Evaluation of the Schirmer Tear Test in two Turkish breeds of
Transkript
Evaluation of the Schirmer Tear Test in two Turkish breeds of
Evaluation of the Schirmer Tear Test in two Turkish breeds of Shepherd dogs ° F. ALKAN, ° C. IZCI, °° C. TEPELI and ° Y. KOC ° Assistant Professor, Department of Surgery, Collage of Veterinary Medicine, University of Selcuk, Konya, Turkey °° Assistant Professor, Department of Animal Breeding, Collage of Veterinary Medicine, University of Selcuk, Konya, Turkey Corresponding author : Dr. Fahrettin Alkan, Departman of Surgery, College of Veterinary Medicine, The University of Selcuk, 42031 Kampus, Konya, Turkey Tlf: 00 90 332 2410041 / 2746 ; Fax: 00 90 332 2410063 ; e-mail: falkan@selcuk.edu.tr SUMMARY RÉSUMÉ The Schirmer tear test 1 and 2 (STT-1 and STT-2) were performed to evaluate tear production in 20 Turkish Akbas Shepherd Dogs and 21 Turkish Kangal Shepherd Dogs. The mean values for STT-1 and STT-2 in Turkish Akbas and Kangal Shepherd Dogs were 20.7 ± 2.9 mm/min and 21.5 ± 3.8 mm/min, and 9.8 ± 2.3 mm/min and 9.8 ± 3.0 mm/min, respectively. It was determined that neither body weight nor age had a statistically significant effect on these values. There were significantly differences in both STT-1 and STT-2 values between females and males in Shepherd dogs of both breeds (p < 0.05). There were significant fluctuations daily, weekly, or over time for STT-1and STT-2 values for each breed (p < 0.05). This study has shown that the STT-1 and STT-2 values in both Turkish Akbas Shepherd Dogs and Turkish Kangal Shepherd Dogs are normally distributed and are significantly affected by breed, sex, or measurement sequences. Évaluation du test de Schirmer chez deux races de chiens berger turcs. Par F. ALKAN, C. IZCI, C. TEPELI et Y. KOC. KEY-WORDS : Turkish Akbas shepherd dog - Turkish Kangal shepherd dog - Schirmer tear test - tear production. MOTS-CLÉS : Chien Turc berger de Kangal - Chien Turc berger d’Akbas - test de Schirmer - production de larmes. Introduction provide specific and nonspecific antimicrobial actions [9, 14, 15, 18]. Deficiency in tear production results in inflammation of the conjunctiva and cornea known as dry eye, xerophthalmia, or keratoconjunctivitis sicca [1, 7,10,17]. Clinical signs of keratoconjunctivitis sicca (KCS) include mucoid discharge, blepharospasm, conjunctival hyperemia, chemosis, corneal ulceration, vascularization, and pigmention. KCS may be difficult to detect clinically, which can lead to more serious ocular damage by the time an accurate diagnosis is made [8, 10, 14, 15, 18]. Traditionally, the diagnosis of KCS, xerophthalmia, or dry eye is based on clinical signs, laboratory analyses and on results of Schirmer tear test (STT). The STT values in healthy dogs tend to cluster between 14 and 24 mm. wetting/ minute [2, 3, 4, 5, 6, 9, 11, 14, 19]. Dogs with wetting of The preocular tear film comprises the secretions of several glands [1, 7, 8, 14]. The outermost lipid layer is produced by the Meibomian and Zeis glands in the upper and lower eyelids. The middle aqueous layer is produced by the orbital lacrimal gland and the gland of the third eyelid. The inner mucoprotein layer is produced by conjunctival goblet cells and corneal epithelial cells [3, 15, 17, 18]. The preocular tear film distribution occurs as a result of the movements of the upper and lower eyelids, and the third eyelid. It plays an important role in maintaining the health and normal function of the conjunctiva and cornea. Tears help remove foreign substances, provide moisture, lubrication, and essential nutrients (oxygen and glucose) to the avascular cornea, and contain immunoglobulins, enzymes and other proteins that Revue Méd. Vét., 2004, 155, 2, 67-70 Des tests de Schirmer 1 et 2 (STT-1 et STT-2) ont été réalisés pour évaluer la production de larmes chez 20 chiens turcs berger d’Akbas et 21 chiens turcs berger de Kangal. Les valeurs moyennes pour STT-1 et STT-2 chez les chiens turcs berger d’Akbas et Kangal étaient 20.7 ± 2.9 mm/min et 21.5 ± 3.8 mm/min, et 9.8 ± 2.3 mm/min et 9.8 + 3.0 mm/min, respectivement. Il est montré que ni le poids corporel ni l’âge n’a eu un effet statistiquement significatif sur ces valeurs. Des différences significatives (p < 0.05) dans les valeurs de STT-1 et STT-2 entre femelles et mâles chez les chiens de berger des deux races ont été trouvées. Des fluctuations significatives (p < 0.05) dans le temps (jour, semaine...) pour des valeurs de STT-1 et STT-2 ont été mises en évidence pour chaque race. Cette étude a prouvé que les valeurs des STT-1 et STT-2 chez les chiens turcs de berger d’Akbas et les chiens turcs de berger de Kangal sont normalement distribuées et sont sensiblement affectées par la race, le sexe, ou les ordres de mesure. 68 10 to 14 millimeters may have xerophthalmia or keratoconjunctivitis sicca [1, 8, 14, 15, 18]. In the presence of typical clinical signs and less than 8 or 10 millimeters of wetting per minute is diagnostic for the disease. More severe clinical signs are usually evident with STT values of 0 to 5 mm/minute [1, 9, 10, 18]. However, significant differences are found in both Schirmer tear test values between dogs of different breeds [4, 5, 12, 13]. Thus, what is considered normal tear production in the former would be deficient in the latter. Therefore, it would be most difficult to rule out KCS as a differential diagnosis for those breeds in which normal values are not known [5, 8]. It is very important to establish mean baseline values because keratoconjunctivitis has been diagnosed in dogs of different breeds [9, 10, 15, 17]. In the literature, however, very little was known on the STT-1 and STT-2 values in Shepherd dogs of different breeds. The purpose of this study was to determine the normal values for the STT-1 and STT-2 in Turkish Akbas Shepherd Dogs and Turkish Kangal Shepherd Dogs ; to determine the values between normal tear and tear deficiency status on the basis of the KCS ; to determine whether the age of dogs has any effect upon Schirmer values or not, and to attempt to identify the variables that might influence these findings. Materials and Methods ANIMALS Turkish Akbas Shepherd Dogs and Turkish Kangal Shepherd Dogs reared at the Veterinary Faculty Farm of Selcuk University were used in this study. All dogs were used following general physical and ocular examination to rule out pre-existing ocular or physical abnormalities. Breed, age, body weight and sex were recorded for each dog within each breed. They were housed inside room temperature 17 °C, humidity 55 ± 10 %, and fed once a day between 10 a.m. and noon. EXPERIMENTAL DESIGN The experimental protocol was approved by the managerial board of the animal farm of the Veterinary Faculty, University of Selcuk in Turkey. The Schirmer tear testing paper (Clement Clarke International Limited) was used for the Schirmer test. The STT-1 was measured by inserting a bent portion of the test paper into the anterior medial onethird of the conjunctival sac. The test paper was removed after the eyelids were closed for 60 seconds and the wet portion of the test paper was measured as mm. For STT-2, 0.4 % oxybuprocaine hydrochloride (Benoxinate 0.4 % Thilo, Liba A.S) was instilled on the surface of the eye, and a second drop was instilled 30 seconds later. After 5 minutes residual tear in the conjunctival sac was gently dried with a cotton-tipped swab (Soffio, Sogedv, Brascia) and the STT-2 was performed as described for the STT-1 [4, 5, 9, 11, 15]. The STT1 and STT-2 measurements were performed between 8 and 10 a.m. and again between 3 and 5 p.m. twice daily for seven consecutive days and twice for 14th, 21th, and 28th days (weekly) on each eye of each dog. All tests were performed by the same investigators (F.A. and C.I.). For data analyses, dogs within each breed were divided into three age categories ALKAN (F.) AND COLLABORATORS which are young (6 months to 18 months), middle-aged (two to five years), and old (older than five years). STATISTICAL ANALYSES The experimental analyses of the data were carried out by one-way analysis of variance (ANOVA). The differences between groups were compared using the Duncan’s multiple range test. Statements of statistical significance are based on P < 0.05. These analyses were accomplished by using statistical analysis system configured for computer (SPSS, Relase 10.0, SPSS. Inc). Results Twenty Turkish Akbas Shepherd Dogs and twenty one Turkish Kangal Shepherd Dogs were used in the study. Turkish Akbas Shepherd Dogs (10 females and 10 males) ranged from 6 months to 8 years old (mean, 3.3 ± 2.3 years), and the mean body weight was 30.2 ± 8.7 kg (range 16 to 42 kg). The mean values for STT-1 and STT-2 are shown in table II. The mean STT-1 and STT-2 values in Turkish shepherd dogs of both breeds were 21.1 ± 3.4 mm/min and 9.8 ± 2.7 mm/min, respectively (Table I). There were significant fluctuations daily and weekly for STT-1 and STT-2 values for each breed (P < 0.05) (Table I). The young age group contained seven Turkish Akbas Shepherd Dogs (4 females, and 3 males), ranging from 6 months to 1.5 years old (mean 1,1 years) and weighing 20.6 ± 3.8 kg (range 16 to 26 kg). The mean values for STT-1 and STT-2 are shown in table II. The middle age group contained seven Turkish Akbas Shepherd Dogs (3 females and 4 males), ranging from 2 to 5 years old (mean 3.1 years) and weighing 33.0 ± 6.2 kg (range 25 to 41 kg). The mean values for STT-1 and STT-2 are shown in table II. The old age group contained six Turkish Akbas Shepherd Dogs (3 females, 3 males) ranging from 5 years to 8 years old (mean 6.2 years ) and weighing 38.2 ± 2.6 kg (range 35 to 42 kg). The mean values for STT-1 and STT-2 are shown in table II. Turkish Kangal Shepherd Dogs (10 females and 11 males) ranged from 6 months to 8 years old (mean 3.6 ± 2.6 years), and the mean body weight was 37.0 ± 12.5 kg (range 18 to TABLE II. — Values of STT-1 and STT-2 of different age groups in Turkish Akbas Shepherd Dogs and Turkish Kangal Shepherd Dogs. Revue Méd. Vét., 2004, 155, 2, 67-70 EVALUATION OF THE SCHIRMER TEAR TEST IN TWO TURKISH BREEDS OF SHEPHERD DOGS abcd 69 Values in the same column with different superscripts are significantly different (P < 0.05). Data expressed as mean ± SEM mm wetting minute. TABLE I. — Values of STT-1 and STT-2 in Turkish Akbas Shepherd Dogs and Turkish Kangal Shepherd Dogs. 57 kg). The mean values for STT-1 and STT-2 are shown in table II. The young age group contained seven Turkish Kangal Shepherd Dogs (4 females, and 3 males), ranging from 6 to 18 months old (mean 11 months) and weighing 22.7 ± 3.4 kg (range 18 to 28 kg). The mean values for STT-1 and STT-2 are shown in table II. The middle age group contained seven Turkish Kangal Shepherd Dogs (3 females, and 4 males), ranging from 2 to 4 years old (mean 3.0 ± 0.7 years) and weighing 39.1 ±7.6 kg (range 28 to 52 kg). The mean values for STT-1 and STT-2 were shown in table II. The old age group contained seven Turkish Kangal Shepherd Dogs (3 females and 4 males), ranging from 5 years to 8 years old (mean 6.8 ± 1.1 years) and weighing 49.0 ± 6.6 kg (range 40 to 57 kg). The mean values for STT1 and STT-2 are shown in table II. The mean values for STT-1 and STT-2 in the female and male dogs of both breeds were shown in table III. There were significant differences in both STT-1 and STT-2 values between females and males in both Turkish Akbas and Kangal Shepherd Dogs (P < 0.05), (Table III). The mean values for STT-1 and STT-2 in the morning and afternoon in Turkish Akbas Shepherd Dogs and Turkish Kangal Shepherd Dogs are shown in table IV. There were significant differences at over time in both STT-1 and STT-2 values for each breed (P < 0.05) (Table IV). Discussion The Schirmer tear test that is a semiquantitave method can be performed with or without topical anesthesia. The STT-1 is performed in clinical setting to determine baseline and reflex lacrimation. The STT-2, which is performed after the instillation of a topical anesthetic evaluates solely basal tear production in dogs [2, 4, 8, 11, 13]. The mean values for the STT-1 and STT-2 in healthy dogs have been established as 19.8 ± 5.3 mm/min and 11.6 ± 6.1 mm/min, respectively [3, 7, 11]. However, in our study, we determined that the mean values for STT-1 and STT-2 in the shepherd dogs of both breeds were 21.1 + 3.4 mm/min, and 9.8 + 2.7 mm/min, respectively (Table I). The mean STT-2 value has been reported to be approximately 30.5 % to 58.5 % [1, 5, 8, 12, 13], which is nearly consistent with our mean values relating to STT-2 (46.5 %). These results are due to the effect of the local anesthetic drop on the corneal and conjunctival nervous system ab Values in the same column with different superscripts are significantly different (P < 0.05). Data expressed as mean ± SEM mm wetting per minute. ab TABLE III. — Values of STT-1 and STT-2 in female and male Turkish Akbas Shepherd Dogs and Turkish Kangal Shepherd Dogs. TABLE IV. — Values of the STT-1 and STT-2 in morning and afternoon in Turkish Akbas Shepherd Dogs and Turkish Kangal Shepherd Dogs. Revue Méd. Vét., 2004, 155, 2, 67-70 Values in the same column with different superscripts are significantly different (P < 0.05). Data expressed as mean ± SEM mm wetting per minute. 70 which control the reflex tear production as reported earlier [5, 9, 14, 15]. It has been reported that body weight [11, 19], head shape [11] and age [5, 11, 19] have no effect on STT values in dogs. However, BERGER and KING [2] reported that the values of the STT-1 and STT-2 may be influenced by the dog’s weight. In our study, there was no statistically significant difference in both STT-1 and STT-2 values related to body weight or to the age groups for each dog of both breeds (Table II), howewer, the related-values have been found to be a little higher in dogs of each breed with both old age and higher body weight than in the other groups. These results revealed that the dogs with small body weight may predispose to KCS in further years. The STT values have been reported to be higher in females than in males [4, 19], but not to be influenced by sex [11]. The findings of this study are consistent with those of the former two (P < 0.05), (Table III). Regarding the related-findings, we have suggested that female sex hormones may have a protective function on lacrimation. It has been suggested that the STT-1 and STT-2 values in dogs may be influenced by dog’s breed [4, 5, 7, 12, 13]. Howewer, another author denied such a variation [11]. Previous reported STT-1 values in various breeds include 20.2 ± 2.5 mm/min in the Beagle, 22.9 ± 4.1 mm/min in the Labrador Retriever, 20.7 ± 3.2 mm/min in the English Spinger Spaniel, 21.8 ± 3.7 mm/min in the Golden Retriever, and 15.8 ± 1.8 mm/min in Shetland Sheepdog [5]. In this study, we showed that the mean STT-1 value was 20.7 ± 2.9 mm/min in Turkish Akbas Shepherd Dogs and was 21.5 ± 3.8 mm/min in Turkish Kangal Shepherd Dogs. In our study, the mean STT-1 values in dogs of both breeds was found to be consistent with breeds mentioned above. We have suggested that the breed differences of the dogs with healthy and KCS should be taken into consideration as a contributing factor during clinical examinations. Previous reported STT-2 values in various breeds are 3.8 ± 2.7 mm/min in the Beagle, 9.6 ± 3.8 mm/min in the Labrador Retriever, 5.4 ± 3.4 mm/min in the English Spinger Spaniel, 8.8 ± 3.1 mm/min in the Golden Retriever, and 3.6 ± 2.8 mm/min in Shetland Sheepdog [5]. In the present study, the mean STT-2 values in both Turkish Akbas Shepherd Dogs (9.8 ± 2.3 mm/min) and Turkish Kangal Shepherd Dogs (9.8 ± 3.0 mm/min) were similar or higher than those reported for any other breeds. We suggest that the mean STT-1 and STT-2 values in Turkish Akbas Shepherd Dogs and Turkish Kangal Shepherd Dogs are similar because of the very close relationship between breeds. It has previously been reported that there are daily and weekly fluctuations in the STT-1 and STT-2 values in healthy dogs [2, 4, 7]. Results of the present study indicated that the dogs of both breeds had typical fluctuations in daily and weekly tear production. In other hand, significant differences were detected in both the STT-1 and the STT-2 values over time (P < 0.05). SMITH et al. [16] have shown that there was a diurnal variation with the lowest values at midday and the highest values in the late afternoon, which is consistent with our findings. The results from our study have proposed that repetitive testing may affect changes in both STT-1 and STT2 values daily, weekly and within over time, by means of irritation, stress, physical condition. ALKAN (F.) AND COLLABORATORS This study has shown that the STT-1 and STT-2 values in both Turkish Akbas Shepherd Dogs and Turkish Kangal Shepherd Dogs are normally distributed and are significantly affected by breed, sex, or measurement sequences. Howewer, we have suggested that the age, body weight, sex, head type, breed and ecological conditions should be considered for all mesurements so that tear production can be accurately determined. We think that further studies are needed to properly appreciate the differences among the shepherd dogs of various breeds, and to avoid the misdiagnosis of KCS. Acknowledgements The authors thank the students of the veterinary medicine who helped us during the study. References 1. — AGUIRRE G.A., RUBIN L.F. and HARVEY C.E. : Keratokonjunctivitis sicca in dogs. J. Am. Vet. Med. Assoc., 1995, 206, 1286-1289. 2. — BERGER S.L. and KING V.L. : The Fluctuation of tear production in the dog. J. Am. Anim. Hosp. 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