Laying problems

Year in, year out, we are consulted during the breeding period because hens (of course) are laying irregularly or not at all. The latter refers to hens that lay very late, for example more than 2.5 weeks after pairing or produce abnormal eggs such as one or two soft-shelled eggs, sometimes eggs with weak, too thin shells and often shells with calcium lumps.

Fallopian tube inflammation

Nearly all these problems indicate fallopian tube inflammation (pigeons do not have a uterus, but a fallopian tube). It is often assumed that there is a lack of calcium, but I disagree with that, as so often! A simple treatment with the right antibiotic or a combination of a few antibiotics gives, in more than 80% of the cases, normal eggs without extra calcium being added.
The fallopian tube is in open connection with the outside world through the cloaca, but the cloaca is also connected with the intestine because it flows into it. The fallopian tube leads into the left side of the cloaca and then 2 more channels end up in it, namely the ureteral outlets.
The dorsal wall (top wall) of the cloaca also contains the so-called bursa of Fabricius. This is the lymphoid organ that plays a role in building up the immunity of the pigeon. With age, the organ goes into regression, slightly similar to the thymus in mammals. In calves this organ is also called the ‘thymus’.

Circoviruses

You can imagine that the cloaca is normally teeming with bacteria. Usually these are benign bacteria, but there are also malignant ones! And if ‘enough’ of the latter are present, it can be a reason for inflammations in the cloacal region.
It is commonly known that circoviruses can infect the Fabricius’ bursa. Consequently, it may not work as well as it should and therefore a less good general resistance is built up. About 8 years ago, quite a few colleagues became very nervous about this circovirus. It could have been the cause of all kinds of calamities, such as the death of squabs and the ‘adeno-coli’ outbreaks. I didn’t really believe it, after all I had 40 years of experience with pigeons in my clinic and had seen no new diseases appear in all those years except Paramyxo  (1983).
The scientists found that in a large percentage of young pigeons circoviruses were detectable in the bursa and that in many cases there were no medical problems or none were arising.
Of course, it is possible that the suppression of general resistance (immunosuppression) may cause some simpler juvenile diseases such as coli, but circoviruses are not the primary cause. Sometimes ‘breakthroughs’ by PMV vaccinations are also attributed to circoviruses. I rather believe it is due to vaccinations made during the incubation period, up to 6 weeks in the case of PMV, or by using ‘wrong’ vaccinations.  That means expired, not well stored, or not well injected etc.