Did disease constrain the spread of domestic dogs (Canis familiaris) into Sub-Saharan Africa?

Dogs are not native to the African continent and appear to have been introduced there from the Middle East. While they spread relatively swiftly across North Africa — perhaps in association with a pastoralist economy — their expansion south of the Sahara appears to have been much slower and more staggered. Although their rarity in many Sub-Saharan faunal assemblages has sometimes been explained on taphonomic grounds, this paper argues that when they entered Sub-Saharan Africa dogs must have encountered a series of endemic diseases for which native mammalian species (including wild canids) acted as reservoirs. Having reviewed the archaeological evidence for their presence in Africa, it then discusses the challenges posed to dogs by five such diseases: canine tryopanosomiasis, canine babesiosis, African horse sickness, canine monocytic ehrlichiosis and visceral leishmaniasis. The paper concludes by considering possible ways in which the disease constraint model advanced here might be evaluated further and asks whether dogs may themselves have posed health risks to people or livestock and whether disease may also have constrained their expansion into other tropical parts of the world.