Coccidia and Racing Performance

A Small Survey

During the past summer, I received a basic question from the editor of the British Homing World about the amount of actual evidence that exists with regard to the effects of disease and performance in racing pigeons. In that context, he also asked�.�How much research has actually been carried out by the veterinary profession on the health of birds in top performing lofts, in relationship to the actual performance of individual birds? For example, has much testing been done on pigeons just prior to basketing for a race, with these results then being studied alongside the actual performance of the birds?�

This was really a very interesting, incisive question, and one for which, I am embarrassed to say, I had no ready answer. Accordingly over the next few weeks I contacted u\quite a number of my veterinary colleagues and some knowledgeable fanciers her in North America, as well as some in South Africa, Australia, the UK and Europe. The uniform answer to this question was that no one who responded to my inquiry was aware that the kind veterinary study mentioned had ever been carried out or published. It would, therefore, seem that such a study has yet to be done and published, at least by the veterinary profession. In the light of these questions, I also mentioned to my veterinary colleagues and the fanciers I contacted, the example of an oocyst count of 96,000 found in one British fancier�s birds after they had poor results from a 700 mile race. (Oocysts are the egg-like stage of the coccidial life cycle found in droppings. They are what fanciers refer to as �cocci counts.� To me, at the microscopic lever, oocysts very much resemble hard-boiled eggs that have been cu in cross section or lengthwise, depending on the species of Coccidia involved.) The following information was extracted from replies from individuals who responded, and from one published report.

On the question of coccidian in pigeons, one veterinary reference from Britain (Wallis, AS, 1991. Common Conditions Of Domestic Pigeons. In Practice, pps. 96-100) indicated that ��a count that was under 3,000 oocysts per gram (opg) of droppings was considered to be normal, with no expected response to treatment.� A count of 3,000_20,000 opg was considered to be moderate, with treatment often providing a significant improvement in performance. A count of 20,000_50,000 opg was considered to be severe, with improvement in condition and performance as a response to treatment. A count of greater than 50,000 opg was considered to be very severe, with marked improvement in the associated clinical picture following treatment. However, Wallis also made the point that counts greater than 100,000 opg had been seen occasionally, without evidence of any observable abnormality in the birds shedding these large numbers of oocysts.

On the topic of threadworm (Capillaria sp.) problems, this same reference indicated that infestations with this species of worm is always considered to be significant. The following findings and interpretations were presented. Egg counts up to 1,000 eggs per gram (epg) of droppings were considered to be normal with little clinical response to treatment, although eggs were no longer shed in droppings. A count of 1,000_5,000 epg was considered to be severe, with improved condition and performance to be expected following treatment. A count over 5,000 was considered to be very severe, with marked improvement following treatment.

Once again, in this same reference, ��roundworm eggs were classified in the same way as those for the threadworm. Disease from roundworms was much less severe than that caused by threadworms, although heavy infestations often lead to blockage of the intestines and to a chronically enlarged liver which may well have had a fatal outcome, even though the worms were removed successfully.�

Another prominent, very experienced British veterinarian, Frank DW Harper, commented on coccidia as follows:

1.� Is coccidiosis ever a primary disease in pigeons?

2. A high oocyst count (25,000+?) may well be evidence of heavy infection and, therefore, a cause of stress, but my perspective is that it is more likely to be a result of stress (concurrent disease, environment, ect. Look how the counts vary from section to section (�of the loft). It is easy to identify from a group of samples those birds housed in the northeast corner (�of the loft). Specific treatment gives a transient improvement at best, but the underlying cause needs to be addressed.

3. Given my perspective, I seldom �Treat for cocci,� but use the count to monitor the birds. A change in the count is of far greater significance than the actual figure.

4. Although sampling and counting of (oocysts in) individual birds is tedious, it can be of value in predicting performance. Samples from a given bird will vary through the day, but the overnight sample from a resting bird is of greatest value.

5. The �standing count�_ the average or �normal� in successful lofts�is usually below 20,000 without treatment. That varies greatly between the individual birds, but regardless of the actual figure, a rising count usually predicts a fall off in performance (and vice versa). This applies to the team, but particularly to individuals. Other things being equal, the bird with a count of X thousand, but falling, will beat a loft mate with the same count but rising.

6. Using these principles, I have bee able to predict the first three home from nine or ten bird widowhood teams, and have been able to suggest to clients which birds to pool for the following race, with considerable success�. I have never published my data.

& ) A count of 96,000 after a bad time at 700 miles? I would regard this as a result, not a cause.

A reply from Dr. GA van Oortmersson, a biologist/racing fancier from Holland reads as follows: ��I was asked to answer your question about pigeon performance and oocyst counts. I have been asking around whether someone knew anything in this area. The result, however, is negative.

�The only incidental data which I can recall myself stems from about 20 years ago. Then, in my local club we checked youngsters for oocysts, just to inform and entertain club members. We, however, did not make real counts. The pigeons of our champion at the moment (Mister B) contained many, many more oocysts than the pigeons of the rest of the club members. So Mister B nervously asked what he should do about it. We advised him to do nothing as his birds performed so well! Next race, his results went down, and he admitted he had given his birds some medicine. This experience is not worth much, but anyway it tells that the presence of so many oocysts des not inevitably lead to bad results.�

A reply from Dr. Ludger Kamphausen of Germany reads, in part, ��when we have pigeons in our clinic, we investigate their droppings daily. Sometimes it happens that we can�t find anything in these droppings for several days, and suddenly one pigeon starts excreting coccidia.� It seems that the weekend is a kind of stress for the pigeon because the rhythm of feeding and cleaning has changed. This stress seems to start the excreting of cocicdia. Do you have similar findings?�

The latter two experiences seem to tie in nicely with the findings reported by Frank Harper of Britain, i.e., that stress can induce increased in �cocci counts,� and, indeed, that these increased counts are the result of stress, rather than the cause of the problem. Note again the supportive findings of Wallis, who indicated that occasionally, counts of over 100,0000 opg are seen, with no indication of a health problem in these birds. At this point it should be noted that some veterinary practitioners don� conduct actual counts, but instead, rely on their years of experience to make practical judgments of low, moderate or high numbers of the oocysts seen on microscopic examinations of droppings.

So, stressful events like basketing, handling, mixing with strange birds in a strange environment, shipping, lack of water, liberation, and the physical effects of the race itself, ect. may well have an influence on the level of shedding, and result in an increased �cocci count.� These stresses cause a release of corticosteriod hormones from the adrenal� glands. In turn, these hormones suppress the immune system and allow the coccidial life cycle to �gear up� again, with the production and release of greater numbers of oocysts in droppings.

In general, it is known that a few coccidian in the intestines of any species cause very little harm, and are useful in stimulating the immune system to remain alert. The situation resembles a classical standoff, in which, on the one hand, the coccidian are prevented by an active immune system from multiplying and causing disease. On the other hand, the immune system is unable to eliminate them completely, but because of the presence of a few coccidian, the system is kept in a state of readiness. My concern over time hasn�t been the low numbers of coccidian present in the individual bird, but instead, to the potential for an explosive outbreak of coccidiosis in susceptible birds, especially youngster, if loft conditions become favourable. This means conditions such as the presence of persistently wet floor areas from such diverse causes as overflowing drinkers to a leaky roof during days of rain, ect. Under such condition, the oocysts passed in droppings incubate in this cool, damp environment, and develop in a process called sporulation to become infective. Recently passed oocysts are not infective, but must go through the sporulation process before they can infect susceptible birds_ and this usually means weaned youngsters in which there can be explosive outbreaks. I environmental conditions are favourable for the further development of coccidian, shed in droppings.

These common findings and comments from several sources suggest to me that fanciers who do their own microscopic examinations of droppings for oocyst may well respond to the presence of a few oocysts by treating quickly to eliminate any hint of this parasite in their birds.

A few oocysts in droppings really don�t represent a serious threat to the individual bird, and in fact, they are likely completely innocuous. As pointed out by Frank Harper, the most significant feature associated with coccidian in his experience, is not the actual �cocci count,� but rather, is likely related to any change, that is, an increase or decrease in the total count. Thus, it would seem that those who rush to treat when they find a very few oocysts in a sample of droppings are very likely overreacting by a wide margin, and would be better advised to sit tight and re-examine overnight samples from individual birds on a daily basis to determine whether counts are either rising or falling, and based on these results, to plan racing/pooling strategies accordingly.

This small survey of veterinarians and fanciers was very much an eye opener for me, so in reporting these results, I hope that the subject of coccidian and �cocci counts� may now be in better perspective for racing fanciers. It is for me.

Published to "In the Loft" with permission from Dr. Gordon Chalmers DMV.