Gallinaceæ and Palmipeds. Causes; Overfeeding after privation;
fermentation; lack of water; green food in geese and chickens; food
containing paralyzing element. Symptoms; dull; motionless; erect
plumes; drooping wings and head; gapes; ejects liquid from bill; firm
cervical swelling. Treatment; manipulation; incision; surgical
precautions. Convalescent feeding.
The cervical dilatation of the œsophagus known as the crop is well
developed in all granivorous birds, (Gallinaceæ, etc.;) and like the
macerating cavities of the ox (first two stomachs) is subject to
overdistension and paralysis. In the palmipeds (ducks, geese) there is
no distinct crop but in its place the cervical portion of the gullet has
a fusiform dilatation, and under given conditions this may be also the
seat of impaction.
_Causes._ The impaction may result from overfeeding when the bird has
been starved, or when it suddenly gains access to food of a specially
appetizing kind and to which it has been unaccustomed. The crop like
every other hollow viscus is rendered paretic by overdistension. Then
the food undergoes fermentation still further distending the cavity,
affecting the brain by reflex action, and paralyzing the vagus and its
peripheral branches in the lungs, heart, stomach, liver, intestines,
etc. When the food is dry as in the case of beans, peas, bran, farinas,
it may be a simple firm impaction which the muscular walls of the crop
are unable to break up or move onward. When green food is taken there is
often superadded the additional evil of active fermentation from the
great number and activity of the bacterial ferments contained in it and
the soft aqueous fermentescible nature of the food (See _tympany in
ruminants_). Dupont states that young geese led out to fresh spring
grass may lose two-thirds of their number in a few hours from such
overloading and that some species of _Carex_ and cynodon dactylon are
particularly injurious. Chickens also gorge the crop with clover, etc.
In all such cases, plants that contain a paralyzing principle like
lolium temulentum, ripening lolium perenne, chick vetch, etc., are to be
specially dreaded. (See Trichosoma Contortum).
_Symptoms._ There are first dullness and sluggish movements, followed by
indisposition to move, the bird standing in one place with ruffled
feathers and drooping wings, and at intervals, projecting the head
forward with open beak and in some cases a little liquid is rejected. If
the bird is now caught and examined the crop is found to be firmly
distended, and more or less compressible or indentable according to the
nature of the food impacted. In most cases and especially if the food
has been green or aqueous, there is a certain resiliency from the
presence of gas outside the solid impacted mass.
_Treatment._ This must be in the line of seconding the physiological
efforts of regurgitation which is a normal and common act in birds. The
duck which has gulped a mouse half-way down the cervical part of the
œsophagus will readily disgorge it when he finds it impossible to pass
it further. The carnivorous birds often reject by vomiting the
indigestible debris such as feathers and bones, after all the more
soluble parts have been disposed of in the stomach. The pigeon even
feeds its young by disgorging into their open bills, the semi-digested
food and milk from its crop. Following these indications we must break
up the contents of the crop by manipulation and force them in small
masses upward into the bill and downward to the proventriculus. The
rejection by the bill may be further stimulated by introducing the
finger into the fauces to rouse the reflex active emesis. Usually the
crop can be quickly and satisfactorily emptied in this way.
When this proves impossible there remains the operation of direct
incision through the walls of the crop and the evacuation of its
contents. This can be done by a pocket knife or even a pair of scissors.
The crop is punctured in its lower part and the incision is continued
upward as far as may be necessary to allow the escape of the contents.
Usually half an inch will suffice. Then the crop is squeezed so as to
press the contents through this opening and it is emptied by a process
of enucleation. If the contents are fibrous it may be necessary to
employ forceps to dislodge the material. The empty crop may be washed
out with tepid water, any food attached to the raw edges of the wound
must be removed and the skin stitched accurately together. The wound
rarely fails to heal by first intention. To avoid stretching it, the
food for a day or two should be restricted to milk, gruels, or a little
soft mash.
Lerein notices jaundice as a sequel of impacted crop, and recommends
treatment by sulphate of soda in the water.