Management of Disease - Equine Flashcards
What is anaemia
Anaemia is the reduction of circulating red blood cells or reduced haemoglobin concentration. Functionally it is the reduced oxygen carrying capacity of the blood.
What is the normal PCV for:
a. hot blooded horses
b. cold blooded horses and ponies
Thoroughbred or hot blooded horse = 35-40%
Cold blooded horse or pony = 25-35%
what is so important about the equine spleen?
The spleen stores 1/3 of the horses’ entire blood volume which it can expel when excited, scared or during exercise to increase the PCV by up to 25%. Can compensate for blood loss for a significant while and is also a main store for platelets
what are the clinical signs of anaemia?
Tachypnoea, tachycardia, pale mucous membranes, exercise intolerance, collapse, weakness, lethargy. Can sometimes hear a flow murmur due to changes in blood flow upon auscultation
What are the clinical signs of hypovolaemic shock
Tachypnoea, tachycardia, hypothermia, cold extremities, weak pulses, muscle weakness, pale, tacky mucous membranes, increased capillary refill time
Why is melena so uncommon in horses?
the bacteria in the large intestine break down the blood
What is the normal blood volume of a horse?
8% of it’s body weight
how much blood can a horse lose before going into shock?
30% of it’s total blood volume
What compensatory mechanisms are there for coping with blood loss other than the spleen?
Catecholamines induce vasoconstriction and increase cardiac output
Plasma volume is expanded by increased renal absorption of fluid due to ADH release
what is polychromasia?
variation in cell colour
what is anisocytosis?
increase in cell size
Why is it difficult to determine if anaemia in a horse is regenerative and how can you tell?
Horses don’t have circulating reticulocytes so instead you must take a blood test then take another a week apart and compare the PCV
what colour is normal horse serum?
very yellow
What test would you use to check for equine infectious anaemia?
coggins test
name some causes of acute blood loss anaemia
Epistaxis, uterine artery rupture, guttural pouch mycosis, tumours, rib fracture in foals, thoracic vessel rupture in race horses, mesenteric artery rupture due to strongyle parasites, renal haemorrhage
name some causes of coagulopathies
Secondary to sepsis, SIRS (systemic inflammatory response syndrome) or severe liver failure
name some causes of haemolytic anaemia
Neonatal isoerythrolysis ( mare has antibodies against foal’s blood group), blood parasites, equine infectious anaemia, oxidant induced haemolytic anaemia due to toxicity (red maple leaf)
Name some causes of non-regenerative anaemia
Bone marrow disorders, anaemia of chronic disease – renal failure resulting in reduced levels of erythropoietin, iron deficiency (chronic blood loss), folic acid deficiency (medication)
what are the main three causes of anaemia?
Increased destruction, reduced production or blood loss
When carrying out a clinical exam what questions should you ask the owner as part of your subjective exam?
Taking a History, questions to ask in addition to the normal ones (has he been eating, drinking, coughing, sneezing, diarrhoea, urinating, defeacating, exercising ok etc):
• How long have you owned the horse
• Was a pre-purchase exam performed before buying the horse?
• Is the horse up to date with its worming and vaccinations?
• When was it last visited by the farrier?
• When was it last visited by the dentist?
• Is this a problem with an individual or with a group of animals?
• Has the horse recently travelled?
Signalment - some horses of a certain breed, age, gender, colour are more susceptible to certain diseases. e.g. grey horses are more susceptible to melonomas and Squamous cell carcinomas are more common in pink eyed animals.
Ponies can be more pre-disposed to hyperlipaemia (abnormally high conc of lipids in blood )and laminitis
Horses are more prone to atrial fibrillation (irregular heart rate due to chaotic beating of the atria causing poor blood flow to the rest of the body), cervical vertebral instability and idiopathic laryngeal neuropathy (dysfunction of the larynx) - roaring horses.
When examining the horse from a distance what should you look at?
demeanour, body condition, resp rate, any increased respiratory effort or unusual posture, any unusual behaviour, look at where it is housed, is it eating, what do it’s droppings look like
what is the normal rectal temperature of a horse
Temp 36.5 - 38.5 (exercised or hot day) degrees
When hospitalised how often should foals be weighed and how much weight should they gain?
Foals should gain 0.5-1kg every day - should be weighed every day when hospitalised.
when examining the respiratory tract what should you look for?
Clinical Examination
• Noises — Coughing, Grunting, Stridor
• Nasal Discharge — Serous, Mucopurulent or Sanguinous
• Rate — Influenced by temperature, stress, metabolic
state
• Depth — Increased depth provides better alveolar
ventilation
Pattern — biphasic (both inspirator,’ and expiratory)
• Heave Line — external abdominal oblique muscle
• Nasal airflow — feel for equal airflow
• AUSCULTATION -with rebreathingbag
Scant, moderate or marked to describe quantities
Heave line is also a classic presentation for animals trying to take weight off their feet e.g. laminitis
upon auscultation:
Remember to check the trachea and larynx
Locate point of most intensity if you hear an abnormal noise
Larynx palpable in most horses - feel arytenoid cartilages
• Breath Sounds
— Loud
— Quiet
Wheezes — long sounds
• Crackles — short, sharp popping sounds
Area over which sounds can be heard
• Pleural friction rubs
Constriction of bronchioles - wheezes
Moisture or effusion in the lungs - crackles
Calves with pneumonia - friction rubs
Effusion can cause absence of lung sounds
Nostrils - symmetry, flexible, no mucous , air coming through both, look at nasal mucosa, smell air that comes out of each nostril
Palpate and percuss paranasal sinuses - should be filled with air so sound hollow and check facial symmetry
Larynx - obvious solid structure felt high up in the throat, above this can feel the muscular processes of the arytenoids - should be symmetrical
Palpate traches - rings can be palpated in the upper neck
Auscultate trachea for fluid accumulation
Re-breathing bag - Should increase resp rate significantly - can make it easier to auscultate lungs
When examining the cardiovascular system what should you look for?
Rate — Influenced by temperature, stress,
metabolic state
Rhythm — Regular, regularly irregular, irregularly
irregular
• Pulse —Quality, deficits
Venous engorgement — Jugular pulse, jugular
distension
Oedema — Limb oedema, ascites
Murmurs — Point of Maximal Intensity, Grade 1-6
Regularly irregular rhythm can be quite normal in the horse
Increased preload can cause venous engorgement
Many horses have functional heart murmurs
Check mucous membranes
Transverse facial artery, over the heart ( fit horse can feel heart beat) and under mandible can be used to check pulse
Heart located quite cranially - straight up behind elbow P on left and T on right
when examining the gut what would you look for
Normal to hear background gut noises
4 quadrants - should hear gut sounds in all
Right dorsal - caecum - caecal flush - one every minute
Auscultate the abdomen - gut sounds should not be high pitched
Left:
Dorsal - small intestinal movement,
Ventral quadrant - colonic movement
Right:
Dorsal - caecum
Vetral - Right ventral and right dorsal colon - soft sounds
look for urine and diarrhoea staining around the anus and check muscle tone and integrity
when doing a musculoskeletal exam what would you look for?
Forelimb:
Palpate limb for swelling, heat pain or deformity - pay particular attention to soft tissue areas
Lift the foot - palpate, test movement of major joints
The foot - always clean it out thoroughly first, look for evidence of a foreign body, next apply a hoof tester across the entire foot including the heel and across the frog. Also tap the foot to assess for a focus of pain
Palpate the leg once more before allowing the foot to fall.
Hindlimb:
Palpate as for the forelimb, look for digital pulses - exaggerated with some conditions
Lift the foot, check range of movement and palpate
Clean the hoof, check for foreign bodies, use hoof testers as for the forelimb and tap in all areas
Palpate once more before allowing foot to fall
Examine horse during movement - At walk - At trot - Turning in a circle - Sometimes on different elevations and ground types Sometimes with a rider
What are your list of differentials upon an equine clinical exam?
Infectious: Virus Bacterial Fungal Protozoa Parasitic
Non-infectious: GIN 'N' THONIC Genetic/ developmental Immunological/ allergic Nutritional/ toxic Neurological Traumatic Hormonal Neoplastic Idiopathic/ iatrogenic
What to look for on diagnostic imaging of the equine leg
soft tissue:
- swelling
- abnormal presence of air and gas
- mineralisation
- foreign bodies
Bone:
- margins
- medulary cavity and the cortex
- look at the trabecular pattern
- look at the bone density
- look for areas of bone re-modelling
Articulation:
- symmetry
- joint space
- orientation
What is Sclerosis
increased bone density
can be to wall off infection
due to joint stress
to protect a weakened area
what is osteolysis
decreased bone density
can be due to fracture, blunt trauma, infection or excessive pressure on a joint
How can you tell the difference between active and in-active lesions
active lesions have irregular, poorly demarcated, sharp edges
in-active lesions have smooth, well defined, rounded edges
what are osteophytes
bony projections associated with cartilage degeneration
What are enthesiophytes
focal areas of new bone production at the origin or insertion of soft tissue, often caused by stress at the point of soft tissue attachment
Name the indigenous poisonous plants
v Ragwort - associated with weight loss due to severe liver failure v Giant hogweed v Water hemlock v Foxglove v Bracken v Deadly nightshade v Oak tree and acorns – severe gastrointestinal problems rhododendron
