West Toowoomba Veterinary Surgery (07) 4636 2027
by Bob Doneley
by Bob DoneleyBVSc FANZCVS (Avian Medicine) CMAV
External parasites, known scientifically as 'ectoparasites', can be broadly divided into lice, mites, and the rest! While lice are insects (with six legs), mites are arthropods (eight legs - like spiders). Other parasites occasionally seen on birds include ticks, fleas and hippoboscid flies (pigeon flies).
The most common mite seen on parrots (and occasionally canaries and chickens) is Cnemidocoptes - the Scaly Face/Leg mite. This tiny mite feeds on keratin, the protein that makes up the surface layer of the skin, beak and feet. In order to get this keratin the mite tunnels into these layers, creating minute holes that gives the characteristic 'honeycomb' appearance that gives this infection its name. In canaries and chickens the infection is found most commonly on the feet, causing the scales to thicken and lift slightly. In some canaries, tags of keratin come off the back of the leg, leading to another name for this condition - 'tasslefoot'. Left untreated, Scaly Face mite can cause disruption of the growth areas of the beak, leading to distortion of the beak. Thickening of the scales on the legs can lead to pain and lameness.
Old treatments for this mite include painting the affected areas with paraffin oil (to drown the mites), Dettol®, or benzyl benzoate (Scaly Mite Treatment®). The problems with these treatments are numerous: the mites can be so widespread on the body that paraffin oil can never hope to control it without soaking the bird in oil; Dettol® and benzyl benzoate are both toxic to the bird if it ingests it or absorbs it through the skin; and with all of these treatments repeated daily applications are necessary. Since the 1980's vets have been using ivermectin (Ivomec Sheep Drench®) or moxidectin (Cydectin Sheep Drench®, Scatt®, Moxidectin Plus®) with much greater success and safety. Depending on the formulation used, these drugs can be applied to the skin on the back of the neck; crop drenched; or put in the bird's drinking water. I like to give 3 treatments, each 2 weeks apart, but other vets find that only 1 or 2 treatments are usually necessary.
Lice are quite common on wild birds and in some aviaries, but are rarely seen in pet birds. They feed on skin scales and feather debris - lice are not blood suckers. They live on the bird their whole life, and lay their eggs along the shaft of a feather - these eggs are easily seen with the naked eye, and are known as 'nits'. The lice themselves are also usually easy to see - holding your bird's wing up to a bright light and examining the under side of it may reveal nits and lice. Heavy infestations can make a bird itchy, and give the feathers a 'moth-eaten' look. However, feather lice are vastly over-rated as a cause of feather-picking in birds. Virtually every feather-picking bird that I have seen has been treated for lice by its owners on the recommendations of a bird breeder, pet shop, or inexperienced veterinarian. Not only is this treatment usually unnecessary, but the time wasted while waiting to see if the bird gets better can be critical in controlling a behavioural problem.
Treatment for lice requires spraying with a pyrethrin spray (eg Avian Insect Liquidator®, Vetafarm) or wash. Be careful using older sprays containing maldison or malathion (eg Malawash®). These are organophosphates and can be very poisonous - both to the birds and to you. Although registered for use in birds, every avian vet I know has seen birds poisoned and die after been washed or sprayed, even when done according to the manufacturer's directions. With the advent of the safer pyrethrin sprays, veterinarians no longer recommend these products. The advice given by some pet shops to treat pet birds every 3 months for lice is inappropriate - once a pet bird has been treated properly when purchased, and so long as it is not exposed to other birds, there is no reason to treat it again.
Mites are a different proposition, as they are blood suckers. With a heavy enough burden, an infected bird may die from blood loss over a period of time. Young birds in the nest are particularly prone to this problem, as the Red Mite (the most common mite seen in aviaries) lives in the nest box, feeding on the birds at night and leaving them by day - so a nest box check during daylight hours may miss the presence of the mites. There are other mites that affect pet and aviary birds, and their presence can also be difficult to detect. Some live on the bird all the time, others will leave at certain times of their life cycle or in daylight hours. Affected birds are often itchy, with damaged skin and feathers, and may be weak from blood loss. Treatment with ivermectin or moxidectin, combined with pyrethrin sprays, is usually effective. It is vital that the environment also be treated eg the nest box should be sprayed with a safe residual insecticide such as Coopex®, Cisilin® or Avian Insect Liquidator®.
Hippoboscid flies are uncommonly seen in pet and aviary birds, but they are very common in wild birds. (So be careful of placing rescued wild birds near your own birds). They are a small flat fly, living between the feathers. Their biggest problem is that they may carry a form of Avian Malaria. Pyrethrin sprays are usually effective against them.
Although dog and cat fleas rarely live on birds, the poultry Stickfast Flea definitely will. This small flea attaches itself to the bird's skin and sucks blood from them. I have seen cockatoos, housed in chicken runs, develop severe anaemia because of this flea. It is difficult to treat with sprays, so I prefer to use ivermectin or moxidectin. Be aware that the fleas do not fall out immediately when they die, and you may think the treatment hasn't worked.
Ticks are occasionally seen on waterfowl, poultry and other birds, but rarely cause problems. I have seen birds paralysed by paralysis ticks, so it is worth removing a tick if you find one. Pyrethrin sprays and washes are usually effective.