Now for the Canker info. The symptoms are really similar to the wet pox.
Canker
CANKER - ITS PREVENTION, CONTROL AND TREATMENT
Nature of the disease
The disease canker is caused by a protozoan Trichomonas columbae. This is a microscopic single-celled organism. It lives within the digestive tract of pigeons, in particular the throat and crop, and can also involve associated areas such as the bile duct. The organism is fragile in the environment, only surviving for a few minutes once outside the bird. This helps with control of the disease and means that the birds cannot become infected from the loft or immediate environment as happens with other diseases such as worms and paratyphoid. The organism (trichomonad) requires intimate contact between birds to be spread and is usually transmitted by saliva or pigeon milk.
Saliva contaminates food and water. As a pigeon drinks, the organism swims away from its beak and, when another pigeon or bird comes to drink, it not only drinks the water but also the trichomonads there.
When a pigeon sorts through grain, each dropped grain contains a small amount of saliva. In this way, the disease can also be spread through a feed hopper. Adult birds 'billing' can transmit the organism, as do parents when feeding their nestlings.
There is no drug that by itself will cure canker.
It is a matter of using medication correctly so that the birds can establish a strong natural immunity to the disease. It is this natural immunity that, in the longer term, protects them from the disease.
Signs of infection can be subtle and quite varied. Typical signs that would alert the fancier to its possible presence include:
1. 'Penguin' posture - Associated with proventricular (glandular stomach) and crop pain. Birds will lean back on their tails and gulp. Noticed particularly after eating and drinking.
2. 'Dry feather' - Due to lack of down feather drop and bloom production.
3. 'Leady' feel - Affected birds will not come into condition and feel heavy in the hand.
4. Wet dropping - Inflammation in the digestive tract creates a thirst, leading to elevated water intake and urine production. This produces a clear watery rim around the dropping.
5. Green droppings - Due to digestive tract irritation and in some birds decreased food intake.
6. Inflammation in the throat - Tonsillitis and increased clear to grey bubbly mucus.
7. Interference with crop function - Delayed crop emptying and sometimes vomiting.
8. Increased food consumption by team as a whole
9. Dry yellow canker - In birds of any age, this tells you that many other birds have elevated trichomonad levels, which have not yet passed the threshold for yellow material to form.
10. Indirect signs - Poor loft flying, poor tossing, respiratory problems that respond poorly to medication or quickly relapse, a dramatic improvement in the birds' general vigour in response to anticanker medication are all suggestive.
Definitive diagnosis, however, depends on microscopic examination of a crop flush. Microscopic changes that are suggestive of the problem also develop in the dropping,. These changes are associated with the stress of the disease and include elevated E. coli and yeast levels. These changes, however, do not occur in all birds.
Other sites of canker
As fanciers would be aware, most canker lesions are found in the bird's throat and are often associated with their tonsils here. However, canker can affect a variety of other sites.
Sour crop
In pigeons with sour crop, at least 90% have an internal canker nodule located at the base of the crop or within the glandular stomach (proventriculus). As the nodule increases in size, it squashes the windpipe making breathing difficult and blocking the crop outlet. This interferes with crop emptying, leading to bacterial infection of the crop and secondary starvation and dehydration due to the crop contents not being able to pass into the bird's system. Usually by the time the bird is noticed to be unwell, the condition has passed the point where it will respond to treatment. Deaths often occur due to the nodule growing through the stomach wall, leading to stomach contents leaking into the chest. Alternatively, the nodule can damage the heart or large blood vessels within the chest, causing sudden and severe bleeding. Such birds are often found dead on the floor with blood coming from the mouth. It is always worth attempting to treat valuable birds and I suggest :
• Manually empty the crop
• Give electrolytes in water
• Treat bird with 3 drops Baytril twice daily
• Treat bird with 1 tablet of Spartrix or a 1/4 Flagyl tablet or 0.5 ml Flagyl syrup once daily
• Separate unwell bird from loft mates
Cloacal canker
The cloaca is the pigeon's bottom. Within its wall is a gland called the Bursa of Fabricius. This gland is an important part of the youngster's immune system. It shrivels up and disappears during puberty. If pigeon milk containing trichomonads contaminates the nest bowl, the trichomonads can cause a trichomonad nodule to develop in the cloaca. Affected birds are usually noticed to be a bit quiet or their growth is slightly retarded compared to others of their age. On examination of the cloaca, a firm lump can be felt in the skin above it. Sometimes these lumps do not become apparent until the postweaning period. Affected birds should be treated daily with either Spartrix or Flagyl, usually for 3 - 4 days, by which time the nodule has usually localized and can be expressed by gentle but firm pressure through the cloaca.
Canker nodule in throat or crop
Older youngsters or mature stock birds with a reasonably strong natural immunity will often try and localize a canker infection, leading to nodule formation. If in the throat, these nodules can usually be seen or if in the crop wall can usually be felt as firm mobile lumps ranging in size from 0.5 cm to 4 cm in diameter. Affected birds are treated daily with Spartrix or Flagyl tablets. Once localized (usually 1 - 4 days), throat lesions can usually be teased free with a cotton bud or crop lesions pinched free into the crop. Occasionally, surgical removal is necessary. Premature attempts at removal usually result in excessive bleeding.
Internal canker
Canker can infect internal sites associated with the digestive tract, notably the bile duct, which drains bile from the liver into the bowel. Birds with internal canker nodules usually display non-specific signs of illness, including weight loss, lethargy, reluctance to eat and green diarrhoea. The final diagnosis is often made at autopsy. In lofts with a canker problem, it is usually best to include a daily Spartrix or Flagyl tablet in the treatment regime of an unwell bird in case this is the problem.
Sinus canker
Sometimes canker organisms can invade the sinuses through the slot in the roof of the mouth and form a canker nodule here. The birds present with a firm swelling across the forehead between the base of the cere and the eyes. Anticanker medication is given for 4 - 5 days to kill the active infection. After this, lancing the area by making an incision in the skin over the most prominent area of the nodule enables the canker nodule to be expressed. Once the nodule is removed, it is best to continue with anticanker medication for several days. Healing is usually uneventful.
Other sites
It is important not to confuse infection in other parts of the body with canker. Trichomonads, partially because of their fragility, can only infect the digestive tract and associated structures. Pigeons are very restricted in their response to infection. Their white blood cells lack many of the enzymes (called lysosomes) that are normally found in mammals and therefore cannot produce pus. For this reason, no matter where the site of infection, the resultant reaction often looks like a canker infection. Bacterial (or other) infections of the skin, feet and eye, etc. for this reason are often confused with canker because of their appearance.
Medications Available
Any one of a group of medications called nitro imidazoles are effective against trichomonads. There are four commonly in use:
1. Dimetradazole - The common brand name here is Emtryl, available as a water-soluble powder. Dimetradazole was the first nitro imidazole available and is still an effective drug, although trichomonad resistance to it in some areas is a problem because it has been used for the longest. It must be used with care as it has a narrow safety margin. Overdose leads to a reversible loss of balance and coordination and, in high doses, death. The medication can interfere with sperm production in cocks, leading to a temporary infertility, and so is not recommended for use during breeding. The usual dose is 1 teaspoon (3 grams) to 4½ - 8 litres of water. Lower dose rates should be used in stock birds feeding youngsters and during hot weather when water intake increases and evaporation occurs from drinkers, increasing the concentration of the medication.
2. Carnadazole - The common brand name here is Spartrix. It is only available in tablet form. It has a wide safety margin and is very useful for individual bird dosing, particularly youngsters in the nest. The dose is one 10-mg tablet daily.
3. Metronidazole - The common brand name is Flagyl. This is available as a water-soluble syrup and as tablets in a variety of strengths. It is very economical, with the tablets being useful to dose individual birds. Individual birds are given ¼ of a 200-mg Flagyl tablet once daily. Flagyl syrup is water soluble and is given at the dose of 5 - 10 ml per litre but is very sugary and not very palatable to the birds.
4. Ronidazole - This is available as a water-soluble powder under a number of brand names world-wide, including Ridsol-S, Turbosole, Tricho-Plus and Ronivet. The usual strength used is 10%. The dose at this strength is ½ teaspoon per litre. Weaker preparations are available but the birds need to be treated longer with these. The drug is very bitter so preparations stronger than 10% tend to be unpalatable to the birds. It has a very wide safety margin and is safe to use during breeding, racing and moulting. World-wide, ronidazole is the current medication of choice to treat canker. However, in some countries it is not available for use in pigeons, authorities being concerned that resistant organisms may develop. As the drug is used in food-producing animals such as pigs, its use is reserved for these.
In any canker-control program, it is often best to rotate between at least two of these medications in order to decrease the chance of a resistant trichomonad strain developing. Currently, ronidazole-based preparations are used as the primary treatment because of their effectiveness and wide safety margin, but it is a good idea to swap to one of the other available drugs every third or fourth treatment.
Reference: Dr. Colin Walker
