Acid base and neonatal calf diarrhea

Question 1

An optimal oral electrolyte solution will correct what four things in a scouring calf?

Answer 1

electrolyte imbalance (big one!)
Energy deficits (glucose)
Dehydration
strong ion acidosis

Question 2

What unmeasured anion contributes (uniquely) to metabolic acidosis in calves?

Answer 2

D-lactate
this is produced from bacterial fermentation of nutrients in the gut that were not properly absorbed. Malabsorption happens because of loss of lactate from denuded villi

Question 3

Increased SID (strong ion difference) means

a. Acidosis
b. Alkalosis

Answer 3

b. Alkalosis

Question 4

Describe the principal of electroneutrality

Answer 4

sum of anions = sum of cations

Question 5

Describe the principal of strong ion difference, including how to calculate it and why it matters

Answer 5

Na + K - Cl - Lac

SID determines the [H+]

a. high SID = alkalosis
b. low SID = acidosis

Question 6

What role do proteins play in acid base? What are the major proteins present in blood

Answer 6

Negative ions (anions)
Weak acids --> more protein = more acidic  
Most important weak electrolytes present in plasma (95%)

Major proteins in the blood: albumin (degree of bound Ca changes with acid-base conditions), globulins,

Question 7

Describe the difference in dissociation behavior (in H2O) of strong vs. weak electrolytes

Answer 7

strong: always completely dissociate
Weak: Only partially dissociate. Degree of dissociation is dependent on conditions (acidic, alkalotic) ie. buffers, amount of Ca bound to albumin

Question 8

List the different fluid compartments that exist in the body

Answer 8

1. ECF –> ISF & plasma

2. ICF

Question 9

What are the 3 laws of chemistry of aqueous solutions that biologic fluids follow?

Answer 9

1. Law of electroneutrality ([H+] + [OH-] = 0)
   - consequence: can’t add single species of ion to sol’n
2. law of dissociation equilibria
3. Law of conservation of mass

Question 10

Foals & Calves have a greater ECF space relative to body weight, which means they are more susceptible to what (compared to adults)?

Answer 10

Dehydration

Question 11

Cows are net excretors of which electrolyte?

Answer 11

Potassium

A cow off feed will be in a hypokalemic state –> smaller SID –> acidosis

Question 12

Hydronium (H3O) is present in (large/small) amounts in body fluids. Enzyme activity is (dependent/independent) on/of hydronium

Answer 12

small (much lower than Na for example)

dependent (effects other molecules even at very low concentrations)

Question 13

Conservation of mass

amount of each substance within an H2O solution stays the same unless (2 things):

Answer 13

1. A substance is added/removed from the outside (important for [H+])
2. Produced/destroyed from a chemical reaction within the substance (has no bearing on H+)

Question 14

What is the pH of:

a. Water at 37degrees
b. Bovine urine

Answer 14

a. 6.68

b. 8.5

Question 15

Questions about CO2

a. It is a product of what?
b. what fluid compartment is it in highest concentrations
c. Does it act most like a weak base, or acid?

Answer 15

a. Body metabolism
b. ICF –> cellular metabolism
c. weak acid

Question 16

What are the two primary determinants of [H+] in plasma?

Answer 16

1. SID

2. pCO2

Question 17

What is the most important difference between substance composition of plasma & CSF (wrt acid-base)

Answer 17

No protein present in CSF (A-)

Question 18

What is the effect of CO2 on

1. pH
2. metabolic compensation

Answer 18

1. major effect, increased CO2 = acidic

2. very little effect, increased CO2 causes slight increase in HCO3

Question 19

What is the effect of increasing SID on HCO3?

Answer 19

increases

Question 20

What is the anion gap?

Answer 20

AG = A- + Lac-

where, A- is all weak acids: protein, small organic molecules

Question 21

1. Is ISF: plasma highly permeable?
2. Is ISF: ICF highly permeable?
3. What is the significance?

Answer 21

1. Yes –> what we do to plasma effectively happens to ISF too
2. No –> except for CO2 & H2O. ISF has practically no A-, ICF has a lot. Lactate ions key regulators of interaction between ISF & ICF.

Question 22

What might the biochemical profile of a cow with Johnes be abnormal? What is the effect on acid-base?

Answer 22

Hypoproteinemic

metabolic alkalosis

Question 23

What major electrolyte is lost when a cow has a displaced abomasum? What does this mean for acid-base? How do we treat it?

Answer 23

Chloride –> hypochloremia
Increased SID –> metabolic alkalosis
Replace lost chloride, correct alkalosis with an acidifying solution (LRS, SID = 0)

Question 24

Describe the treatment protocol for neonatal calf diarrhea when

1. mildly ill, early detection
2. > 8% dehydrated
3. Signs of hypovolemic shock

Answer 24

1. oral electrolytes, choose based on acid-base status of calf (usually acidotic, so we gave an alkalanizing solution)
2. IV fluid therapy with balanced electrolytes (LRS)
3. 1x hypertonic saline to reverse hypovolemia, followed by 10x isotonic fluids

Question 25

For neonatal calf diarrhea caused by e.coli 1. average age of onset 2. common symptoms 3. mechanism of action of e.coli 4. treatment 5. Preventative measures

Answer 25

1. 4-7 days of age 2. secretory diarrhea, dehydration & weakness (can progress quickly to more severe symptoms & death, w. mortality rates of 10-50%) 3. acid-base imbalance (usually acidosis) since toxins cause secretion of Na & Cl 4. Fluid therapy, anti-inflam to help w. inflammation & pain (ketoprofen). Ab therapy only recommended if septicemic or high risk of septicemia 5. prompt and adequate colostrum, good hygiene, reduced stress. Vaccine can be given to cow 30 days before calving (designed to increase anti-F5 Ab)

Question 26

For NCD caused by rotavirus 1. average age of onset 2. common symptoms 3. mechanism of action of rotavirus & maintenance in environ. 4. treatment 5. preventative measures

Answer 26

1. 5-14 days 2. profuse watery diarrhea and dehydration, may be subclinical 3. a.infects epithelial cells along brush border of small intestine, causing sloughing/denuding of brush border. Malabsorption and maldigestion result --> loss of some lactase action since in the villi. 3. b. shed by calves and adults for weeks after clinical or subclinical infxn 4. fluid therapy, lactase supplement before feeding, no indication for Ab therapy 5. two vxns available but neither efficacious

Question 27

For NCD caused by coronavirus, 1. Age of onset 2. Common symptoms, severity? 3. MofA of the virus 4. Can this virus affect adults? 5. What other body system can it cause disease in (besides GI) 6. how is it maintained and spread in a herd, and what time of year is it most associated with?

Answer 27

1. 1 day-3mos, but most commonly 7-14 days 2. profuse watery diarrhea that lasts longer than rotavirus, dehydration, depression, acidosis. Animals are quite sick, and more likely to die 3. attacks crypt and epithelial cells of small & large intestine 4. Yes - winter dysentery 5. respiratory 6. ubiquitous in all cattle, shed in large amounts around time of calving and in the winter

Question 28

What are the two most common parasites that cause neonatal calf diarrhea? Are they zoonotic? Which one is more commonly associated w. diarrhea in young calves? Are they intracellular organisms? Do they cause malabsorption/maldigestion? Do these parasites have an environmental developmental phase (ie. freshly shed are not infective)?

Answer 28

1. Cryptosporidium & Giardia 2. Yes - both are zoonotic 3. Cryptosporidium is more commonly associated w. diarrhea in calves 5-15 days of age. Giardia that causes disease in young animals is usually because of co-infection with another. 4. Crypto. is intracellular, damage to villi is due to inflammatory response 5. Yes, they both can cause malabsorption/maldigestion of lactose because of villar atrophy. Crypto goes inside epithelial cells, giardia attaches to outside 6. No, freshly passed crypto & giardia are immediately infective

Question 29

What causes lactose intolerance in calves? What can be done to treat them? Is primary lactose intolerance a problem in calves?

Answer 29

1. Secondary lactose intolerance --> infectious enteritis of any etiology 2. Supplement with lactase 1/2 hour prior to feeding. Given 4x daily 3. No, congenital lack of lactose production has never been noted in calves

Question 30

For NCD caused by salmonella 1. what are the classic clinical signs? 2. Can mortality be sudden, and rates high? 3. Typical age of affected animals 4. mechanism of action of salmonella --> diarrhea 5. Treatment 6. zoonotic? 7. Prevention

Answer 30

1. diarrhea, fever, leukopenia 2. Yes, mortality may precede diarrhea, and rates can be 50% 3. 5-42 days of age 4. Invade epithelial of mostly distal sm. intestine (intracellular). inflammatory response causes destruction of villi & possibly bloody diarrhea. This bacterium is dose-dependent 5. fluid therapy, Ab to prevent or treat extra-intestinal infections (high risk of bacteremia) 6. Yes, can cause serious disease in humans 7. Herd testing, ID & isolate infected animals (clinical & subclinical can shed high amounts). Good hygiene, ensure adequate colostrum & passive transfer, reduce stressors

Question 31

What bacterial agents can cause bloody NCD?

Answer 31

Salmonella, non-ETEC e.coli (EPEC, EHEC), Clostridium perfringens (enterotoxemia)

Question 32

Is coccidiosis a problem in young, or older calves? What about BVD?

Answer 32

Older, usually >30 days | BVD --> also older

Question 33

Is there a potential risk behind giving antibiotics to a septicemic, diarrheic calf? Does it warrant avoiding Ab use?

Answer 33

Yes --> if causative agent is a gram negative bacterium, Ab can cause mass death of bacteria & subsequent large amounts of endotoxin release --> marked deterioration of animal. Does NOT outweigh the benefit of Ab.

Question 34

What is the classic presentation of a calf with lactose intolerance (but cured of infection)?

Answer 34

Bright, alert, suckling calf, but watery diarrhea continues

Question 35

What are most common bacterial agents causing septicemia in a calf?

Answer 35

E.coli, salmonella, strep, pasteurella, listeria

Question 36

For assessing passive transfer status: What is a cheap, quick, calf-side test? What is the gold standard (most accurate)?

Answer 36

1. Cheap --> TP determination by refractometry (hemoconcentration, & in-uter infections resulting in high fibrinogen can skew results) 2. IgG quantification by radial-immuno-diffusion (RID), but expensive and long turn-around time