Calf Problems: Dx, Tx, Prevention and Control of D+

Question 1

Clinical features of calf scours?

Answer 1

Demeanour:
- presence of suck reflex.
- BAR etc.
- ataxia / weak.
Hydration status - sunken eyes? skin tent?
Age of calf and duration of scour.
Condition score - indication of energy status.
Faecal score.
TPR.
Other conditions.

Question 2

Why do calves scour and sometimes die?

Answer 2

Pathogen multiplication leads to epithelial damage.
D+ can be hypersecretory or malabsorptive, or both.
Loss of water + electrolytes = alkaline faeces (can cause chemical burns and loss of hair at the hind end).
- dehydration and metabolic acidosis.
– hyperventilation to correct acidosis.
– acidosis leads to loss of potassium and sodium from cells.
- hyperkalaemia causes disruption of the p-wave, arrhythmia and eventually cardiac arrest.

Question 3

Dx of clinically important acidosis.

Answer 3

Blood gas analysis - <12.5 mmol/l HCO3.
pH meter - <7.1, but pH is measure of respiratory and metabolic acidosis – assess in light of clinical findings or rehydrate calf (e.g. 5L, then measure pH).

Question 4

Acidosis and age of calf as a rule.

Answer 4

Best indicator of likelihood of very severe acidosis:
- <6d old – mild/moderate acidosis.
- >6d old – more severe acidosis.

Question 5

Clinical signs of metabolic acidosis?

Answer 5

Ataxic/recumbent.
Hydration status.
- do not respond to rehydration.

Question 6

Primary and common pathogens of calf scouring.

Answer 6

Rotavirus, cryptosporidiosis and coronavirus widespread on farms.
Probability of clinical disease = degree of challenge x susceptibility.

Question 7

Factors affecting degree of susceptibility.

Answer 7

Inadequate colostrum.
Environmental stress.
Nutritional errors.
Concurrent disease.

Question 8

Dx of scours in young calves.

Answer 8

Ascertaining which pathogen(s) involved can be difficult and expensive - Is it worth it?
Watch out for “nutritional looseness”.
Aim for whole group diagnosis.
Sample sick and healthy.
Sample early in clinical cases.
Most valuable is a moribund calf.

Question 9

Tx of the scouring calf.

Answer 9

Broadly similar regardless of aetiology.
ABX unnecessary (contraindicated) except for E. coli and Salmonella.
Major aspects of treatment are:
- fluid therapy.
- nursing.
- improve environment.
Strategy of fluid therapy determined by assessment of dehydration.

Question 10

Assessing dehydration.

Answer 10

<5% = normal (increased thirst).
6-8% = dry muzzle, mouth, sunken eyes, reduced skin elasticity.
9-10% = cold legs and mouth, recumbent.
11-12% = comatosed and shocked.
13-14% = death.

Question 11

Effects of diarrhoea.

Answer 11

Dehydration and haemoconcentration:
- reduced tissue perfusion.
- reduced liver function.
- increased lactic acid production.
Metabolic acidosis - hyperpnoea, bradycardia, cardiac arrhythmia, poor pulse volume:
- increased lactic acid production in tissues.
- increased colon-derived acids.
- increased bicarbonate loss via gut.
- decreased H+ loss via kidney.

Question 12

Further metabolic effects of D+.

Answer 12

Reduction in plasma Na+
- intestinal loss.
Plasma K+ falls, then later rises.
- exchange of intracellular K+ for extracellular H+ to buffer extracellular fluid.
BUN rises.
- Reduced renal perfusion.
Plasma glucose falls.

Question 13

1. Dx of D+.
2. Tx of D+.

Answer 13

1. May argue that do not need Dx for most cases as Tx same for most.
   Several samples (minimum 6 pots of faeces).
   PM exam.
2. Rehydration using oral / IV fluids.
   Nutrition - milk +/- oral fluids.
   (ABX).
   - if zoonotic risk etc.

Question 14

Aim of Tx in the scouring calf?

Answer 14

Maintain calf growth rates.
Return calves to normal feeding.
Minimise mortality.
Reduce spread to other calves.
Reduce risk of human infection.
(To stop the D+).

Question 15

Fluid therapy for the scouring calf.

Answer 15

Orally for mild and moderate dehydration.
Oral and IV for severe dehydration.
Oral = simple, non-sterile and effective if dehydration <8%.
- get to suckle if possible due to oesophageal reflex as ST goes into rumen.
- Some oral products better formulated than others.
– Do not mix with milk.
– Mix with water and measure water exactly.
Problems with low energy and poor correction of acidosis.

Question 16

WHO fluids oral (simplest).

Answer 16

Na+ – 100mmol/l.
anions – 100mmol/l.
glucose – 100mmol/l.
= 0.6% NaCl, 2% glucose.

Question 17

Oral fluids more complex.

Answer 17

Na+ and K+ (replace ionic losses and H2O).
Glucose and glycine (co-transport with Na+ and provide some energy).
Citrate and acetate (stimulate absorption of Na+ and metabolised to bicarbonate by liver).
Bicarbonate (alkalinisation).

Question 18

Oral fluids considerations.

Answer 18

Osmolarity needs to iso-osmotic.
Multiple small feeds – 1-2L repeatedly.
Alkalinisation levels will reduce plasma K+ levels but these will correct themselves eventually.
Calves still require milk while on oral fluids - do not mix products with milk.
Some contain fibre but no real benefit of this.
Can stomach tube but ensure calf not in a state where it will regurgitate and aspirate.

Question 19

Produce your own fluid therapy orally.

Answer 19

Glucose - 300g.
NaCl - 52.5g.
NaHCO3 - 37.5g.
KCl - 22.5g.
Make up to 15L with clean water.

Question 20

1. When should IV fluid be considered for a calf?
2. How are IV fluids given to the calf?
3. Why would you give IV fluids to a calf?
4. What will the IV fluids contain?
5. How much fluid will you give?

Answer 20

1. When a calf is severely dehydrated and cannot suck.
2. Intravenously into the jugular vein.
3. The calf is too severe to respond to oral fluid therapy.
   Too dangerous to attempt fluid therapy.
4. K+, HCO3-, Ca2+ (Hartmann’s).
5. As much as can be given until you can get the calf to take oral fluids.

Question 21

Procedure of administering IV fluids?

Answer 21

Position calf over bale with head down to distend jugular.
Small cut over vein first w/ 11 blade, 14G 3” catheter pointing down w/ angiocath and 3-way tap (anchor), glue or sew catheter and giving set, bales of straw to support and restrict movement of the calf.
DON’T FORGET CLEANLINESS!
Hartmann’s is a poor alkaliniser - need bicarbonate to correct acidosis, but cannot mix with Hartmann’s (as precipitation will order).
- Use sterile saline and add bicarbonate.

Question 22

Correction of acidosis.

Answer 22

Alert, standing, strong suck reflex:
- No acidosis.
– oral electrolyte solutions.
Tired, almost secure standing:
- Mild acidosis w/ base deficit about 10mmol/l.
– 20-30g sodium bicarbonate.
Tired/listless, wobbly, has t be helped up:
- Moderate acidosis w/ base deficit about 10-20mmol/l.
– 30-40g sodium bicarbonate.
Apathetic to comatose:
- Severe acidosis w/ base deficit over 20mmol/l.
– 40-60g sodium bicarbonate.

Question 23

If calf still recumbent and weak after giving isotonic fluids?

Answer 23

Likely to be severely acidotic so give bicarbonate-rich fluids slowly IV.

Question 24

Usual adequate amount of IV fluid.

Answer 24

Usually 5-10L over 24hrs.
Maintain during hospitalisation.
Use oral route for ENERGY (milk), IV route for additional fluids.

Question 25

Mode of action of oral fluids.

Answer 25

Na+/glucose co-transporter mechanism transports Na+ through mucosa into extracellular fluids.
- water follows passively.
– Na+/glucose co-transporter is at villus tips.
Basic fluids simply correct dehydration.
More advanced contain bicarbonate precursor to correct acidosis.
- then added glucose as a source of energy to address nutritional demands.
– now assists in gut repair by including glutamine which promotes villus repair and regeneration.

Question 26

Choosing oral fluid.

Answer 26

Rehydration ability firstly - depends on Na – optimum is 120-130mmol/l.
Ability to correct acidosis - must be at least 25-30mmol/l bicarbonate, optimum 80-120mmol/l.
Nutritional ability - depends on glucose conc. – Energaid (375mmol/l) fed twice daily can supply 50% of requirements.

Question 27

Oral fluids:
1. when?
2. route?
3. how much?
4. how often?
5. milk feeding?

Answer 27

1. as soon as scour starts.
2. teat and bucket best.
3. 4-8L / day (AND 4L milk).
4. little and often.
5. yes.

Question 28

Feeding the diarrhoeic calf.

Answer 28

Introduce milk as soon as a suck reflex present.
500ml-1L per feed.
High quality powder (or quality whole milk).
Pre-weigh sachets (saves time).
Give 2-4L daily.
+ maintain BC.
+ feeds gut mucosa and microbes to assist repair.
+ ensures intake of Ca, Mg, vits, etc.
+ improve renal function (energy, assists in fluid and electrolyte correction).

Question 29

Further therapy.

Answer 29

Warn farmer that fluid therapy will often prolong D+ so look instead for clinical improvement of the calf.
Good nursing as calves in negative energy balance and often have poor thermoregulation.
Provide heat lamp, good bedding, protection from weather/wind.
Calf coats.
ABX only for E. coli and Salmonella.
- not against viruses, protozoa, normal gut bacteria.
– development of resistance.

Question 30

Main reasons for poor treatment success of the diarrhoeic calf.

Answer 30

Electrolyte given too infrequently.
Electrolyte at wrong dilution.
Removal of milk feeding for too long.
Failure to give electrolyte in favour of a “jab of ABX”.
Failure to give appropriate nursing care.
Delaying tx.
Hopeless case due to lack of colostrum.
Tx missed as “someone else was doing it”.
Presence of concurrent disease.

Question 31

Preventing diarrhoea in the calf.

Answer 31

Adequate colostrum (10% bwt, within 6hrs birth, dry period length important, dam BCS).
Store colostrum from dam and feed diluted (10-20%) w/ milk replacer for first 7-10d.
Immunise dams against rotavirus and coronavirus - e.g. Rotavec Corona (MSD) – 1 IM injection 3-12w prior to calving.
- Bovilis Cryptium emulsion works in same way.
Improve hygiene, depopulate and clean out infected calf accommodation, more bedding, reduce stocking density, individual accommodation if possible.

Question 32

Bovilis Cryptium emulsion for injection for cattle.

Answer 32

Crytosporidium vac.
Active immunity of dam to provide passive immunity to progeny.
Primary = 2 doses 4-5w apart in 3rd trimester completed at least 3w before calving, preferably at different sides of the animal.
Revaccination = 1 dose in 3rd trimester of each next pregnancy completed at least 3w before calving.
2ml SC on neck.

Question 33

Lactovac - Zoetis.

Answer 33

Rotavirus, Coronavirus and K99/F41 E. coli.
SC, 2 doses 4-5w apart completed 2-3w before calving.

Question 34

Provita Protect.

Answer 34

Contains Lactobacillus acidophilus and Enterococcus faecium.
Competitive exclusion in digestive tract.
Antimicrobial effects.
Lactic acid production.
Immune stimulation.

Question 35

Halocur.

Answer 35

0.5mg/ml halofuginone lactate.
Prevention of D+ caused by Cryptosporidium parvum in calves.
Oral after feeding.
Once daily for 7d from 24-48hrs after birth or within 24hrs of onset of D+ (acute dose calculation essential as 2x dose leads to toxicity).
Reduces oocyte excretion therefore reduces environmental contamination - helps management.