Rickets in Rheas
The Avian Disease Section has received phone calls about
an increased incidence of rickets (soft bones) in young rheas.
The growing ration for these birds, which is often a commercial
product, has been criticized. It is important to fully document
a case of rickets before attributing blame to the feed. Enteritis
and/or diarrhea, which are commonly observed in young rheas
that are submitted to the ADDL, can be a major contributor
to rickets by causing malabsorbtion of calcium, phosphorus,
and vitamin D3. Therefore, infectious disease must be ruled
out and the bone condition must be characterized before a
nutrition-related rickets can be diagnosed. In other words,
rickets may not be the only problem in these birds; dead or
affected birds should be submitted to the ADDL to rule out
nonnutritional factors that can contribute to rickets.
The ADDL has diagnosed two cases of rickets in young rheas,
ages 2-6 weeks, in the last month. There was no evidence
of infectious disease in these birds. No predisposing cause,
such as enteritis, could be identified. Histologicevaluation
of the bones from these rachitic birds revealed a bone pattern
that was suggestive of a hypercalcemic/hypo-phosphatemic
state (as has been documented in experiments with chickens).
It is evident that much remains to be learned about the nutritional
requirements of the different ratite species. Perhaps the
differences in the digestive tract anatomy of these species
may indicate different dietary needs.
Comparative Lengths (Percent of total length) of the Intestines
of Various Ratites
| |
Ostrich |
Rhea |
Emu |
| Small intestine |
36% |
61% |
94% |
| Cecum |
7% |
21% |
2% |
| Colon |
57% |
17% |
4% |
Fowler, M.E. Comparative clinical anatomy of ratites.J. Zoo
and Wildlife Medicine. 22:204-227, 1991.
It is evident that further research is required on the management,
disease, and nutrition of rheas. Practitioners should encourage
their clients to submit dead or diseased birds to the ADDL
in order to determine what variety of factors could be contributing
to mortality or production problems.
Rob Porter, DVM,PhD
Chief of Avian-ADDL
|
