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Oral lesions

Oral lesions or cankers are particularly prevalent in laying hens or breeders and may arise from different etiological agents. Alkaline acting mycotoxins, such as type-A trichothecenes may cause lesions to the epithelium and increase the speed of epithelial cell renovation (see table).  

Also related to feed factors is feed granulometry in which small particles of feed may obstruct saliva ducts thus causing oral lesions. Other frequently ignored factors are, for example, an excess of organic acids or copper sulphate and/or a mismanagement of injectors which may produce points of high concentration of methionine and other components in the feed, ultimately leading to similar lesions. Although difficult to diagnose, the onset of mycotoxicosis in poultry is often related to a new batch of feed. 

Mycotoxin analysis of the feed by high performance liquid chromatography (HPLC) or to commodities (by ELISA or HPLC) must be performed if the presence of mycotoxins is suspected. This will provide valuable information which can be gathered in addition to observing clinical signs and necropsy examinations.

If other diseases are to be ruled out, then histopathology, bacterial and viral cultures and serology should be performed. Quite frequently, the effects of mycotoxins in animals are subclinical and are therefore overlooked by farm technicians. If there are already financial losses in the case of subclinical mycotoxicosis, these losses escalate when symptoms are observed. 

These include not only the loss of genetic potential but the investment required to treat symptoms or underlying illnesses. Prevention can be undertaken through the use of a proper mycotoxin risk management tool which adsorbs and/or biotransforms mycotoxins, thus eliminating their toxic effects for the animals, while guaranteeing liver and immune protection.  


Potential causeChecklistCorrective action
T-2 toxin (T-2) or Diacetoxyscirpenol (DAS) 
  • Histopathology: Proliferating epithelial cells. Hepatic vacuolization.
  • Decline in the overall performance of the flock. 
  • Origin of raw materials from supplier/region with history of T-2/DAS contamination.
  • Check average contamination levels.
  • Positive for T-2 and/or DAS in raw materials (ELISA) or feed (HPLC). 
  • Prevent mold growth, purchase clean raw materials.
  • Avoid contamination of feed bins or feed/water lines by stale, wet or moldy feed.
  • Use Mycofix® at a correct dosage level.


Potential causeChecklistCorrective action
Feed granulometry
  • Pelletized feed: fine particles >20%.
  • Histopathology: Presence of inflammatory cells and bacteria.
  • No decline in overall flock performance. 
Mashed feed: Check geometric mean particle diameter.
  • Adjust the pelleting process.
  • Increase in sieve diameter.
  • Use of pellet binders to improve pellet quality.temperature (LT) fishmeal.
Feed structure
  • Feed structure too hard or soya overcooked, beside others.
  • Histopathology: Presence of inflammatory cells and bacteria.
  • Decline in overall flock performance.
Check feed structure and composition of commodities.Add electrolytes together with vitamins, increasing Chlorine levels beyond the standard recommendation but take care on water intake. 
Liquid methionine 
  • Histopathology: Infiltration of inflammatory cells. Necrotic lesions.
  • No decline in overall flock performance.
Methionine injector dripping inside masher.

Clean/replace methionine injectors.

Organic acids 
  • Histopathology: Infiltration of inflammatory cells. Necrotic lesions.
  • No decline in overall flock performance.
Acids injector dripping inside masher.
  • Clean/replace acid injectors.
  • Adjust dosage of organic acids.
Copper sulphate 

Concentration between 0.05 to 0.2% in feed and excess in drinking water can promote oral lesions. 

  • Check concentration of CuSO4 in premix.
  • Check concentration of CuSO4 in water.
  • Check if water dosing system is working correctly (if applicable).
  • Apply group B vitamins and K3 vitamin in water.
  • Correct set up of the water dosing system.

Pathogens & Parasites

Potential causeChecklistCorrective action
Candida albicans (Candidiasis) 
  • The yeast C. albicans can lead to lesions detected in the crop but can extend to other parts, including the proventriculus and mouth.
  • More common in birds with longer lifespans, such as layers and breeders.
Histopathology: Fungal hyphae present in affected mucosa.Nystatin or diflucan or imidazoles such as ketoconazole, fluconazole, etc. as treatment. 
Fowl pox (Avian pox)
  • Viral disease caused by Poxviridae (Avipoxvirus) often lead to cutaneous lesions on head, neck, legs and feet.
  • Dry pox: Raised, wart-like lesions on feathered areas (head, legs, vent, etc.) which heal in about 2 weeks. Unthriftiness and retarded growth are typical symptoms. 
  • In laying hens, infection results in a transient decline in egg production. 
  • Wet pox: Canker-like lesions in the mouth, pharynx, larynx, and trachea. May also cause respiratory distress by obstructing the upper air passages.
  • Flock history and presence of typical lesion
  • Laboratory diagnosis by tissue or transmission studies
  • Use preventive vaccination depending on prevalence and season (typically fall) 
  • Treat affected birds with antibiotics to reduce secondary infection, although the disease has to run its course.

Protozoans are more prevalent in birds with a longer lifespan, such as layers, breeders and turkeys, game birds and/or free-range birds.

Histopathology: Microscopic examination of a smear of mucus or fluid from the throat demonstrates the presence of trichomonas.Separate chronically infected birds from breeding birds.
Trichomonas gallinae

First lesions appear as small, yellowish areas on the oral mucosa.

Cankers referred as “yellow buttons” - yellow, rounded areas with central caseous necrotic foci.Use nitroimidazoles (not approved in US by FDA and prohibited in the EU).
Histomonas meleagridis
  • Also known as histomoniasis or blackhead disease.
  • Common in commercial turkeys and chickens.
Cecal inflammation, ulceration, thickening of wall, ceca containing yellowish cheese like exudate.Use nitroimidazoles (not approved in US by FDA and prohibited in the EU).


Potential causeChecklistCorrective action
High temperatures
  • Histopathology: Infiltration of inflammatory cells. Necrotic lesions.
  • Possible decline in overall flock performance.
  • Increased mortality.
Calibration of the temperature control system.
  • Apply vitamins in water.
  • Apply organic acids in water.
  • Increase chlorine level in water.
  • Provide fresh water.

Find this handy checklist and more in our Science & Solutions special issue.



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