The bane of most keepers’ lives are those dreaded protozoans. Just as a reminder, these are small, single-celled organisms that have the ability to swim around in the gut with whip-like appendages, causing damage to the gut wall, and competing with the bird for nutrients.
There are two regularly identified protozoans: Trichomonas, which is larger and is generally seen to be slower-moving under the microscope, and Hexamita, which is smaller and faster, and is often described as having a darting movement. They both seem to colonise the lower small intestine and caecae, although a recent investigation by two students from Nottingham University did regularly find these organisms higher up the gut in the upper small intestine.
The clinical signs of an infection are weight loss, inappetance, dull, ruffled-looking birds, often with a creeping walk. They remind me sometimes of an elder gentleman just about ready for a walking stick. The droppings are often a brighter green than normal, and frothy in severe cases, although I’ll expand more on the source of this frothiness later.
The cleaning of drinkers and feeders, and moving drinkers and feeders to clean, dry ground will help. One of our major clients has now used nipple bars in the rearing pens for some years, because the bell drinkers ended up getting so filthy. This year I have one client who has gone to nipple and cup lines, which have the benefit of an additional reservoir of water for those birds who are maybe not strong enough to hit the nipple. In some cases, we have also resorted to the re-introduction of bells just to get the volume of water intake up, because we were finding many birds dying of dehydration just because they weren’t prepared to hit the nipple drinkers. It’s a difficult balance to maintain, between keeping the birds hydrated and keeping the drinkers contaminant-free.
The resting of pens – even if only for a few days – has been proven to help. Moving to clean ground in each season will be beneficial too. We have also found that the addition of extra feeders and supplementary drinkers helps if the birds are ill, because if the birds feel so poorly that they don’t want to walk to food or water you sometimes have to literally put it in front of them. One of our other clients has gone to rearing pens with three boards as the base before the netting, because it gives the birds more shelter and protection. The provision of protection and shade has also proved useful for birds that feel so awful that they don’t want to move all the way back to the main shelter.
None of these provisions are going to break the bank in terms of the cost of providing them, but you may well find you reap the benefits in terms of disease control and survival rates if you do have an outbreak. Finally, birds are like sheep in some respects in that a bird’s worst enemy is its neighbour, and the closer that neighbour is the greater the threat. Reducing stocking density is a great method for disease control.
Historically, protozoan diseases were treated very well by Emtryl in one of its formats, but when that drug was banned and all the previously purchased stock had been used, the industry had to face life without it. We actually coped well, and work by Tom Pennycott at the Scottish Agricultural College proved that, by using good biosecurity and reduced stocking densities, the disease incidence did not rise and cause the major epidemic, welfare issues and general industry meltdown which had been predicted. In fact, the situation got better, which actually proved you could prevent this disease using the above measures.
In terms of the commonly used drugs available if you do have an outbreak, there are a variety of drugs currently in use. All are used under the veterinary cascade system where, if there is no appropriately licensed drug available, the vet can prescribe a drug that they consider safe and suitable according to a series of prescribed rules.
It has been suggested that the cyclines (oxy, doxy, and chlor), though they sound like three cartoon ducks, will have an effect on the causal organisms in high doses. As with their actions on bacteria, they are drugs which slow the organism down rather than kill it.
Tiamulin is a drug which has also been used in this condition. It is available from various manufacturers, but its main drawback is that it is very bitter, and unless great care is taken to sweeten the water to remove the taste the birds may refuse to drink.
Electrolytes and glucose can also help. Game Conservancy and Cambridge University work suggested that the organisms affect the uptake of glucose from the bowel, so adding additional glucose and electrolytes is beneficial.
As with all water treatments, the water should be clean and wholesome, drinkers should be clean, and plenty of drinker space available close to the birds. The medicated water should be the only source of drinking water available. The uptake of water after rain will be reduced because the birds will drink from the grass rather than any peculiar-tasting medicated water, so there are a lot of factors involved in successfully medicating via the water. Some of the cylines are available to go into food, but we generally only use these as birds go to release where the control over the birds’ water sources diminishes.
I spoke about Coccidiosis a couple of issues ago, and we all know control of it is vital. We are currently conducting a trial using a novel drug combination in feed, and we are finding it mainly successful, but only on sites where the Coccidiosis is controlled by strategic dosing with a water-based product to support the Avatec in the food at around one week after the birds are first experiencing the grass. Hopefully, we will be able to bring you more results on the trial results later in the year.
Now for the million dollar question: is there a third player in the birds’ bowel in the summer time? For some years we have been seeing things that look like little wrapped presents under the microscope when examining samples from the very thin, badly affected birds. Because they were square we thought they were a crystal, because Mother Nature doesn’t usually do symmetrical. We thought they were crystals forming as a result of dehydration in these very poorly birds.
At a BVPA conference last year one of my colleagues presented a paper on these ‘presents’, and identified them as a bacteria which lives in clumps of eight or more, and appear to form a cube. The most common form of this bacteria is Sarcina, which is defined as ‘a genus of Gram-positive cocci bacteria in the family Clostridiaceae. A synthesiser of microbial cellulose, they have a cuboidal cell arrangement. Various members of the genus are human flora and may be found in the skin and large intestine.’
The genus’s type species is Sarcina ventriculi, and is a variety that can be found on the surface of cereal seeds, in soil, and in the stomachs of humans, rabbits, and guinea pigs. They digest cellulose, which is a plant material, and act like the fermenting bacteria of a cow’s stomach. Since fermentation produces gas, these bacteria may well be the cause of the fermentation and frothiness we see in the faeces of damaged birds with swollen caecae.
On a number of occasions we have used either Amoxycillin, Lincocin or Aivlosin in severely damaged birds, because it seemed to make the birds brighter and get them eating again, but it had no apparent effect on the number of motile protozoans. So we believe that in these cases, we are killing the bacteria which cause the gas and discomfort, and therefore probably the inappetance, making the birds more comfortable and brighter. Vets are always willing to discuss possible treatments if a higher than normal protozoan count, combined with these bacteria, is affecting your birds.