November 3, 2018

The Effect of Inbreeding on Human Aversion in Pointer Dogs

In 1978, C.J. Brown, O.D. Murphree, and J.E.O. Newton endeavored to discover the effects of inbreeding on the social behavior of a nervous strain of pointer dogs. Previously, O.D. Murphree and Murphree et al. discovered that selective breeding had resulted in two distinct types of pointer dogs, a normal (A) strain of pointer dogs and a nervous (E) strain (Brown et al. 362). Researchers used the pedigrees of 294 strain E (Nervous) dogs and compared them to 309 strain A (normal) dogs in order to discover the effects of inbreeding on the E strain of pointer dogs and if inbreeding had increased their human aversion, rate of heart issues, and morbidity scores (Brown et al. 362, 363). Morbidity scores were used to judge the nervousness/behaviors of human aversion and is based on 5 tests: a “nervous score” (a general nervousness checklist), “general exploratory activity” (test to see how curious the dog is), a “noise test” (loud noise is played and dog’s reaction is recorded),  “Person sits in room with dogs for two minutes” (dog's reaction/sociability towards human is tested), and “Reaction to human” (level of aversion in the dog is recorded) (Brown et al. 362, 363). Morbidity scores were taken at months three, six, nine, and twelve, activity, nervousness, and noise responses were recorded at month 6, and two cardiovascular statistics were taken, heart rate and atrioventricular blocks per second, throughout the entire experiment (Brown et al. 362, 363).


Brown, Murphree, and Newman used the yearly litter’s results and compared them using a linear regression test to see if there was statistical evidence that a change in breeding score in the litter or in the dam (mother) resulted in a change in morbidity scores, heart issues, or other related tests in pointer dogs (Brown et al. 364). Results showed that:

There were highly significant effects from inbreeding of litter on morbidity scores at 9 and 12 months. Each increase of 1 percent inbreeding increased morbidity scores at 9 and 12 months 0.11 ± 0.04, and 0.11 ± 0.04, respectively. (Brown et al. 364)

And that:

One percent inbreeding of litter was an increase of 0.12 ± 0.04 [atrioventricular] blocks and the effect of one percent inbreeding of the dam was a decrease of —0.10 ± 0.03 A V blocks. (Brown et al. 364)

All other tests did not prove statistically significant (Brown et al. 364). Of the tests that were statistically significant the relationship between inbreeding and that aspect of human aversion was relatively small. This indicates that there is not a strong relationship between inbreeding and human aversion in pointers. However, the highest predicted inbreeding coefficient for the litter was 57.2 which would result in a nine-and-twelve-month morbidity score increase of 4.0-8.6, a large change in behavior. It is also interesting that although inbreeding in the litter will increase the occurance of AV blocks, inbreeding in the mother will reduce AV blocks. Despite this, these results are not an issue for the average dog (which likely has a lower inbreeding coefficient) but can be helpful for purebred breeders who may need to inbreed their dogs.




C. J. BROWN, O. D. MURPHREE, J. E. O. NEWTON; The effect of inbreeding on human aversion in pointer dogs, Journal of Heredity, Volume 69, Issue 6, 1 November 1978, Pages 362–365,


Reviewed by Ian J. Sessions | 1 November 2018