Goff/Duke's Chapter Questions (Vitamins) Flashcards
Why are animals suffering from vitamin A deficiency susceptible to respiratory infections?
Vit A is necessary for the maintenance of normal epithelial structure.
During deficiency the ciliated columnar epithelium of the bronchioles becomes more squamous, losing the ability to move mucus and the bacterial filtered and trapped within the mucus up ad out of the respiratory tract.
A cat is brought in for you to examine that it is exhibiting pain while walking. On radiographic examination, you notice new periosteal bone formation extending up the tendon sheaths. The cat’s diet includes a large proportion of liver. What could be the problem?
Vit A toxicity.
Sometimes liver can be a massive source of vit A.
The calcification of tendons and spinal column is a common finding in vit A intoxication.
How does vitamin D affect bone metabolism?
Vit D helps increase Ca and Phos absorption from the diet.
This allows the animal to maintain normal blood Ca and Phos concentrations.
This is necessary to allow mineralization of the organic matrix laid down by osteoblasts during bone formation.
How does vitamin D affect intestinal Ca absorption?
Hormonal 1,25-dihydroxyvitamin D interacts with its receptor located in the intestinal epithelial cells.
This stimulates transcription and translation of genes coding for proteins involved in Ca absorption.
2 examples are Ca-binding protein, which attaches to Ca at the luminal surface and carries it across the cell cytosol, and a Ca-ATPase pump protein, which helps move Ca from the cytosol to the blood across the cell membrane.
What form of vitamin D is required by poultry? By New World monkeys?
Both have a requirement for vit D3. Neither can use D2.
What is the main antioxidant of cell membranes?
Vitamin E
Accidental rodenticide ingestion in dogs and cats involve two different vitamins. What are they and what is the mechanism of the toxicity?
The first rodenticides contained coumarin types of compounds, which interfere with the action of Vit K.
This leads to blood coagulation problems causing the rodents to die of internal hemorrhaging.
The 2nd type contains analogs of the hormonal form of Vit D.
These kill by causing excessive hypercalcemia and hyperphosphatemia, leading first to renal failure.
Do ruminants require any of the B vitamins? Why?
Not usually once they are fully ruminating.
Rumen microbes can usually make all B vitamins in quantities above the level required by ruminant tissues.
Feeding raw eggs to your dog every day could lead to a deficiency of what vitamin? What symptoms would you expect to see?
Biotin, due to avidin in egg whites, which binds biotin making it unavailable.
Biotin-deficient animals have poor hair coats and exhibit alopecia, scaly dermatitis, and achromotrichia (lack of hair color).
Sheep that graze pasture low in cobalt may suffer from a vitamin deficiency. Why? What are the symptoms?
Rumen bacteria need to utilize cobalt to produce cyanocobalamin for themselves and for the ruminant.
Poor rumen function leads to reduced feed efficiency and growth primarily due to energy deficiency.
The bacteria and the ruminant are unable to utilize enrgy-producing pathways requiring cyanocobalamin.
You place a group of turkey pouts on a coccidiostat (drug to fight off Coccidia parasites). Two weeks later you are called because the turkey poults are acting strangely. They stand with their neck extended and gaze at the ground. What happened?
Some coccidiostats work by preventing folate production by Coccidia so that they have no source of it, thus stopping their growth.
Occasionally it also causes folate deficiency bc it can also reduce bacterial production of folate, important if no folate is added to the diet!
Another important coccidiostat is amprolium, which interferes with thiamine uptake and thus the parasite develops thiamine deficiency preventing it from replicating.
However, prolonged high doses cause thiamine deficiency.
Thiamine-deficient birds exhibit opisthotonus: the head and neck are extended backwards to an extreme degree.
A group of beef steers on full feed are exhibiting neurological signs that include circling and apparent blindness. As you stand watching them, one keels over dead. You do a necropsy and on examination of the brain you see areas of the cerebral cortex that appear soft and mushy. You pull out your black light (UV light) and the brain autofluoresces. What is your diagnosis? Explain to the owner how this occurs.
Thiamine deficiency.
Steers on full feed can undergo rumen flora changes that don’t favor production of thiaminases within the rumen.
The net effect is a lack of thiamine reaching the small intestine.
Ruminant diets are generally not supplemented with B vitamins since they produce them in the rumen flora.
If the rumen does not deliver the thiamine to the intestine, the steers become deficient.
A child brings in his guinea pig for an examination. You examine the mouth and note that the teeth are loose and the animal has a scruffy looking hair coat. What do you suspect? How will you cure it?
Scurvy. Start supplying the guinea pig with vitamin C every day.
