by Charles Simmins

Created on: February 02, 2009   Last Updated: May 27, 2009

Animals can catch the flu. Influenza can be found in birds, pigs, and many other animals. More of the influenza virus variants infect animals than they do people.

When it comes to flu, birds catch it much more than any other animal. The "bird flu", designated A)H5N1, is the influenza strain that has captured the media's attention for the last several years. While about 300 cases in humans have been seen, there have been thousands of cases in birds. Millions of birds, domesticated poultry, have been culled because of the disease.

Influenza viruses are broadly broken down into three classes, A, B and C. A and B class viruses can cause illness in humans. A class viruses are those that kill birds.

There are sub-types for each class, named for genetic markers in the virus. In the A sequence, the markers are named H and N. There are 16 H sub-types and 9 N sub-types, creating many possible combinations in the form A)H?N?. All of these combinations infect birds.

Most of these infections are minor. The sub-types H5, H7 and H9 are not and these infections are very serious, usually fatal. These are also the sub-types that may infect humans.

Wild fowl can carry the virus and not be infected while domesticated poultry seem to be less resistant and do become ill. Water birds seem to be the predominate carrier. Their normal migration each year brings them into contact with domestic birds over a wide geographic area.

Influenza is also seen in other animals. Pigs are one species that is susceptible. It is believed that many of the human influenza viruses begin in pigs because of their immune system's similarity to humans. Horses can catch the flu, as can whales and seals.

In a unique case, zoos in Thailand experienced deaths from A)H5N1 among their big cats, tigers and snow leopards. It is believed that these animals were fed sick birds. The Germans report one case of a domestic cat, probably feral, who also died of A)H5N1.

The feces of wild fowl seem to be a potent source of influenza viruses and the source of infection for many animals. Despite the occasional appearances in other species, influenza seems to be primarily a disease infecting birds, and pigs. The losses in the domestic poultry industry due to these infections, and the mass cullings that are required are enormous.

Your dog or cat should be safe from the flu if you do not let them near poultry, or wild fowl. Keep them away from dead or sick birds and do not let them eat raw meat. If you have to be around wild fowl or poultry, practice safe handling and disposal techniques including wearing a mask, gloves and washing after exposure. Don't forget your boots, since feces can be tracked into a building easily.

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