Refining the APGAR Score Cutoff Values and Viability Classes According to Breed Body Size in Newborn Dogs

SIMPLE SUMMARY: The Apgar score, based on the easy and quick evaluation of some neonatal parameters, represents a key tool in the routine assessment of newborns in many species, dog included. Recently, a reevaluation of the Apgar score used in canine species has become necessary to verify possible adjustment and redefinition of cutoff and newborn viability classes, also according to the breed. With this aim, data from 234 dog litters born by caesarean section were retrospectively evaluated and grouped according to breed body size. According to results, new cutoff values and viability classes were refined and a narrower class of moderately distressed puppy was defined, especially for small-sized breeds; moreover, the small-sized puppies were the most represented in the severely distressed class, but had the best chance of survival in comparison to large-sized newborns. In conclusion, the refining of the Apgar score in dog species is imperative, and one must consider the differences related to breed body-size characteristics, with cutoff values and viability classifications adapted to the specific breed body size. ABSTRACT: The Apgar score (AS) represents a key tool for neonate assessment, but the possible breed effect on AS in newborn puppies has never been investigated. Therefore, data from 234 dog litters born by caesarean section, grouped according to breed body size (BBS) (small, medium, large), were evaluated. Live-birth puppies were assessed through AS within 5 min of delivery, and classified in viability classes: 0–3 severely distressed, 4–6 moderately distressed, 7–10 not distressed. Statistical analysis evaluated possible differences of AS and viability class according to BBS, and between BBS and puppies’ mortality. Results showed no differences in the distribution of mortalities among BBSs. However, an effect of BBS on the AS was found, with small-sized puppies being the most represented in the severely distressed class, but having the best survival chance compared to large-sized newborns. Through receiver-operating-characteristics analysis, the AS new cutoff values for survival and for death <24 h and 24 h–7 days of age were identified, and the viability classes were redefined, with a narrower class of moderately distressed puppy specific for each BBS. In conclusion, the refining of the AS in dog species is imperative, with cutoff values and viability classifications that must be adapted to the BBS.