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Blood Gas Analysis and Management of Canine Brachycephalic Airway Syndrome (BAS) in Brachycephalic Dogs.

Abstract

The study was aimed to estimate the various blood gas parameters in brachycephalic breeds presented with severe respiratory distress and their successfull management. The parameters studied were Sp[O.sub.2] (%), EtC[O.sub.2] (mm/Hg), pH, Pa[O.sub.2] and PaC[O.sub.2] The incidence of brachycephalic airway syndrome among the brachycephalic dogs was 27.27 percent. The common breeds recorded in the study were pugs and boxers. The dogs had a costoabdominal respiration and inspiratory dyspnea characterized by stretor. Reduced Sp[O.sub.2] and Pa[O.sub.2] with an increase PaC[O.sub.2] were recorded in these dogs.. The common acid base abnormality recorded was respiratory acidosis. The dogs were successfully managed with sedation using Butorphanol @0.2mg/kg and passive cooling by ice cold packs and cold water enema.

Keywords: Brachycephalic breeds; blood gas analysis.

Introduction

The Brachycephalic Air Syndrome (BAS) is characterized by increased upper airway resistance because of narrowed nostrils, an elongated and thickened soft palate, everted laryngeal saccules and hypoplastic trachea (Koch et al., 2003). Prominent nasopharyngeal turbinates have also been reported. BAS is commonly encountered in small animal practice owing to increasing popularity of breeds affected. It is an emergency condition which requires prompt therapy (Houreau et al., 2013). Blood gas analysis plays a major role in assessment and response to treatment in these dogs. With an increase in incidence of BAS in small animal practice, the current project work was taken up with the objectives to estimate the various blood gas parameters in brachycephalic breeds presented with respiratory distress and to successfully manage them.

Materials and Method

The study was carried out by utilizing the clinical cases presented. The study consisted of apparently healthy animals and clinical cases. Ten apparently healthy brachycephalic breed dogs brought for routine check up and vaccination were randomly selected to collect reference values of parameters under study (Group I). During the study period, 6 dogs were presented with brachycephalic airway obstructive syndrome (Group II). A complete physical examination was performed in dogs under Group I and Group II. The pH, PaC[O.sub.2] and Pa[O.sub.2] were studied in all these dogs. An automated blood gas analyser (Siemens 0L085-Rapidlab 348) was used to assess the blood gas parameters like pH, Pa[O.sub.2] and PaC[O.sub.2] as per recommended protocols of Rieser (2013). Dogs presented with respiratory distress were medically managed. Medical management associated with brachycephalic syndrome was aimed at decreasing airway turbulence and resulting in inflammation and edema. These dogs were sedated with either Butorphanol at the dose rate of 0.2-0.4 mg/kg intramuscularly or Diazepam 0.2mg/kg intravenously with supplemental oxygen therapy. Short acting anti-inflammatory glucocorticoid (prednisolone) at the dose rate of 0.2mg/kg intramuscularly was administered (Lodato and Hedlund, 2012). The data obtained were subjected to statistical analysis using SPSS 20.0 as described by Snedocar and Cochran (1994).

Results and Discussion

Among the brachycephalic breeds, during the study period, six dogs (27.27 percent) were presented with brachycephalic airway syndrome. The common breeds recorded in the study were Pugs and Boxer. Group II included five Pug and one Boxer. The reported common breeds with brachycephalic airway obstructive syndrome include Pug, Perkingese, Boston terriers, English bull dogs and Boxers (Trapple and Moore, 2013). Since the population of Pug and Boxer are high in Chennai, the incidence in these dogs were recorded.

The dogs under group II with airway obstruction had costoabdominal type of respiration, inspiratory dyspnoea, synchronous movement of thoracic and abdominal wall, increased auscultatory sounds characterized by stridor or stertor. Sirgrist et al. (2011) reported similar findings in their study and Meola (2013) stated that increased resistance also leads to turbulent airflow, oedema and increased inspiratory noise commonly heard with brachycephalic dogs, the dogs with airway obstruction had a nonsignificant increase in mean temperature (40.3[+ or -]0.20[degrees]C). Rozanski and Chan (2005) reported that dogs with upper airway obstruction are initially presented with hyperthermia.

A highly significant increase heart rate and respiration rate (Table 1) while a non-significant increase in temperature were recorded in these dogs. Rozanski and Chan (2005) reported that dogs with upper airway obstruction are initially presented with hyperthermia. Hamlin (2000) recorded an increase in respiration rate in dogs with airway obstruction.

A highly significant decrease in Sp[O.sub.2] values were recorded in dogs with airway obstruction (Group II). A highly significant increase in ETC[O.sub.2] was recorded in dogs under Group II with airway obstruction -Group II (Table I) indicative of hypoventilation as suggested by Tseng and Waddell (2000).

A significant increase in PaC[O.sub.2] was recorded in dogs under Group II when compared with Group I. The dogs with airway obstruction like brachycephalic syndrome have an increase in PaC[O.sub.2] due to obstruction in the airway resulting in accumulation on carbon dioxide in the system which concurred in our study (Rozanski and Chan, 2005). A significant difference was recorded in dogs under Group III when compared with control dogs which suggested that respiratory acidosis was observed in Group II as suggested by Johnson, (2008).

A significant decrease in Pa[O.sub.2] was recorded in dogs in Group II when compared with normal dogs. Owing to the anatomic differences, brachycephalic dogs have an increased resistance to airflow and an increased intraluminal pressure gradient during inspiration. The decrease in size of opening of nares, nasal passage way and larynx by half would increase the airway resistance in brachycephalic breed 16 times that of non brachycephalic breed (Loato and Hedlund, 2012). The increased negative pressure created to overcome the resistance causes soft tissue to become inflamed, tonsil and laryngeal saccules to evert and larynx and trachea to collapse. A vicious cycle of increased airway resistance that leads to oedema and swelling and worsening resistance is often responsible for acute respiratory distress and hypoxemia.

All dogs presented with respiratory distress due to BAS were sedated with either Butorphanol at the dose rate of 0.2-0.4 mg/kg intramuscularly or Diazepam 0.2mg/kg intravenously with supplemental oxygen therapy. Short acting anti-inflammatory glucocorticoid, Prednisolone at the dose rate of 0.2mg/kg intramuscularly was administered. A highly significant increase in Sp[O.sub.2] and Pa[O.sub.2] and decrease in respiration rate (Table II) were recorded after oxygen therapy in dogs under Group III with airway obstruction in as suggested by Meola, (2013). The temperature was reduced by passive cooling using cold ice backs, cold water enema and keeping them in room with temperature less than 20[degrees]C.

All dogs presented with respiratory distress were successfully managed and referred for bronchoscopy and surgery for identifying and correction of underlying pathology.

Conclusion

Brachycephalic airway obstruction syndrome is a common complaint in brachycephalic breeds. It is a life threatening emergency condition which requires prompt therapy. Assessment of blood gas analysis and correct management of dogs presented with BAS is aimed for better survival of these dogs. Emergency management should focus on oxygenation, ventilation and temperature management for initial stabilization before surgical intervention which can be monitored by blood gas analysis.

References

Hamlin, R. (2000). Physical examination of the pulmonary system. Vet. Clin. North Am. Small Anim. Pract. 30: 1175-85.

Horeau, G.L., Jourdan, G., Mellema, M. and Verwaerde, P. (2012). Evaluation of arterial blood gases and arterial blood pressures in brachycephalic dogs. J. Vet. Intern. Med. 26: 897-04.

Johnson, R.A. (2008). Respiratory acidosis: A quick reference. Vet. Clin. North Am. Small Anim. Pract. 38: 431-34.

Koch, D.A., Arnold, S. and Hubler, M. (2003). Brachycephalic syndrome in dogs. Compend. Contin. Educ. Pract. Vet. 25: 48-55.

Lodato, D.L and Hedlund, C.S. (2012). Brachycephalic airway syndrome: Management. Compend. Contin. Educ. Pract. Vet. 34: 1-7.

Meola, S.D. (2013). Brachycephalic airway syndrome. Top. Comp. Anim. Med. 28: 91-96.

Rozanski, E.A. and Chan, D.L., (2005). Approach to the patient with respiratory distress. Vet. Clin. North Am. Small Anim. Pract. 35: 307-17.

Sirgrist, N.E., Adamik, K.N., Doherr, M.G. and Spreng, D.E., (2011) Evaluation of respiratory parameters at presentation as clinical indicators of the respiratory localization in dogs and cats with respiratory distress. J. Vet. Emerg. Crit. Care. 21: 19-23.

Snedecor, C.W. and Cochran, W.C. (1994). Statistical Methods. 8 (th) Edn., Iowa State University Press, USA.

Trapple, M. and Moore, K.W. (2011). Canine Brachycephalic Airway Syndrome: Pathophysiology, Diagnosis, and Nonsurgical management. Compend. Contin. Educ. Pract. Vet. 33: 1-4.

Tseng,W.L. and Waddell, L.S. (2000). Approach to the Patient in Respiratory Distress. Clin. Tec. Small Anim. Pract. 15: 53-62.

S. Hamsa Yamini (1), S. Kavitha and A.P. Nambi

Department of Veterinary Clinical Medicine

Madras Veterinary College

Tamil Nadu Veterinary and Animal Sciences University (TANUVAS)

Chennai - 600007 (Tamil Nadu).

(1.) Ph.D. Scholar and Corresponding author.

E-mail: hamsa.yamini@gmail.com
Table 1: Physical Parameters and blood gas parameters in dogs presented
with BAS compared to normal dogs

Parameters                Group I             Group II
                          Apparently          Airway
                          healthy             obstruction
                          animals             n= 6
                          n=10

Temperature([degrees]C)   38.50[+ or -]0.09   40.30[+ or -]0.20
Heart rate (bpm)          88.00[+ or -]2.46   119.67[+ or -]2.79 (**)
Respiration rate          31.20[+ or -]1.11   93.17[+ or -]2.26 (**)
(per min.)
Sp[o.sub.2](%)            97.30[+ or -]0.45   68.67[+ or -]3.74 (**)
EtC[O.sub.2] (mm/Hg)      22.30[+ or -]1.17   41.50[+ or -]6.80 (**)
pH                        7.44[+ or -]0.005   7.29[+ or -]0.033 (**)
Pa[O.sub.2]               90.93[+ or -]1.81   53.13[+ or -]3.18 (**)
PaC[O.sub.2]              33.65[+ or -]1.31   56.77[+ or -]2.61 (**)

Table 2 : Mean [+ or -] S.E values of Sp[O.sub.2] Pa[O.sub.2] and
respiratory rate in dogs with airway obstruction treated with oxygen
therapy

Parameter             Airway obstruction
                      Before               After
                      treatment            treatment

Sp[o.sub.2](%)        68.67[+ or -]3.74    92.83[+ or -]2.86 (*)
Pa[O.sub.2] (mm/Hg)   53.13[+ or -]3.18    81.68[+ or -]1.61 (**)
Respiratory rate      93.17[+ or -]2.26    41.67[+ or -]1.43 (**)
(per min.)

(**) - Statistically highly significant (P[less than or equal to]0.01)
(*) - Statistically significant (P[less than or equal to]0.01)
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Title Annotation:Research Article
Author:Yamini, S. Hamsa; Kavitha, S.; Nambi, A.P.
Publication:Intas Polivet
Article Type:Report
Date:Jul 1, 2016
Words:1726
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