CASE REPORT POSSIBLE PHYCOMYCETES GRANULOMA IN THE LARYNX OF A HORSE P. FREIrZ AND R. FIscHERu
History An eight year old Hackney mare was pre-
sented to the clinic of the Western College of Veterinary Medicine with a history of stertorous respiration of six months duration. Initially the stertor occurred only after mild exercise or while eating grain, but it became progressively more frequent as time passed. For the past four years, the mare had been stabled in a box stall and turned out for daily exercise with other horses. The only medical history was of a mild cough and nasal discharge that occurred nine months before presentation to the clinic. This problem was not treated and recovery was uneventful. Clinical Findings The mare was in excellent physical condition and responded favorably to attendants. The abnormal clinical findings were restricted to the respiratory system. There was a loud stertor FIGURE 1. Photograph taken with the colonoduring the inspiratory phase of respiration. The right arytenoid (arrow) is enlarged. fiberscope. There The respiratory rate was 20 per' minute. was no anxiety or stress except during mild exercise when the stertor became intense and larynx immediately behind the vocal fold the nostrils flared. A loud stertor was auscul- (Figure 2). An exploratory laryngotomy was tated over the tracheal and laryngeal regions. deemed necessary to further assess the larynThe horse resented palpation of the larynx but geal lesion. A hemogram was normal. alterations in size or contour could not be deSurgical Procedure tected. Surgical anesthesia was induced with 2 g The upper respiratory tract was examined of thiamylal sodium2 and maintained with nasal and the with a fiber-optic colonoscopyl passages were observed to be patent and the halothane.3 A tracheostomy was performed in scope passed with normal resistance. The gut- the midcervical region to maintain adequate tural pouches and their openings were normal, ventilation and prevent aspiration from the the right arytenoid cartilage appeared thick- surgery site. A ventral midline approach to the larynx, simened throughout its length and failed to retract during inspiration (Figure 1). On pass- ilar to that described for laryngeal ventricing the scope through the vocal folds, a mass ulectomy (2) was used. The technique was was seen projecting from the right wall of the modified slightly by incising the cricoid cartilage ventrally and extending the incision an additional 2 cm to gain adequate exposure to *Departinent of Veterinary Clinical Studies, the area where the mass was located. Western College of Veterinary Medicine, Saskatoon, Saskatchewan (Fretz) and 95 Wallace 2Surtal, Parke Davis & Co. Ltd., Detroit, MichAvenue North, Listowel, Ontario (Fischer). 'Colonofiberscope - Olympus - C.F.L.B., W. igan. 3Somnothane, Hoechst Pharmaceuticals, MontCarsen Co. Ltd., 31 Scarsdale Rd., Don Mills, Onreal, Quebec. tario. 293 CAN. VET. JOUR., VOL. 17, no. 11, November, 1976
CANADIAN VETERINARY JOURNAL
FIGURE 2. Photograph taken with colonofiberscope passed through vocal folds. Note presence of space occupying lesion (arrow) on right wall of larynx.
1 cm FIGuRE 4. Appearance of mass upon removal. The incised cricoid was reapposed with one stainless steel suture and the laryngotomy incision was closed. A Papes-type tracheostomy tube was placed in the tracheostomy site and left in place for two days after which the wound was allowed to heal by second intention. After surgery, the horse was given 70 mg of dexamethasone4 intravenously once daily for six days and 3 million I.U. of penicillin5 intramuscularly daily for 15 days. Tetanus toxoid and tetanus antitoxin were also included in the postoperative therapy.
FIGURE 3. Appearance of mass on right laryngeal wall visualized through a ventral midline laryngostomy. Arrow pointing to mass.
Histopathology of Surgical Specimen The impression smears made from the mass contained an abundance of neutrophils and giant cells. Well vascularized granulation tissue with a
The mass was found on the right laryngeal wall; it was slightly hyperemic, firm, lobulated and 1.5 cm in diameter (Figures 3 and 4). 4Azium, Schering Corp. Ltd., Pointe Claire, The mass was removed by severing its discrete Quebec. attachment to the larynx with electrocautery 5Penicillin G Procaine, Pfizer Co. Ltd., Montreal, Quebec. (Figure 5). 294
PHYCOMYCETES GRANULOMA
Outcome The mare's condition immediately following surgery was somewhat improved. However, as the tracheostomy incision closed, the stertor became more intense. Thirty-seven days after the surgery, the stertor had reached an intensity equal to or greater than that prior to surgery. Endoscopy was repeated at this time to assess the status of the laryngeal area. The right arytenoid was similar in appearance to that when first viewed. A small mass was identified on the laryngeal wall at the site of the original surgery. No further changes were observed. As the horse showed no signs of improvement and the prognosis, based on the diagnosis of phycomycosis was guarded, the horse was euthanized and necropsy performed.
FIGURE 5. Appearance of defect in right laryngeal wall after removal of mass.
wide variety of inflammatory cells, neocapillary proliferation, extensive subepithelial edema and a large focus of granulocytes was seen on histological examination of biopsy sections. With Periodic Acid Schiff stain, fungal elements were visible deep in the granulomatous structure. The pathology diagnosis was phycomycosis.
Treatment Radical excision is reported to be necessary for successful treatment of equine phycomycosis (3). In this case, the extent of our surgical excisions, or the percentage of infected tissue removed, was difficult to assess. The prognosis therefore was guarded. The horse was given 1 g sodium iodide in aqueous solution for 15 kg body weight intravenously once a day for six days (9) beginning three days after surgery. The dosage was then increased to 1 g for 10 kg body weight intravenously once a day for 11 days. Sodium iodide" is stated to induce the resolution of granulomatous lesious of various fungal diseases (7).
Pathology and Bacteriology The left arytenoid was thickened through its length to 1.5 times the thickness of the right arytenoid. On removal of the larynx, there was some evidence of asymmetry, the right side appeared larger (Figure 6). A granulomatous mass 0.75 cm in diameter projected 0.5 cm from the laryngeal wall at the point where the biopsy had been taken. On dissection, the right lamina and arch of the cricoid were approximately doubled in diameter when compared with the left. The enlargement was firm in consistency. A cross section through the right lamina revealed a cavity, 1 cm by 0.5 cm by 0.5 cm which contained purulent exudate (Figure 7). All other body systems were normal. Sections of tissue from the laryngeal area were obtained for culture and histopathology. On culture there was a moderate growth of
/3-streptococci. /3-streptococci
0Sodium iodide solution, Haver-Lockhart Ltd., Calgary, Alberta. 295
are not con-
sidered to be of primary etiological significance (5). The results of fungal culture and wet mounts are in Table I. On histopathology of the cricoid cartilage there was extensive proliferation of fibrous connective tissue, with diffuse infiltration of large number of monocytes, plasma cells and a few giant cells, however, fungal elements were not evident in any of the tissue sections. Discussion The significance of the presence of phycomyces in abnormal tissue is not well understood. They are abundant in nature and are common contaminants at necropsy. Phycomycetes are generally considered to be opportunists and commonly infect animals debilitated by disease and those rendered more
CANADIAN VETERINARY JOURNAL
0cm FIGURE 6. Appearance of the larynx at the time of necropsy. Note the enlarged right arytenoid.
FIGURE 7. A cross section of the right cricoid lamina. Note the thickened cartilage and the area of necrosis within the cartilage.
susceptible by long antibiotic therapy or with cutaneous lesions offering access to the fungi (6). The tissue reaction to phycomycetes usually involves the presence of numerous macrophages and reactional giant cells accompanying granulomatous inflammation (10). Examination of laryngeal tissue taken at necropsy indicated a granulomatous reaction but failed to confirm a phycomycetes infection. No fungal elements were detected on histopathology and culture results were suggestive of contamination. An explanation for the extensive reaction found at necropsy is therefore a matter of speculation. A hypersensitive reaction to the fungal agent may have contributed to the lesion. Deep exposure to the agent, as was evident on the biopsy, would sensitize the horse. Although the surgery appeared to remove the fungi present within the tissues, daily exposure of the inflamed laryngeal mucosa to environmental phycomycetes may have been sufficient to continue granuloma production. Intradermal testing for delayed-type hypersensitivity to prepared phycomycin would assist in the assessment of this hypersensitivity to prepared
phycomycin would assist in the assessment of this hypothesis. It is most probable that irritation, of some nature, contributed to or was responsible for the observed lesion. The source of this irritation may have been the laryngeal mass, the identified fungal agents or some unidentified source which may have initiated a granulomatous response prior and predisposing to the fungal infection. It is known that the horse is prone to develop granulation tissue. It develops with conditions of blastomycosis, cutaneous strephtothricosis, staphylococcal mastitis, scirrhous cord and many cases of traumatic injury. Homey (8) reported fibroma formation, following laryngeal surgery, which was attributed to trauma or foreign body reaction when cartilage was sutured with stainless steel material. For some reason, not yet understood, the horse reacts to tissue insults of various forms in a somewhat consistent manner. This is especially true of the laryngeal region. One must appreciate and respect the vulnerable nature of these tissues and their ability to react to
296
PHYCOMYCETES GRANULOMA
TABLE I SUMMARY OF BACTERIOLOGICAL FINDINGS
OF
POST MORTEM SPECIMENS
Specimen Laryngeal mass Pharyngeal mucosa Left arytenoid Necrotic cricoid
Suspicious of fungal elements Suspicious of fungal elements No fungal elements seen Suspicious of fungal elements
Rhizopus sp. Aspergillus sp. Aspergillus sp. Aspergillus sp.
2. BAHER, G. J. Equine Medicine and Surgery, 2nd Edition. p. 784. Wheaton, Illinois: American Veterinary Publications Inc. 1972. 3. BRIDGES, C. H. and C. W. EMMONS. A phycomycosis of horses caused by Hyphomyces destruens. J. Am. vet. med. Ass. 138: 579589. 1961. 4. BRIDGES, C. H., W. M. ROMANE and C. W. EMMONS. Phycomycosis of horses caused by Entomophthora coronata. J. Am. vet. med. Ass. 140: 673-677. 1962. 5. CARTER, G. R. Diagnostic Procedures in Veterinary Microbiology. p. 5. Springfield: Charles C. Thomas. 1973. 6. DAVIS, B. D., R. DULBECCO, H. N. EISEN, H. S. GINSBERG and W. B. WOOD. Microbiology. p. 995. New York: Harper and Row Publishers. 1967. 7. GOODMAN, L. A. and A. GILMAN. The Pharmacological Basis of Therapeutics. 4th Edition. p. 822. Toronto: The Macmillan Company. 1970. 8. HORNEY, F. D. Laryngeal polyp in a horse following surgery for laryngeal hemiplegia. Can. vet. J. 10: 319-320. 1969. 9. HUTCHINS, D. R. and K. G. JOHNSTON. Phycomycosis in the horse. Aust. vet. J. 48: 269278. 1972. 10. JUNGERMAN, P. P. and R. M. SCHWARTZMAN. Veterinary Medical Mycology. p. 51. Philadelphia: Lea & Febiger. 1972.
insult when evaluating disease and when performing surgery in the laryngeal area. Summary An eight year old Hackney mare developed respiratory stertor associated with extensive granuloma formation in the larynx. The gross and histological post mortem lesions of the larynx are presented with possible etiological possibilities. Resume
Une jument Hackney, agee de huit ans, developpa une respiration stertoreuse, attribuable a la presence d'un granulome s'infiltrant dans le larynx. Les auteurs rapportent les lesions macroscopiques et histologiques de cette affection; ils en commentent aussi les causes plausibles. Acknowledgments The authors thank Dr. F. D. Homey, Ontario Veterinary College, University of Guelph, Guelph, Ontario for his assistance in preparing this paper. References 1. AUSTIN, R. J. Disseminated phycomycosis in a horse. Can. vet. J. 17: 86-89. 1976.
LETTER TO THE EDITOR MANPOWER SHORTAGE? Dear Sir: At the CVMA Convention '76 in Vancouver, the plenary session concerned itself with manpower requirements in the veterinary profession.
At the finale of the excellent entertainment offered by Doctors Archibald and Hulland, we could probably surmise that we are still not sure what questions to ask when we speak of over or under supply of veterinarians in Canada. To add some fuel to Dr. Hulland's fire, may I point out that we at St. Clair College have
been trying to attract a veterinarian to teach in our A.H.T. program with a singular lack of success, indeed with few nibbles at the bait. If in fact we have an over supply of veterinarians in Canada, I do not believe that the surplus is very hungry.
2917
Sincerely, WM. B. RAMSAY, D.V.M. Co-ordinator A.H.T. Program St. Clair College 2000 Talbot Road West Windsor, Ontario N9A 6S4
History An eight year old Hackney mare was pre-
sented to the clinic of the Western College of Veterinary Medicine with a history of stertorous respiration of six months duration. Initially the stertor occurred only after mild exercise or while eating grain, but it became progressively more frequent as time passed. For the past four years, the mare had been stabled in a box stall and turned out for daily exercise with other horses. The only medical history was of a mild cough and nasal discharge that occurred nine months before presentation to the clinic. This problem was not treated and recovery was uneventful. Clinical Findings The mare was in excellent physical condition and responded favorably to attendants. The abnormal clinical findings were restricted to the respiratory system. There was a loud stertor FIGURE 1. Photograph taken with the colonoduring the inspiratory phase of respiration. The right arytenoid (arrow) is enlarged. fiberscope. There The respiratory rate was 20 per' minute. was no anxiety or stress except during mild exercise when the stertor became intense and larynx immediately behind the vocal fold the nostrils flared. A loud stertor was auscul- (Figure 2). An exploratory laryngotomy was tated over the tracheal and laryngeal regions. deemed necessary to further assess the larynThe horse resented palpation of the larynx but geal lesion. A hemogram was normal. alterations in size or contour could not be deSurgical Procedure tected. Surgical anesthesia was induced with 2 g The upper respiratory tract was examined of thiamylal sodium2 and maintained with nasal and the with a fiber-optic colonoscopyl passages were observed to be patent and the halothane.3 A tracheostomy was performed in scope passed with normal resistance. The gut- the midcervical region to maintain adequate tural pouches and their openings were normal, ventilation and prevent aspiration from the the right arytenoid cartilage appeared thick- surgery site. A ventral midline approach to the larynx, simened throughout its length and failed to retract during inspiration (Figure 1). On pass- ilar to that described for laryngeal ventricing the scope through the vocal folds, a mass ulectomy (2) was used. The technique was was seen projecting from the right wall of the modified slightly by incising the cricoid cartilage ventrally and extending the incision an additional 2 cm to gain adequate exposure to *Departinent of Veterinary Clinical Studies, the area where the mass was located. Western College of Veterinary Medicine, Saskatoon, Saskatchewan (Fretz) and 95 Wallace 2Surtal, Parke Davis & Co. Ltd., Detroit, MichAvenue North, Listowel, Ontario (Fischer). 'Colonofiberscope - Olympus - C.F.L.B., W. igan. 3Somnothane, Hoechst Pharmaceuticals, MontCarsen Co. Ltd., 31 Scarsdale Rd., Don Mills, Onreal, Quebec. tario. 293 CAN. VET. JOUR., VOL. 17, no. 11, November, 1976
CANADIAN VETERINARY JOURNAL
FIGURE 2. Photograph taken with colonofiberscope passed through vocal folds. Note presence of space occupying lesion (arrow) on right wall of larynx.
1 cm FIGuRE 4. Appearance of mass upon removal. The incised cricoid was reapposed with one stainless steel suture and the laryngotomy incision was closed. A Papes-type tracheostomy tube was placed in the tracheostomy site and left in place for two days after which the wound was allowed to heal by second intention. After surgery, the horse was given 70 mg of dexamethasone4 intravenously once daily for six days and 3 million I.U. of penicillin5 intramuscularly daily for 15 days. Tetanus toxoid and tetanus antitoxin were also included in the postoperative therapy.
FIGURE 3. Appearance of mass on right laryngeal wall visualized through a ventral midline laryngostomy. Arrow pointing to mass.
Histopathology of Surgical Specimen The impression smears made from the mass contained an abundance of neutrophils and giant cells. Well vascularized granulation tissue with a
The mass was found on the right laryngeal wall; it was slightly hyperemic, firm, lobulated and 1.5 cm in diameter (Figures 3 and 4). 4Azium, Schering Corp. Ltd., Pointe Claire, The mass was removed by severing its discrete Quebec. attachment to the larynx with electrocautery 5Penicillin G Procaine, Pfizer Co. Ltd., Montreal, Quebec. (Figure 5). 294
PHYCOMYCETES GRANULOMA
Outcome The mare's condition immediately following surgery was somewhat improved. However, as the tracheostomy incision closed, the stertor became more intense. Thirty-seven days after the surgery, the stertor had reached an intensity equal to or greater than that prior to surgery. Endoscopy was repeated at this time to assess the status of the laryngeal area. The right arytenoid was similar in appearance to that when first viewed. A small mass was identified on the laryngeal wall at the site of the original surgery. No further changes were observed. As the horse showed no signs of improvement and the prognosis, based on the diagnosis of phycomycosis was guarded, the horse was euthanized and necropsy performed.
FIGURE 5. Appearance of defect in right laryngeal wall after removal of mass.
wide variety of inflammatory cells, neocapillary proliferation, extensive subepithelial edema and a large focus of granulocytes was seen on histological examination of biopsy sections. With Periodic Acid Schiff stain, fungal elements were visible deep in the granulomatous structure. The pathology diagnosis was phycomycosis.
Treatment Radical excision is reported to be necessary for successful treatment of equine phycomycosis (3). In this case, the extent of our surgical excisions, or the percentage of infected tissue removed, was difficult to assess. The prognosis therefore was guarded. The horse was given 1 g sodium iodide in aqueous solution for 15 kg body weight intravenously once a day for six days (9) beginning three days after surgery. The dosage was then increased to 1 g for 10 kg body weight intravenously once a day for 11 days. Sodium iodide" is stated to induce the resolution of granulomatous lesious of various fungal diseases (7).
Pathology and Bacteriology The left arytenoid was thickened through its length to 1.5 times the thickness of the right arytenoid. On removal of the larynx, there was some evidence of asymmetry, the right side appeared larger (Figure 6). A granulomatous mass 0.75 cm in diameter projected 0.5 cm from the laryngeal wall at the point where the biopsy had been taken. On dissection, the right lamina and arch of the cricoid were approximately doubled in diameter when compared with the left. The enlargement was firm in consistency. A cross section through the right lamina revealed a cavity, 1 cm by 0.5 cm by 0.5 cm which contained purulent exudate (Figure 7). All other body systems were normal. Sections of tissue from the laryngeal area were obtained for culture and histopathology. On culture there was a moderate growth of
/3-streptococci. /3-streptococci
0Sodium iodide solution, Haver-Lockhart Ltd., Calgary, Alberta. 295
are not con-
sidered to be of primary etiological significance (5). The results of fungal culture and wet mounts are in Table I. On histopathology of the cricoid cartilage there was extensive proliferation of fibrous connective tissue, with diffuse infiltration of large number of monocytes, plasma cells and a few giant cells, however, fungal elements were not evident in any of the tissue sections. Discussion The significance of the presence of phycomyces in abnormal tissue is not well understood. They are abundant in nature and are common contaminants at necropsy. Phycomycetes are generally considered to be opportunists and commonly infect animals debilitated by disease and those rendered more
CANADIAN VETERINARY JOURNAL
0cm FIGURE 6. Appearance of the larynx at the time of necropsy. Note the enlarged right arytenoid.
FIGURE 7. A cross section of the right cricoid lamina. Note the thickened cartilage and the area of necrosis within the cartilage.
susceptible by long antibiotic therapy or with cutaneous lesions offering access to the fungi (6). The tissue reaction to phycomycetes usually involves the presence of numerous macrophages and reactional giant cells accompanying granulomatous inflammation (10). Examination of laryngeal tissue taken at necropsy indicated a granulomatous reaction but failed to confirm a phycomycetes infection. No fungal elements were detected on histopathology and culture results were suggestive of contamination. An explanation for the extensive reaction found at necropsy is therefore a matter of speculation. A hypersensitive reaction to the fungal agent may have contributed to the lesion. Deep exposure to the agent, as was evident on the biopsy, would sensitize the horse. Although the surgery appeared to remove the fungi present within the tissues, daily exposure of the inflamed laryngeal mucosa to environmental phycomycetes may have been sufficient to continue granuloma production. Intradermal testing for delayed-type hypersensitivity to prepared phycomycin would assist in the assessment of this hypersensitivity to prepared
phycomycin would assist in the assessment of this hypothesis. It is most probable that irritation, of some nature, contributed to or was responsible for the observed lesion. The source of this irritation may have been the laryngeal mass, the identified fungal agents or some unidentified source which may have initiated a granulomatous response prior and predisposing to the fungal infection. It is known that the horse is prone to develop granulation tissue. It develops with conditions of blastomycosis, cutaneous strephtothricosis, staphylococcal mastitis, scirrhous cord and many cases of traumatic injury. Homey (8) reported fibroma formation, following laryngeal surgery, which was attributed to trauma or foreign body reaction when cartilage was sutured with stainless steel material. For some reason, not yet understood, the horse reacts to tissue insults of various forms in a somewhat consistent manner. This is especially true of the laryngeal region. One must appreciate and respect the vulnerable nature of these tissues and their ability to react to
296
PHYCOMYCETES GRANULOMA
TABLE I SUMMARY OF BACTERIOLOGICAL FINDINGS
OF
POST MORTEM SPECIMENS
Specimen Laryngeal mass Pharyngeal mucosa Left arytenoid Necrotic cricoid
Suspicious of fungal elements Suspicious of fungal elements No fungal elements seen Suspicious of fungal elements
Rhizopus sp. Aspergillus sp. Aspergillus sp. Aspergillus sp.
2. BAHER, G. J. Equine Medicine and Surgery, 2nd Edition. p. 784. Wheaton, Illinois: American Veterinary Publications Inc. 1972. 3. BRIDGES, C. H. and C. W. EMMONS. A phycomycosis of horses caused by Hyphomyces destruens. J. Am. vet. med. Ass. 138: 579589. 1961. 4. BRIDGES, C. H., W. M. ROMANE and C. W. EMMONS. Phycomycosis of horses caused by Entomophthora coronata. J. Am. vet. med. Ass. 140: 673-677. 1962. 5. CARTER, G. R. Diagnostic Procedures in Veterinary Microbiology. p. 5. Springfield: Charles C. Thomas. 1973. 6. DAVIS, B. D., R. DULBECCO, H. N. EISEN, H. S. GINSBERG and W. B. WOOD. Microbiology. p. 995. New York: Harper and Row Publishers. 1967. 7. GOODMAN, L. A. and A. GILMAN. The Pharmacological Basis of Therapeutics. 4th Edition. p. 822. Toronto: The Macmillan Company. 1970. 8. HORNEY, F. D. Laryngeal polyp in a horse following surgery for laryngeal hemiplegia. Can. vet. J. 10: 319-320. 1969. 9. HUTCHINS, D. R. and K. G. JOHNSTON. Phycomycosis in the horse. Aust. vet. J. 48: 269278. 1972. 10. JUNGERMAN, P. P. and R. M. SCHWARTZMAN. Veterinary Medical Mycology. p. 51. Philadelphia: Lea & Febiger. 1972.
insult when evaluating disease and when performing surgery in the laryngeal area. Summary An eight year old Hackney mare developed respiratory stertor associated with extensive granuloma formation in the larynx. The gross and histological post mortem lesions of the larynx are presented with possible etiological possibilities. Resume
Une jument Hackney, agee de huit ans, developpa une respiration stertoreuse, attribuable a la presence d'un granulome s'infiltrant dans le larynx. Les auteurs rapportent les lesions macroscopiques et histologiques de cette affection; ils en commentent aussi les causes plausibles. Acknowledgments The authors thank Dr. F. D. Homey, Ontario Veterinary College, University of Guelph, Guelph, Ontario for his assistance in preparing this paper. References 1. AUSTIN, R. J. Disseminated phycomycosis in a horse. Can. vet. J. 17: 86-89. 1976.
LETTER TO THE EDITOR MANPOWER SHORTAGE? Dear Sir: At the CVMA Convention '76 in Vancouver, the plenary session concerned itself with manpower requirements in the veterinary profession.
At the finale of the excellent entertainment offered by Doctors Archibald and Hulland, we could probably surmise that we are still not sure what questions to ask when we speak of over or under supply of veterinarians in Canada. To add some fuel to Dr. Hulland's fire, may I point out that we at St. Clair College have
been trying to attract a veterinarian to teach in our A.H.T. program with a singular lack of success, indeed with few nibbles at the bait. If in fact we have an over supply of veterinarians in Canada, I do not believe that the surplus is very hungry.
2917
Sincerely, WM. B. RAMSAY, D.V.M. Co-ordinator A.H.T. Program St. Clair College 2000 Talbot Road West Windsor, Ontario N9A 6S4
