Study population
The animal population consisted of 93 dogs, including 45 males (48%) and 48 females (52%) with an age range of 0.2–16 years (median 4.65 years). All the dogs were pure-breeds, representing seven different breeds: French Bulldog (n = 38), Shih-Tzu (n = 22), Pug (n = 17), English Bulldog (n = 5), Boxer (n = 4), Pekingese (n = 4) and Boston Terrier (n = 3). No statistically significant correlation (p > 0.05) between the distribution of breed, sex or age and the prevalence of ocular disorders was found.
Ophthalmological examination and complementary exams
In relation to Schirmer tear test (STT) values, sixteen of the animals had values below the normal range. From these, ten of them presented with values between 10 and 14 mmHg, considered low, and six of them corresponded to severe cases of keratoconjunctivitis sicca (KCS), with STT values varying between 0 and 10 mm/min. This exam, in addition to the remaining clinical signs, allowed for the diagnosis of KCS in a total of eleven animals (11/93).
Tonometry values were also altered in some cases. Twelve of the patients (12/93) presented values outside the reference range, from which six cases were below and six were above it. The low values varied between 5 and 12 mmHg, compatible with uveitis, and the increased ones varied between 40 and 80 mmHg, compatible with glaucoma.
The fluorescein test was the most commonly performed complementary exam, used in eighteen cases of suspected corneal ulcers (18/93).
Ocular ultrasound was used five times (5/93) and allowed for confirmation of two lens changes, one lens luxation and one modification in the vitreous chamber.
Electroretinography was performed in four cases of bilateral cataracts (4/93), and the result was always within the reference range.
Measurement of the arterial pressure was one of the non-ophthalmic complementary exams performed and was crucial to obtain a diagnosis in one dog (1/93), allowing for the confirmation of arterial hypertension, as the value for systolic arterial pressure was 250 mmHg.
Ocular disorders
Eyelids
Macroblepharon was very common among the population (44/93), affecting almost half of the population; two French Bulldogs presented with extreme phenotypes.
A significant number of patients was affected with eyelid disorders including entropion, excessive nasal folds, ectopic cilia, trichiasis and distichiasis. Among these, entropion was the most frequent problem, with an incidence of 22% (20/93). Not only that, but it affected every breed included in this study, excluding Boxer and Pekingese, and was especially recurrent in Pugs. which represented almost half of the affected dogs, probably due to the fact that it was one of the most well represented breeds in this study. The entropion’s location was always medial and bilateral. In two cases, a Bullmastiffand an English Bulldog, entropion affected not only the inferior eyelid, but also the upper one.
Trichiasis was the second most common eyelid related disorder, being present in fifteen dogs (15/93), from which eleven corresponded to the caruncular type.
Distichiasis presented an incidence of 16% (15/93), excessive nasal folds were seen in three Pugs and one Pekingese, affecting 4% of the population (4/93) (Fig. 1), and ectopic cilia were only found in one Boston Terrier and one Shih Tzu, concerning 2% of the population (2/93).
Six cases of palpebral masses were registered (6/93), corresponding to one Shih Tzu and five French Bulldogs. Prolapse of the gland of the nictitating membrane was seen in five dogs, unilaterally in one Boston Terrier and in one English Bulldog, and bilaterally in three French Bulldogs.
Cornea
Corneal lesions were quite commonly present and included corneal ulcers, degeneration, pigmentation and fibrosis. Corneal ulcers (41/93) affected the majority of breeds included in the study except for Boston Terrier and Boxer (Fig. 2). From the total of 41 cases, 36 were unilateral and 5 were bilateral. Seventeen of them corresponded to stromal medium or deep lesions, and were diagnosed in seven French Bulldogs and five Shih Tzus, while the remaining corneal ulcers were superficial lesions. Ten cases of eyelash alterations and concomitant corneal ulcers were observed.
Corneal pigmentation (33/93) and fibrosis (23/93) were diagnosed in every breed included in the study, excluding Pekingese.
Corneal pigmentation presented an incidence of 35%, being present in six of the brachycephalic breeds included in the study, and the majority of cases were attributed to Pugs (9/93) and Shih Tzus (8/93) (Fig. 3). The only unaffected breed was the Boston Terrier. The percentage of affected Pugs was 53% and that of Shih Tzus was 36%.
On the other hand, corneal fibrosis had an incidence of 25% and affected mainly Shih Tzus (7/93) and French Bulldogs (10/93). The total percentage of affected Shih Tzus was 36%, and of French Bulldogs was 29%.
Corneal dystrophy was the corneal event that presented with the lowest frequency in this study (6/93).
Intraocular disorders
The iris also presented with a low number of lesions, since only five cases of alterations in this ocular structure (5/93) were registered, including Pugs with a sand type pattern in the iris and iris’ discoria, and one Boston Terrier plus one French Bulldog with iris’ cysts.
Two French Bulldogs and two Pekingese dogs presented with lens subluxation and inflammation (4/93), and two Shih Tzus had nuclear sclerosis (2/93), their age being between 10.6 and 16 years old. Anterior chamber abnormalities (3/93) included hyphema and hypopyon. There were also three cases of cataracts seen in three French Bulldogs and two Pugs (5/93) with an age range between of 2 and 10 years old.
Treatment protocols
According to clinical presentation, patients were submitted for medical or surgical treatment.
Medical treatment
Medical treatment was often indicated, mostly in cases of corneal ulcers, management of KCS and during surgical recovery. Superficial corneal ulcers were systematically treated with topical drugs that involved a combination of lubricating eye drops with polyacrylic acid (Vidisic®- Bausch and Lomb, New York, USA) or hyaluronic acid (Vislube®- TRB Chemedica, Genève, Switzerland) 3-6x/day, topical antibiotic, such as tobramycin (Tobrex®- Alcon, Barcelona, Spain) or gentamicin (Gentamycin-POS®- Ursapharm, Saarbrücken, Germany) 5x/day and atropine (Atropocil®- Edol, Linda-a-Velha, Portugal; Atropin-POS 0,5%®; Ursapharm, Saarbrücken, Germany) SID, with the concomitant use of an Elizabethan collar.
Dogs with deep and severe ulcers were medicated with a topical antibiotic, such as ofloxacin (Oflex®– VAPP, Carnaxide, Portugal; Floxal®, Bausch + Lomb, Berlin, Germany) or chlortetracycline (Cepemycin®- CPPharma, Burgdorf, Germany) 5x/day, lubricating eye drops 3-6x/day, atropine BID and a systemic antibiotic, such as cephalexin for ten days, and then were submitted to a surgical treatment that involved placement of a conjunctival pediculated flap.
If a surgical treatment was not pursued, a conservative medical approach was considered and included the same drugs as in the superficial ulcers, but with a higher frequency of administration, and a placement of a contact lens in the injured eye until healing was achieved.
Surgical treatments
More than half of the studied population underwentsome type of ophthalmic surgery. The surgical procedure most frequently recommended to address BOS was medial canthoplasty, with twenty indications to do so (22%, 20/93) (Fig. 4). However, surgery was only performed in eleven of the referred cases (55%, 11/20). When considering the surgical approach, it was advised in members from four of the brachycephalic breeds: ten Pugs, six Shih Tzus, three French Bulldogs and one English Bulldog,
Corneo-conjunctival flap was the second most common surgical procedure, being performed nine times (10%, 9/93), from which eight were based on conjunctival tissue and one flap (1%, 1/93) was made from amniotic membrane.
Electroepilation was advised six times (6/93) and manual epilation of distichia and ectopic cilia was needed an additional three times (3/93).
Superficial keratectomy was performed in four cases (4/93) and Hotz-Celsus blepharoplasty was performed in four dogs (4/93).
Replacement of the gland of the nictitating membrane was achieved in five cases of prolapse (5%, 5/93), through the Morgan and Moore conjunctival pocket technique, and resection of excessive nasal fold was necessary in two Pugs (2%, 2/93) (Fig. 5) [11].
Mass excision was performed in six cases (7%, 6/93), enucleation in three patients (3%, 3/93) and phacoemulsification was helpful in the resolution of two cataract cases (2%, 2/93).