CASE 1: A 22 year old Quarter horse mare present to you for acute onset of lameness. The
mare had been treated at your clinic the previous year for grain overload, but you have not seen
her or the owners since that time. The owners have retired the horse, and only see her on the
weekends. She is fed a round bale in the winter, and has free access to 20 acres of grass and a
pond.
On physical examination, mild tachycardia was note (52 bpm), with a grade III/VI systolic heart
murmur, with increased facial and digital pulses. Rings were noted on the hoof wall capsule, and
the horse was Obel grade 2/4 at a walk. A systemic blood pressure was obtained from the
coccygeal artery using oscillometric techniques, and noted a mean NIBP of 135 mmHg
(systolic=175 mmHg, diastolic=135).
Describe the method for measurement of indirect arterial blood pressure.
List 5 causes of secondary systemic hypertension in horses.
You obtain an echocardiogram and the following M mode image of the left ventricle at the
level of the papillary muscles:
Describe the changes you see.
What type of hypertrophy is this? How does it differ from a horse with mitral
regurgitation?
What is the cause of pseudohypertrophy of the left ventricle and how can it be
differentiated from hypertrophic cardiomyopathy?
List 4 classes of anti-hypertensive medications available for use in horses. For each class,
list one drug, the mechanism of action and 2 side effect.
How would you differentiate left and right sided heart failure?
Describe activation of the renin-angiotensin system (RAS) in patients with SHA. List 8
physiologic effects of angiotensin II.
Specifically describe the mechanism/s via which hyperaldosteronism affects each of the
following:
a. Effective circulating volume
b. Serum potassium concentration
c. Systemic acid-base balance
CASE 2: A 5 yr. old, primiparous, Miniature Horse mare foaled uneventfully 3 days ago and has
a healthy foal running at her side always attempting to nurse. Since foaling, the owners report the
mare has been lethargic and has difficulty eating and swallowing. She wants to eat but can’t
seem to chew or move food to back of mouth for swallowing. Today her tongue is sticking out of
mouth, and she also has diarrhoea. There are 37 animals on farm and no other animals appear
affected. The owners keep the mare in a dry lot, with access to a round bale of coastal Burmuda
hay. She shares the field with 9 other mares.
On physical examination, the mare is depressed, and you note tachycardia (86 bpm), tachypnea
(56 brpm) and pyrexia (102.5 F). Her weight is about 100 kg. Her mucous membranes were
tachy and icteric, and both masseters were grossly swollen. The mare resisted a brief oral
examination, and was hypersalivating. You obtain bloodwork for further evaluation of her
general condition and the following abnormalities were noted on her serum chemistry (results are
given followed by the reference range in parentheses):
Bilirubin (direct): 18.5 mol/L (<6-8 mol/L)
Bilirubin indirect: 42.2 mol/L (3.4-34.2 mol/L)
Total bilirubin: 60.7 mol/L(8.5-47.9)
Lactate dehydrogenase: 7763 iu/L (162-412)
GGT: 460 iu/L (5.5-17)
ALP: 3352 iu/L (181-500)
Bile acids: 132.6 mol/L (<15)
AST: 13030 iu/L (160-260)
CK: 57040 iu/L (3.8-55)
SDH: 362 iu/L (11-22)
Glucose: 212 mg/dl (72-119)
Triglycerides: 11.46 mmol/L (0.2-1.2)
The mare urinates once she has been placed in a stall. The
urine is dark in color. What do you suspect and what should
you test for?
What is your main concern for this mare, in regards to her
signalment and history?
What additional testing would be supportive of a diagnosis of nutritional deficiencies in this
mare?
How would you treat this mare? Calculate the maintenance energy requirements.
What are two concerns you consider when administering insulin in horses?
What is the scientific word for inability to open the mouth?
Serum selenium was obtained and registered 0 (ref 17-25 g/dL). What is your diagnosis
and the cause of this condition?
What is the enzyme that this nutrient is required to activate?
What additional test may be helpful in diagnosis of this condition?
How would you treat this condition?