Abstract
Apair of East African Superb Starlings Spreo superbus, in apparently good condition, was obtained during mild weather at the beginning of November 1994 and put straight outside. Two weeks later, night temperatures fell off sharply and the Sprees were seen to sneeze occasionally. The birds were brought inside, where the cock rapidly got worse. Dry sneezing, in the absence of mucous and other respiratory or ocular implications, is the classic symptom of lung mites. This may proceed to include a loud whistling, wheeze or a dry cough.
The connection between the onset of cold weather and the appearance or recurrence of symptoms was obvious. This also happened previously with a symptomless Gouldian Finch which was kept outside in an unheated greenhouse, built against the house window. A few cold nights and the bird's respiratory whistling could be heard indoors. This finch successfully responded to dichlorvos.1
The Spreo pair was put under an 18.6% dichlorvos pest strip for two periods of a week, with a week in between. This made no difference whatsoever. A tracheal swab from the cock confirmed that he did indeed have mites (which were not speciated). The hen continued to sneeze only very occasionally.
Some ivermectin was obtained but no specific information was available for its use in the treatment of birds - only the dose for cattle was given in the package insert, amounting to 0.2 mg/kg. In this study, all doses are given in the customary mg/kg and refer to the actual amount of ivermectin, not the liquid, which is 1 % strength. The odd numbers are a result of even amounts of liquid being administered. Note that some articles mention ivermectin in micrograms and this may be misread, with resultant
confusion.
The male Spreo, weighing 70g, was given various doses, trom 0.14 up to l.U/ mg/kg, with no effect. Then six doses of 1.8 mg/kg were administered over 33 days, also with no effect.
All the above doses were given in mealworms, because handling the birds brought on increased and quite severe respiratory distress. The innards of mealworms are under high pressure and injecting them successfully takes a little practice. Inject the larva slowly over several seconds, then withdraw the needle very slowly, waiting to make sure none of the dose comes hack out. Alternatively, the tail can he nicked off the mealworm. This depressurizes it hut it also shrinks, leaving less room for a dose.
It is easier to dose the birds directly and if using this route, he careful to get well past the epiglottis. Also avoid touching the tongue for, like a lot of medicines, ivermectin tastes foul! For this reason, birds will not eat mealworms that have leaked and may remain suspicious of them for half a day or more.
Things were at the serious stage with the Spreos. for now the cock was sneezing between two and five times in succession, about every three minutes. The hen was still not so had. hut had increased her rate from the original.
Belatedly. some House Sparrows and European Starlings were caught for dosing experiments - something that should have been done in the first place. All of these were dosed directly down the throat, using a 1 cc syringe.
The two starlings were given 21.5 mg/kg each. This did not slow them down in the least and they took off at high speed two days later.
The sparrows (all males), weighing between 26 and 28g, were given doses ranging from 13.17 - 76.92 mg/kg. This latter figure is 384.6 times the recom-
mended dose for cattle! A hen sparrow was left untreated to monitor the feeding, etc.
The bird on the lowest dose was visibly unaffected, hut scarcely ate. Twentyfour hours later, it was given a further 15.25 mg/kg. In three hours, it looked very ill. It sat fluffed up, either on the perch or on the floor, usually with its eyes shut and shivering occasionally. Ivermectin does not clear the system within a day, the half-life being 22-28 hours in humans (though no doubt less in birds) so the symptoms were due to the accumulation of about 20-22 mg/kg. This sparrow hardly ate at all during the two days of dosing but on the third day it recovered completely - flying against the bars and eating well. Along with the hen, this bird was kept for a month then released, still in good condition.
The other sparrows, on single doses of from 38.5 - 76.92 mg/kg, all showed the above symptoms, except that one did not fluff up. None appeared to be any better or worse than the others, in spite of the dose range. Like the first bird, they were all fine one day after treatment and took off rapidly when released in three days.
The Spreos and some other birds (which arrived from China oia California and were all sneezing) were now treated with more confidence.
After the earlier months of futile treatment with increasing doses, the male Spree's symptoms now disappeared the day following a single administration of 5 mg/kg. The hen, which had become much worse by this time, did not respond to this dose and needed 7.2 mg/kg, after which she became symptomless overnight. It was by now the end of March, and the pair went on to have three nests of chicks in the summer. At the end of the year, they were still symptom-free.
Of the rest, a 17g Siberian Blue Robin Erithacus cyane with a slight infection, judging from the sporadic and light sneezing, was eventually (in March) given 14.7 mg/kg. Like the cock Spree, it had not responded to many lesser doses given over a four month period. Although symptoms now abated, it recommenced sneezing lightly and infrequently at a friend's place about three weeks later (exact time not recorded).
A hen Scarlet Minivet Pericrocotus flammeus, with several problems, was neither affected nor cured by 11.7 mg/kg.