THE MAINTENANCE OF RACE FORM - PART 3
A Review of Worming Control and Available Medications
By Dr. Colin Walker B.Sc. B.V.Sc. M.A.C.V.S (avian health)
As pigeon fanciers, probably the first disease any of us became aware of was worms. We all know birds and animals get worms and that it is necessary to periodically worm them. Yet worms are still surprisingly common. When doing investigations at the clinic into poor race performance we often think of the more recently understood diseases and the intricacies of diet and training but still find quite commonly that the problem is just…worms. Why is this?
Part of the answer is the fact that a pigeon with just a few worms can pass literally thousands of eggs in its droppings everyday, that another bird only needs to swallow one to become infected and that the worm life cycle can be completed very quickly . The potential for disease build up and spread is enormous. Another part of the answer is the use (and misuse) of worming medications. Worms have also developed resistance to many of the worming preparations on the market.
Basically there are three different types of worms that pigeons get. These are roundworms, hairworms and tapeworms. All worms because of their parasitic effect weaken the birds and create a vulnerability to disease generally
Roundworms are large enough to see and basically look like white earth worms. They can be up to 3-4 cm long, 1-2 mm wide and are readily visible when passed in the droppings. Their life cycle is very simple. The adult worms live in the bowel. Here they breed and release microscopic eggs that are passed in the pigeons droppings. Other pigeons accidentally swallow these eggs when eating, drinking or pecking around the loft floor or loft environment. Once swallowed these eggs hatch and mature in the bowel of the newly infected pigeon. It only takes three weeks for a swallowed egg to hatch, grow into an adult and start producing eggs itself.
If a pigeon has 6 roundworms, then on average half will be female. Each of these females can produce up to 5000 eggs per day meaning that this pigeon with only six worms can release approximately 15,000 eggs per day in its droppings. Another pigeon only needs to swallow one of these to become infected.
At my clinic we have seen pigeons with 300 or more roundworms. Using the above figures these birds would release three quarters of a million eggs every day. Once in the environment eggs remain viable for about 6 months. Very quickly therefore the environment becomes heavily contaminated. Combining this with the very short life cycle of only three weeks one can see how quickly worms can negatively impact on the health of the loft.
Worming your birds once before the start of racing doesn’t really achieve a lot. The treatment may kill the worms present but if the pigeon goes back into the same loft and environment it is likely to swallow more eggs the next day and in three weeks be infected again. At the very minimum birds should be wormed twice, three weeks apart. Worming at this interval means that the next lot of worms that the birds are infected with are killed before they can, in turn, produce eggs themselves. In this way the life cycle is broken. Each treatment should be followed up by a particularly thorough clean of the loft to minimize the chance of re infection. Remember that disinfectants do not kill worm eggs. Their thick shells protect them. It really comes down to manual removal of all the droppings as any droppings passed prior to treatment may contain eggs and have the potential to re infect the birds. Torching with a flame is however effective at killing eggs. Although normal cleaning and torching are good I don’t think it is possible to eradicate every last egg and so some re- infection is inevitable. In a contaminated environment a good protocol to follow is to re worm every three weeks for at east 6 months. Because round worm eggs only survive for about 6 months, after this time all of the eggs in the environment will have died and no longer be capable of infecting the birds.
Once worms are eradicated they can re-enter at any time with a stray or late returning bird or indeed as some round worms are not species specific [ and can infect many different types of birds], with wild birds in particular doves. Ideally droppings should be regularly checked under the microscope by your avian veterinarian for worm eggs. During racing I recommend this be done at least every three weeks. The on- going maintenance of dry hygienic conditions will minimize environmental build up of eggs.
Hairworms are microscopic worms. This means they cannot be seen with the naked eye. Rather than live in the hollow tube of the bowel, like round worms, they live in the wall of the bowel. This means that they do much more harm.As they migrate through the bowel wall they damage it. This means that not only can the bowel not digest and assimilate its food properly but blood and tissue protein is lost through the bowel wall. The hair worm life cycle takes longer (approximately 6 weeks) and they don’t lay as many eggs per day as round worms (about 500 per day). Birds can become infected directly by swallowing eggs as with roundworms but sometimes the eggs hatch is the environment and birds become infected by eating the free living larvae. Sometimes the larvae are ingested by worms or beetles and pigeons can also become infected by eating these in turn.
There are many different types of tapeworms. They vary tremendously in their size. Some are almost microscopic while others are really large. Some types can be 1cm wide and 10 cm long. The parasites head or scolex is imbedded into the wall of the bowel where it feeds. Behind the head, the body of the tape worm is made up of a segmented ribbon of maturing packets of eggs called proglottids which trail down the gut. As each egg packet matures it snap off the end of the body and is the swept down the bowel and passed in the droppings. Pigeons cannot become infected by eating these eggs (unlike roundworms and hairworms). The eggs must be eaten by what is called an intermediate host, usually a worm or beetle. The parasite undergoes several life cycle changes in the intermediate host. Pigeon can only become infected by eating these intermediate hosts. In Australia, the common intermediate hosts are weevils and pigeons simply become infected by eating these with their food
One of the important decisions, as far as worm control is concerned, is which wormer to use. These days there is really no reason to use anything except a macrocyclic lactone and my preferred macrocyclic lactone is moxidectin. Macrocyclic lactones are a relatively new group of drugs that kill round and hair worms. They are very effective., enormously safe in birds, do not effect race form, do not effect the moult, food does not have to be withdrawn during treatment, they do not cause vomiting, are readily drunk by the birds, kill all life cycle stages (larvae and adults) and also have the handy side effect of killing any external parasites that feed off blood or tissue fluid. This means they kill all mites. Macrocyclic lactones were initially used in dogs and cats where they not only kill worms but also fleas.
There are lots of different macrocyclic lactone-ivermecton, doramectin, abamectin and selamectin etc. Moxidectin is the one that is most widely used in Australia. To treat a flock I use moxidectin 2mg/ml at a dose of 5mls/1L of drinking water for 24 hours. Individual birds can be wormed by giving 0.25ml (about five drops) of the nett solution. Because lice live off feather debris and dandruff they are hard to kill by giving moxidectin orally. However a common trick is to put the moxidectin, one tenth strength i.e. 1/2ml/1L in the bath water. Here it kills the lice by touch. This is so easy, the birds simply dip themselves and it does not affect the feathers in any way. The only restriction on the use of macrocyclic lactones is that ( like many drugs) they should not be used in the drinking water of breeding birds feeding babies less than 3 weeks of age. During this time the birds drink so much water that the chicks get a very high dose of the drug and some may die.
Moxidectin is available by itself or combined with another drug, praziquantel, under the brand name Moxidectin Plus. Praziquantel is the drug of choice for tapeworms. This means that this drug combination literally kills all worms and mites. Praziquantel is however a bitter drug and altough the birds will drink it they do so reluctantly. When using this I prefer to pick each bird up and give 0.25ml of the solution directly down the throat to ensure each bird gets a full dose.
There are lots of different brands of wormers on the market but if you look at their labels it is likely that they will contain one of the active ingredients below;
1/ piperazine- a very old drug, used now for over 40 years, only kills round worms, worm resistance to this is commonly seen.
2/ levamisole- a useful drug but has the disadvantage that it can cause vomiting, and when used in its tablet form, food needs to be withdrawn for at least 12 hours making it hard to use during racing.
3/ fenbendazole- a useful drug, has the disadvantage that it and other drugs in the same group cannot be used during moulting otherwise a ‘fret mark’ will form in the feathers that were growing at the time of treatment.
At the clinic when we are investigating potential health causes of a team performing below expectations and we make a diagnosis of worm infestation we think that this is pleasing. If birds have got to have a health problem worms are probably a good thing for them to have. This is because there are effective medications available and response to treatment is usually very rapid. Having said that though it is better if worms can be avoided in the first place.
In summary the stock loft should be absolutely parasite free and maintained as a mini quarantine station. Worms should be eradicated through repeat worming and ongoing hygeiene as outlined earlier. All new birds should be wormed prior to entry.
In the racing lost it is inevitable that the birds will be exposed in the home environment or while away in race baskets. Ongoing hygiene, regular dropping checks, strategic preventative wormings and a complete worming program when the parasites are identified will minimize their impact on race performance and health generally.