Page 448 - Hand rearing birds second

442 Hand-Rearing Birds

Trichomonas
Trichomonas is a flagellated protozoan parasite transmitted through mouth‐to‐mouth contact
between parents or when adults feed chicks and is a serious threat to many dove and pigeon spe-
cies (Girard et al. 2014). Shared water sources are common points of infection, as is wet, contami-
nated seed in bird feeders. Fortunately, this organism is not environmentally stable, does not have
a cystic stage, and is effectively killed by drying or exposure to many disinfecting agents. Oral
lesions consisting of cheesy, foul‐smelling masses cause gagging, neck stretching, difficulty swal-
lowing or breathing, and regurgitation. When the lesions begin to block the esophagus, the bird is
unable to eat and a slimy discharge is produced from the beak. Birds with severe cases may present
emaciated with obvious masses in the throat and seed spilling out (Figure 27.1). Mild cases may
not be readily apparent on physical exam. Definitive diagnosis is made by identifying the flagellate
on a wet smear taken from the mouth or crop. However, many experienced caregivers can often
make a presumptive diagnosis based on the overall presentation of the case. Treatment with carni-
dazole dosed at 25 mg/kg orally once (Hawkins et al. 2018) is generally effective in cases before
caseous plaques have formed. For more severe cases, carnidazole given once daily for 3–5 days is
recommended. Metronidazole has been used by some rehabilitators, but the author (GP) has found
this to have very poor efficacy for this parasite. In situations where “azole” antibiotics cannot be
used, some treatment success may occur with daily crop washes using dilute chlorhexidine. Be
aware that federal and state regulations can limit the administration of certain drugs in birds that
might enter the human food chain.
If the esophagus is blocked such that a feeding tube cannot be inserted into the crop, if the bird
is neurologically abnormal, if skeletal structures have been eroded by the infection, or if the crop
has ruptured, euthanasia is indicated. Special care must be taken to disinfect dishes and feeding
implements because trichomoniasis is highly contagious among many avian species and can
quickly kill some passerines. It is prudent to house passerines away from columbids for this reason.
All columbids can be given one dose of carnidazole on arrival at a shelter to avoid the rapid spread
of this parasite through the patient population. In some high‐volume shelters, it has proven
necessary to re‐dose susceptible species weekly.

Figure 27.1 Severe trichomonas plaques blocking a pigeon’s throat.