The Basenji Club of America African Stock Project

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The Basenji Annual Estrus:
African Origins

by James E. Johannes

Introduction
  The Basenji is the only breed, out of 150 currently recognized by the AKC, to have an annual estrus cycle. Unlike the other breeds that have two estruses anytime during the year, the Basenji’s annual estrus is seasonal. For the most part, estrus occurs within the months of September and October for Basenjis living in the Northern Hemisphere. Breeders have also noticed a second estrus sometimes occurs around March or April. In England many Basenjis have a second estrus (Burns, 1952). This has created some concern that the Basenji is losing its annual cycle since leaving Africa. The tendency for a second annual cycle has existed in Africa and in the Bitches imported from Africa.

The estrus cycle in Africa

  Using birth dates of Basenjis imported from Africa (Coe, 2001), two figures were created showing the estrus of the Imports' Dams in Africa. Figure 1A shows the occurrence of estrus for Basenjis north of the equator, and figure 1B for those south of the equator. The estrus cycle for Basenjis south of the equator is opposite of those north of the equator. As noted by Ford (1997) an American Basenji imported into Rhodesia switched it’s annual estrus to the spring. The reason why this occurs will be described in a future article. To find the estrus start date for the Imports' Dams two methods were used. If only the month and date of the Imports birth was known, then the date of estrus was determined by counting back two months. For those Imports with a complete birth date, date of estrus was determined by counting back 70 days using the same method employed by Scott and Fuller (1965). Only those Imports where the area discovered in Africa was known were included. Two African Imports were also included who had litters in Africa, one north and the other south of the equator. The date for the start of estrus for these two African Imports was calculated from their litters birth date.


Number of bitches

FIGURE 1A. Occurrence of  estrus for African Imports' Dams and one Import having litters north of the equator in the DR Congo, S. Sudan, Nigeria, Benin or Liberia from 1937 to 1996.
6                        
5                        
4                        
3                        
2                        
1                        
Month estrus occurred => JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

 

Number of bitches

FIGURE 1B. Occurrence of estrus for African Imports' Dams and one Import having litters south of the equator in the DR Congo from 1935 to 1937.
2                        
1                        
Month estrus occurred => JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

African rainy season indicated by months in bold (Dry season can vary from 4 to 2 months depending on latitude).

 

   The number of estrus recorded (30) is probably not high enough to be statistically significant, but a trend does appear. In figure 1A the majority of estruses occur around November resulting in most litters being born during the dry season. What is most interesting is that a second estrus peak shows up in March through May. Most of these litters would be born in the middle of the rainy season. For the bitches south of the equator, figure 1B shows estruses occurs from January to May. Their litters were born during the end of the rainy season and start of the dry season.

Imported African Bitches
  To see if the pattern in Africa would continue with the Imported African Bitches having litters out of Africa the same methods in compiling figures 1A and 1B were used to create figure 2. All litters were born north of the equator. There were 19 bitches having a total of 41 litters.

 

Number of occurrences

FIGURE 2. Occurrence of estrus for Imported African Bitches having litters in the U.K., U.S., Germany, or Italy from 1937 to 1999.
17                        
16                        
15                        
14                        
13                        
12                        
11                        
10                        
9                        
8                        
7                        
6                        
5                        
4                        
3                        
2                        
1                        
Month estrus occurred => JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

  The bitches imported out of Africa show a similar pattern as figure 1A. Two peaks appear during the same time of the year. The majority occurred between August and November with a smaller number between March and May. One of the original imports was recorded having a litter about 5 months apart. Amatangazig of the Congo had borne a litter on January 1, 1942 and on June 10, 1942.

Conclusion
  While the Basenji for the most part has a seasonal annual cycle there is a tendency for some Basenjis to have a second estrus. This pattern originated in Africa and continued in the first generation out of Africa.

Bibliography
Burns, M. 1952. The Genetics of the Dog. Farnham Royal, England: Commonwealth Agricultural
Bureaux. viii + 122 pp.

Coe, S. (ed.). 2001. The African Stock Project. Newtown, PA: Basenji Club of America. [various
paginations]

Dean, R. 2002. [Basenjis_African]West Africans – history. Email to Basenjis_Africans Yahoo
group
March 13, 2002.

Ford, E. 1997. The Complete Basenji. N.Y.: Macmillan Pub. Co. 160 pp.

Scott, J. P. & J. L. Fuller. 1965. Genetics and the Social Behavior of the Dog. Chicago:
University of Chicago Press. xviii + 468 pp.

Scott, J. P., J. L. Fuller & J. A. King. 1959. Inheritance of annual breeding cycyes [sic: cycles] in
hybrid Basenji-Cocker Spaniel Dogs. The Journal of Heredity, 50:255-261.


 Revised from
The Basenji
Volume XXVIII Number 10 October 2002 p. 10
Copyright © 2002 Bar Harbor Media, All Rights Reserved
Used with permission.