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In page Inbreeding:

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Breeders must avoid breeding from individuals that demonstrate either homozygosity or heterozygosity for disease causing alleles.[3] The goal of preventing the transfer of deleterious alleles may be achieved by reproductive isolation, sterilization, or, in the extreme case, culling. Culling is not strictly necessary if genetics are the only issue in hand. Small animals such as cats and dogs may be sterilized, but in the case of large agricultural animals, such as cattle, culling is usually the only economic option.[citation needed]