Initially treating fading puppies and kittens
Timely treatment of ill neonates will provide the best chances of survival. Although time-consuming, intensive care of these puppies and kittens, which requires serial monitoring, can be extremely rewarding. Because the exact causes of fading puppy and kitten syndrome are often not apparent at the time of presentation, therapy should focus on supportive care and treating the treatable causes while awaiting further diagnostic information. Initial therapy includes providing supplemental warmth, hydration, supplemental glucose, and nutrition, and sometimes blood transfusion and oxygen supplementation.
Neonates whose temperatures fall to 94 F (34.4 C) or below suffer ileus and marked bradycardia.1 Without correction, hypothermia results in a fatal spiral of events. Warming should take place gradually, over one to four hours.2 Rapid warming may result in peripheral vasodilation and core collapse.3,4Good methods for heating include incubators, warmed circulating air or water pads, and covered warm-water bottles. Electric heating pads are not recommended because of uneven heating and a high risk of thermal burns. Only use heat lamps with appropriate technique and supervision. Neonates must be able to move away from the heat. Neonates easily suffer thermal burns because of their thin skin, and the dehydration often present in ill neonates results in poor circulation that increases the risk of burns. In neonates that have or are suspected of having canine herpesvirus infection, body temperatures should be maintained just above 100 F (37.8 C) regardless of age to interfere with viral replication.5
Once the patient is warmed, the ambient temperature should be 85 to 95 F (29.4 to 35 C), with humidity at 55% to 65%.2 Serial monitoring of body temperature is needed to ensure that the hypothermia does not relapse and that the rectal temperature does not rise above what is normal for the neonate's age.
DEXTROSE, FLUID, AND VITAMIN K THERAPY
Hypoglycemia often accompanies hypothermia. Warmed isotonic dextrose solution can be given through a stomach tube, and then 1 to 2 ml 5% to 10% glucose solution can be administered orally or through a tube once the neonate is warmed.2,4 Once venous or intraosseous access is acquired, 20% dextrose solution can be given at a dose of 0.25 ml/25 g in patients that are severely dehydrated, are in shock, or have neurologic signs.4
Venous access is problematic in neonates because of vein size. Jugular catheterization can be performed, but the intraosseous route is most commonly used. Clip and prepare the area over the trochanteric fossa of the femur, and place a 20- to 22-ga spinal needle in a sterile manner. Keep the area covered, and handle it only with sterile gloved hands. Up to 11 ml/min of fluid can be administered by gravity flow with this technique, but unattended gravity flow is contraindicated in neonates.2 Fluid therapy should be provided by pump or slow bolus. If the neonate is in shock, 1 ml/30 g can be given over five to 10 minutes. Maintenance is 60 to 200 ml/kg/day.6,7
Subcutaneous fluid absorption is slow and should be used only for maintenance in stable neonates.6 Fluid injected intraperitoneally can take 24 to 48 hours to absorb, so it is not useful in neonates.8 When choosing a crystalloid fluid, take into account the neonate's immature metabolic processes and avoid lactate-containing fluids. If colloid therapy is needed, hetastarch or dextran 70 can be given at a dose not to exceed 20 ml/kg/day.4 Warm all fluids given to neonates.
In neonates 48 hours of age or younger, vitamin K should be given at a dose of 0.5 to 2.5 mg/kg subcutaneously because thrombin activity is decreased at birth.4
Once the neonate is warmed and has been given dextrose, if needed, feeding is the next requirement. Hypothermic neonates should not be fed because they cannot digest or absorb their food, and formula sitting in the stomach increases the risk of aspiration pneumonia.