Total 5,148 dogs were registered at Veterinary Clinical Complex (VCC), Co.V.Sc Jabalpur during a period of six months (May to October, 2024). Out of which 300 (5.82%) dogs were suffered from various ocular affections (Plate 2). Pigmentary keratitis was recorded in 42 (0.81%) dogs after clinical examination. The incidence of ocular affections in dogs has varied over the years.
Makode (2024) reported an incidence of 4.36%,
Beniwal (2022) 2.08%,
Das et al., (2019) 1.39% and
Mishra et al., (2021) 2.23%. Overall, the reported rate of various eye problems in the dog population being observed with higher rates in recent years potentially due to changes in pet ownership trends and greater owner vigilance regarding pet eye health.
Distribution of various ocular affections and corneal affections
Among ocular affections, majority of the dogs were diagnosed with cataract (20.0%), consistent with previous finding by
Das et al., (2019) followed by pigmentary keratitis (14.0%) and corneal ulcer (8.33%). The incidence of other ocular affections was lesser in number (Table 2).
According to recent studies,
Makode (2024) reported an incidence of pigmentary keratitis at 10.66%. Likewise,
Beniwal (2022) and
Mishra et al., (2021) recorded an incidence rate of 7.29% and 5.68%, respectively.
In the present investigation, corneal disorders revealed a specific distribution pattern, with pigmentary keratitis accounting for 49.41% of cases, followed by corneal ulcers at 29.41%, corneal opacity at 17.64% and corneal dystrophy at 3.52% (Table 2).
These findings closely corroborate with the results of
Rajasekaran (2021) and
Ratnu (2017), who similarly documented pigmentary keratitis as the most frequently occurring corneal disorder, with percentages of 52.94% and 19.4% respectively.
Age wise distribution of ocular affections and pigmentary keratitis
In the present research, the prevalence of ocular affections varied across different age groups, with adult dogs showing the highest percentage (36.33%) followed by young dogs (34.0%) and geriatric dogs (29.66%) (Table 3).
These findings align with the observations of
Pandey et al., (2018), who documented that the majority of animals with ocular conditions were predominantly in the age group of 6 to 10 years (47.54%). However, these results are in contrast with the findings of
Tamilmahan et al., (2013), who reported a different distribution, with animals over 5 years of age exhibiting the highest incidence at 47.68%.
Ocular affections were more common in adult dogs, which may be attributed to their larger population, higher frequency of clinical presentation and the effects of the aging process.
Pigmentary keratitis was most prominent in adult animals (42.85%), while young and elderly age groups showed an equal distribution of cases at 28.57% each (Table 3).
Consistent with these findings,
Rajasekaran (2021) reported the mean age of animals was 5.27±0.29 years, with their ages ranging from 0.4 months to 10 years. Corneal pigmentation was most frequently seen in the adult group (57.29%), followed by the elderly group (29.17%) and the younger age group (13.54%). Contrary to these findings,
Anoop et al., (2015) reported pigmentary keratitis was most frequently seen in dogs aged between 1 and 3 years (53%).
Sex wise distribution of ocular affections and pigmentary keratitis
The distribution of ocular affections showed a notable gender disparity, with 61.33% of cases observed in male dogs and 38.66% in females, indicating a higher prevalence among males (Table 4). The incidence was slightly higher in females (6.75%) as compared to males (5.36%).
This pattern of predominance of ocular affections in males is consistent with the findings by
Tamilmahan et al., (2013), who similarly reported a higher distribution of ocular conditions in males at 60.32% versus females at 39.29%. However,
Akinrinmade and Ogungbenro (2015) documented a contrasting scenario with a higher distribution of ocular affections in females (42.42%) as compared to males (35.49%).
The greater distribution of ocular affections in male dogs in the current study may be attributed to their typically larger population.
In the present study, 66.66% of the affected dogs were male, while the remaining 33.33% were female, indicating a higher prevalence of pigmentary keratitis in males (Table 4).
These findings align with those of
Labelle et al., (2013) who observed that male dogs more frequently exhibited moderate to severe corneal pigmentation as compared to female dogs. However, in contrast,
Maini et al., (2019) reported a higher incidence of pigmentary keratitis in females (57.7%) than in males (42.3%).
These findings might be attributed to the preference of male dogs as pets by the majority of owners.
Relationship between the presence of ocular affection with sex of the animal
The study analyzed the association between sex and ocular affection. Among males (3,432), out of 5,148 dogs, 184 cases were found to have ocular affection. While, females (1,716), 116 of them were found to have ocular affection. The chi-square value was 4.0776, with a P value of 0.043**, indicating a statistically significant relationship between sex and ocular affection (Table 4).
Breed wise distribution of ocular affections and pigmentary keratitis
Among different breeds of dogs, the highest distribution of ocular affections was in Labrador Retriever (25.33%) followed by Non-descript (17.33%), Pug (11.66%), German Shepherd (9.66%), Pomeranian (8.66%), Shih Tzu (7.66%), Beagle (4.33%), Spitz (3.66%), Golden Retriever (3.00%), Lhasa Apso (1.66%), Chow-Chow and Rottweiler (1.00% each), Dalmatian, American Bully, French Bulldog, Great Dane and Saint Bernard (0.66% each), Belgian Shepherd, Boxer, Siberian Husky, French Mastiff and Poodle (0.33% each) (Table 5).
These findings were in contrast with findings of
Kalaiselvan et al., (2009) identified Spitz breeds as the most commonly affected at 35.86%, while
Kumar et al., (2018) found that Pugs to be the most prevalent at 28.3%.
These variations primarily may be attributed to the higher population of Labrador Retriever dogs in and around the Jabalpur region, suggesting that breed-specific ocular affection may be influenced by local canine demographics.
In the present study, majority of dogs diagnosed with pigmentary keratitis were Pug (69.04%), followed by Labrador Retriever (16.66%), German Shepherd (9.52%), French Bulldog (2.38%), Lhasa Apso (2.38%), Non-descript (2.38%) and Shih Tzu (2.38%) (Table 5).
These results were closely similar with
Anoop et al., (2015) who reported that Chinese Pugs showed the highest incidence (92.7%), followed by Lhasa Apso (4%), Cocker Spaniel (2%) and Bull Mastiff (2%).
Vallone et al., (2017) also found a high incidence of pigmentary keratitis in Pugs.
The increasing prevalence of corneal pigmentation in Pugs can largely be attributed to the breed’s growing popularity and distinctive anatomical traits, including shallow eye sockets, breed-specific exophthalmos and a large palpebral fissure. Additional contributing factors include nasal folds that frequently contact the cornea and caruncular trichiasis, both of which promote corneal irritation and pigmentation (
Van der Woerdt, 2004).
Distribution of ocular affections and pigmentary keratitis based on eye affected
The distribution of bilateral ocular affections was (35.00%), followed by right eye affections (34.00%) and left eye affections (31.00%) (Table 6).
These finding aligns with the observations of
Akinrinmade and Ogungbenro (2015), who reported an even more pronounced bilateral prevalence, with 54.98% of the cases involving both eyes compared to 21.11% for the right eye and 13.42% for the left eye. However, these results are in contrast with the findings of
Pratap et al., (2005), who observed no significant difference between left (45.7%) and right (42.4%) eye involvement, with a markedly lower rate of bilateral cases at 12.00%.
In the current study, 80.95% of the dogs exhibited bilateral pigmentary keratitis, while 19.04% of them were affected unilaterally. These findings suggest that bilateral manifestation of pigmentary keratitis is the most common (Table 6).
Supporting this observation,
Maini et al., (2019) also reported that 91.2% of pugs displayed bilateral pigmentary keratitis, while only 8.8% were affected unilaterally.
Distribution of ocular affections based on anatomical location
The investigation revealed that corneal conditions were the most common (28.33%), followed by lens-related issues (23.00%), eyelid and nictitating membrane involvement (13.66%). Other affected areas included the orbit and globe (12.00%), conjunctiva (9.66%), lacrimal system (8.66%), fundus (2.66%) and uvea (2.00%) (Table 7).
These findings align with the findings of
Pratap et al., (2005) and
Tamilmahan et al., (2013), who similarly reported corneal conditions as the most frequent, with percentages of 40% and 28% respectively. However, this pattern diverges from the observations of
Sale et al., (2013) who identified lens-related conditions with the highest incidence.
Corneal affections were more common than other ocular conditions, likely because the cornea is the most exposed part of the eye, making it highly vulnerable to trauma, environmental irritants and infections.
Distribution according to degree of corneal pigmentation
The corneal photographs were assessed for pigmentation levels based on the grading system proposed by
Maini et al., (2019). Among the 76 corneas evaluated, 40 (52.63%) of them exhibited severe pigmentary keratitis, 30 (39.47%) showed a moderate degree and 6 (7.89%) had a mild degree of pigmentary keratitis. These results indicate that most eyes were affected by a severe degree of pigmentary keratitis (Table 8).
In contrast,
Quintana et al., (2024) reported varying degrees of corneal pigmentation, with the distribution as very mild (20.3%), mild (16.4%), moderate (38.2%) and severe (25.1%).
Etiology wise distribution of pigmentary keratitis
The major causative factor found to be responsible for the pigmentary keratitis was nasal fold trichiasis (32.89%) followed by medial entropion lower eyelid (26.31%), macropalpebral fissure (19.73%), keratoconjunctivitis sicca (07.89%), eyelid mass (05.26), trichiasis (03.12%), chronic superficial keratitis (02.63%) and distichiasis (01.31%) (Table 9).
These findings were in accordance to those of
Charbiwala (2019), who stated that brachycephalic ocular syndrome (medial lower eyelid entropion, medial caruncle, trichiasis, macropalpebral fissure and nasal fold trichiasis) was the most common cause (34.85%).
Ratnu (2017) Identified that both nasal fold trichiasis and distichiasis (50%) were the most common cause of pigmentary keratitis.
Pigmentation was thought to result from pigmented corneal epithelial injury exceeding the regenerative capacity of epithelial cells. However, the exact cause remains unclear.
Distribution based on pattern of corneal pigmentation
The corneal pigmentation pattern was classified based on the criterias suggested by
Charbiwala (2019) and
Rajasekaran (2021). In this study the majority of the affected eyes exhibited a diffuse pattern of corneal pigmentation (52.63%), followed by medial pyramid (22.36%), patchy (11.84%), paintbrush (7.89%) and streak (5.26%) patterns (Table 10, Plate 3).
These findings were consistent with
Rajasekaran (2021) and
Charbiwala (2019), who found that the diffuse pattern was the most common, observed in 34.38% and 43.94% of cases, respectively, followed by other patterns occurring less frequently.
Relationship between presence of pigmentary keratitis with animal variables
The study evaluated 300 animals, including 42 with pigmentary keratitis and 258 without pigmentary keratitis, to identify associated factors. No significant associations were found with sex (X2=0.585, P = 0.44) or age (X2=1.0151, P = 0.60). However, a strong association was observed with breed (X2=151.28, P=<0.00001), with Pug being the most affected (29/35 cases) and with bilateral eye involvement (X2=45.33, P=<0.00001). These findings indicate that breed and bilateral presentation are significant risk factors for pigmentary keratitis (Table 11).
The results were closely similar to
Labelle et al., (2013) who observed that no significant correlation between the age of the dogs and corneal pigmentation detection. In contrast to this,
Quintana et al., (2024) reported that the presence of pigmentary keratitis showed a statistically significant relationship with the age of the studied animals.
