ArticlePDF Available

Exercise-Induced Collapse of Labrador Retrievers: Survey Results and Preliminary Investigation of Heritability

Authors:

Abstract and Figures

Completed surveys were obtained from owners of 225 Labrador retrievers affected by the syndrome of exercise-induced collapse. Questions addressed signalment, age of onset, description of collapse episodes, and owner perception of activities and factors associated with collapse. Most dogs were young (mean 12 months) when collapse episodes began. Retrieving was the activity most commonly associated with collapse. Owners felt that excitement (187/225; 83%) and high environmental temperatures (71/225; 31%) increased the likelihood of collapse. Analysis of pedigrees collected from 169 affected dogs was most consistent with an autosomal recessive mode of inheritance.
Content may be subject to copyright.
Exercise-Induced Collapse of Labrador
Retrievers: Survey Results and Preliminary
Investigation of Heritability
Completed surveys were obtained from owners of 225 Labrador retrievers affected by the syn-
drome of exercise-induced collapse. Questions addressed signalment, age of onset, descrip-
tion of collapse episodes, and owner perception of activities and factors associated with
collapse. Most dogs were young (mean 12 months) when collapse episodes began. Retrieving
was the activity most commonly associated with collapse. Owners felt that excitement
(187/225; 83%) and high environmental temperatures (71/225; 31%) increased the likelihood
of collapse. Analysis of pedigrees collected from 169 affected dogs was most consistent with
an autosomal recessive mode of inheritance. J Am Anim Hosp Assoc 2008;44:295-301.
Susan M. Taylor, DVM,
Diplomate ACVIM (Internal Medicine)
Cindy L. Shmon, DVM, DVSc,
Diplomate ACVS (Surgery)
G. Diane Shelton, DVM, PhD,
Diplomate ACVIM (Internal Medicine)
Edward (Ned) E. Patterson, DVM,
PhD, Diplomate ACVIM
(Internal Medicine)
Katie Minor, BS
James R. Mickelson, PhD
Introduction
A syndrome of exercise intolerance and collapse in young adult Labrador
retrievers was first described in the veterinary literature in 1993.1
Elevated rectal temperatures and increased plasma lactate concentrations
after exercise, and normal findings on examination of muscle biopsies
were documented in a few affected dogs.1Recently this syndrome has
been shown to be an important cause of exercise intolerance, interfering
with performance in otherwise healthy, young adult, competitive field
trial and hunting Labrador retrievers.2-4 Veterinarians evaluating affected
dogs have attributed collapse to heat intolerance, hypoglycemia, a car-
diac rhythm disturbance, or a possible metabolic myopathy, but no con-
sistent abnormalities have been identified in affected dogs.1-4 The
syndrome has come to be called exercise-induced collapse (EIC) of
Labrador retrievers.4,5 Affected dogs sometimes develop an abnormal
gait or collapse when subjected to strenuous exercise, but factors impor-
tant in inducing episodes of collapse have not been well established.
This study reports results of surveys completed by owners of 225
Labrador retrievers with presumed EIC. Also presented are preliminary
results of an investigation into the heritability of this condition. This is
the first large-scale descriptive study of EIC, providing veterinarians with
the information needed to recognize the syndrome and make informed
decisions regarding management and prognosis of affected dogs.
Materials and Methods
Descriptive Study
A survey was developed to obtain demographic and descriptive clinical
histories on dogs with presumed EIC [see Appendix]. The survey was
distributed to owners of Labrador retrievers with a collapse syndrome
determined by their veterinarian to most likely be EIC. Owners were
identified when they contacted investigators after learning about the
study through their veterinarian or magazine articles targeting owners of
working retrievers.2,3 Between the years of 2000 and 2006, 361 owner-
completed surveys were received.
In order to be included in the descriptive study, dogs had to meet
three criteria: (1) be a purebred Labrador retriever registered with the
Canadian Kennel Club (CKC) or American Kennel Club (AKC); (2)
O
JOURNAL of the American Animal Hospital Association 295
From the Department of Small Animal
Clinical Sciences (Taylor, Shmon),
Western College of Veterinary Medicine,
University of Saskatchewan, Saskatoon,
Saskatchewan S7N 5B4 Canada;
the Comparative Neuromuscular Laboratory
(Shelton), Department of Pathology,
School of Medicine,
University of California-San Diego,
La Jolla, California 92093-0709;
and the Departments of Veterinary
Clinical Sciences (Patterson) and
Biomedical Sciences (Minor, Mickelson),
College of Veterinary Medicine,
University of Minnesota,
St. Paul, Minnesota 55108.
Funding provided by the Morris Animal
Foundation and the Western College of
Veterinary Medicine’s Companion
Animal Health Fund.
have experienced at least three observed episodes of exer-
cise-induced collapse; and (3) veterinary evaluation must
have ruled out commonly recognized systemic and cardiac
causes of collapse. Minimum requirements for veterinary
evaluation included physical and neurological examina-
tions, complete blood count and serum biochemical profile,
and thoracic radiographs. Normal results were reported for
some dogs on additional tests including electrocardio-
grams, cardiac echocardiography, adrenocorticotropic hor-
mone stimulation tests, and muscle biopsies. Completed
surveys were obtained from 223 owners describing 225
dogs meeting all of these criteria, and those results were
tabulated and analyzed. Descriptive statistics were calcu-
lated and are reported as median and minimum and maxi-
mum values for all data.
Heritability
Pedigrees and whole blood were collected from 169 affect-
ed Labradors and 157 unaffected, related dogs. Affected
dogs were determined by their veterinarians to have EIC
based on at least two episodes of collapse or incoordination
typical of EIC and failure to identify a systemic, cardiac, or
neurological reason for the collapse. Many of these affect-
ed dogs had at least three episodes of collapse, so they
qualified for and participated in the descriptive study as
well. Dogs were considered unaffected if they had never
experienced weakness or collapse in spite of rigorous field
training. Pedigrees were assembled for analysis using
Pedigraph software,aand they were examined for evidence
of heritability.6,7
Results
Descriptive Study
Completed surveys were obtained from the owners of 225
Labrador retrievers that met the study criteria [see
Appendix]. Male (53.8%) and female (46.7%) dogs were
approximately equally represented, and all of the dogs were
sexually intact when their episodes of collapse began. Black
(53.8%), yellow (36.9%), and chocolate (9.3%) dogs were
affected. Age at the first episode of collapse ranged from 5
to 60 months (median 12 months). When asked to comment
on their dog’s body condition, level of fitness, and tempera-
ment, all owners reported that their dogs were in good phys-
ical condition; dogs were commonly described as extremely
fit, muscular, and excitable.
Dogs had experienced from three to 34 (a median of five)
observed episodes of collapse at the time the survey was
completed. Twenty-two (10%) dogs had experienced >25
episodes. Seven (3%) of the dogs for which surveys were
completed had died during their last episode of collapse;
these dogs had experienced three to 10 (a median of four)
previous episodes of collapse. Three of the seven dogs that
died during collapse were observed to experience what the
owners reported as a short, generalized seizure just before
death.
Owners described in their own words the clinical find-
ings during each collapse episode, and they completed
checklists [Table 1]. Most (78%) owners reported that their
dog’s rear legs were floppy and unable to support weight
during episodes and that many continued to run while drag-
ging their rear legs. A wobbly, incoordinated, base-wide or
loose” gait was described in 135 (60%) dogs. Although
rear limbs alone were most often affected, all four limbs
were abnormal during at least one episode of collapse in
18% of dogs. Staggering and falling to the side or difficul-
ty maintaining balance was reported in 68% of the dogs
during at least one episode, but no head tilt or nystagmus
was noted.
When dogs were recumbent during an episode, 18% of
owners noticed forelimb extensor rigidity. Most (77%) dogs
were reported by their owners to be mentally normal during
every episode, but 52 (23%) dogs had experienced one or
more episodes where the owners felt they lost concentration
or appeared dazed or confused. Excessive or loud panting
was noted during at least one episode in 43 (19%) dogs, and
an abnormally enlarged tongue and ropey saliva were
reported in 18 (8%) dogs. Seven (3%) dogs experienced a
short, generalized seizure during a single episode of col-
lapse, and three of these dogs died. Body temperature was
measured during at least one episode of collapse in 82 dogs
and ranged from 39.4˚C to 42.8˚C (median 41.1˚C). Owners
described recoveries from episodes as gradual, with the time
required for return to a normal gait estimated at 5 to 45 min-
utes (median 10 minutes).
Activities most often associated with collapse are pre-
sented in Table 2. Not all dogs participated in all activities
listed, making it impossible to assess the comparative risk
associated with each activity. Commonly cited trigger activ-
ities included hand-thrown “fun” retrieves of balls, toys, or
296 JOURNAL of the American Animal Hospital Association November/December 2008, Vol. 44
Table 1
Owner Description of Collapse Episodes in
225 Labrador Retrievers With Exercise-
Induced Collapse
Description % of Dogs
Rear limbs floppy/dragged 78
Wobbly, incoordinated 60
Falling to side/balance problem 1 episode 68
Rear limbs only affected 82
All four limbs affected 1 episode 18
Forelimb rigidity 1 episode 18
Dazed/disoriented 1 episode 23
Loud/excessive panting 1 episode 19
Generalized seizure during 1 episode 3
bumpers (a soft, plastic tube or retrieving dummy), espe-
cially in competition with other dogs; retrieving bumpers or
birds on land as part of a training exercise or field trial;
excited play with other dogs; and hunting on land for pheas-
ant, dove, or quail (upland hunting). Collapse during trained
swimming retrieves or waterfowl hunting were less com-
mon, and many owners commented that collapse was less
likely to occur when the dog was swimming. Individual col-
lapse episodes were also reported in dogs chasing horses
(one dog), deer (three dogs), and rabbits (two dogs).
Owners were asked to speculate on possible factors con-
tributing to collapse in their dog [Table 3]. Excitement asso-
ciated with a trigger activity was the most commonly
reported factor (187 dogs, 83%). Some owners reported
they “could tell” that their dog was going to have an
episode, because the dog would bark or be excessively
excited when starting the trigger activity. The use of live
birds in retriever training, chasing crippled birds during
hunting, and stress during formal retriever training (e.g.,
difficulty finding a marked retrieve, electronic collar cor-
rection, repeating an unsuccessful marked retrieve) were all
cited as factors leading to collapse.
Competition with other dogs during play or retrieving
was also considered to be a factor increasing the level of
excitement and likelihood of collapse. All owners reported
that they believed their dogs could engage indefinitely in
moderately strenuous activity not associated with excite-
ment, such as jogging or running alongside a bicycle, with-
out exhibiting signs of collapse.
Some owners (71 dogs, 31%) felt that excessive envi-
ronmental heat and humidity increased the likelihood of
collapse in their dogs. Owners were asked to report the
environmental conditions during observed episodes of col-
lapse, and their estimates of ambient temperature were cat-
egorized as hot (>21˚C), moderate or cool (5˚C to 21˚C), or
cold (-20˚C to 5˚C). Ambient temperatures were estimated
for 834 episodes of collapse in the 225 dogs. Forty-two per-
cent of the individual collapse episodes were reported to
occur in hot weather; 55% were reported to occur in mod-
erate or cool weather; and 3% were reported to occur in cold
weather.
Most owners were unable to state with certainty whether
other dogs related to theirs were affected with EIC, but 29
(13%) dogs were known to have one or multiple littermates
affected with a collapse syndrome. Occasional observations
were reported of other closely related dogs being affected
and a few instances of sudden exercise- or heat-associated
death in related dogs.
Owners were asked to assess the impact that EIC had on
their dog’s life and to describe the responses to treatments
they had tried. Seven (3%) dogs had died during an episode
of collapse. Twenty (9%) dogs were euthanized or placed in
a pet home because they could no longer be bred or inten-
sively trained for field competition. The response to treat-
ment or management was difficult to determine from the
questionnaires. Most owners who had tried restricting their
dog’s participation in trigger activities (135/138) reported
either a dramatic decrease in the number of collapse
episodes or a complete resolution of the clinical syndrome.
Five owners commented that if they observed their dog
carefully and stopped exercise at the first sign of an abnor-
mal gait, they could prevent collapse. Owners of 10 dogs
(eight males, two females) concluded that neutering had
resulted in clinical improvement; they reported no further
episodes of collapse with moderately restricted exercise.
Four competitive field trial dogs treated with phenobarbital
(2 mg/kg once or twice a day) had a dramatic decrease in
episodes or complete resolution of the syndrome, despite
continued participation in training and field trial competi-
tion. None of the dogs with EIC developed unusual sys-
November/December 2008, Vol. 44 Exercise-Induced Collapse of Labrador Retrievers 297
Table 2
Owner-Reported Activities Associated With
Collapse in 225 Labrador Retrievers With
Exercise-Induced Collapse
Activity % of Dogs
Fun retrieves 46
Training retrieves on land 43
Upland hunting (pheasant, dove, quail) 25
Excited play with other dogs 22
Training retrieves in water 12
Waterfowl hunting 2
Table 3
Factors Reported by Owners as
Contributing to Collapse in 225 Labrador
Retrievers With Exercise-Induced Collapse
Factor % of Dogs
Excitement 83
Heat and humidity 31
Live birds in training or hunting 25
Stress during training 13
Competition with other dogs 9
temic or neurological abnormalities during the follow-up
period of 3 months to 13 years (median 1.5 years) between
the first collapse episode and completion of the survey.
Heritability
Examination of the pedigrees established that many affect-
ed dogs were closely related. All EIC dogs for which the
authors had a sufficient amount of generational information
could be assembled into one large kindred, indicating a
familial basis for the condition. Eight more manageable
pedigrees containing three to 49 affected individuals were
assembled for analysis. Within these eight pedigrees, 16
matings resulted in two or more affected offspring. Males
and females were equally represented (51%:49%), exclud-
ing an X-linked mode of inheritance. In the authors’ sample
set of 326 dogs, only nine of 169 affected dogs were known
to have an affected parent. Six known affected parents
appear in these pedigrees. From these affected parents, one
family with full phenotypic information (in which one
affected parent mated to an unaffected parent) produced two
affected and two unaffected offspring. In three families, an
affected dog produced multiple (in one case 15) affected
second- and third-generation offspring. The pedigree analy-
sis was most consistent with an autosomal recessive mode
of inheritance, although a dominant disorder with partial
penetrance or a polygenic disorder could not be excluded.
Discussion
The syndrome of EIC is a relatively common cause of exer-
cise intolerance, limiting performance in working Labrador
retrievers; but detailed descriptions of the syndrome are not
available in the veterinary literature. No test for EIC cur-
rently exists, so presumptive diagnosis requires recognition
of the syndrome and elimination of other causes of exercise
intolerance and collapse. This report describes owner sur-
vey responses of the demographic and clinical features of
EIC as well as the types of activities most likely to lead to
collapse in affected dogs.
Dogs with EIC often continued to run while dragging
their crouched rear legs during episodes of collapse.
Incoordination was noted in the rear legs or, occasionally, in
all four legs; falling to the side suggested a problem with
balance in >50% of the dogs. These findings are more sug-
gestive of a neurological disorder than a condition affecting
skeletal muscle.8-10 Dogs with weakness due to an abnor-
mality of muscle, peripheral nerve, or the neuromuscular
junction are normally reluctant to continue exercising. They
typically develop a short-strided, stiff gait rather than the
“wobbly,” base-wide, or incoordinated gait described in
these dogs.10-13 Dogs with EIC, upon recovery, exhibited
no evidence of muscle pain or stiffness suggesting overex-
ertion.
Some owners reported that once they learned to recog-
nize early signs of incoordination in their dog, they could
prevent collapse by halting activity. Recovery after collapse
was gradual, occurring over 5 to 45 minutes. The progres-
sive nature of the collapse and the gradual recovery make it
unlikely that EIC is a manifestation of a paroxysmal disor-
der like epilepsy or cataplexy.14,15
Most affected dogs were mentally normal during EIC
episodes, but 23% were reported to be dazed or confused
during at least one episode. Seven dogs died during collapse;
in three of these seven, a short, generalized seizure was
observed terminally. Veterinarians must recognize that EIC
can be fatal, and owners and trainers must be counseled to
halt activity in their dog when signs of incoordination or gait
abnormality first become apparent. The authors know of sev-
eral instances where dogs with EIC have died during an
episode of collapse induced for the purpose of veterinary
evaluation.
Exercise-induced collapse has been speculated to be a
heat-related disease.9,12,16 Body temperature recorded dur-
ing collapse was extremely elevated in some dogs of this
study; body temperature may have been underestimated if it
was measured as dogs were recovering rather than at the
onset of collapse. Body temperatures have, however, been
shown to be similarly increased in normal exercise-tolerant
Labrador retrievers immediately after 10 minutes of inten-
sive retrieving exercise (mean 41.8˚C) and following com-
pletion of a 3.5-minute land retrieve test (mean 40.8˚C)
during an AKC retriever field trial.17,18 Other breeds of
dogs engaging in less intensive or shorter-duration exercise
have been reported to experience body temperatures
between 40.1˚C and 42˚C.19-22 Owners of dogs with EIC
commonly reported that excessive environmental heat and
humidity increased the likelihood of collapse, and many
individual collapse episodes occurred in hot weather. It was
apparent, however, that extreme heat was not absolutely
necessary for collapse to occur, as the majority of the col-
lapse episodes for which ambient temperature was reported
occurred during moderate or cool weather (≤21˚C), and
occasional episodes of collapse occurred in snow or while
dogs were swimming in cold water or breaking through ice.
Nonetheless, recommendations are that dogs with EIC
should avoid trigger activities and intensive exercise, espe-
cially when the ambient temperature is hot.
Dogs with EIC seem to tolerate mild to moderate exer-
cise and can engage normally in activities such as jogging,
hiking, or swimming. Activities with continuous, intense
exercise accompanied by a high level of excitement or anx-
iety most commonly caused collapse. Competition with
other dogs, hunting for live birds, and the stress of formal
training were all cited as factors contributing to collapse in
these dogs. Genetically affected dogs not being trained for
hunting or retriever competition may go unrecognized if
they never experience the necessary combination of activi-
ty and excitement to induce an episode of collapse.
The consequences of a dog having EIC were variable in
this population of dogs and largely related to owner expec-
tations. Dogs with EIC were rarely able to continue training
or competition without some restrictions, and some of the
dogs in this study were euthanized if their primary purpose
was for competition or for breeding. Limiting trigger activ-
ities and excitement allowed some dogs to continue as
298 JOURNAL of the American Animal Hospital Association November/December 2008, Vol. 44
working dogs or pets. Exercise-induced collapse does not
seem to be a progressive disorder, and most affected dogs
are able to live a normal life if trigger activities are avoided.
Although some owners reported that neutering or the
administration of phenobarbital may decrease the likelihood
of episodes of collapse and allow some dogs to participate
in trigger activities, further investigation into potential treat-
ments for EIC is necessary.
The occurrence of EIC in littermates and the estab-
lished tendency for dogs from specific pedigree lines to be
affected strongly suggest that EIC is hereditary, but the
precise mode of inheritance has not been determined.
Pedigree analysis was most consistent with an autosomal
recessive mode of inheritance.7Thus, owners and breeders
must be aware that mating apparently unaffected dogs that
are carriers of an EIC susceptibility gene can produce
affected puppies. By using pedigrees and deoxyribonucle-
ic acid collected from affected dogs in this study, investi-
gators recently have identified multiple genetic markers
linking EIC to a particular chromosomal locus and have
identified a genetic mutation that is highly associated with
EIC susceptibility.b
Conclusion
At the present time, EIC is a presumptive diagnosis made by
ruling out other disorders causing exercise intolerance and
by observing characteristic clinical features in affected
Labrador retrievers. This descriptive study of EIC should
help practicing veterinarians recognize the syndrome and
counsel owners of affected dogs regarding management
strategies and prognosis.
Footnotes
aPedigraph software; University of Minnesota, St. Paul, MN 55108
bMickelson, personal communication, 2008
Acknowledgments
The authors acknowledge the substantial contributions that
Monica Roberts, a PhD student at the University of
Minnesota, made to their understanding of the genetics of
exercise-induced collapse. Monica was a major collaborator
in this research until her untimely death in 2006.
References
11. Shelton GD. Exercise intolerance in dogs. In: Proceedings of the
ACVIM Forum, 1993;11:888-891.
12. Taylor SM. Exercise induced collapse in Labrador retrievers.
Retriever Field Trial News 2000;July:24-27.
13. Moore AK. Exercise induced collapse. North American Hunting
Retriever Association News 2003;Summer:20-21.
14. Taylor SM, Shelton GD. The syndrome of exercise induced collapse
in Labrador retrievers. In: Proceedings of the ACVIM Forum,
2002:315-318.
15. Taylor SM. Exercise induced weakness/collapse in Labrador retriev-
ers. In: Tilley LP, Smith FW, eds. Blackwell’s Five Minute
Veterinary Consult: Canine and Feline, 4th ed. Williston, VT:
Blackwell Publishing, 2008:458-459.
16. Garbe JR, Da Y. A software tool for the graphical visualization of
large and complex populations. Yi Chuan Xue Bao
2003;30(12):1193-1195.
17. Roberts M. Genetic basis of exercise induced collapse in Labrador
retrievers. In: Mapping Neurological and Neuromuscular Disease
Genes in Dogs. PhD thesis. University of Minnesota, 2003.
18. Braund KG. Degenerative causes of myopathies in dogs and cats. Vet
Med 1997;7:607-617.
19. Shelton GD, Engvall E. Muscular dystrophies and other inherited
myopathies. Vet Clin North Am Small Anim Pract 2002;32:103-124.
10. De Lahunta A. Neurological examination. In: Braund KG, ed.
Clinical Neurology in Small Animals—Localization, Diagnosis and
Treatment. Ithaca, NY: International Veterinary Information Service
(www.ivis.org). 2001.
11. Cuddon P. Acquired canine peripheral neuropathies. Vet Clin North
Am Small Anim Pract 2002;32:207-249.
12. Braund KG. Myopathic disorders. In: Braund KG, ed. Clinical
Neurology in Small Animals—Localization, Diagnosis and
Treatment. Ithaca, NY: International Veterinary Information Service
(www.ivis.org). 2005.
13. Taylor SM. Selected disorders of muscle and the neuromuscular
junction. Vet Clin North Am Small Anim Pract 2000;30:59-75.
14. Heynold Y, Faissler D, Steffen F, et al. Clinical, epidemiological, and
treatment results of idiopathic epilepsy in 54 Labrador retrievers—a
long term study. J Small Anim Pract 1997;38:7-14.
15. Braund KG. Paroxysmal disorders. In: Braund KG, ed. Clinical
Neurology in Small Animals—Localization, Diagnosis and
Treatment. Ithaca, NY: International Veterinary Information Service
(www.ivis.org). 2003.
16. Axlund TW. Exercise induced collapse in dogs. In: Proceedings of
the Western Veterinary Conference, 2004:244-245.
17. Matwichuk CL, Taylor SM, Shmon CL, et al. Changes in rectal tem-
perature and hematologic, biochemical, blood gas, and acid-base val-
ues in healthy Labrador retrievers before and after strenuous
exercise. Am J Vet Res 1999;60:88-92.
18. Steiss J, Ahmad HA, Cooper P, et al. Physiologic responses in
healthy Labrador retrievers during field trial training and competi-
tion. J Vet Int Med 2004;18:147-151.
19. Hastings AB, White FC, Sanders TM, et al. Comparative physiologic
responses to exercise stress. J Appl Physiol 1982;52:1077-1083.
20. Ilkiw JE, Davis PE, Church DB. Hematologic, biochemical, blood-
gas, and acid-base values in greyhounds before and after exercise.
Am J Vet Res 1989;50:583-586.
21. Musch TI, Friedman DB, Haidet GC, et al. Arterial blood gases and
acid-base status of dogs during graded dynamic exercise. J Appl
Physiol 1986;61:1914-1919.
22. Rose RJ, Bloomberg MS. Responses to sprint exercise in the grey-
hound: effect on hematology, serum biochemistry and muscle
metabolites. Res Vet Sci 1989;47:212-218.
November/December 2008, Vol. 44 Exercise-Induced Collapse of Labrador Retrievers 299
300 JOURNAL of the American Animal Hospital Association November/December 2008, Vol. 44
Appendix
Survey Completed by Owners of Labrador Retrievers With Exercise-Induced Collapse
Dog name: Color: Sex:
11. What is the birth date of your dog?
12. Has your dog ever had any medical problems except for collapse episodes?
13. Is your dog on any medications?
14. When was the first collapse noted?
What was the dog doing at the time?
What was the weather like?
What did you see first?
What did you do and what happened next?
How long did the collapse last?
Could your dog walk?
How long until your dog was normal?
15. How many episodes has your dog had?
16. Have all episodes been the same as the first, or were there differences?
17. What have been the circumstances (activity and weather) for each collapse?
18. Has there been anything abnormal that you note before, during, or after an episode?
19. Has there been anything that you think seems to make your dog more or less likely to have an episode on a
given day?
10. Does it seem to you that it has gotten easier to induce an episode, or is it harder to induce or unchanged?
11. Have you tried any treatments or changed management? If so, do you think this has helped?
12. Is your dog always completely conscious and aware during the collapse?
13. Are just rear legs affected, or all four legs?
14. During collapse and recovery, which of the following best describes your dog:
(circle all that apply)
a. Legs seem floppier than normal, don’t seem to be able to hold up my dog’s weight
b. My dog seems to have trouble maintaining balance and will fall over to the side
c. Legs seem to be stiffer than normal, and held straight
15. Have you taken your dog’s temperature during an episode of collapse? What was it?
(Continued on next page)
November/December 2008, Vol. 44 Exercise-Induced Collapse of Labrador Retrievers 301
Appendix (cont’d)
Survey Completed by Owners of Labrador Retrievers With Exercise-Induced Collapse
16. Do you know of any other related dogs that are affected?
17. Have other dogs from this dog’s litter been used for competitive retrieving events?
18. What do you feed your dog?
19. When was the last time you observed an episode of collapse?
20. How would you judge your dog’s body condition right now?
a. Fat, out of shape
b. A little heavy, but in good shape
c. In perfect condition
d. Very thin
... El síndrome de colapso inducido por ejercicio (de su sigla en inglés EIC) es una enfermedad hereditaria de transmisión au- tosómica recesiva. Ocurre predominante- mente en Labrador Retriever y sus mestizos ( Taylor et al. 2008) pero también se observa en Retriever de la bahía de Chesapeake, Re- triever revestido rizado y Retriever de Nueva Escocia, todas ellas razas que poseen una alta relación de parentesco con el Labrador Retriever ( Patterson et al. 2008). Se ha co- municado además en Boykin Spaniel y Corgi Galés de Pembroke ( Minor et al. 2011). ...
... Los signos clínicos consisten en debilidad muscular y falta de coordinación asociados a la actividad física, e incluso colapso mortal al participar en un ejercicio extenuante. Los pe- rros homocigotas para la mutación c.767G>T son normales en el reposo y pueden tolerar un ejercicio leve a moderado, pero períodos de 5 a 20 minutos de actividad vigorosa o la excitación extrema pueden inducir debilidad o colapso ( Patterson et al. 2008;Taylor et al. 2009;Minor et al. 2011;Basso et al. 2014Basso et al. , 2015, e incluso la muerte en el 2% de los animales afectados ( Taylor et al. 2008). Los perros con EIC no pueden realizar un entre- namiento intenso o trabajo de campo, pero pueden vivir vidas normales como mascotas ( Taylor et al. 2008;Taylor et al. 2009). ...
... Los pe- rros homocigotas para la mutación c.767G>T son normales en el reposo y pueden tolerar un ejercicio leve a moderado, pero períodos de 5 a 20 minutos de actividad vigorosa o la excitación extrema pueden inducir debilidad o colapso ( Patterson et al. 2008;Taylor et al. 2009;Minor et al. 2011;Basso et al. 2014Basso et al. , 2015, e incluso la muerte en el 2% de los animales afectados ( Taylor et al. 2008). Los perros con EIC no pueden realizar un entre- namiento intenso o trabajo de campo, pero pueden vivir vidas normales como mascotas ( Taylor et al. 2008;Taylor et al. 2009). En la ac- tualidad se encuentra disponible una prueba de ADN para identificar la mutación EIC en varias de las razas afectadas por este síndro- me genético ( Minor et al. 2011). ...
... Neoplasia (14.7%) and mass-associated disorders (10.7%) may largely both reflect underlying neoplastic processes and together accounted for 25.4% of the mortality. Collapse accounted for 13.3% of deaths but underlying causes for collapse are varied and can involve neurological, orthopaedic, cardiac and other medical conditions [54]. Brain related causes accounted for 10.7% of deaths and this term again covers a range of underlying possible aetiologies [55]. ...
Article
Full-text available
Background Individual dog breeds are often reported as predisposed to specific breed-related disorders but reliable epidemiological data on disease prevalence are sparse. The Miniature Schnauzer in the UK is a popular small breed dog that is often considered as relatively healthy and long-lived, but is this really true? This study aimed to use data from the VetCompass™ Programme at the Royal Veterinary College to characterise the demography, mortality and common disorders of the general population of Miniature Schnauzers under veterinary care in the UK. Results The study population of 455,557 dogs from 304 clinics in the VetCompass™ database under veterinary care during 2013 included 3857 Miniature Schnauzers (0.85%). For dogs with data available, 1771 (56.9%) were neutered and 1893 (49.2%) were females. Mean adult bodyweight overall was 9.9 kg (SD 2.2 kg) and median longevity was 11.6 years (IQR 9.3–13.1, range 0.5–17.0). The most prevalent fine-level precision disorders recorded were periodontal disease (n = 343, prevalence 17.4, 95% CI: 15.7–19.1), obesity/overweight (164, 8.3, 95% CI: 7.1–9.6), anal sac impaction (114, 5.8, 95% CI: 4.8–6.9), vomiting (100, 5.1, 95% CI% 4.1–6.1) and otitis externa (99, 5.0, 95% CI% 4.1–6.1). The most prevalent grouped-level precision disorders were dental (n = 378, prevalence: 19.2, 95% CI: 17.5–21.0), enteropathy (270, 13.7, 95% CI: 12.2–15.3), cutaneous (250, 12.7, 95% CI: 11.2–14.2) and aural (197, 10.0, 95% CI: 8.7–11.4). Conclusions This study provides generalisable evidence on the demography, longevity and most prevalent disorders in the Miniature Schnauzer breed in the UK. Awareness of common diseases and breed predispositions can support evidence-based policies to improve breed health, guide veterinary surgeons when producing differential diagnosis lists, and assist owners when purchasing or caring for their pets.
... Dogs experiencing EIC-specific collapse lose coordination, often use a crouched posture (knee flexion) with their pelvic limbs [1], and may drag themselves by their forelimbs. According to Taylor et al., dogs with EIC often continue to run, dragging their crouched rear legs despite being in a collapse episode [10]. Taken together, these scenarios may subject the cranial cruciate ligament (CCL) to unknown additional mechanical stressors or damaging forces that could influence CCL integrity. ...
Article
Full-text available
Background: Exercise-induced collapse (EIC) due to DNM1 mutation and rupture of the cranial cruciate ligament are both common syndromes in the Labrador retriever breed. A cohort of 313 Labradors was recruited based on their CCLR status and were subsequently genetically tested for EIC. Epidemiological aspects of the cohort were also described, including sex, sterilization status, and age at sterilization. Results: No sex difference was observed in dogs susceptible to EIC (homozygous for the mutant genotype) compared to dogs not susceptible to EIC (heterozygotes and dogs homozygous for the normal genotype). No evidence for association was detected between CCLR status and EIC status (p =0.357), although the sample cohort was not of sufficient size to entirely rule out an association. A significant difference (p = 0.031) was observed in the sex distribution of dogs affected with CCLR compared to those without CCLR. An increased number of female CCLR cases were observed compared to the number of female controls; male CCLR cases and controls were approximately the same number. When CCLR status was examined in each sex, no significant differences were observed between those that were sterilized and those that weren't. However, for female dogs that were sterilized, CCLR cases were significantly higher in dogs sterilized at one year of age or younger compared to those sterilized when over the age of one year (p = 0.0021, OR 4.30, 95% CI 1.55-12.72); for males, this finding was suggestive, but not statistically significant (p = 0.0913, OR 3.57, 95% CI 0.809-14.476). Conclusions: CCLR is not associated with a large increase in EIC occurrence. Statistically, these two syndromes cannot be proven to be unrelated; however, concomitant occurrence of CCLR and EIC in Labrador retrievers is rare, despite the high prevalence of both syndromes in this breed. Epidemiological findings suggest that females may be over-represented in CCLR cases and that early sterilization (≤1 year) may increase the risk of Labradors developing CCLR later in life (particularly in females). These results should be considered preliminary and require confirmation in larger populations of Labrador retrievers.
Article
Full-text available
NEUROVET | 109 NEUROLOGÍA Introducción Muchas enfermedades neu-rológicas, tanto centrales como periféricas, resultan de trastor-nos degenerativos hereditarios que suelen heredarse con un pa-trón autosómico recesivo (March 1996; Sisó 2006). Desde el pun-to de vista clínico, suelen tener un comienzo insidioso, un curso lentamente progresivo y no son dolorosas. Al ser hereditarias, ge-neralmente afectan solo a razas determinadas. La edad de inicio es variable; algunas se manifies-tan en animales jóvenes, poco tiempo después del nacimiento (por ejemplo, la mayoría de las degeneraciones cerebelosas cor-ticales); con menos frecuencia se afectan los animales adultos (por ejemplo, la mielopatía degenerati-va), y otras veces la misma enfer-medad muestra una variabilidad en la edad de inicio de los signos clínicos (por ejemplo, algunas en-fermedades de almacenamiento lisosomal); en estos casos, las diferencias en las edades de presentación podrían relacionar-se con las distintas formas de la misma enfermedad descritas en medicina humana. La mayoría de las veces, las lesiones que produ-cen son bilaterales y simétricas. La incidencia de estas enferme-dades es baja en la población general, aunque ocasionalmente pueden tener una frecuencia re-lativamente elevada en una raza determinada. En muchos casos, las descripciones se limitan a unos pocos, o incluso a un solo individuo, o a una sola familia (Montoliu et al. 2012). La reseña del paciente, la edad de inicio, el tipo de progresión y la exclusión de otras causas conocidas, son elementos de vital importancia para la correcta identificación de este tipo de enfermedades (Davis e Irwin 2003). La raza Labrador es una de las más populares en Argentina y en todo el mundo; es susceptible de presentar una cantidad de enfermedades neurodegenerati-vas, que han sido descritas en la literatura veterinaria desde hace muchos años (tabla 1). La real in-cidencia de este tipo de trastor-nos es desconocida, por varias razones. Aunque clínicamente es posible alcanzar un diagnóstico presuntivo, la confirmación ante mortem es muy difícil en general, y a veces inaccesible, y solamen-te se puede realizar en aquellas enfermedades en las que se ha identificado la mutación gené-tica causativa, y se encuentran disponibles las pruebas mole-culares. El diagnóstico definitivo requiere, en la mayoría de los ca-sos, la identificación pos mortem de las lesiones específicas que caracterizan a estos trastornos. Estos estudios habitualmente no se realizan en la práctica clínica, y están limitados a los centros de referencia especializados, o a las universidades. El objetivo de este trabajo es revisar el conocimiento actual de las enfermedades neurológicas degenerativas del sistema nervio-so que han sido comunicadas en perros de raza Labrador, ofrecer Enfermedades neurodegenerativas en la raza Labrador
Article
Full-text available
Article
Paroxysmal events are notoriously difficult to characterise, as they are rarely witnessed by anyone other than the owner and between episodes these dogs are completely normal. Add to this the fact that many of these transient events are caused by a chemical interference within the central nervous system that upsets the balance between neuronal excitation and inhibition, leaving no trace of their activity, it becomes clear that definitive diagnosis is extremely difficult. Such events include those reported to occur during intense exercise, often in extremes of heat. Unless you are feeling particularly active and wish to exercise the dog to the point of precipitating an episode, it is advisable to consider video footage from the owner to avoid ambiguous descriptions and to actually observe the problem for which the owners are presenting the dog. This article describes the syndrome of exercise-induced collapse in dogs, including when to suspect it; what other conditions may mimic it; and how to diagnose and manage the disorder.
Article
In 2008, it has been reported that the syndrome of exercise-induced collapse in Labrador retrievers, the most common breed for service dog, was associated with a mutation in the dynamin 1 gene. To facilitate the service dog in a society, control of public health including zoonosis and management of genetic diseases which associated with potential as service dogs might be essential elements. In this study, genotypic frequency of dynamin 1 mutation was examined in service dog colonies in Japan. When DNA derived from 162 Labrador retrievers in breeding colonies of service dog were analyzed by restriction fragment length polymorphism for dynamin 1 gene mutation, percentages of wild type, heterozygous mutant and homozygous mutant were 66%, 30% and 4%, respectively. As intense exercises are not requested during their training and/or working in service dogs, homozygous mutation of dynamin 1 may not affect their potential as a service dog. When service dogs are made alterations in their role as career changed dogs, however, the genotype of dynamin 1 may influence their activities. Thus, knowing the degree of density and distribution of the gene mutations in breeding colony is expected to contribute to facilitate service dogs to a society. These results might contribute to make a plan for effective breeding in service dog colony.
Article
Full-text available
Rectal body temperature (BT) has been documented in exercising dogs to monitor thermoregulation, heat stress risk, and performance during physical activity. Eye (BTeye) and ear (BTear) temperature measured with infrared thermography (IRT) were compared to rectal (BTrec) temperature as the reference method and assess alternative sites to track hyperthermia, possibly to establish BTeye IRT as a passive and non-contact method. BT measures were recorded at 09:00, 11:30, 12:30, and 02:30 from Labrador Retrievers (N=16) and Beagles (N=16) while sedentary and with 30-min play-exercise (pre- and 0, 15, 30-min post-exercise). Total exercise locomotor activity counts were recorded to compare relative intensity of play-exercise between breeds. BTrec, BTeye, and BTear were measured within 5 min of the target time. Each BT method was analyzed by ANOVA for main effects of breed and time. Method differences were compared using Bland-Altman plots and linear regression. Sedentary BT differed by breed for BTrec (p
Article
Full-text available
To measure changes in rectal temperature and hematologic, biochemical, blood gas, and acid-base values before and after exercise. 14 healthy adult Labrador Retrievers. Dogs exercised continuously for 10 minutes by repeatedly retrieving a dummy thrown approximately 40 to 50 yards on land. The ambient temperature during each exercise period was recorded. Rectal temperature, pulse, and respiratory rate were measured; CBC and serum biochemical profile were determined; and arterial blood gas tensions, acid-base status, and plasma lactate and pyruvate concentrations were measured at rest and immediately after exercise. Rectal temperature, pulse, respiratory rate, and lactate and pyruvate concentrations were evaluated at intervals up to 120 minutes after exercise. Immediately after exercise, rectal temperature increased markedly; ambient temperature did not affect rectal temperature. Arterial blood pH and PaO2 were significantly increased after exercise, and PaCO2 and bicarbonate concentration were significantly decreased after exercise. Also, statistically, but not clinically, significant increases were observed in RBC, WBC, and segmented neutrophil counts; hemoglobin, total protein, and serum sodium and potassium concentrations; PCV; anion gap; and creatine kinase activity. Plasma lactate and pyruvate concentrations increased significantly after exercise, but there was no change in the lactate-to-pyruvate ratio. Reference values for healthy Laborador Retrievers during a standardized exercise protocol were established to compare data obtained from Laborador Retrievers with exercise intolerance and collapse. Important characteristics of lactate and pyruvate metabolism were documented that will enable more precise evaluation of exercise intolerance in this breed.
Article
A syndrome of exercise intolerance and collapse (EIC) has been recognized in young adult Labrador Retrievers. A comprehensive study of this condition is underway involving collaborators from the Western College of Veterinary Medicine (WCVM) of the University of Saskatchewan (Taylor, Shmon), the College of Veterinary Medicine at the University of Minnesota (Mickelson, Patterson, Minor), and the Comparative Neuromuscular Unit at the University of California (Shelton). The objectives of this study are to (1) describe the syndrome so that it can be recognized by dog owners, veterinarians and trainers, (2) to thoroughly evaluate affected dogs to try to establish an efficient means of diagnosis and to gain some insight into the cause of the collapse and (3) to determine the genetic basis for the collapse syndrome. This research has been supported by generous grants from the Morris Animal Foundation and the WCVM's Companion Animal Health Fund. This document will summarize some of what we have learned in the last 7 years about the syndrome of Exercise Induced Collapse in Labrador Retrievers. Descriptions of the syndrome and the results of our experimental study have been submitted for publication in the veterinary literature. WHO GETS IT? The syndrome of exercise intolerance and collapse (EIC) is being observed with increasing frequency in young adult Labrador Retrievers. Most, but not all, affected dogs have been from field-trial breedings. Black, yellow and chocolate Labradors of both sexes are affected, with the distribution of colors and sexes closely reflecting the typical distribution in field trials (black males most common). Signs first become apparent in young dogs -usually between 5 months and 3 years of age (average 14 months). In dogs used for field trials, this usually coincides with the age at which they enter heavy training. Littermates and other related dogs are commonly affected but depending on their temperament and lifestyle they may or may not manifest symptoms. Affected dogs exhibiting symptoms of collapse are usually described as being extremely fit, muscular, prime athletic specimens of their breed with an excitable temperament and lots of drive.
Article
After racing 722 m, 16 Greyhounds were evaluated to determine changes in hematologic, biochemical, blood-gas, and acid-base values following exercise. Values were determined before racing (T0), immediately after racing (T1), and 3 hours after racing (T2). Significant changes detected immediately after racing included increased heart rate, respiratory rate, and rectal temperature. Significant changes in hematologic values included increases in PCV, total plasma protein, hemoglobin, RBC, WBC, neutrophils, and lymphocytes. Change was not detected in values for monocytes, eosinophils, and neutrophil/lymphocyte ratio. Other increases included those for plasma concentrations of sodium, chloride, calcium, lactic acid, aspartate transaminase, alanine transaminase, alkaline phosphatase, creatine kinase, lactate dehydrogenase, and glucose. Concentrations of potassium and urea did not change. Measurement of blood-gas and acid-base status revealed significant increases in PaO2 and base deficit, whereas PaCO2, pH, and bicarbonate decreased. Three hours after exercise, all vital signs and blood-gas and acid-base values, except for PaCO2, which was still slightly low, had returned to baseline (T0) values. Most biochemical values had also returned to baseline, although sodium, chloride, aspartate transaminase, and creatine kinase were still high, and urea was low. Many hematologic values were still different from baseline values, with high values for WBC, neutrophils and neutrophil/lymphocyte ratio, and low values for PCV, total plasma protein, hemoglobin, RBC, and lymphocytes.
Article
To investigate the haematological, biochemical and metabolic response of greyhounds to sprint exercise, five greyhound dogs with previously placed carotid arterial catheters were sprinted over a distance of 400 m, chasing a lure. The time to complete the 400 m ranged from 25 to 27 seconds. Before exercise and at intervals for up to one hour after exercise, arterial blood samples were collected for haematology, serum biochemistry, plasma lactate and arterial blood gas measurements. Muscle samples for metabolite measurements were collected by needle biopsy of the vastus lateralis muscle. Red cell indices were increased for up to 20 minutes after exercise and there was a transient leucocytosis and neutrophilia. Serum biochemical changes reflected some fluid movement from the vascular compartment, there being increases in osmolality and total protein. Other changes included significant increases over resting control values for serum glucose, creatinine and potassium. The tension of oxygen in arterial blood was increased after exercise, while that of carbon dioxide fell, and there was a decrease in arterial pH. These changes were no longer significant by 30 minutes after exercise. The mean rectal temperature increased to 41 degrees C after exercise and remained elevated up to and including the 30 minutes after exercise measurement. No changes were found in muscle ATP or glycogen from before to after exercise. However, concentrations of muscle glucose and glucose-6-phosphate were increased immediately after exercise. Muscle and plasma lactate concentrations showed a similar time course for disappearance and after peaking at 27 mmol litre-1, five minutes after exercise, the plasma lactate returned towards pre-exercise values by 30 minutes after exercise.
Article
The objective of this study was to determine whether arterial PCO2 (PaCO2) decreases or remains unchanged from resting levels during mild to moderate steady-state exercise in the dog. To accomplish this, O2 consumption (VO2) arterial blood gases and acid-base status, arterial lactate concentration ([LA-]a), and rectal temperature (Tr) were measured in 27 chronically instrumented dogs at rest, during different levels of submaximal exercise, and during maximal exercise on a motor-driven treadmill. During mild exercise [35% of maximal O2 consumption (VO2 max)], PaCO2 decreased 5.3 +/- 0.4 Torr and resulted in a respiratory alkalosis (delta pHa = +0.029 +/- 0.005). Arterial PO2 (PaO2) increased 5.9 +/- 1.5 Torr and Tr increased 0.5 +/- 0.1 degree C. As the exercise levels progressed from mild to moderate exercise (64% of VO2 max) the magnitude of the hypocapnia and the resultant respiratory alkalosis remained unchanged as PaCO2 remained 5.9 +/- 0.7 Torr below and delta pHa remained 0.029 +/- 0.008 above resting values. When the exercise work rate was increased to elicit VO2 max (96 +/- 2 ml X kg-1 X min-1) the amount of hypocapnia again remained unchanged from submaximal exercise levels and PaCO2 remained 6.0 +/- 0.6 Torr below resting values; however, this response occurred despite continued increases in Tr (delta Tr = 1.7 +/- 0.1 degree C), significant increases in [LA-]a (delta [LA-]a = 2.5 +/- 0.4), and a resultant metabolic acidosis (delta pHa = -0.031 +/- 0.011). The dog, like other nonhuman vertebrates, responded to mild and moderate steady-state exercise with a significant hyperventilation and respiratory alkalosis.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
We determined the effect of exhaustive exercise on the acid-base balance, O2 consumption, and cardiac output in dogs and pigs to examine which species was comparable with humans in its physiological response to exercise. We ran 11 dogs and 11 pigs on a motor-driven treadmill at steady-state (heart rate 75% maximum) and exhaustive (maximum heart rate) exercise levels. Measuring heart rate, cardiac output, and aortic pressure via implanted probes we obtained arterial and venous blood samples before, during, and after exercise to determine hematocrit, blood gas tensions, pH, and lactic acid levels. Dogs had a twofold greater work capacity than the pigs, but the dogs could not run at maximal heart rate as long as the pigs did. Although O2 consumption correlated well with cardiac output and total work in both species, dogs were capable of a greater range of values. The acid-base studies showed that exhaustive exercise in the pigs resulted in a severe metabolic acidosis, whereas this did not occur in dogs. Respiratory alkalosis was noted in dogs. This suggested that the supply of O2 to the working muscles of the pig was insufficient to maintain aerobic metabolism. The pigs' responses to exercise conformed to those found by others in the human, suggesting that the pig is a more appropriate model for some exercise studies.
Article
The records of 54 labrador retrievers with idiopathic epilepsy were reviewed. Exogenous factors played a minor role in the transmission of the epilepsy. Prodromal phase and aura were present in the majority of the dogs with generalised seizures. The ictal phase was characterised by long-lasting automatisms. Approximately half of the dogs had seizures more than once a month: the remainder ranged from one every two months to one every 12 months. The average frequency in dogs with generalized seizures (n = 49) was one every 65 days and in dogs with partial seizures (n = 5) one every 205 days. Long-term follow-up was performed in 46 dogs, 37 of which followed a strict treatment protocol. Possible causes for the large variations in treatment results were analysed. One goal was to identify objective aspects enabling a realistic prognosis prior to treatment. Animals with a high age at onset of seizure (mean, four years) showed an excellent outcome, even if treatment began late. Dogs with low frequency rates and low total numbers of seizures responded well to therapy if treated as early as possible.
Article
A variety of disorders affect the muscles or the neuromuscular junction of dogs and cats, most often causing weakness, exercise intolerance, and muscular pain or atrophy. The myopathies are infectious, immune-mediated, inherited or acquired secondary to systemic disease. Acquired myasthenia gravis is a common disorder of the neuromuscular junction, which clinically resembles a myopathy. Reaching a specific diagnosis is essential to determine optimal therapy and prognosis for each of the commonly recognized disorders.
Article
Accurate diagnosis of the many causes of acute and chronic peripheral neuropathy in the dog presents a challenging prospect for any clinician. Being able to accurately localize the observed neurologic signs to the peripheral nervous system is the first challenge. Once this is accomplished, a logical series of diagnostic steps should be pursued so as to have the best chance of reaching a final etiologic diagnosis. Specific therapy can then be instituted to attempt to halt or, in some cases, reverse the peripheral nerve dysfunction.