Lecture 10 - Equine Nutrition 2 Flashcards
Normal cardiac function, acid-base balance, renal function, and neural function are all highly dependent on which mineral?
Potassium
True or False: Potassium excess is a common problem
False; excess of potassium in the body is NOT common
What are some clinical signs of potassium deficiency?
Inappetence, fatigue, weakness, lethargy
Increased aldosterone secretion, increased Na+ retention, and increased K+ excretion are all associated with excess __________.
Sweating
What type of medications are typically used to treat potassium deficiency?
Diuretics (Furosemide)
True or False: Magnesium metabolism closely adheres to calcium and phosphorus
True
While dietary deficiency is uncommon, high _________ may reduce magnesium absorption.
Phosphorus
An acute neurological condition caused by magnesium deficiency (Mg <1.6 mg/dl) seen in lactating mares and stressed fasted animals in transport
Hypomagnesemic tetany
Magnesium is necessary for adenyl cyclase activity, which is required for ___________ hormone release.
Parathyroid
True or False: Iodine excess and iodine deficiency both cause clinical signs of hyperthyroidism
False; iodine excess and deficiency both cause clinical signs of HYPOthyroidism
Why do iodine excess and deficiency both cause clinical signs of hypothyroidism? (Briefly explain mechanisms for both)
- Iodine is a component of T3 and T4, so low iodine leads to low thyroid hormone production
- Excess iodine causes negative feedback for TSH release from pituitary, leading to low thyroid hormone production
Dry coat, alopecia, impaired growth, decreased bone mineralization, lethargy, inappetence, and cold intolerance are all clinical signs of… (name the disease)
Hypothyroidism
Why is copper dangerous in excess?
It promotes oxidation when on its own (and not acting as a cofactor), and excess may cause liver and kidney damage
Collagen/elastin synthesis, iron mobilization, and melatonin synthesis all rely on which mineral?
Copper
A mineral that accumulates in plants, according to soil content, and interferes with copper absorption; may or may not be required in the diet
Molybdenum
What is a consequence excess zinc can have on foals?
Joint disease
Which mineral deficiency causes parakeratosis in the lower limbs?
Zinc
Why is iron supplementation dangerous for foals?
It is generally unnecessary and can cause liver failure
Which vitamin and mineral combo has a synergistic antioxidant effect (low amounts in one require supplementation of the other)?
Vitamin E and selenium
What disease is associated with Vitamin E and selenium deficiency? (Name disease and some clinical signs)
White muscle disease; common signs are lethargy, inability to curl tongue to suckle, and aspiration pneumonia (if tracheal muscles affected)
True or False: Vitamin E excess is uncommon, but selenium has a comparatively narrow safety range
True
(Extra note: 5 to 10 times the required amount of selenium can be toxic)
True or False: Diets with high fat/oil content correlate with a decreased vitamin E requirement
False; a high fat/oil diet INCREASES vitamin E requirement
Vitamins that are generally present in adequate amounts, carry a greater risk for toxicity due to slow excretion rates, and share the same absorption mechanisms with each other (causing competition)
Fat soluble vitamins (A, D, E, and K) - A and D have highest toxicity risk!
Vitamins that are rarely deficient or in excess, can be synthesized endogenously or by colonic microbes, and can be filtered in urine and excreted when in excess
Water soluble vitamins (B and C)
Grain mixtures are usually fortified with vitamins, but additional vitamin supplementation can be beneficial if… (multiple answers)
- Hay/feed quality is poor or stored for too long
- During periods of colic/GI disease (dysbiosis)
- When animal is on antibiotics (dysbiosis)
(Extra note: dysbiosis = anything that causes disruption of normal gut microbiota)
True or False: Mares do not require an increase in food intake until the last trimester of their pregnancy to maintain proper nutrition
True
(Extra note: 12 to 20% increase in intake in last trimester)
Grass hay is lower in ________, so supplementation may be required for lactating mares
Calcium
What is an ideal BCS for a pregnant mare to maintain?
BCS of 5 to 6 (on a 9 point scale)
Which mineral may need to be supplemented if a lactating mare is primarily eating legume hay in her diet?
Phosphorus
The feed that is offered to suckling animals to support growth in addition to milk
Creep feed
What does creep feed typically consist of?
Corn, oat, and barley
What is the ideal BCS for a weanling foal?
BCS of 4 (on a 9 point scale)
What are some potential causes of orthopedic disease in growing foals?
- Accelerated growth (genetics)
- Conformational abnormalities (toe-in or straight fetlock)
- Nutritional factors (excesses/deficiencies)
List some vitamins and minerals associated with orthopedic disease in growing foals (when deficient or in excess)
Vitamins A & D, calcium, phosphorous, magnesium, copper, zinc
Legume grass, green grass, and grains are all good sources of _______________. (Name the macronutrient)
Carbohydrates
A good high ________ feed for performance horses may consist of alfalfa (legume hay), grass hay, oat hay, and grain.
Protein
True or False: It is important to feed performance horses diets that consist of more forage than grain
True
Which electrolyte deficiencies are the most concerning in performance horse?
Na, Cl, K, Mg, and Ca
What can be given to horses to make up for a lack of sodium in their diet, or to raise their sodium levels after prolonged activity/sweating?
Salt blocks
Damage/destruction of muscles, usually as a result of extreme exercise and excretion; results in severe muscle damage that is extensive enough to have considerable metabolic effects
Rhabdomyolysis
List some potential causes of rhabdomyolysis
- High fat/low antioxidant intake in active horses
- Physical trauma (burns, bites, heat stroke, electrocution)
- Vitamin E/selenium deficiency
- Electrolyte imbalance
- Underlying disease
- Polysaccharide myopathy-glycogen storage disorder
What are some clinical signs of rhabdomyolysis?
- Muscle pain, swollen muscles, stiff gait
- Myoglobinuria (can progress to renal failure)
- Cardiac arrhythmia/arrest (due to K+ leak from myocytes)
What type of diet should be regularly given to horses diagnosed with rhabdomyolysis?
High-fiber, high fat, and low-starch
True or False: Hyperlipidemia rarely occurs secondary to stress, disease, pregnancy, lactation, or poor feed intake
False; hyperlipidemia OFTEN occurs secondary to these factors
Inappetence, dullness, depression, poor feed intake, colic, and sometimes liver failure are all clinical signs of…
Hyperlipidemia
Hyperlipidemia occurs when…
FFAs are mobilized to provide energy at a rate that exceeds the metabolism (causes fatty acid oxidation or ketone body formation)
What can occur when too much fat accumulates in hepatocytes?
Clots/emboli in blood vessels
What is the most efficient method of treating hyperlipidemia?
Treat the primary illness (but prevention is key if possible)
What is the general name for abdominal pain in horses?
Colic
List some common symptoms of colic
Pawing, rolling, bloating, sweating, distress, uneasiness, no interest in food/water, peculiar postures, absence of gut sounds
Where does “impaction colic” typically occur in the horse GI tract?
Large intestines (usually palpable)
What are three important things to check in a horse if colic is prevalent?
Diet, dentition, parasite control
Name the type of colic:
Palpable in large intestines; result of excessive fermentation and gas production; may be caused by high energy feeds such as grain and lush forage
Gas colic
Name the type of colic:
Hard to palpate in large intestines; suspected according to environment and sand in feces
Sand colic
When is medical (as opposed to surgical) intervention appropriate for horses diagnosed with colic?
When the horse is mildly painful and cardiovascular systems are functioning normally
What should be the primary focus of treatment in colicky horses with evidence of intestinal obstruction with dry ingesta on rectal exam?
Rehydration and evacuating intestinal contents
Why is it important to address severe pain in colicky horses?
Too much pain can negatively affect GI motility
An inflammatory condition caused by disruption of blood flow to the laminae; inflammation often causes permanent weakness to laminae that interferes with wall/bone bond
Laminitis
True or False: Laminitis can be caused by certain toxins, such as bacterial toxins
True
(Examples: GI dysbiosis, nutritional factors, infection)
List some clinical signs of laminitis
Lameness, pain, change in hoof structure (when chronic)
Can be fatal
How can excessive carbohydrate intake lead to laminitis?
If all carbs cannot be digested in small intestines, they ferment in large intestines and cause acidosis. Bacteria die-off and release endotoxins as a result of the acidosis.
Laminitis then develops within 24 hours
How can laminitis be prevented?
- Avoid high sugar/water soluble carb feed
- Soak hay in water, then remove the water (can help reduce water-soluble carb that may contribute to dysbiosis)
A characteristic collection of clinical signs and clinicopathologic changes in equids that places them at high risk for developing laminitis
Equine metabolic syndrome (EMS)
What is the hallmark clinical sign of EMS?
Insulin dysregulation/hyper-insulinemia (with normal BG)
(Extra note: usually affects obese horses, but can occur in thinner horses)
What are some clinical signs commonly associated with EMS?
Hyper-insulinemia with normal BG, infertility, altered ovarian activity, and increased appetite
What is an appropriate diet for horses diagnosed with EMS?
- REDUCE high energy concentrates and fats
- INCREASE fiber and roughage
- ELIMINATE or HEAVILY RESTRICT pasture access (until desired BCS reached)
True or False: Chronic kidney disease is very common in horses
False; chronic kidney disease is relatively uncommon in horses
High BP, coagulopathies, pyelonephritis, and tumors are all common causes of…
Chronic kidney disease
Although there are no clear diet recommendations for horses with chronic kidney disease, what are some options that may be beneficial?
- Avoid high protein (like legumes)
- Carb based diet
- Adequate hydration
What are some beneficial dietary options for geriatric horses to help prevent weight loss (assuming no underlying metabolic disorder)?
- High caloric density/increased protein
- More digestible forage (less mature grass hay)
- Highly digestible fiber (beet pulp/soy hulls)
