Parasite Lessons

When most of us think of parasites we think of creepy, crawly, blood-sucking little horrors of no redeeming value whatsoever. However an increasing number of scientists no longer share that view. Instead of taking a villain-victim approach to parasite-host relationships, they look at what parasites can teach us about animal health and behavior.

Lessons From the Field

Some scientific studies suggest that parasites trigger changes in the host’s immune response that could protect the host from other, more serious problems. In the process of creating changes that make the host’s intestinal tract more hospitable for their own survival, for example, some parasites may make that area less hospitable to certain conditions that could lead to other, more serious problems. Other studies indicate that the health of entire ecosystems might depend on the presence of parasites as much or even more than on some species higher up the food chain. Although individuals belonging to a certain species of fish may not fare too well because of a parasitic infestation, the changes caused by that particular parasite make the fish easy prey for certain bird species who would die without this readily available food supply.

At that same time though, the awareness that parasites can kill lies deeply embedded in many animal species. The willingness to effectively groom another to remove external parasites ranks as a primary method of gaining a friend or even a mate in primate species. Scientists now believe that the brightly colored plumage of male birds and other breeding male adornments and displays communicate the animals’ parasite status. The male peacock’s splendid feathered frock, like the buck’s elegant antler’s, both depend on good health.  When males must share their food with internal parasites or if they lack the necessary grooming skills to keep themselves free of external ones, the resulting scruffy appearance will serve as a turn-off for females seeking the best sire for their offspring.

Parasites also may serve as an efficient method of population and quality control in wild species. When numbers of animals exceed the food supply’s ability to nourish them all, parasites previously kept at bay may flourish at the host’s expense, and only the healthiest animals most skilled at finding and utilizing any available food will survive. Offspring of parents who keep their nests or dens free of parasite-harboring wastes and who groom their young regularly stand a greater chance of surviving than those whose parents don’t supply this quality care.

Within the wild animal kingdom then, we may say that parasite and host are partners in a dance that ultimately leads to the evolution of both species. But does the same hold true for our pets?

Lessons From Suburbia

Domestication leads to several parasite-related problems for our pets. First, the very process of domestication changes the the way animals handle a substance called cortisol, chronic elevation of which may undermine the animal’s immune response. Second, some companion animals lead relatively stressful lives. Although images of predators stalking wild dogs or small wildcats appear far more stressful to us than life in the average human household, our pets may need to cope with far more stimulus input (such as that from traffic, meter readers, loud televisions, kids squabbling, other animals in the neighborhood) over which they may have little or no control. Additionally a certain amount of stability and consistency underlies wild animal life while inconsistency ranks as the hallmark of many pet owners’ lives.

Because of this, it’s fortunate that many excellent options for parasite control now exist, and regular veterinary check-ups to determine the best one(s) should remain high on everyone’s list of pet-owning responsibilities. At the same time though, we don’t want to put so much faith in these products that we forget to address those two other critical aspects of parasite prevention and control: good nutrition and cleanliness.

Offering our pets a good quality diet in a calm environment nourishes both mind and body. Doing so also ensures we won’t miss early signs of parasite problems–such as diarrhea or a scruffy haircoat–because a poor diet or lots of table scraps led to those same results.

As far as cleanliness goes, too much simply can’t be said about it. Regular grooming does more than enable us to check for signs of  external parasites. It stimulates the skin as well as strengthens the bond between owner and animal. The longer wastes remain in yards on in litter boxes, the more time any parasites have to infect the pet again. Daily removal of waste prevents this problem.

And even though taking Danny for a walk so he doesn’t mess in the yard sends many owners to the local park every day, waiting until he eliminates in the yard before going to the park confers several important benefits. Because dogs mark their territories with their urine and stool, a dog who only eliminates in his own yard only has to protect this space. This can take an enormous amount of stress off an animal who previously eliminated in an area that he couldn’t monitor from his owner’s home, and which contained the marks of numerous other, sometimes hostile animals. Home-ground elimination also makes it easier for owners to clean up as well as monitor pet waste for signs of problems.

Once Danny eliminates in his own yard, keeping him moving at a brisk pace provides two more benefits. Not only does he get more exercise, he doesn’t have time to sniff and mark the areas where others have marked. Although many owners see such sniffing as fun for the dog, in areas with lots of animals, such sniffing (and the nose-licking that follows it) may serve as good way for pets to pick up parasites and disease.

From all this we can see that, although parasites might give us the creeps, they can also help us develop an expanded view of nature and our relationship with our animals. Effective treatments may appear to make concern about parasites a thing of the past. But we should never forget the basic lessons of good husbandry and quality interaction that these creatures teach us.