Dr. Colin Walker
What is it?
Coccidia are a group of parasitic organisms that have the amazing ability to reproduce themselves both sexually and asexually in various organs throughout the body. There are lots of different types. Some reproduce in the kidney, others in the liver, some are carried throughout the body in red blood cells, but the common one that infects racing pigeons affects the bowel.
Basically what happens is that the organism releases eggs that come out in the droppings. These have to sit in the environment for at least a couple of days to become infective. They do however become infective quicker in damp conditions. Once infective, if a pigeon accidentally swallows one of these eggs, they move down into the bowel and hatch. In the common type of coccidia in pigeons four “larvae” come out of each egg. These then burrow into the bowel wall where initially they reproduce asexually –essentially they just keep dividing so that two become four become eight etc. After a while these “larvae” differentiate into males and females. These then reproduce sexually resulting in the formation of eggs. These eggs then rupture back into the bowel before passing out of the body in the droppings. In this way the lifecycle is completed.
What is the significance of coccidiosis?
When the parasites are reproducing in the wall of the bowel they damage it. This means that the bowel cannot digest food and absorb nutrients properly. Affected youngsters usually lose a bit of weight and start to become a bit quiet. Often in race birds all that is seen is a loss of form. Powder down feather drop stops and some birds will develop a ‘pica’- pecking at perches or eating droppings apparently to source the nutrients they are missing.
Of equal importance for race birds is that the inflamed bowel wall actually weeps inflammatory fluid into the bowel so that the pigeon looses tissue protein and blood from its system. When we draw blood for testing from birds with coccidiosis we find that both the red blood cell count and the level of total protein in the blood are low. Having low total protein causes absolute fatigue even after moderate exercise while, of course, red blood cells carry oxygen throughout the body. Pigeons with coccidiosis therefore become breathless and tired after moderate exercise. Even low infections have drastic effects on performance and returns particularly on low velocity or distance flys.
What to do?
As with wet canker, pigeons need exposure to coccidia when young to form a natural immunity. Repeatedly treating young growing healthy pigeons makes no sense. Certainly this will mean that they have no coccidia but at one stage treatment will have to stop. As they would not have had any exposure, their immunity would be low and they would in fact be quite vulnerable to the disease as adult birds. Regularly treating in this way simply interrupts the ongoing exposure they need to form a strong natural immunity. Keeping the loft clean and dry will limit exposure and in most cases make treatment not necessary
If coccidiosis levels rise in young birds it usually makes some of them a bit quiet and fluffed and some will develop a green or watery dropping. If some of your young birds show these symptoms don’t assume it is coccidiosis. Get a vet with avian experience to check some dropping under the microscope. If it is diagnosed and the level has risen to the point where it is compromising their development then the birds should be treated. In young birds treatment is only given if the parasite is causing clinical disease and compromising the bird’s development. In race birds the situation is entirely different. Fanciers should have their birds droppings checked several weeks before the first race and if any coccidia are present the birds should be treated. It is good to let the growing young pigeon form as strong a natural immunity as possible but then get the birds droppings checked before racing to make sure no infection is present. If coccidia are present the team should then be treated to make sure the season is started with healthy birds.
In summary allow a controlled exposure to the disease in young birds through maintaining a clean dry loft and avoiding treatment unless the parasite is actually making the birds sick. In most cases, you will find when the birds are checked prior to the first race that they are clear of the disease, having formed a strong natural immunity. This however should not be assumed and checking is essential. Any residual infection should be treated prior to racing so that the birds can give their best.