Hair loss or alopecia in cattle is the partial or total absence of hair on a cow’s body. The causes of alopecia are diverse and require tests to diagnose properly, though a parasitic infestation or an infectious disease are the most common causes.
This guide will help you better diagnose why your cattle are losing hair and some ways to prevent this.
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Reasons Why Cows Lose Hair
Cattle will lose hair for various reasons that may be internal or external. Not all causes should be a cause of worry to a farmer or rancher since some are natural or go away naturally in a short time.
Here’s a comprehensive list of causes of hair loss in cows:
1. Seasonal Shedding Of Winter Coat
Most cattle usually develop a thick coat of hair in the winter months as an adaptative trait to shield them from the biting cold.
When winter ends and the warm summer months kick in, cows lose hair as a heat tolerance measure to withstand the summer heat stress.
Hair loss caused by winter hair coat shedding shouldn’t be a concern under normal circumstances.
2. External Parasites
Cattle are prone to parasitization by cattle lice and mites, which cause excessive irritations and itching that force them to rub themselves against hard objects, leading to hair loss.
Mites (mange) and lice also cause patches of damaged skin to develop lesions characterized by hair loss.
Both lice and mites are spread passively from one affected animal to another through direct contact, even if they do not actively jump from cow to cow. Lice are also transferred from one cow to another when they stick to the hairy legs of houseflies or horn flies.
Mites and lice infestations are common during winter when animals are housed closely in the barns, although they also occur when cattle are out on the range. Cattle can pick mites and lice from fomites or the immediate environment.
Cattle lice are classified into two groups—biting lice or Bicola bovis, which eat debris on the skin, such as secreted oil, hair, and dead skin cells, and sucking lice or Linogthanus vituli, which suck blood and serum from the cow.
The US has four prevalent species of lice, which include:
- Short-nosed cattle lice
- Long-nosed lice
- Little blue lice (Grey or blue grey lice)
- Red lice or cattle-chewing lice
The first three varieties are sucking lice. Different areas in the country will have different species of lice in varying numbers.
Biting lice lay their eggs in hair shafts close to the cow’s skin, where they hatch and continue with their life cycle. The sucking lice are highly mobile, especially the little blue variety, and they can spend part of their life cycle shifting between animals when the hair moves.
3. Metabolic Causes
Although not common in young ruminants, hair loss can result from metabolic shortcomings such as lipid disorder, diarrhea, and ruminal drinking in young or newborn calves.
Lipid metabolic disorder usually arises when calves are fed on milk replacers with high-fat content and certain fatty acids in the pre-weaned stage. These components typically disrupt the hair growth cycle.
Ruminal drinking in pre-ruminant calves happens when the oesophageal groove reflex fails by closing partially or not at all, such that liquid food material like milk flows directly into the rumen.
The ruminal acidosis that results from ruminal drinking is a metabolic disorder that could disrupt normal hair growth. If a calf has diarrhea and stress from a high fever, her hair follicles become inactive and stop producing hair, which results in hair loss when the old hair falls off, and new hair doesn’t grow.
4. Abnormality/Malfunction Of Hair Follicles
Primary alopecia is caused by abnormality or malfunction of hair follicles, which makes hair not grow well or have a long lifespan.
5. Genetic Defects
Congenital or acquired alopecia is temporary hair loss caused by nutritional deficiencies or severe infestations by bacteria, parasites, flies, and fungus. It may also be caused by genetic defects. For example, alopecia anemia, which may be misconstrued as hairlessness, has been proven in Polled Hereford calves born of the same sire.
The autosomal recessive hereditary defect is also referred to as congenital progressive alopecia. It co-occurs with anemia and often turns fatal. Hypotrichosis is also an inherited genetic disorder that causes calves to be born without hair or lose it shortly after birth.
Older cattle experience more hair loss than younger cattle. As cattle grow older, their skin degenerates and loses the ability to hold too much hair. The growth rate of new hair also declines.
7. Environmental Causes
Cattle may lose hair if they become photosensitized, which causes hairless, non-pigmented or light-colored skin patches on the teats, the area around the eyes, and the nose.
Photosensitization may be on the skin or the liver. It happens when phototoxins (components that react to light) enter the cow’s skin and get into contact with ultraviolet light.
8. Poor Farm Management Practices
A typical poor farm management practice that causes hair loss is feeding calves with a milk replacer incorrectly by mixing the replacer wrongly at the incorrect mixing temperature using insufficiently heated water.
Lipid metabolic disorder results from the malabsorption of dietary fat caused by incorrect milk replacer feeding. The disorder, in turn, leads to hairlessness.
9. Nutritional Causes
Nutrition-related alopecia stems from situations such as:
- Vitamin E deficiency or milk allergy
- Folic acid deficiency (once proven as a cause of hair loss in a 3-week-old Charolais calf)
- Vitamin A deficiency
- Vitamin C deficiency in growing calves
10. Diseases That Precipitate Secondary Alopecia
Hair loss in cattle may manifest as a secondary condition after various diseases, such as:
- Fungal infections like ringworm. Ringworm penetrates hair follicles and causes hair to fall off. Localized skin lesions may also join and cause the presentation of extensive patches of hair loss.
- Bacterial infections, such as Dermatophilus bacteria, cause extreme chronic skin infections characterized by hair loss in cattle raised in moist climates.
- Life-threatening diarrhea (again!)
- Salmonellosis (causes hair loss on lower limbs)
- Viral infections, such as warts (Papillomatosis). These are fibrous skin or mucous membrane tumors caused by varieties of Papillomavirus transmitted through direct contact with affected animals or propagation by stable flies from animal to animal.
- Autoimmune disease: Alopecia areata in cattle (pelade) results when a cow’s immune system erroneously attacks its own hair follicles, disrupting their growth.
In some cases, prolonged disease periods or persistent disease outbreaks may cause hair loss when potentially toxic components such as D-lactate form (ruminal drinking may cause d-Lactic metabolic acidosis) or when lack of essential substances leads to extensive hair loss at various stages of hair growth.
How To Stop Cows Losing Hair
As mentioned, you may not have to do anything to correct bovine hair loss if the cow can weather it naturally and recover. However, some causes will require human intervention, which can take a few days, several months, or a year, depending on the extent of hairlessness in a herd.
You must ensure a proper diagnosis (preferably by a vet) to rule out other possible causes and pinpoint the actual culprit. Diagnosis methods include checking for lice or mites with a magnifying glass under strong light and professional skin biopsy tests on skin scrapings from affected areas.
Here’s how to stop hair loss in cows:
- Vaccination: Such as the Bovilis Ringvac vaccine for reducing the clinical signs of ringworm.
- Change milk replacers and feeding management practices to provide correct replacers mixed at the right temperature with sufficiently heated water.
- Avoid overcrowding your cattle to minimize direct contact and unnecessary huddling.
- Allow nature to take its course, where applicable. (But you should separate cattle.) For example, spontaneous recovery is possible in alopecia caused by ringworm.
Warm summer weather reduces mite and lice populations as the surface temperature of the host cow rises. However, the infected cattle carrying the parasites will still propagate them in winter.
Viral infections like warts can self-correct over time in affected calves as they develop immunity against them.
- Treat all the infected and in-contact animals simultaneously.
- Quarantine all newly purchased cows for several weeks until a vet clears them as lice- or mite-free.
- Feed cattle well for excellent individual and overall herd health. Well-fed cattle have more active immune systems because they dedicate enough dietary energy to boosting the immune system.
- Treat organically by applying canola oil or vegetable oil on the skin to coat affected areas to smother adults and kill eggs by cutting their oxygen supply.
- Use insecticides like ivermectin to control lice. Insecticides are also ideal for killing cattle barn flies that propagate lice and mites.
- Control mites or mange with injectables or pour-ons (such as Dectomax Pour-on and Permethrin Pour-on, which you can also use as a ready-to-use spray or a back rubber.