A questionnaire-based study of gestation, parturition and neonatal mortality in pedigree breeding cats in the UK

Abstract

This study was based on a convenience-sampling questionnaire study of pedigree cat breeding in the UK. Data were collated for the births of 1,056 litters from 14 different pedigree breeds and 942 different households. Significant relationships between various outcomes and relevant predictors were assessed by multiple linear regression or logistic regression as appropriate. The overall mean gestation length of 65.1 days varied significantly between the breeds (P<0.0001), and larger litter sizes were associated with shorter gestation lengths (P=0.04). The mean litter size of 4.6 kittens also varied significantly according to breed (P<0.0001). The weight of kittens born alive (overall mean 93.5 g) increased with longer gestation lengths (P=0.0003), decreased with larger litter sizes (P<0.0001) and varied between the breeds (P<0.0001). A total of 8.0% of pregnancies resulted in a caesarean section, with a higher risk associated with smaller litter sizes (P=0.002). Although the frequency of caesarean sections varied from 0 to 18.5% between individual breeds, breed itself was not shown to have a significant independent effect on this likelihood. A mean of 7.2% of all the kittens were stillborn, which varied according to breed (P=0.0003), and the risk of a stillborn kitten increased with litter size (P=0.0001), and with the presence of congenital defects in the litter (P=0.0002). The mean kitten mortality between birth and 8 weeks of age was 9.1%, and the majority of these occurred in the first week of life. Parturition intervals varied widely. The duration of first stage of labour was less than 2h in 82.9% of cats. The interval between the birth of the first and last kitten was less than 6h in 85.7%, but more than 48 h in three cats. A maximum of 48 h was recorded between the births of individual kittens in unassisted deliveries.

Fig 1

Feline Advisory Bureau cat breeding questionnaire.

Fig 2

Mean gestation length analysed by breed.

Fig 3

Mean litter size analysed by breed.

Fig 4

Mean weight of kittens born alive analysed by breed.

Fig 5

Relationship between length of gestation and litter size, controlling for covariates (Table 2). The graph shows the ‘best fit’ for the data from three representative breeds. The relationship was significant (P=0.04) on average with a decrease of 0.1 days gestation per kitten in the litter.

Fig 6

Relationship between mean weight of the kittens born alive and the litter size, controlling for covariates (Table 2). The graph shows the ‘best fit’ for the data from three representative breeds. The relationship was significant (P<0.0001) on average with a decrease of 2.2 g per kitten for each additional kitten in the litter.

Fig 7

Relationship between the mean weight of kittens born alive and the gestation length, controlling for covariates (Table 2). The graph shows the ‘best fit’ for the data from three representative breeds. The relationship was significant (P=0.0003) on average with an increase in mean weight of 1.4 g per day of gestation.

Fig 8

The relationship between the likelihood of a caesarean section, the litter size and the proportion of kittens born alive, controlling for covariates (Table 2). The graph shows the ‘best fit’ for the data derived from two litter sizes. The relationships were significant (P≤0.0002) with an increased likelihood associated with smaller litter sizes and the presence of dead kittens.

Fig 9

Proportion of gestations that resulted in a caesarean section analysed by breed. (None of the litters of Korat or Maine Coon cats required a caesarean section.)

Fig 10

Cumulative mean proportion of kittens in each litter dying through to 8 weeks of age analysed by breed.