A 2023 study by Jørgensen et al described a genetic study looking for the cause of distichiasis in Staffordshire Bull Terriers. Distichiasis is the presence of aberrant hairs on the eyelid margins, which can cause problems ranging from mild irritation to corneal ulceration. It has a particularly high prevalence (18%) in Norwegian Staffordshire Bull Terriers. It has been assumed to have a complex inheritance pattern, but little is known about the genetics of distichiasis in dogs.
This study involved a genome-wide association study and an attempt to predict genomic values for distichiasis. Four genetic regions of interest were identified that were associated with distichiasis. This suggests that distichiasis in this breed is a complex trait with multiple genes involved. The dogs in the highest quartile for genetic prediction of distichiasis had an approximately four times higher risk of developing distichiasis compared to the quarter predicted least likely to develop the disease. The authors concluded that the genomic prediction method can be useful when developing breed health schemes for the reduction of distichiasis, although it may be less useful for prediction in individual dogs.
Brachycephalic dogs are prone to a large number of diseases related to their conformation. Problems related to the respiratory system and the spine are well-recognised, but the increased prevalence of ocular problems related to being brachycephalic is becoming increasingly recognised. The collection of ocular diseases in these breeds is termed brachycephalic ocular syndrome. Medial canthoplasty is sometimes recommended as a surgical procedure to address conformational anomalies that can lead to corneal disease. Andrews et al (2023) report the results of a retrospective study of dogs that had had medial canthoplasty recommended. A questionnaire was used to assess owners’ perceptions of their dogs’ quality of life and clinical signs before and after surgery. A total of 271 dogs had medial canthoplasty recommended, but only 43.5% underwent the surgery. Of the dogs that underwent surgery, 72% were pugs, and most dogs that had surgery had a history of current or previous corneal ulceration. Of the 104 dogs that had follow-up information available, six (5.7%) had documented corneal ulceration after surgery. However, of the 64 owners that completed the questionnaire, eight (12.5%) reported postoperative corneal ulceration. The owners also commonly reported reduced ocular discharge, irritation and reduced periocular cleaning. A total of 86% of owners were satisfied with the clinical outcome and 88% with the cosmetic outcome. The authors concluded that medial canthoplasty is important in the surgical management of brachycephalic ocular syndrome, and that the procedure helps restore a healthier conformation and improves the animal's quality of life.
Allergic conjunctivitis is commonly recognised in people, but the literature on this condition in dogs is sparse. Canine allergic conjunctivitis can be related to atopy but is often underdiagnosed and undertreated. Delgado et al (2023) reported a retrospective study of 122 dogs with allergic conjunctivitis that had had full ophthalmological and dermatological investigations. Six ophthalmic clinical signs were found to be characteristic of the condition:
- Conjunctival hyperaemia
- Chemosis
- Ocular pruritus
- Epiphora
- Keratitis
- Discharge (either seromucoid or mucopurulent).
The authors created a scoring system with a severity from 0 to 3 for each sign (absent to severe). Overall scores of 1–5 were rated as mild, 6–10 as moderate and 11–18 as severe. The authors found that 64% of cases were of moderate severity, 24% had mild signs and 12% had severe signs. Severity appeared to be independent of age and sex at diagnosis. All cases were bilateral. Chemosis, hyperaemia and ocular pruritus were the most common signs. Keratitis severity correlated with overall severity and duration of the disease. The authors note that hyperaemia, chemosis and ocular pruritus are used to diagnose human allergic conjunctivitis and this may also be helpful in diagnosis of the disease in dogs. The proposed diagnostic approach and grading system may be helpful to dermatologists, ophthalmologists and general practitioners.