Ammonia intoxication in rabbits
Esther van
Praag, Ph.D.
|
Ammonia
(NH3) is a heavy gas, whose presence in greater concentration is
toxic. It is formed by bacteria that degrade litter, urine, excrements, and
takes place in warm conditions. It is thus more likely to observe NH3
intoxication during the summer months, rather than in the winter. NH3
is rapidly absorbed by the mucosal cells lining the respiratory tract of the
rabbit, where it will be transformed into an alkaline molecule with
aggressive properties. This leads to the destruction of the mucociliary
epithelial cells lining the respiratory tract, whose role is to protect the
respiratory tract against bacterial aggressions.
Although
NH3 is a toxic molecule, intoxication is often ignored in the differential
diagnosis of respiratory diseases. The problem is seen more often in
commercial rabbitries, seldom in private homes where a rabbit is kept in good
hygienic conditions. The
prevention of NH3 intoxication is done by regular cleaning of the
litter boxes, and a good aeration. Clinical signs
The disease is characterized by different stages, depending on
the length of exposure and the concentration of ammonia in the air. In the very beginning, typical problems related to upper
respiratory disease are observed: nasal and ocular discharge, swollen eyelids
and irritation of the corneal surface of the eye, sneezing and snoring,
rarely fever. If the problem is not treated, pharyngeal and tracheal
inflammation is observed, followed by lower respiratory tract disease. At
this stage, secondary bacterial infection is possible, due to the destruction
of the mucociliary barrier and depression of the immune system. At this
stage, the disease develops in an acute form, with difficult respiration and
sometimes coughing. The rabbit is often anorexic, depressed, shows signs of dyspnea
(abnormal or difficult breathing) and cyanosis (blue discoloration of tongue,
lips, gums, due to shortage of oxygen), fever or hypothermia. The disease is difficult to treat and often becomes chronic, even
when the rabbits are transferred to a clean well-aerated environment. For
information of the treatment of bacteria induced respiratory diseases, see: Upper
respiratory tract disease in rabbits. Acknowledgement
Thanks
are due to Katleen Hermans, DVM, (Kliniek voor Pluimvee en Bijzondere Dieren,
Universiteit Gent, Belgium) for the permission to use her pictures. Further
Information
1.
Boucher S,
Nouaille L. Maladies des Lapins. Manual pratique. Editions France Agricole.
2002. pp 182-183 2. Kruckenberg SM,
Cook JE, Feldman BF. Clinical toxicities of pet and caged
rodents and rabbits. Vet Clin North Am. 1975;5(4):675-84. 3. Makarenko ON,
Skorik LV, Mel'nichuk DA. The characteristics
of nitrogen metabolism in the tissues of rabbits with ammonium toxicosis. Ukr
Biokhim Zh. 1992; 64(6):105-9. 4. |
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