Puppies and kittens are often the pride and joy of owners or breeders who only want the best for their animals. In certain cases, these animals have a high monetary value to the owner. To general veterinary practitioners, however, critically ill neonates can represent fear of the unfamiliar.
Knowing the common emergencies that occur in neonates and the differences between neonatal and adult physiology can help you manage these delicate patients in a manner that provides the highest possible survival rate. Although important decisions must often be made quickly, an intensive treatment effort will often be rewarded with lifelong loyal clients. In this article, we focus on the specific challenges of treating sick neonatal puppies and kittens, emphasizing the importance of addressing hypoxia, hypothermia, hypoglycemia, and dehydration to stabilize these patients.
FACTORS IN MORTALITY
The pediatric period in puppies and kittens is considered 0 to 12 weeks of age.1
This period is subdivided into three groups: neonates (0 to 2 weeks of age), infants (2 to 6 weeks of age), and juveniles (6 to 12 weeks of age).2 The overall mortality of healthy litters of kittens or puppies from a full-term birth to weaning should be no more than 15%.3
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Neonates face an increased risk of mortality if they are born to dams that are older or overweight, or both,4 if they are born to queens that are more than 3 years old,4 or if they are underweight at birth or fail to steadily gain weight thereafter.3 Low birth weight and rate of weight gain are the most important predictors of neonatal mortality.
In one study of 477 kittens, 60% of those with low birth weights died before weaning, while 68% of the remaining kittens that had a normal birth weight survived past the weaning period.5 Neonates born prematurely have low birth weights, have not reached their full physiologic maturity, have decreased lung surfactant, and are not ready to face environmental challenges.5 Also, puppies and kittens with lower birth weights, even if born full-term, can rapidly become hypothermic because of a higher body surface area to body mass ratio and, if too weak to nurse, may not be able to maintain proper blood glucose concentrations.6,7
A normal birth weight for a medium-sized dog (about 30 to 60 lb adult weight) is 500 ± 150 g (varies greatly among breeds and individuals) and for a kitten is 100 ± 10 g.8 Neonates may lose about 10% their body weight within the first 24 hours after birth because of water evaporation from the body, but they should gain weight steadily thereafter. Puppies and kittens should gain roughly 10% of their body weight per day during the neonatal period.8 Monitoring weight at least twice a day will detect neonates that are failing to gain weight.
Other factors that can contribute to neonatal mortality include genetics (e.g. feline neonatal isoerythrolysis), environmental factors (dystocia, maternal neglect, neonatal management), and viral diseases (e.g. canine herpesvirus and parvovirus infections; canine distemper; infectious canine hepatitis; feline herpesvirus, feline leukemia virus, and feline calicivirus infections; feline panleukopenia).