Vet on call: What that purple comb says about your chickens

Sammy Muchendu feeds kienyeji chicken in his farm at Turi Farmers in Elburgon. Fowl pox is a common disease caused by a virus, and occurs on the comb, wattles and around the face as swellings that dry up and form black scabs in the dry form of the disease. PHOTO | JOHN NJOROGE | NMG

What you need to know:

  • Under normal circumstances, these organs are bright red due to their abundant blood supply. Their main role is cooling the body by shedding excess heat into the environment.
  • Should you see similar occurrences in your chickens, please let me know on 0721386871 or write to me using the email provided.
  • The main causes of injury are physical force as in pecking or fighting, low environmental temperature or being hit with a blunt object.
  • The most common cause of blue or purplish combs in chickens is diseases. Any disease that causes pneumonia and reduces the level of oxygen in the blood will turn the comb bluish or purple.

Last September, I worked very well with you readers to unveil the gapeworm crisis in chickens in the country after doing the first article on the parasite.

To date, I still get reports of the worm from different parts of the country. The latest was in April from Nandi County.

The farmer had opened up dead chicken and found the worms in the trachea. His problem was resolved when he used levermisole poultry formulation in water as I had instructed him.

Now, there is another issue I would like us to look out for, which is frost bite. In very cold weather, chicken, especially cocks and cockerels, may experience death of some tissues of the comb resulting into what many people describe as blue, purple or black combs.

Wattles, the ear-like organs that hang on the lower jaws of cocks, may also be affected.

Under normal circumstances, these organs are bright red due to their abundant blood supply. Their main role is cooling the body by shedding excess heat into the environment.

For the cocks, they are also organs of beauty that endear the males to the hens and facilitate the choice of breeding mates. Did you know that in birds, the males are the fairer sex? They are more colourful and elegant than the females.

During the course of my practice, I have never seen combs getting blue because of cold weather. However, two weeks ago, Charlie from Kitengela sent me an email saying his 20 cockerels were being affected by the current cold weather.

He said that he had observed as the weather becomes progressively cold, the combs of his Kienyeji cockerels were turning purplish or bluish especially in the mornings.

One cockerel died when its whole comb turned bluish. He further said he gave antibiotics to the rest and they are still alive. Charlie sought to know the cause of this phenomenon and what he could do to prevent it.

Should you see similar occurrences in your chickens, please let me know on 0721386871 or write to me using the email provided.

In the meantime, I will explain Charlie’s predicament based on what is scientifically known about bluish/purple or black colouration of the combs in chickens.

LOW ENVIRONMENTAL TEMPERATURE

First, it is important to appreciate that bluish, purple or black colour change of the combs is not a disease in itself but an indicator of disease, disease process or injury.

The main causes of injury are physical force as in pecking or fighting, low environmental temperature or being hit with a blunt object.

When the comb is hit or pecked, some tissues get squashed, tiny blood vessels are broken and blood accumulates in the broken tissues.

Therefore, it loses its bright red colour because it is no longer oxygenated. The affected areas initially look bluish or purplish and later turn black.

Eventually, the injured areas may form a scab that peels off and the red colour of the comb is restored.

If the environmental temperature drops substantially, it may cause the formation of ice crystals in the comb tissues.

This results in the death of affected cells which decompose and turn black. The process is scientifically called necrosis or frostbite in layman’s terms.

The most common cause of blue or purplish combs in chickens is diseases. Any disease that causes pneumonia and reduces the level of oxygen in the blood will turn the comb bluish or purple.

This is called cyanosis, simply meaning the blue disease. When the blood is well oxygenated, it has a bright red colour.

When poorly oxygenated, it has a dark colour which attains a bluish or purplish hue when viewed through overlying tissues.

The most common cause of heavy cyanosis of the combs in chickens is fowl cholera. This is a bacterial disease caused by the organism Pasteurella multocida.

Most birds die within 6 -18 hours after getting infected. Cold stress may trigger rapid multiplication of the bacteria.

Prompt treatment with antibiotics to which the bacteria is sensitive may not save the seriously sick birds but may save the mildly affected and those still incubating the disease.

PREVENTED THROUGH VACCINATION

It is likely that Charlie’s birds were suffering from fowl cholera because none died after treatment with antibiotics. I strongly advise farmers to seek animal health assistance from veterinary doctors or veterinary para professionals if they see the combs of their chickens turning blue, purple or black. Sheltering the birds from cold may help, but it is not the final solution.

There are other diseases that may alter the colour of the comb. Fowl pox, a common disease caused by a virus, occurs on the comb, wattles and around the face as swellings that dry up and form black scabs in the dry form of the disease.

The wet form causes oozing ulcers in the mouth and upper respiratory tract making it difficult for the birds to breath.

The disease is prevented through vaccination and has no cure once it sets in. Some birds die but survivors overcome the disease within three to five weeks.

Avian influenza, another viral disease, also causes purplish colouration of the comb. In addition, it also causes bleeding under the skin, which is clearly visible in the legs.

The disease has not occurred in Kenya but has been reported in neighbouring Uganda and Nigeria, among other countries.

It also affects humans and has great potential of causing the deadly influenza pandemic. During the outbreaks of 2001 to 2009, it ravaged South East Asian countries and threatened to spread to the rest of the world.

Finally, heart and liver conditions that limit efficient blood circulation may cause cyanosis of the combs due to reduction in the volume of blood passing through the lungs and reaching the peripheral tissues.

To prevent comb cyanosis, farmers should house their chickens well, feed them well and carry out all the required vaccinations.

They should be observant on their birds and promptly report any colour changes of their chickens’ combs to their animal health service providers.