Veterinary Update - September

Blood testing of vaccinated and non- vaccinated Rota birds.
As discussed in the last Journal I was keen to run some biochemistry /haematology profiles on vaccinated and non –vaccinated birds to see if there was any difference after exposure to Rota virus. To run a blood profile is quite expensive and so we were restricted to running 6 blood profiles. Three VHA lofts had reported symptoms in their birds consistent with a Rota virus infection. Droppings had been collected from each loft and forwarded to Agribio for a Rota virus PCR (DNA) test. The 3 lofts were each confirmed with having a Rota virus infection. Four weeks were allowed to pass. I then travelled to each loft and collected blood from 2 birds at each loft. The blood was then forwarded to IDEXX  laboratories for biochemistry and haematology testing. We therefore had 6 samples, two from non- vaccinated birds, 4 weeks post Rota exposure ( bird IDs 18520 and 18540 ) and four from vaccinated birds (  bird IDs – 8210. 8188, 16, 6833) also 4 weeks post exposure. The complete profiles are included in this article. Bird numbers are in the top left hand corner. Fanciers will see that there are many changes in the blood profiles. To discuss the clinical significance in detail of all of these is not appropriate in this setting however if fanciers are particularly interested they are welcome to contact me privately. I am happy to explain what each change means. Fanciers can also refer to pages 42 and 43 in my book “The Pigeon” for some explanatory notes. Fanciers should however look at and compare the AST values . Rota virus targets the liver and bowel wall. AST is an enzyme that is released into the blood circulation when cells in these areas are damaged. Essentially the cells rupture, release their contents, including AST, and the lab technicians then measure this amount of AST in the blood . The higher the AST value, then the greater is the amount of cell damage and inflammation in these areas. In health the AST value should be between 45 and 123 . The 4 lowest AST values are in the vaccinated birds ( 2 are within normal range, 105 and 119, and 2 are not significantly elevated, 124 and 145). The 2 highest are in the non- vaccinated birds and these are significantly elevated ( 188 and 296 ). These results suggest that vaccination does have a protective effect on the liver and bowel of birds that subsequently are exposed to Rota virus. It is reasonable to assume that vaccinated birds with little or no internal damage are more likely to make good race birds than non- vaccinated birds that are exposed to Rota virus and suffer internal damage as indicated by these blood tests. I would personally like to thank John van Beers, Paul Gardiner and Ergun Avci for entrusting their birds to me for testing. It would be interesting to further test these birds to monitor their ongoing values, in particular to see if the liver damage is reversible with time. Unfortunately, however, we have no funding. I have paid for these PCRs and blood profiles out of my own pocket. I am however happy to do further testing if funds become available.
 
Beware Social Media
One morning in late July I had two prominent VHA members contact me about one hour apart. Someone had posted on Facebook that “Dr Angela Scott from South Australia Biosecurity has stated that the current vaccines do not work on the new PMV virus in South Australia”. The post sounded authoritative and definite. Obviously they were concerned about a new PMV strain and an ineffective vaccine.  Dr Angela Scott is a veterinarian that now works at the Australian Animal Health Laboratory (AAHL) in Geelong, Victoria but at that time was working at Primary Industry and Regions South Australia (PIRSA). The comment seemed strange to me and so I googled PIRSA, rang them, introduced myself and was connected to Dr Scott. She was concerned that her name had been used in this way and said “ I would never say that, I am well aware of the effective of the PMV vaccine”. She went on to say that working primarily in the poultry industry as she does, that “the poultry industry  could not operate without effective vaccines because of large vulnerable populations”. She thought that she was able to identify the pigeon fancier who made the post. Apparently the fancier had been having health problems and deaths in his pigeons. Some of the birds had been presented for diagnostic work to PIRSA. Testing showed the birds had PMV. The fancier had advised that he had vaccinated them. Dr Scott explained to me ,that she had spent a lot of time on the phone with the fancier and in the end had referred him back to his local veterinarian to work through his vaccination protocol to hopefully identify where he was going wrong. I rang the fancier concerned. He confirmed that he had indeed made the post on a pigeon forum site.

For a new strain to be identified it would need to have its genome sequenced and then this sequence compared and found to be significantly different from the known strain. This has not been done. Also, even if this had been done and there had been a significant number of mutations or viral re-combinations occur so that the genome had become different, it would still be largely the same and so the vaccine would still be expected to “work”.

We do not need to have the discussion again about the use and effectiveness of the PMV vaccine. La Sota based vaccines, like those available in Australia have been used by thousands, if not millions, of fanciers around the world for literally decades now to safely protect their birds against PMV. In addition, the actual vaccine available in Australia has been extensively trialed in Australia and has been shown to be safe and effective. Also, each further batch produced has to pass a number of quality control measures prior to being cleared for release and sale. The efficacy of the vaccine is beyond doubt.

Just why the fancier chose to put this statement on social media remains unclear to me. He did give me permission to mention his name but I have chosen not to here. The important message is that fanciers need to critically assess material that is placed on social media and preferably should check information with a recognised veterinary authority.
 
Highly pathogenic Avian Influenza outbreak in Victoria
Much of the following information is from the Agriculture Victoria website. On Sunday 2nd August Victorian veterinarians received a biosecurity alert from Agriculture Victoria.
There has been an outbreak of highly pathogenic Avian Influenza H7N7 at a free-range egg farm, at Lethbridge, near Geelong. Agriculture Victoria is responding to the incident. Avian Influenza is a serious disease of poultry, and can cause a high mortality rate in production birds. This disease was reported when a drop in egg production was observed, and high bird mortality rates occurred in one of the poultry sheds. Samples were submitted to Agriculture Victoria on 29 July 2020 where they tested positive for Avian Influenza H7. The CSIRO’s Australian Centre for Disease Preparedness confirmed the disease as highly pathogenic Avian Influenza H7N7 on 31 July 2020.

How is Agriculture Victoria responding.
The affected property has been quarantined and depopulated. Movement controls are in place to stop any birds, eggs and equipment from leaving the premises. A Restricted Area of about 10 k radius is in place around the property. Agriculture Victoria will be in contact with property owners in the vicinity of the infected property and will conduct further surveillance and sampling of domestic birds in this area. A  larger Control Area across a wider area, about 80 km wide, extending up to Ballarat, has also been created. Control of movement within both the Restricted and Control areas depends on the risk. On the 7th August a second outbreak was detected in a nearby property. Australia has previously had a small number of outbreaks of H7 Avian Influenza. These were all quickly and successfully eradicated.

Human Health.
The H7N7 virus is not a risk to the public as it rarely affects humans unless there is direct and close contact with sick birds.

About Avian Influenza.
Avian Influenza (AI) is a highly infectious viral disease of birds which occurs worldwide.. All Avian Influenza viruses are members of the family Orthomyxoviridae. The influenza viruses of this family are categorised into types A, B, C or D, and only influenza A viruses have been isolated from avian species. Influenza A viruses are further divided into subtypes determined by haemagglutinin (H) and neuraminidase (N) antigens. At present, 18 H subtypes and 11 N subtypes have been identified. Each virus has one of each subtype in any combination. There are many combinations of subtypes (strains) of avian influenza virus that cause infections of different severity. These range from low pathogenic or mild strains (causing ‘low pathogenicity avian influenza or LPAI), to highly pathogenic strains that are associated with severe disease and high mortality in poultry (highly pathogenic avian influenza or HPAI). H5 and H7 strains can be highly pathogenic. Chickens, ducks, geese, turkeys, guinea fowl, quail, pheasants and ostriches are included in the more than 140 species that are susceptible to avian influenza. AI virus is carried by wild birds, particularly waterfowl and shorebirds, around the world; for the most part without causing any apparent clinical disease. Wild ducks in particular can carry the virus and can then contaminate food and water supplies. Occasionally, when exposure to wild birds occurs, AI can infect domestic birds and spread rapidly. Migratory birds, predominantly shore birds and waders from nearby countries in South East Asia, can pose a risk if they harbour avian influenza infection and then mingle with, and transmit this infection to waterfowl that are nomadic within Australia. These nomadic birds can then mingle with and spread the infection to domestic birds such as poultry. It is not unusual for avian influenza virus to be detected in wild birds in Australia. Avian influenza can also spread by the movement of eggs, birds, people, vehicles and equipment between farms, and by clothing, footwear, aerosols, water, feed, litter, biting insects and vermin. There is currently no effective treatment available for birds once clinical signs of avian influenza appear. Vaccines are available for certain subtypes of the AI virus, which may protect poultry from clinical signs of disease if they subsequently become infected. However, routine vaccination for avian influenza is not permitted in Australia.

Pigeons and Avian Influenza.
Pigeons are not particularly susceptible to AI. They can however become transiently infected with the virus and transmit the virus during this time. Infected pigeons usually display either mild or no symptoms . Birds with symptoms are usually quiet, fluffed, less active ,have a reduced food intake and show a variety of symptoms associated with respiratory distress including coughing, sneezing and a noisy respiration. Pigeons clear the virus relatively quickly and a long term carrier state does not occur. The significance for pigeon fanciers is that because pigeons can transmit the virus, pigeon movement can be restricted. In the past , both in Australia and overseas, restrictions on pigeons have ranged from totally depopulating lofts in the Restricted Area, through to not allowing the exercise of pigeons in the Controlled Area and prohibiting the release of pigeons in races where they would be expected to fly over quarantined areas. At the time of writing Melbourne fanciers are in stage 4 lockdown and racing is not permitted. Had we been racing, this outbreak would have the potential to cause disruption. For the time being, it is too early to say what will happen in this current outbreak. Decisions will be made depending on how effectively the outbreak can be controlled. As for now, pigeon fanciers should just monitor the situation.  Further information can be obtained on the Agriculture Victoria website

Baytril.
Most pigeon racers will be familiar with the medication Baytril. In some circles it has gained the reputation as a veritable ‘cure all’. Yet, of all the medications available to pigeon racers, this is the one that is most often used inappropriately – usually at the wrong dose and often in the wrong situation. Used in the correct way, however, it can be a very useful medication. So what are the facts?

What is Baytril?
Baytril is the brand name of an antibiotic called enrofloxacin. It is available in tablet form, as an injection and also an oral syrup. The oral syrup can be given directly to the mouth or dissolved in the drinking water. Enrofloxacin is also sold under other brand names in Australia, notably Enrotril. All brands of enrofloxacin oral syrup in Australia are the same strength. Enrotril and Baytril oral syrups both contain enrofloxacin at a strength of 25mg/ml and therefore from a therapeutic point of view are identical. Enrofloxacin belongs to a group of antibiotics called fluoroquinolones. Another antibiotic in the same group, used more overseas, is ciprofloxacin which is often abbreviated to ‘cipro’ by pigeon fanciers.

What do these antibiotics do?
Fluoroquinolone antibiotics such as enrofloxacin (for example, Baytril and Enrotril) and ciprofloxacin work principally by interfering with the function of an enzyme called DNA gyrase that is required for bacteria to replicate themselves. If an infectious organism can’t reproduce itself then an infection caused by it resolves. Essentially the organism “dies out”. These antibiotics have excellent activity against Mycoplasma (the principle agent of air sac disease). They are also effective against most of what are called gram negative bacteria, which includes Salmonella (which causes the disease Paratyphoid) and E. Coli.

They are, however, less effective against what are called gram positive bacteria (such as Streptococcus). Baytril is therefore a poor first choice of an antibiotic for this type of infection. Fluoroquinolones do have some Chlamydial activity. Chlamydia is the agent that commonly causes ‘eye colds’, dirty ceres and deeper infections of the respiratory tract including the air sacs. Although treating Chlamydia infections with fluoroquinolones may eliminate clinical signs, this group of medications is not as effective at actually clearing these organisms from the pigeon’s body as other antibiotics such as doxycycline. The birds appear to get better but, as the carrier state persists, are much more likely to relapse. Baytril has no action against fungi, viruses, canker or parasites.

The correct dose
The dose of Baytril in birds is 10–30mg/kg given twice daily. The strength of Baytril and all other oral syrup brands of enrofloxacin in Australia is 25mg/ml. This means the dose for a pigeon is 0.2–0.6ml of the neat syrup per bird twice daily or 5–15ml per litre of water. Years ago, lower doses, adapted from mammal doses, were recommended in birds but were found not to be effective against most infections.

Potential problems with using Baytril
1. Treating pigeons with Baytril, even healthy ones, for more than 4 days, almost invariably causes a yeast infection (often called ‘thrush’). There are always low numbers of yeasts in the bowel of pigeons. Their numbers are kept in check by the normal ‘good’ bacteria in the bowel. Baytril kills many of these. With nothing to keep them in check, the yeasts quickly multiply, leading to the development of green and sometimes watery droppings and, potentially, a loss of race form.
2. Treating young growing pigeons with Baytril may permanently deform their joints. Baytril can interfere with cartilage deposition on the surface of young growing joints, leading to permanent deformity. This side effect is dose-dependent and so young pigeons, and in particular nestlings, should only be treated with extreme caution and obviously only when necessary. When treated, they must be dosed accurately. Often other antibiotics are a better choice in this situation.
3. Treating hens that are about to lay with Baytril has been associated with the embryos in the eggs subsequently dying.
4. Treating pigeons with fungal infections with Baytril makes them worse.
5. Treating unwell pigeons with Baytril in the absence of diagnostic work can waste time treating for the wrong problem while disease advances, and can subsequently interfere with test results when testing is done.
6. Treating pigeons with Baytril is not part of a routine pigeon health management program. At various times of the pigeon year, medication is used to prevent or control disease and prepare the birds for racing, etc. Baytril is not used in this way. It has no preventative property but simply kills organisms that are sensitive to it and which are in the pigeon at the time of treatment. If birds are re-exposed to these organisms the day after the treatment stops they will be re-infected.
I recently had a fancier tell me that every year, as racing approaches, he gives his race team Baytril 1ml to 1 litre of drinking water for 10 days, and that he considered this ‘essential’ for success. Using this drug in this way would achieve absolutely nothing, apart from perhaps making the fancier feel better in some way. I had another fancier ring me about eight weeks before the start of racing. He explained that he had given his race team, in preparation for racing, a long course of doxycycline and a long course of Sulfa AVS (another antibiotic blend). The purpose of his phone call was to ask if he should now give a long course of Baytril. I found this call rather disappointing, for years well-publicised pre-race programs have been published by vets. If nothing else, it just showed how some fanciers have an unreasonable over-reliance on antibiotics. Despite giving all these antibiotics, the fancier had not treated his birds for the common parasitic diseases, had no testing done on his birds to see, in fact, if any medications were necessary, and it had apparently not occurred to him to contact an avian vet earlier for advice.

When to use ‘Baytril’
The first thing to say is that Baytril is a prescription medication that should only be used in the loft after talking to your veterinarian, who should have supplied it to you in an appropriate way.

Baytril is an expensive drug. In Australia, a 100ml bottle costs about $80. At the average dose of 10ml/L (25mg/ml) and based on an average water intake of 45ml per pigeon per day, it costs about $40 per day to treat 100 birds. A five day course therefore costs $200. To treat 300 birds would cost $600. Because of the expense some fanciers try to make the drug go further by giving less and therefore deliberately under-dosing. This achieves nothing, is a total waste of money, and encourages the development of resistant bacteria.

On a lighter note, most fanciers have long-term relationships with their veterinarian, and it is important to that vet that any supply of medication is used appropriately by the fancier. It is common sense and logical really but Baytril should only be used when an infection sensitive to it is diagnosed and, particularly, if other cheaper antibiotic alternatives are thought likely to be less effective. Usually, if individual birds are infected they are separated and treated individually with the straight syrup given to the mouth. If there is evidence of spreading disease, or more than 10% of a flock is infected, then usually the flock is treated through the drinking water. It is worth repeating that Baytril is not a good first line of treatment for respiratory infections caused by Chlamydia, because although it tends to reduce symptoms (that is, make the birds look better) it is not as effective at actually clearing the organism as other antibiotics such as doxycycline, and also causes ‘collateral damage’ by killing a lot of the ‘good bacteria’. Also only approximately 15% of streptococcal strains (a cause of bacterial infection in pigeons) are sensitive to Baytril and so it is not a good choice for this type of infection.
Baytril is, however, widely distributed throughout the body and has good tissue penetrating properties. It is thought to actually achieve higher tissue concentrations than blood concentrations. Because of this property it is a good antibiotic choice for gram negative bacterial infections (in particular Salmonella) and some respiratory infections, in particular those due to Mycoplasma.
As always, it is worth taking a bit of your veterinarian’s time to see if an antibiotic is part of the answer in controlling a health problem, and also to see if that antibiotic should be Baytril or not.

Ask the Vet
1/Is Turbosole an antibiotic?  I have asked three different vet assistants and received three different answers. No, yes, and its somewhere in between.
Turbosole is an antibiotic. Antibiotics are drugs that kill bacteria and Turbosole is effective against some types of bacteria . Turbosole has action against many bacteria called gram positive anaerobes and also some bacteria called gram negative anaerobes. In addition though, Turbosole also kills single celled organisms called flagellates such as those that cause canker. Anaerobic bacteria, ie those that grow in the absence of oxygen, are not commonly associated with disease in pigeons and so the drug is usually used to treat flagellate infections.
 
2/Once a pigeon has had Fat Eye, is it likely to reoccur later in the season or do they appear to have some resistance to it?
We diagnosed “Fat Eye”, in conjunction with the University of Melbourne, as a Mycoplasma infection, when the condition was first identified in 2017. Beyond that no further investigative work has been done on this particular Mycoplasma and unfortunately there are no funds available for this. However, having said that Mycoplasmas do tend to behave as a group in a particular way. When a bird becomes infected with Mycoplasma it is infected for life. After initial infection the bird mounts an immune response and the bird clinically recovers. Anti mycoplasmal drugs can be used to help the bird recover but the organism is not cleared from the bird’s system as the birds regain their health. Older birds become long term carriers and can give the organism to younger uninfected birds. These older birds are , however, unlikely to develop symptoms themselves unless they become severely stressed. So, in answer to your question, “fat eye” is unlikely to reoccur in the same season and it is likely that the birds develop resistance to it. It is important to remember that not all birds with a swollen, red eye have “fat eye”. Other conditions can look very similar including a very common disease—Chlamydia. If in doubt a swab can be taken from the eye  and PCR tests done to check for both Chlamydia and Mycoplasma.
 
3/ Should probiotics only be used after antibiotics or is there advantage in giving them routinely?
Probiotics can be used beneficially following any situation that is likely to disrupt the normal bowel bacteria. Antibiotic use is one of these situations but bacterial populations are disrupted after any stress. Stress induces a disruption of the normal bowel bacteria and , in fact, the beneficial bacteria are the first ones to be lost with stress. Once these beneficial bacteria are lost from the digestive tract they are replaced by an overgrowth of non-beneficial bacteria. This can result in diarrhoea, loss of performance, decreased appetite and, in the stock loft, inhibited growth and limited weight gain in the youngsters. Probiotics restore the balance between beneficial and non-beneficial bacteria. They are best given as soon as possible after the stress or just before the time of the stress. By doing so, disease or performance problems may be avoided.
 
4/ When a hen is sitting on eggs, does she automatically begin to produce milk a 20 days after the eggs have been laid, or does it begin when the eggs start chipping regardless of how many days the hen has been sitting? 
Pigeon milk is produced in response to the release of a hormone called prolactin from, primarily, the pituitary gland ( a small gland at the base of the brain). Prolactin is released in turn, in response to the hen feeling the egg against her “brood patch” and later by feeling the chick move within the egg and starting to pip. In order to produce crop milk the lining of the crop has to significantly modify. This is not something that can happen in a few days. The crop needs prolonged exposure to prolactin to make these changes and produce milk. It usually takes at least 16 days for the crop wall to respond to the prolactin and start releasing its lining cells as crop milk. The hen feeling movement within the egg and the chick starting to pip is insufficient stimulation by itself for the hen to produce milk but it can accelerate the process. So, the simple answer is, if you just put chipping eggs under a hen , she will not produce crop milk . If she has been sitting over 16 days, some crop milk will be there but it will be of lower quality and quantity. It is the combination of sitting and then the stimulation of the hatching chick that combine to produce crop milk. Interestingly pigeons (like some other birds, including budgerigars) have a gland in the crop wall called the Teichman gland. The function of this gland has only recently become more fully understood. When the crop enlarges to produce crop milk, this gland also enlarges. The gland produces immune cells and it is thought that these immune cells move from the Teichman gland into the crop milk, in the process giving freshly hatched chicks some passive immunity directly from their parents. What stimulates the gland is unclear, but suggestions have included the altered hormone status that occurs when pigeons produce crop milk, or the chick itself moving in the egg as it starts to hatch.