All animals carry genetic defects, and all genetic departures from health are not equal. Genetic faults that can be corrected with minor surgery, controlled by good management or medication, or simply do not interfere with a dog's quality of life can be tolerated in a breeding program if breeders make an attempt to weed out serious genetic diseases and are honest with buyers about these faults. The American Kennel Club Canine Health Foundation awards grants to scientists studying genetic diseases and to mapping of the canine genome so that these diseases can be more quickly identified and eliminated from breeding programs. AKC has donated millions to the foundation, and AKC clubs and breeders give heavily tot he effort. Potential puppy buyers can do their part by carefully researching puppy sources and by spaying or neutering any puppy that has a serious genetic abnormality.
Parasites are critters that use a host animal for part of their life cycle.
Some internal parasites are transported to dogs by external parasites. Fleas are intermediate hosts for tapeworms, ticks can carry protozoal disease, and mosquitoes carry heartworm larvae that are injected in the dog when the insect takes a blood meal. Flea bites can also trigger allergic reactions in susceptible dogs, reactions that lead to severe itchiness, hair loss, and infections when bacteria invade skin scratched and bitten raw. Protozoa are microscopic, single-cell parasites that live in water, soil, and the feces of infected animals and invade canine digestive systems and blood streams. Protozoal diseases affecting dogs include coccidiosis, giardia, leishmaniasis, and babesiosis.