3 Two-year-old Labrador retriever with meibomianitis – note the multiple small lid swellings along the palpebral conjunctiva.

Conjunctival hyperaemia will accompany most cases of eyelid inflammation and can be incorrectly assumed to be the primary problem. Sometimes the eyelid swelling can distort the palpebral fissure, resulting in such secondary problems as entropion, ectropion and trichiasis. Corneal ulceration can also develop which will further exacerbate the blepharospasm and a vicious cycle can be established. Normally there is no intraocular involvement with cases of blepharitis, but if any uveitis, for example, is present it might suggest either an immunological condition such as uveodermatological syndrome, or a protozoal infection such as Leishmania.

DIFFERENTIAL DIAGNOSES

These are outlined in Tables 4.1 and 4.2.

Table 4.1 Causes of blepharitis in dogs

Table 4.2 Causes of blepharitis in cats

CASE WORK-UP

Once a thorough general clinical and ophthalmic examination has been performed the appropriate diagnostic tests can be initiated. In many cases swabs for bacterial culture and sensitivity should be taken – both from the ocular discharge and from exudations from the lid margins themselves. Samples for parasitic isolation should also be considered so several swabs might be required in different transport media. Impression smears of the lid margins can be useful, and scrapes and hair plucks to look for parasites can be rewarding. If Leishmania is suspected then serological testing is advised. Additionally, many cases benefit from biopsy – especially since the commonly found bacterial infection might not be the underlying problem – with allergic reactions and immune-mediated disease high on the list of potential underlying conditions. Biopsy specimens should include the eyelid margin whenever possible – a small wedge resection is removed under general anaesthesia and sutured with 6/0–4/0 soft material (such as polyglactin 910, although care should be exercised using braided suture in the face of infection). If meibomian gland involvement is present, samples of inspissated matter can be curetted from the swellings and sent for both bacterial culture and cytology. Biopsy samples from other skin lesions should be considered. If atopy is suspected, then intradermal skin tests can be performed.

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