Rota Vaccine Trial
Fanciers may recall that, in the last Journal, I reported that the latest blood tests in the Rota vaccine trial had been done on the 16th March. The results showed that half of the trial birds had developed an antibody response that the University of Melbourne regarded as protective. The trial pigeons were then given their second Rotavax 0.5ml vaccination on the 18th March. Since then, the birds have been bled three more times at 2-week intervals on the 31st March, 15th April and the 28th April. Results of all of these blood tests are now back. They show that we still only have five birds with antibody levels that are regarded as protective. The reason for this is unclear. As a means of trying to find a way of stimulating more immunity in more birds, the trial birds will be vaccinated a third time on the 11th of May. Blood will continue to be drawn every 2 weeks to track the level of immunity in each bird.
There are a number of people working behind the scenes in the trial. I would like to thank Professor Amir Noormohammadi of the University of Melbourne, who has been overseeing all of the testing. I would also like to thank Dr Denise O’Rourke, who set up and validated the ELISA test, and Dr Abida Mushtaque and Dr Ling Zhu, who did the laboratory work. I would also like to thank Dr Travis Beddoe of LaTrobe University, who supplied the protein to measure the antibody level in the ELISA test and the original ELISA protocol. Dr Mark White has been a much valued source of technical support and is covering the cost of the testing. The aim of the whole team is to provide pigeon fanciers with an effective way of protecting their birds against Rota virus safely so that their birds do not have to go through disease and ill health after exposure to the virus and risk internal damage that compromises subsequent racing.
I have no financial interest in the vaccine. It is, however, my strong belief that it is much more preferable to perfect a vaccine rather than simply fall into the cycle of deliberately exposing healthy young birds to a debilitating disease each year caused by a virus that kills liver cells and causes damage that in some birds is irreversible. It is perhaps disappointing at this stage to have only five birds that are likely to be immune but it is worth noting that the other birds in the trial do have some immunity that at least will decrease the severity of the disease they would get after a Rota exposure. We will keep on with the vaccine trial and further results will be reported next issue.
Treatment of Rota virus
If your birds are unlucky enough to catch Rota virus, they will benefit from treatment. Treatment of Rota virus should not be expensive. In summary, the most important things to do are to put an electrolyte/ sugar preparation (eg Electrolyte P180) in the drinker and a probiotic (eg Probac) on the food as soon as the outbreak is detected. Details are explained below.
General treatment principles
There is no specific treatment for Rota virus infections in people or other animal groups. In particular, antibiotics and antiviral drugs are not thought to be of benefit. Preventing dehydration is the biggest concern. This is also the case with Rota virus infection in pigeons. Treatment is supportive. Supportive treatment aims to keep sick birds alive and minimise viral damage while the virus runs its course. This is achieved by keeping birds hydrated and in a positive energy balance so that normal body functions can continue. In our experience, the treatments that seem most effective are oral rehydration preparations and probiotics.
Oral rehydration preparations
Diarrhoea and vomiting that come on severely and suddenly, as occurs with Rota virus, where death can occur within 12 -24 hours of the onset of symptoms, can cause a quick loss of fluid and electrolytes. Using a specifically formulated veterinary rehydration preparation containing a balance of sugars and electrolytes would be expected to reduce mortalities. When managing a Rota virus outbreak, a rehydration fluid should be given as soon as symptoms are noticed and continued until signs have abated (about 7 days). The Australian Pigeon Company produces Electrolyte P180. This is a blend of electrolytes and simple sugars that is registered in Australia for specific use in pigeons. Originally developed to treat distressed race birds on return, it is proving very useful in the treatment of Rota virus
Probiotics are thought to protect the bowel from disease in a number of ways - by producing protective slime layers, maintaining a weakly acidic environment, setting up a physical barrier of bacteria, preferentially occupying receptor sites etc etc. It is therefore reasonable to presume that probiotics would be of benefit in treating birds with a Rota virus infection. Their use may lead to reduced penetration of the bowel by the virus and aid in reducing mortalities. The Australian Pigeon Company produces one of the two brands of probiotic registered for use in pigeons in Australia, Probac.
Bacterial infections are identified in 10-30 % of Rota virus cases (depending on the area), and almost all are heavy pure E.coli infections in the liver and kidney. In these cases, the E. coli did not cause death. Birds die of overwhelming Rota viral hepatocellular necrosis (death of liver tissue). It does, however, seem reasonable that, by treating a concurrent E. coli infection, some birds are more likely to recover. Essentially we still don’t know if this is the case. Some lofts that have experienced high mortalities have given antibiotics while some lofts with low mortalities did not give antibiotics. I guess all we can say at the moment is that there is no correlation, when looking at cases confirmed by the larger pathology services, with antibiotic use and the mortality rate. Antibiotic use should perhaps be reserved to treat individual birds assessed on an individual basis.
Other treatment considerations
Giving a live vaccine such as the ND4 for PPMV can stimulate the release of an immune mediator called interferon. This may give some protection against other viruses for a period of time. Vaccinating birds at risk, for example birds housed near a Rota-infected loft, before they start to show symptoms may be of benefit.
Anecdotally fennel tea has been shown to help stimulate crop emptying and maintain normal bowel function. Fennel tea can be purchased from health food stores. Simply make a cup of fennel tea as you make a cup of normal tea for yourself. This can then be added to the drinker. There is no strict dose rate. It smells like licorice but, unless mixed too strongly, the birds drink it readily. Chlorophyll, the natural substance that makes plants green, also available from health food stores, has also been shown to stimulate the crop to empty. The green powder can be added to the drinker until the water turns pale green.
Current treatment recommendations for treatment of Rota virus
Mildly affected birds can be managed as a flock. For the flock, the most important things are to maintain hydration and electrolyte balance and protect the normal population of bowel bacteria.
1/ Consider using probiotics on the food or in the drinker. I prefer to place probiotics on the food as they are fragile and can deteriorate in the drinker. Seed can be pre-moistened with a seed oil before the probiotic is applied and the grain prepared immediately prior to feeding.
2/ At the first sign of symptoms, start a rehydration solution, eg Electrolyte P180, and Fennel tea in the drinker.
3/ Grit, pink minerals and bentonite clay-based mineral blocks should be readily available.
4/ Do not give antibiotics on a flock basis.
Recommendations to treat individual unwell birds
The following treatment suggestions tend to be reserved for individual birds of value. The amount of treatment offered is often determined by the genetic or financial value of the bird we are treating. An untried young cock bred off one of the lesser pairs might be culled if severely affected by Rota while a fancier would want to offer much more treatment, for example, to a young stock hen that had already bred several fed birds The more severely affected birds often stop eating and drinking. With Rota virus, this can lead to a rapid decline, with these birds becoming dehydrated, hypoglycaemic (low blood sugar) and hypothermic (low body temperature). Unless these processes are corrected, they quickly progress to a fatal end. With correct management, these trends can be reversed in some birds. What a fancier notices in the loft is a bird that becomes fluffed up, reluctant to move, has vomiting and diarrhoea and often goes to a corner. Because of the rapidly progressive nature of this disease, prompt action is imperative. By far the most important thing is to keep the bird hydrated and in a positive energy balance by keeping its blood sugar level up. The crop of the individual unwell bird that is severely affected must always have fluid in it ready and available for the crop to push through into the bird’s system. If an unwell bird is not voluntarily drinking enough fluid to achieve this, then the crop must be topped up with fluid given via crop tube. This is critical to prevent a fatal dehydration developing. I have seen individual birds saved simply by diluting Electrolyte P180, diluted at 1 measure to 2 litres of water and repeatedly filling the bird’s crop, as it empties, with a crop tube. The electrolytes and fluid combat the dehydration while the simple sugars are passively absorbed through the lining of the digestive tract directly into the blood stream.
If individual birds stop eating, they can be provided with an easy-to-digest, high-energy vitamin and mineral-rich liquid food that is given via crop tube. A common brand is Passwell’s Hand Rearing Food. Details are below. These foods are usually offered frequently in smaller amounts. Debilitated birds often have delayed crop emptying. If the crop is distended by eating a large meal in a bird that is already nauseated, this seems to trigger a vomiting reflex.
1/ Most avian vets find it easiest to crop-feed debilitated birds with commercially available hand-rearing formulas made for seed-eating birds such as parrots eg “Passwells Hand Rearing Food”, which is available from most pet shops and all bird vets. Being formulated for an immature growing bird, they are easy to digest and contain higher levels of vitamins, amino acids and minerals than those found in adult rations. These formulas are ideal to treat pigeons debilitated with diseases such as Rota. These preparations are available as powders. Warm water is added until a smooth creamy preparation is produced. This is fed via crop tube.
Formulas are made more dilute if the crop is slow. Also if the crop is slow, smaller amounts are given more frequently.
2/ If the crop is emptying, rehydration solutions can be given via crop tube. If crop stasis has occurred, injectable solutions can be given using standard veterinary techniques and volumes.
3/ Give antibiotics – not used to treat a team usually but can be used in individual sick birds. If the birds are vomiting or the crop is slow, these will need to be given by injection.
4/ Pigeons with slow crops often develop elevated trichomonad levels. Including a nitro imidazole (canker medication) in the treatment protocol may be of benefit.
5/ Place into a veterinary hospital cage set at 20 -23°C with supplemental oxygen (usually at a veterinary clinic).
Many fanciers are probably aware of the “Yellow Drops” marketed by a number of pigeon product supply companies and recommended by several high-profile European veterinarians. The drops can be applied to the nostrils or the mouth and are advertised as having antiseptic properties, clearing bacteria, fungi and other infectious agents from the mouth and upper airways. They also are advertised as clearing any mucous from the sinuses. Certainly after application, a significant amount of mucous comes away through the “slot” and nostrils. The active ingredient is acriflavine. “Yellow drops” are used by many European fanciers who use it as a general disinfectant for the nose and throat. A prominent European vet explained to me that it works well once these areas are free of infection, to maintain and keep them clean. He advised that the drops do not replace antibiotics in the presence of actual infection. Acriflavine’s use is attractive to some fanciers because acriflavine is a plant extract. They see its use as preferable to that of a “drug”. Some fanciers mistakenly believe that application of the drops to the nostrils causes pre-existent mucous to come away, in the process making it easier for a bird to breathe and therefore be more competitive when racing. Being irritant though, it is the application of the drops that actually stimulates the production of the mucous, which then comes away. My vet friend says that he recommends that, if a fancier wants to use the product, it be placed into the nostril and never the mouth. He said that he has seen birds where even a small amount got into the windpipe and birds then coughed for the rest of their lives. Another Belgian vet also said that it works very well to keep the throat and upper respiratory tract clear of infection once the birds are negative for infections and also added that it should only be applied to the nostrils. Use of the drops is labour intensive as a drop needs to be applied to each nostril of each bird in the hours before basketing. The fact that it is irritating to the point that it causes the production of mucous, which then has to be sneezed and coughed away, bothers me. I also feel that any topical antiseptic benefit would be mild and transient. Fanciers will need to decide whether they want to use this product for themselves but I will not be using it on my own birds.
Preparation for Racing.
It is now looking increasingly likely that we will be able to race our birds this year, even if the season has a later start or is shortened. With this is mind, it is a good idea to start to think about what we should be doing with the birds, apart from vaccinations, to prepare them for racing, from a veterinary point of view.
Pre- race health Program
Principal aim: Having allowed as much time as possible for the birds to form their natural immunity, it is now a matter of assessing what health problems are persistent and then using drugs, if necessary, to get the birds completely healthy before the first race.
In the first few months of life all the fancier really needs to do is just let the pigeon grow up in a healthy environment. This is achieved by making sure that the birds are parasite free, fed a nutritious diet and that the loft is kept clean, dry and not overcrowded.
The veterinary attitude toward health management changes 6-8 weeks before the first race. Up until then, apart from parasite control, medication is avoided unless the birds in themselves become unwell. Sub-clinical levels (non-disease-causing levels) of various potential health problems, in particular wet canker and respiratory infection, are tolerated so that the birds, through exposure to low-grade disease, can develop as strong a natural immunity as possible to them.
In many well-managed lofts, the birds’ natural immunity will be such that, when screened for disease in the last weeks before racing, none is apparent. However, as racing approaches, it is important that any identified health problem be eliminated. I recommend that before fanciers embark on their final long tosses before the first race, and preferably several weeks earlier, droppings and birds be taken to a bird veterinary clinic for a health profile. By this time, the birds have been given as long as possible to build up immunity. Testing reveals any persistent problems; these are then treated so that the season can be started with healthy birds.
For fanciers who are not able to get to an avian vet, droppings can be mailed in. Dropping analysis primarily checks for worms (hairworm and roundworm and sometimes tapeworm) and coccidia. Dropping analysis also gives an indication as to the general health of the birds. Presentation of a live bird enables a more accurate assessment, not only of wet canker and respiratory infection but also of less common problems such as Hexamita (a canker-like organism that lives in the bowel).
Common health problems and how to control them before racing starts.
Before the start of racing, it is essential that the birds are parasite-free. To this end, if parasites are detected in the droppings, or a dropping analysis is not possible, the following protocol can be adopted:
• For hairworm and roundworm, external mites and air sac mites: moxidectin, 2mg/ml, 5ml to 1 litre for 24 hours.
• For tapeworms: moxidectin with added praziquantel; e.g. Moxidectin Plus, 5ml to 1 litre for 24 hours.
• For coccidia: toltrazuril; e.g. Toltravet, 25mg/ml, 5ml to 1 litre of water on days 1, 2, 8 and 9.
• For lice : I find it easiest to simply put moxidectin at 1/10 the oral dose, ie 1ml /2 litres, in the bath water
In the last few weeks before racing, a selection of birds from the race team should have crop flushes done to make sure that they are not still carrying trichomonads (that is, have wet canker). In many lofts, the birds will have developed a good immunity and no trichomonads will be found. If any trichomonads are found, the birds will need to be treated. We want to start the season with healthy birds. Having given the birds as long a time as possible to develop immunity, any persistent infection is cleared with a medication course, such as ronidazole or dimetridazole for 5-7 days. If this is extended to a 7-day course, this will kill any Hexamita present.
3/ Respiratory infection
As racing approaches, the birds have been given as long as possible to develop their natural immunity. It is important, however, that there is no active respiratory infection in the birds when racing starts. This can lead to poor race results and potentially disastrous returns. Chlamydia and Mycoplasma tests can be done by your veterinarian to see if these diseases are still active and if the birds have formed a good immunity. The usual tests available are the Chlamydia Immunocomb and a Chlamydial and Mycoplasmal PCR.
A team should be treated for respiratory infection before racing if it fits into one of the following categories:
1. If testing shows that the disease is still active in the birds, even if they look normal.
2. If respiratory infection was a problem during the early part of the racing season the previous year and the loft parameters have not changed (i.e. same loft design, same genetics, etc.).
3. If there was a significant amount of respiratory disease in the post-weaning time.
4. If the birds have a current visibly obvious respiratory infection.
The most common medications used are the antibiotics doxycycline, tylosin and spiramycin. The length of treatment depends on the severity of the problem and response to treatment, but treatment times of 7–20 days are usual. These courses are usually finished several weeks before racing starts and are best followed by probiotic supplementation. If the birds do not fit into one of the above four categories, then no treatment is required.
Dr Colin Walker