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The Treatment of Canine Otitis Externa with Nitrofurazone
Brit. vet.
J . (1963),
119,
2 II
THE TREATMENT OF CANINE OTITIS EXTERNA WITH NITROFURAZONE By W. N.
SCOTT
Smith, Kline & French Laboratories, Welwyn Garden City, Herts AND ESTHER
M. H.
DENHAM
Welwyn Garden City
The aetiology of otitis externa has been debated (Joshua, 1958; Fraser, 1961; Fraser, Withers & Spreull, 1961). It has been shown that, apart from the increased breed susceptibility to otitis in the case of miniature poodles and spaniels, the commonest predisposing factors in affected dogs were clinical skin complaints and ectoparasitic infestations. Although bacteria and fungi are not often implicated as causal agents, the presence of commensal organisms and their invasion of the primary lesion results in tissue changes which may progress from the acute to the chronic form of the disease. The bacterial flora of healthy and diseased ears has been compared by Fraser (1957). He isolated Gram-positive and Gram-negative organisms from both kinds of ear, but found coliforms and haemolytic streptococci to be more common in the latter. Proteus vulgaris and Pseudomonas aeruginosa were isolated only from diseased ears. The presence of such a variety of potential pathogens would, therefore, seem to favour the use of a broad spectrum antibacterial substance in the treatment of otitis externa. Nitrofurazone is known to show activity in vitro against a wide range of Gram-negative and Gram-positive organisms (Dodd, 1946). Anderson & Steele (1948) found that nitrofurazone was very effective in the treatment of human otitis media caused by bacteria. Following this observation, several workers used nitrofurazone in the treatment of otitis externa and skin conditions in dogs and cats. Kaplan (1948) reported the successful treatment of 16 cases of superficial skin infections in dogs and cats, including one case of suppurative otitis media. Knowles, Knowles & Knowles (1948) used the drug in 89 cases of otitis externa, the infecting organism being bacterial in 48, fungal in 17, mites in one and unclassified in 23. Of the 89 patients, 10 did not complete the course of treatment, though improvement was shown by all of them; of the 79 cases treated to completion, 76 recovered after an average of five treatments and three showed no improvement. Decamps (1949) used nitrofurazone in 18 cases of chronic ear infections and recorded relief of irritation and disappearance of discharge in all but one case. Nillson (1952) reported good results in 18 out of 2 I cases and Alstrom (1953) in treating 72 dogs noted similar results. Dall (1958) said that in treating cases of cellulitis and dermatitis in the dog, the best results were E
BRITISH VETERINARY JOURNAL, Ilg, 5
212
obtained with a 0·2 per cent nitrofurazone soluble ointment. Philips (1959) recommended nitrofurazone for persistent cases not responding to antibiotics. Consequent to these reports, a commercial preparation (Canotane, Smith Kline & French Laboratories Ltd.) containing nitrofurazone was used in a series of 53 cases of canine otitis externa and the results are reported. MATERIALS AND METHODS
The preparation employed consisted of an oil-in-water cream applied twice daily to affected ears for as long as treatment was thought necessary. The cream contained 0·2 per cent nitrofurazone and in some instances, for which no separate records were kept, the topical anaesthetic dimethisoquin or 1-(-dimethylaminoethoxY)-3-n-butylisoquinoline monohydrochloride. This latter substance, which possesses no antibacterial activity, has been recommended as an ancillary in the treatment of skin conditions giving rise to pruritus of local origin. It is comparable in activity to the "caine" group of topical anaesthetics (Fellows & Macko, 1951), but is not related chemically. RESULTS
The 53 cases available were classified as acute, subacute or chronic. Clinical observation was used as the criteria of efficacy. The results are given in Table 1. TABLE I CLINICAL EFFECTS OF 'CANOTANE' IN CANINE OTITIS EXTERNA
Type of otitis
Cases treated
Acute Subacute Chronic Total
9 15 29 53
Cured
Improved
No improvement
5 (55%) 9 (60%) 13 (45%) 27 (5 1%)
4(44%) 3 (20%) 6(21%) 13 (24%)
3 (20%) (34%) 13 (24%) IO
In 25 of the cases, swabs were made from affected ears before treatment. Results of bacteriological examination and the clinical assessment after treatment are shown in Table II. CORRELATION OF
Organism Sterile Yeasts Pseudomonas Coliforms
~-haemolyticstreps. and} non-haemolytic staphs. Staph. aureus Haemolytic staphs. Non-haemolytic staphs. Haemolytic staphso} and Pseudomonas. Total
TABLE II CLINICAL RESULTS WITH ORGANISMS ISOLATED PRIOR TO 'CANOTANE' TREATMENT
Acute Subacute Chronic (a) (b) (a) (b) (a) (b) Cured/ No Cured/ No Cured/ No Total Improved Improvement Improved Improvement Improved Improvement 9
7
4 3
2
5 I
2
.I 2
25
3
2
2
II
7
CANINE OTITIS EXTERNA
21 3
DISCUSSION
This clinical trial confirmed the findings already mentioned that nitrofurazone is a useful drug in the treatment of otitis externa. The observation that 45 per cent of the chronic cases were apparently cured is important, in view of the fact that most of these had previously failed to respond to other forms of therapy. It is also interesting to note the relatively high number of cases from which various yeasts were isolated and the apparent ease with which they were eliminated following treatment with nitrofurazone. SUMMARY
The use of an ointment containing 0'2 per cent nitrofurazone for the treatment of canine otitis extern a was investigated and the results of a clinical trial recorded. Fifty-three cases were treated. Cure or improvement occurred in all acute cases and in 80 per cent of the subacute and 66 per cent of the chronic cases. ACKNOWLEDGEMENTS
We are indebted to Mr. r. M. Smith, Mr. P. H. McCready and Miss Phyllis M. James for their technical co-operation and advice. REFERENCES ALSTROM,1. (1953). Medlemsbl. sver. vet. forb., 5, 280. ANDERSON, j. R. & STEELE, C. H. (1948). Laryngoscop~ (St. Louis), 58, 1279DALL,j. A. (1 958). Vet. Rec., 70,1029. DECAMPS, C. E. (1949). J . Amer. vet. med. Ass., 114,6. DODD, M. C. (1946). J. Pharmacol. expo Therap., 86, 311. FELLOWS, E. j. & MACKO, E. (1951). J . Pharmacol. expo Therap., 1:03, 306. FRASER, G. (1957). Ph. D . Thesis, University of Edinburgh. FRASER, G. (1961). Vet. Rec., 73, 55. FRASER, G., WITHERS, A. R. & SPREULL, j. S. A. (1961). J. ~mall Anim. Pract., 2, 32. JOSHUA, J. O . (1958). Vet. Rec., 70, II 15. KAPLAN, A. D. (1948). Vet. Med., 43, 118. KNOWLES, A. T., KNOWLES, j. O. & KNOWLES, R. P. (1948). N. Amer. Vet., 29, 495. NILLSON, F. (1952). Medlemsbl ..sver. vet. forb., 40 173. PHIUPS, S. E. (1959). The ear. In Canine Medicine, 2nd edition, p. 507. Santa Barbara: American Veterinary Publications. (Received for publication 21 December, 1962)
J . (1963),
119,
2 II
THE TREATMENT OF CANINE OTITIS EXTERNA WITH NITROFURAZONE By W. N.
SCOTT
Smith, Kline & French Laboratories, Welwyn Garden City, Herts AND ESTHER
M. H.
DENHAM
Welwyn Garden City
The aetiology of otitis externa has been debated (Joshua, 1958; Fraser, 1961; Fraser, Withers & Spreull, 1961). It has been shown that, apart from the increased breed susceptibility to otitis in the case of miniature poodles and spaniels, the commonest predisposing factors in affected dogs were clinical skin complaints and ectoparasitic infestations. Although bacteria and fungi are not often implicated as causal agents, the presence of commensal organisms and their invasion of the primary lesion results in tissue changes which may progress from the acute to the chronic form of the disease. The bacterial flora of healthy and diseased ears has been compared by Fraser (1957). He isolated Gram-positive and Gram-negative organisms from both kinds of ear, but found coliforms and haemolytic streptococci to be more common in the latter. Proteus vulgaris and Pseudomonas aeruginosa were isolated only from diseased ears. The presence of such a variety of potential pathogens would, therefore, seem to favour the use of a broad spectrum antibacterial substance in the treatment of otitis externa. Nitrofurazone is known to show activity in vitro against a wide range of Gram-negative and Gram-positive organisms (Dodd, 1946). Anderson & Steele (1948) found that nitrofurazone was very effective in the treatment of human otitis media caused by bacteria. Following this observation, several workers used nitrofurazone in the treatment of otitis externa and skin conditions in dogs and cats. Kaplan (1948) reported the successful treatment of 16 cases of superficial skin infections in dogs and cats, including one case of suppurative otitis media. Knowles, Knowles & Knowles (1948) used the drug in 89 cases of otitis externa, the infecting organism being bacterial in 48, fungal in 17, mites in one and unclassified in 23. Of the 89 patients, 10 did not complete the course of treatment, though improvement was shown by all of them; of the 79 cases treated to completion, 76 recovered after an average of five treatments and three showed no improvement. Decamps (1949) used nitrofurazone in 18 cases of chronic ear infections and recorded relief of irritation and disappearance of discharge in all but one case. Nillson (1952) reported good results in 18 out of 2 I cases and Alstrom (1953) in treating 72 dogs noted similar results. Dall (1958) said that in treating cases of cellulitis and dermatitis in the dog, the best results were E
BRITISH VETERINARY JOURNAL, Ilg, 5
212
obtained with a 0·2 per cent nitrofurazone soluble ointment. Philips (1959) recommended nitrofurazone for persistent cases not responding to antibiotics. Consequent to these reports, a commercial preparation (Canotane, Smith Kline & French Laboratories Ltd.) containing nitrofurazone was used in a series of 53 cases of canine otitis externa and the results are reported. MATERIALS AND METHODS
The preparation employed consisted of an oil-in-water cream applied twice daily to affected ears for as long as treatment was thought necessary. The cream contained 0·2 per cent nitrofurazone and in some instances, for which no separate records were kept, the topical anaesthetic dimethisoquin or 1-(-dimethylaminoethoxY)-3-n-butylisoquinoline monohydrochloride. This latter substance, which possesses no antibacterial activity, has been recommended as an ancillary in the treatment of skin conditions giving rise to pruritus of local origin. It is comparable in activity to the "caine" group of topical anaesthetics (Fellows & Macko, 1951), but is not related chemically. RESULTS
The 53 cases available were classified as acute, subacute or chronic. Clinical observation was used as the criteria of efficacy. The results are given in Table 1. TABLE I CLINICAL EFFECTS OF 'CANOTANE' IN CANINE OTITIS EXTERNA
Type of otitis
Cases treated
Acute Subacute Chronic Total
9 15 29 53
Cured
Improved
No improvement
5 (55%) 9 (60%) 13 (45%) 27 (5 1%)
4(44%) 3 (20%) 6(21%) 13 (24%)
3 (20%) (34%) 13 (24%) IO
In 25 of the cases, swabs were made from affected ears before treatment. Results of bacteriological examination and the clinical assessment after treatment are shown in Table II. CORRELATION OF
Organism Sterile Yeasts Pseudomonas Coliforms
~-haemolyticstreps. and} non-haemolytic staphs. Staph. aureus Haemolytic staphs. Non-haemolytic staphs. Haemolytic staphso} and Pseudomonas. Total
TABLE II CLINICAL RESULTS WITH ORGANISMS ISOLATED PRIOR TO 'CANOTANE' TREATMENT
Acute Subacute Chronic (a) (b) (a) (b) (a) (b) Cured/ No Cured/ No Cured/ No Total Improved Improvement Improved Improvement Improved Improvement 9
7
4 3
2
5 I
2
.I 2
25
3
2
2
II
7
CANINE OTITIS EXTERNA
21 3
DISCUSSION
This clinical trial confirmed the findings already mentioned that nitrofurazone is a useful drug in the treatment of otitis externa. The observation that 45 per cent of the chronic cases were apparently cured is important, in view of the fact that most of these had previously failed to respond to other forms of therapy. It is also interesting to note the relatively high number of cases from which various yeasts were isolated and the apparent ease with which they were eliminated following treatment with nitrofurazone. SUMMARY
The use of an ointment containing 0'2 per cent nitrofurazone for the treatment of canine otitis extern a was investigated and the results of a clinical trial recorded. Fifty-three cases were treated. Cure or improvement occurred in all acute cases and in 80 per cent of the subacute and 66 per cent of the chronic cases. ACKNOWLEDGEMENTS
We are indebted to Mr. r. M. Smith, Mr. P. H. McCready and Miss Phyllis M. James for their technical co-operation and advice. REFERENCES ALSTROM,1. (1953). Medlemsbl. sver. vet. forb., 5, 280. ANDERSON, j. R. & STEELE, C. H. (1948). Laryngoscop~ (St. Louis), 58, 1279DALL,j. A. (1 958). Vet. Rec., 70,1029. DECAMPS, C. E. (1949). J . Amer. vet. med. Ass., 114,6. DODD, M. C. (1946). J. Pharmacol. expo Therap., 86, 311. FELLOWS, E. j. & MACKO, E. (1951). J . Pharmacol. expo Therap., 1:03, 306. FRASER, G. (1957). Ph. D . Thesis, University of Edinburgh. FRASER, G. (1961). Vet. Rec., 73, 55. FRASER, G., WITHERS, A. R. & SPREULL, j. S. A. (1961). J. ~mall Anim. Pract., 2, 32. JOSHUA, J. O . (1958). Vet. Rec., 70, II 15. KAPLAN, A. D. (1948). Vet. Med., 43, 118. KNOWLES, A. T., KNOWLES, j. O. & KNOWLES, R. P. (1948). N. Amer. Vet., 29, 495. NILLSON, F. (1952). Medlemsbl ..sver. vet. forb., 40 173. PHIUPS, S. E. (1959). The ear. In Canine Medicine, 2nd edition, p. 507. Santa Barbara: American Veterinary Publications. (Received for publication 21 December, 1962)