1 | Page
ICVA NAVLE Exam 1 Questions and
Answers
Fifteen of a group of 200, 7 month old feedlot calves are lame. The
calves arrived at the feedlot approximately one month ago, and
one week later, 40 of the animals developed pneumonia. These
calves were treated with oxytetracycline, and the pneumonia
appeared to resolve. On physical examination, the affect calves
have swellings in the carpi, tarsi, and stifles with distension of
associated tendon sheaths, and stiff gait. Two calves are
euthanized. Postmortem eamination shows fibrinous pleuritis and
papillary muscle necrosis. Which of the following organisms is the
most likely cuase of these signs?
a) arcanobacterium (actinomyces) pyogenes
b) histophilus somni
c ) mannheimia hemolytica
d) pasteurella multocida
e) salmonella thyphimurium Ans: B) histophilus somni
Histophilus somni is a well known cause of systemic disease in
feedlot cattle, including respiratory disease, speticemia, and
polyarthritis. In this case, the calves initially developed
pneumonia, and now soe of them show signs of lameness, joint
© 2025 All rights reserved
, 2 | Page
swelling, and stiff gait, which are consistent with septic arthritis,
and polyarthritis that can occur after a histophilus somni infection
- additionally the post mortem finding of fibrinous pleuritis and
papillary muscle necrosis also strongly suggest histophilus soni as
the causative agent.
-Known to cause arthritis, pleuritis, myocarditis, and septicemia in
calves
What is hyperkalemic periodic paralysis in a horse Ans: -a genetic
disorder that affects muscles causing episodes of muscle
weakness or paralysis.
-It is autosomal dominant
What is the cause of hyperkalemic periodic paralysis Ans: THe
disorder is caused by a mutation in the sodium channel gene,
leading to increased potassium levels in the blood. This affects the
electrical activity of muscle cells, causing the muscles to contract
abnormally
What are symptoms of hyperkalemic periodic paralysis in horses
Ans: -muscle twitching or trembling
-weakness or partial paralysis especially in hindquarters
-episodes of muscle stiffness
-respiratory issues in severe cases
-horse remains alert
what are triggers of hyperkalemic periodic paralysis Ans: -high
potassium intake from feed such as alfalfa, molasses or certain
grains
-stress, exercise or fasting
© 2025 All rights reserved
, 3 | Page
how would you manage hyperkalemic periodic paralysis Ans: -
dietary modification like feeding low potassium diets and aoiding
alfala and monitor potassium intake
-medicate with acetazolamide and hydrochlorothiazide
-consistent exercise and minimize stress
A 3-year old Percheron mare is undergoing routine dental
evaluation. Physical examination shows bilateral prolapse of the
nictitating membrane and muscle fasciculations of the neck,
shoulders, and flank. During examination, the mare's hindlimbs
give way, and she leans back in a dog-sitting posture. Rectal
temperature is 100.4 degrees F (38.0 degrees C), heart rate is 60
beats/min, and respiratory rate is 30 breaths/min.
Which of the following is the most likely diagnosis?
A) Equine degenerative myeloneuropathy
B) Equine motor neuron disease
C) Exertional rhabdomyolysis
D) Hyperkalemic periodic paralysis
E) Tetanus Ans: D) hyperkalemic periodic paralysis
HYPP leads to episodes of periodic muscle weakness or paralysis.
-Prolapse of the nictitating membrane is characteristic of HYPP due
to muscle weakness in the face
-Weakness and collapse suggest muscle paralysis or severe
weakness, dog sitting posture strongly supports this
© 2025 All rights reserved
, 4 | Page
A 3-year old Percheron mare is undergoing routine dental
evaluation. Physical examination shows bilateral prolapse of the
nictitating membrane and muscle fasciculations of the neck,
shoulders, and flank. During examination, the mare's hindlimbs
give way, and she leans back in a dog-sitting posture. Rectal
temperature is 100.4 degrees F (38.0 degrees C), heart rate is 60
beats/min, and respiratory rate is 30 breaths/min.
This is a case of HYPP, why would Equine Degenerative
Myeloneuropathy be incorrect Ans: EDM is a neurodegenerative
disease that causes progresse ataxia ( incoordination) and
weakness in young horses, particularly those deficient in vitamin
E.
Although it causes weakness, EDM is more associated with ataxia (
uncoordinated movement) rather than acute muscle fasciculations
or prolapse of the nictitating membrane. It is a chronic,
progressive condition, unlike the episodic nature of HYPP
A 3-year old Percheron mare is undergoing routine dental
evaluation. Physical examination shows bilateral prolapse of the
nictitating membrane and muscle fasciculations of the neck,
shoulders, and flank. During examination, the mare's hindlimbs
give way, and she leans back in a dog-sitting posture. Rectal
temperature is 100.4 degrees F (38.0 degrees C), heart rate is 60
beats/min, and respiratory rate is 30 breaths/min.
This is a case of HYPP, why would Equine Motor Neuron Disease be
incorrect Ans: EMND is a neurodegeneratie disorder and is
associated with vitamin E deficiency
-EMND causes muscle atrophy and weakness, primarily affecting
posture and gait over time. However it does not typically cause
© 2025 All rights reserved
ICVA NAVLE Exam 1 Questions and
Answers
Fifteen of a group of 200, 7 month old feedlot calves are lame. The
calves arrived at the feedlot approximately one month ago, and
one week later, 40 of the animals developed pneumonia. These
calves were treated with oxytetracycline, and the pneumonia
appeared to resolve. On physical examination, the affect calves
have swellings in the carpi, tarsi, and stifles with distension of
associated tendon sheaths, and stiff gait. Two calves are
euthanized. Postmortem eamination shows fibrinous pleuritis and
papillary muscle necrosis. Which of the following organisms is the
most likely cuase of these signs?
a) arcanobacterium (actinomyces) pyogenes
b) histophilus somni
c ) mannheimia hemolytica
d) pasteurella multocida
e) salmonella thyphimurium Ans: B) histophilus somni
Histophilus somni is a well known cause of systemic disease in
feedlot cattle, including respiratory disease, speticemia, and
polyarthritis. In this case, the calves initially developed
pneumonia, and now soe of them show signs of lameness, joint
© 2025 All rights reserved
, 2 | Page
swelling, and stiff gait, which are consistent with septic arthritis,
and polyarthritis that can occur after a histophilus somni infection
- additionally the post mortem finding of fibrinous pleuritis and
papillary muscle necrosis also strongly suggest histophilus soni as
the causative agent.
-Known to cause arthritis, pleuritis, myocarditis, and septicemia in
calves
What is hyperkalemic periodic paralysis in a horse Ans: -a genetic
disorder that affects muscles causing episodes of muscle
weakness or paralysis.
-It is autosomal dominant
What is the cause of hyperkalemic periodic paralysis Ans: THe
disorder is caused by a mutation in the sodium channel gene,
leading to increased potassium levels in the blood. This affects the
electrical activity of muscle cells, causing the muscles to contract
abnormally
What are symptoms of hyperkalemic periodic paralysis in horses
Ans: -muscle twitching or trembling
-weakness or partial paralysis especially in hindquarters
-episodes of muscle stiffness
-respiratory issues in severe cases
-horse remains alert
what are triggers of hyperkalemic periodic paralysis Ans: -high
potassium intake from feed such as alfalfa, molasses or certain
grains
-stress, exercise or fasting
© 2025 All rights reserved
, 3 | Page
how would you manage hyperkalemic periodic paralysis Ans: -
dietary modification like feeding low potassium diets and aoiding
alfala and monitor potassium intake
-medicate with acetazolamide and hydrochlorothiazide
-consistent exercise and minimize stress
A 3-year old Percheron mare is undergoing routine dental
evaluation. Physical examination shows bilateral prolapse of the
nictitating membrane and muscle fasciculations of the neck,
shoulders, and flank. During examination, the mare's hindlimbs
give way, and she leans back in a dog-sitting posture. Rectal
temperature is 100.4 degrees F (38.0 degrees C), heart rate is 60
beats/min, and respiratory rate is 30 breaths/min.
Which of the following is the most likely diagnosis?
A) Equine degenerative myeloneuropathy
B) Equine motor neuron disease
C) Exertional rhabdomyolysis
D) Hyperkalemic periodic paralysis
E) Tetanus Ans: D) hyperkalemic periodic paralysis
HYPP leads to episodes of periodic muscle weakness or paralysis.
-Prolapse of the nictitating membrane is characteristic of HYPP due
to muscle weakness in the face
-Weakness and collapse suggest muscle paralysis or severe
weakness, dog sitting posture strongly supports this
© 2025 All rights reserved
, 4 | Page
A 3-year old Percheron mare is undergoing routine dental
evaluation. Physical examination shows bilateral prolapse of the
nictitating membrane and muscle fasciculations of the neck,
shoulders, and flank. During examination, the mare's hindlimbs
give way, and she leans back in a dog-sitting posture. Rectal
temperature is 100.4 degrees F (38.0 degrees C), heart rate is 60
beats/min, and respiratory rate is 30 breaths/min.
This is a case of HYPP, why would Equine Degenerative
Myeloneuropathy be incorrect Ans: EDM is a neurodegenerative
disease that causes progresse ataxia ( incoordination) and
weakness in young horses, particularly those deficient in vitamin
E.
Although it causes weakness, EDM is more associated with ataxia (
uncoordinated movement) rather than acute muscle fasciculations
or prolapse of the nictitating membrane. It is a chronic,
progressive condition, unlike the episodic nature of HYPP
A 3-year old Percheron mare is undergoing routine dental
evaluation. Physical examination shows bilateral prolapse of the
nictitating membrane and muscle fasciculations of the neck,
shoulders, and flank. During examination, the mare's hindlimbs
give way, and she leans back in a dog-sitting posture. Rectal
temperature is 100.4 degrees F (38.0 degrees C), heart rate is 60
beats/min, and respiratory rate is 30 breaths/min.
This is a case of HYPP, why would Equine Motor Neuron Disease be
incorrect Ans: EMND is a neurodegeneratie disorder and is
associated with vitamin E deficiency
-EMND causes muscle atrophy and weakness, primarily affecting
posture and gait over time. However it does not typically cause
© 2025 All rights reserved
