Page 639 - WSAVA2018
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weight, its body condition (best evaluated by examination of the toes and elbows), its posture and conformation,
its body colour and temperature, its hydration status, whether its crop has food in it, and an evaluation of its droppings.
If possible, a few drops of blood can be collected for a PCV, blood smear, TPP, and blood glucose.
This evaluation, while not exhaustive, can performed rapidly and assessment made as to the chick’s status using the four H’s.
The four H’s
Regardless of the underlying aetiology, the majority of problems with sick chicks can be associated with the “four H’s”:
1. Hypovolaemia
2. Hypoglycaemia
3. Hypothermia
4. Hypoxaemia
Other problems, such as beak abnormalities and angular limb deformities, rarely present as emergent conditions and will not be discussed further in this paper.
Hypovolaemia
Severe dehydration is common in chicks, usually associated with GI dysfunction (vomiting, diarrhoea, and ileus) or decreased intake (poor husbandry, refusal to eat). Respiratory loss due to panting when heat stressed can also lead to dehydration. Dehydration and hypovolaemia lead to decreased tissue perfusion and subsequent organ damage and even failure. As chicks appear to lack the ability to compensate for mild hypovolaemia to increase tissue perfusion (increased heart rate and contractility, and increased vascular tone), they are extremely sensitive to the effects of dehydration.
Clinical signs include:
1. Thickened mucoid saliva
2. Wrinkling of the skin
3. Decreased venous return (assessed by ‘blanching’ the basilic vein)
4. Decreased urine output and thickened urates
5. Crop stasis
If any uncertainty is present, it is usually safe to assume the chick is dehydrated and act accordingly.
peripheral vasoconstriction will slow fluid absorption.
IO catheters can be placed in the tibiotarsus or ulna, while IV catheters can be placed in the jugular, basilic or medial metatarsal veins. An initial fluid bolus of 3% - 4% of the chick’s body weight can be given over 15 minutes, and repeated based on the chick’s response. Ongoing fluid administration at 3mls/kg/hour can then be initiated. Care must be taken to avoid fluid overload (often seen as a dyspnoea associated with non-cardiogenic pulmonary oedema). Once the chick is well hydrated the oral administration of fluids can be expected to maintain a suitable fluid balance.
Hypoglycaemia
Hypoglycaemia often arises due to either poor husbandry (inappropriate diet, infrequent feeding, diluted food, or insufficient volume of food) or severe systemic illness (particularly sepsis or those conditions leading
to GI ileus or other GI dysfunction). When low dietary intake is combined with an immature gluconeogenic response and low body fat, the result can be severe hypoglycaemia. This in turn leads to CNS and cardiac disturbances (weakness, seizures, coma and death).
In the early stages of hypoglycaemia, chicks may be constantly hungry, exhibited as excessive begging behaviour.
Chicks with severe hypoglycaemia should be treated with an IV/IO bolus of dextrose (250-500mg/kg (50% dextrose, 0.5-1ml/kg diluted 1:4) administered over
5 minutes. Repeat boluses can be given, based on response to treatment, and then once normoglycaemic the chick’s IV/IO fluids can be supplemented with 5% dextrose until the chick is eating.
Less severe hypoglycaemia may be effectively dealt with by an early return to feeding (or by feeding a more appropriate diet).
Hypothermia
Hypothermia in chicks arises because of the effect of the following factors:
1. Low reserves of white (insulating) fat
2. Large surface area to body mass ratio
3. Lack of feathers to insulate the body
4. Reduced ability to vasoconstrict or shiver
5. Reduced activity (chicks are usually sleeping or eating)
When these factors are combined with inappropriate environmental temperatures or reduced food intake (decreased metabolic energy), the result can be profound hypothermia.
Hypothermic chicks are lethargic and poorly responsive to stimulus. Their limbs and bodies are cool to the touch.
Treatment requires the administration of warmed isotonic fluids. These can be given IV, IO or SC, but if the SC route is chosen the chick should be normothermic, as
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