- Email: [email protected]
Collapse, syncope, and exercise intolerance
A D VA N C E S
Objectives To retrospectively assess the long-term outcome for dogs that were presented with idiopathic collapse, syncope, or exercise intolerance.
Procedure The clinical records of 153 dogs presented for collapse, syncope, or exercise intolerance within at least 6 months previously and did not receive a definitive diagnosis despite investigation were evaluated. Telephone interviews with the owners were conducted to determine outcomes.
Results Clinical signs resolved in 64 cases (42%), and 35 dogs (23%) were continuing to exhibit clinical signs, although 22 of these had improved without medical intervention. In 17 cases (11%), a diagnosis had subsequently been made or treatment was being administered. Thirty-seven dogs (24%) had died, of which 18 (12%) were considered to be related to the original presentation. The overall prevalence of death and deterioration related to the problems investigated was 16.2% of cases. Death in boxer dogs was significantly more common than in other breeds (36%).
Author Conclusion
COLLAPSE, SYNCOPE, AND EXERCISE INTOLERANCE Background Episodic collapse, syncope, and exercise intolerance are all clinical signs that occur intermittently. As a result, it is difficult to investigate the cause of these clinical signs. A definitive diagnosis is reached for only about 40 to 50% of dogs presenting with collapse, syncope, or exercise intolerance. The term collapse is used to describe any occurrence of unintentional prostration. Syncope is typically associated with a transient loss of consciousness, collapse, and spontaneous recovery. Syncope is caused by factors that produce a shortterm interruption of cerebral perfusion, oxygen, or glucose. The syndromes of exercise intolerance and episodic weakness cause lethargy progressing to recumbence. Both syndromes worsen with exercise but improve with rest.
Death and deterioration are uncommon outcomes for dogs other than boxers presenting with idiopathic collapse, syncope, and exercise intolerance.
Inclusions Two figures, 4 tables, 23 references.
Editor Annotation This study shows that many dogs with unidentified causes of collapse, syncope, or exercise have spontaneous resolution of their clinical signs. Others improve with empirical therapy or after a subsequent diagnosis and cause-directed therapy. It is also not surprising to see that boxer dogs were more likely to die, as this breed is prone to arrhythmic sudden death. Similarly, Doberman pinschers with subclinical dilated cardiomyopathy can die suddenly. The biggest weakness of this study is the efforts at diagnosing the cause of collapse. The cases were not exhaustively evaluated (e.g., Holter or event monitoring, MRI scans, muscle biopsies, and genetic testing
PAG E 3
for exercise-induced collapse). Therefore, it is unknown how many of the dogs considered “undiagnosed” or “idiopathic” could have been treated effectively (e.g., boxers with arrhythmogenic right ventricular cardiomyopathy or Dobermans with dilated cardiomyopathy). Similarly, the authors do not detail whether conditions such as pulmonary artery hypertension were ruled out in each case. It is encouraging to believe that younger dogs (other than predisposed breeds) with singular episodes of collapse, weakness, or syncope often resolve their clinical signs spontaneously. However, this requires proof from a study in which each patient is comprehensively and exhaustively evaluated to exclude all possible diagnoses. (MR) Barnett L, Martin MWS, Todd J, et al. A retrospective study of 153 cases of undiagnosed collapse, syncope or exercise intolerance: the outcomes. J Small Anim Pract 2011;52:26-31.
Objectives To retrospectively assess the long-term outcome for dogs that were presented with idiopathic collapse, syncope, or exercise intolerance.
Procedure The clinical records of 153 dogs presented for collapse, syncope, or exercise intolerance within at least 6 months previously and did not receive a definitive diagnosis despite investigation were evaluated. Telephone interviews with the owners were conducted to determine outcomes.
Results Clinical signs resolved in 64 cases (42%), and 35 dogs (23%) were continuing to exhibit clinical signs, although 22 of these had improved without medical intervention. In 17 cases (11%), a diagnosis had subsequently been made or treatment was being administered. Thirty-seven dogs (24%) had died, of which 18 (12%) were considered to be related to the original presentation. The overall prevalence of death and deterioration related to the problems investigated was 16.2% of cases. Death in boxer dogs was significantly more common than in other breeds (36%).
Author Conclusion
COLLAPSE, SYNCOPE, AND EXERCISE INTOLERANCE Background Episodic collapse, syncope, and exercise intolerance are all clinical signs that occur intermittently. As a result, it is difficult to investigate the cause of these clinical signs. A definitive diagnosis is reached for only about 40 to 50% of dogs presenting with collapse, syncope, or exercise intolerance. The term collapse is used to describe any occurrence of unintentional prostration. Syncope is typically associated with a transient loss of consciousness, collapse, and spontaneous recovery. Syncope is caused by factors that produce a shortterm interruption of cerebral perfusion, oxygen, or glucose. The syndromes of exercise intolerance and episodic weakness cause lethargy progressing to recumbence. Both syndromes worsen with exercise but improve with rest.
Death and deterioration are uncommon outcomes for dogs other than boxers presenting with idiopathic collapse, syncope, and exercise intolerance.
Inclusions Two figures, 4 tables, 23 references.
Editor Annotation This study shows that many dogs with unidentified causes of collapse, syncope, or exercise have spontaneous resolution of their clinical signs. Others improve with empirical therapy or after a subsequent diagnosis and cause-directed therapy. It is also not surprising to see that boxer dogs were more likely to die, as this breed is prone to arrhythmic sudden death. Similarly, Doberman pinschers with subclinical dilated cardiomyopathy can die suddenly. The biggest weakness of this study is the efforts at diagnosing the cause of collapse. The cases were not exhaustively evaluated (e.g., Holter or event monitoring, MRI scans, muscle biopsies, and genetic testing
PAG E 3
for exercise-induced collapse). Therefore, it is unknown how many of the dogs considered “undiagnosed” or “idiopathic” could have been treated effectively (e.g., boxers with arrhythmogenic right ventricular cardiomyopathy or Dobermans with dilated cardiomyopathy). Similarly, the authors do not detail whether conditions such as pulmonary artery hypertension were ruled out in each case. It is encouraging to believe that younger dogs (other than predisposed breeds) with singular episodes of collapse, weakness, or syncope often resolve their clinical signs spontaneously. However, this requires proof from a study in which each patient is comprehensively and exhaustively evaluated to exclude all possible diagnoses. (MR) Barnett L, Martin MWS, Todd J, et al. A retrospective study of 153 cases of undiagnosed collapse, syncope or exercise intolerance: the outcomes. J Small Anim Pract 2011;52:26-31.