Ruminant animals such as cattle, sheep, goats, and camels form a critical part of Kenya’s agricultural economy, providing meat, milk, hides, and manure. Effective management of ruminant diseases is essential for maintaining herd health, ensuring productivity, and safeguarding livelihoods of farmers and pastoralists. This chapter addresses the types of diseases that affect ruminants and the ability of extension professionals to recognize their signs and symptoms promptly. By understanding these aspects, agricultural extension workers can advise farmers on timely interventions that reduce losses and improve animal welfare.

4.1 Ruminant diseases

Ruminant diseases pose significant challenges to livestock production systems in Kenya, affecting both commercial and smallholder farmers. These diseases can be infectious or non-infectious, and their management requires a clear understanding of causative agents, transmission modes, and environmental factors. Agricultural extension professionals must be familiar with prevalent ruminant diseases in Kenyan contexts to provide relevant advice on prevention, control, and treatment.

4.1.1 Definition of terms

The following terms are used throughout this chapter, and an extension officer must use them correctly when talking to farmers and veterinary officers.

• Disease: Any departure from normal health that impairs the animal's functions.
• Pathogen: The organism that causes a disease: bacterium, virus, protozoan, fungus or helminth.
• Morbidity: The proportion of animals in a herd that fall sick.
• Mortality: The proportion that die.
• Incubation period: The time between infection and the first signs appearing.
• Carrier: An animal that harbours and spreads a pathogen while appearing healthy.
• Vector: An organism, usually an insect or tick, that carries a pathogen from one animal to another.
• Zoonosis: A disease that passes between animals and people.
• Notifiable disease: A disease that must be reported to the veterinary authority by law as soon as it is suspected.
• Endemic: Constantly present in an area at a predictable level.
• Epidemic or outbreak: A sudden rise in cases above the expected level.

4.1.2 Types of ruminant diseases

Classifying ruminant diseases helps in diagnosing and managing them effectively. Diseases are broadly categorised as infectious or non-infectious, with further subdivisions based on the causative agent. For example, a cow that aborts because of brucellosis needs herd-level control, while a cow that goes down with milk fever needs correction of her mineral feeding.

Kenyan livestock farmers frequently encounter certain diseases due to climatic conditions, farming practices, and wildlife interactions. The diseases below are grouped by the type of organism that causes them, because the cause decides the type of treatment and the method of control. For each disease the notes give the cause, the animals affected, the main signs, how it spreads and how it is controlled.

Classification of ruminant diseases

Infectious diseases:

• Bacterial diseases: Caused by bacteria and often affecting herd fertility, milk quality or survival.
• Viral diseases: Caused by viruses, including rinderpest (eradicated worldwide in 2011), foot-and-mouth disease (FMD) and peste des petits ruminants (PPR), which cause severe economic losses due to high morbidity.
• Protozoan and other parasitic diseases: Result from single-celled parasites, many of them carried by ticks or tsetse flies, and cause anaemia and weight loss.
• Rickettsial diseases: Caused by small bacteria-like organisms that live inside the animal's cells and are spread by ticks.
• Fungal diseases: Caused by moulds and yeasts that affect the skin or contaminate stored feed.

Non-infectious diseases:

• Nutritional diseases: Result from deficiencies or imbalances of essential nutrients.
• Metabolic diseases: Disorders of body chemistry arising from energy or mineral imbalances around calving and early lactation, such as milk fever and ketosis.
• Toxic diseases: Caused by ingestion of poisonous plants, chemicals or contaminated feeds, like Lantana camara or bracken fern poisoning.
• Physical injuries: Including wounds and fractures that predispose animals to secondary infections.
• Genetic disorders: Inherited conditions present from birth, such as atresia ani and cryptorchidism, controlled by culling affected breeding stock rather than by treatment.

Viral diseases

Viral diseases are not listed among the five types below, but they cause some of the heaviest losses in Kenyan ruminants. There is no treatment for the virus itself, so control depends on vaccination, movement control and reporting.

Foot-and-mouth disease (FMD):

• Cause: FMD virus, with several serotypes circulating in Kenya. Immunity to one serotype does not protect against another, which is why outbreaks recur in vaccinated herds.
• Animals affected: All cloven-hoofed animals: cattle, sheep, goats, pigs and wild ungulates.
• Signs: High fever, drooling, smacking of the lips, blisters in the mouth and on the tongue, teats and between the hooves. Lameness, reluctance to move, sudden drop in milk yield, and loss of condition.
• Transmission: Direct contact, saliva and discharges, and readily on fomites: shoes, clothing, vehicles, equipment and feed.
• Economic effect: Mortality is low in adults but production losses are severe, and the disease closes export markets.
• Control: Vaccination with the serotypes present, quarantine, movement restriction, and disinfection of vehicles and footwear. Report immediately to the veterinary authority.

Peste des petits ruminants (PPR):

• Cause: PPR virus, related to rinderpest.
• Animals affected: Goats and sheep. Goats are usually worse affected.
• Signs: Sudden fever, watery then thick nasal and eye discharge that crusts around the nostrils, sores in the mouth, severe diarrhoea, pneumonia, rapid loss of condition.
• Transmission: Close contact, discharges and contaminated feed and water, especially where flocks mix at watering points and markets.
• Economic effect: Mortality can be very high in unvaccinated flocks.
• Control: Vaccination gives long-lasting protection. Quarantine new stock, and avoid mixing flocks during an outbreak.

Lumpy skin disease (LSD):

• Cause: Lumpy skin disease virus.
• Animals affected: Cattle.
• Signs: Firm, raised nodules over the skin, fever, swollen lymph nodes, nasal discharge, drop in milk yield and damaged hides.
• Transmission: Biting flies, mosquitoes and ticks, so outbreaks follow the wet season.
• Control: Vaccination, vector control, and isolation of affected animals.

Rift Valley fever (RVF):

• Cause: Rift Valley fever virus.
• Animals affected: Sheep, goats, cattle and camels, and also people.
• Signs: Storms of abortion in pregnant animals, heavy death of young lambs and kids, fever, bloody diarrhoea and jaundice.
• Transmission: Mosquitoes, which multiply after unusually heavy rainfall and flooding. People are infected by handling infected carcasses, meat and fluids, or by mosquito bite.
• Control: Vaccination ahead of the season where forecast rainfall is high, mosquito control, and avoiding slaughter of sick animals. Protective gloves when handling aborted material.

Zoonotic diseases: diseases that pass to people

Several of the diseases in this topic infect people as well as animals, and the extension officer has a duty to warn farmers of the risk.

Three practices prevent most of these: boil or pasteurise all milk, never slaughter or butcher a sick animal, and wear gloves when handling afterbirth, aborted material or any carcass.

Notifiable diseases

Anthrax, foot-and-mouth disease, CBPP, Rift Valley fever and lumpy skin disease are among the diseases that must be reported to the nearest veterinary officer as soon as they are suspected, whether or not a diagnosis has been confirmed. Reporting is the duty of the owner, not a choice, and concealing an outbreak allows it to spread to other farms.

Confirm the current notifiable list with the veterinary office, since it is revised from time to time.

Transmission and spread of ruminant diseases

Understanding disease transmission is vital for designing control strategies. Transmission can be direct or indirect and varies by disease.

• Direct contact: Diseases like CBPP spread through close contact between infected and healthy animals during grazing or at watering points.
• Vector-borne transmission: Tsetse flies transmit trypanosomiasis by feeding on infected animals, making vector control critical in affected areas. Ticks transmit East Coast fever, anaplasmosis, babesiosis and heartwater, and biting flies transmit lumpy skin disease.
• Fomites and contaminated equipment: Foot-and-mouth disease virus can survive on shoes, vehicles and equipment, facilitating spread between farms.
• Vertical transmission: Some diseases, such as brucellosis, pass from mother to offspring during pregnancy, causing abortions.
• Environmental contamination: Spores of anthrax and blackquarter bacteria can persist in soil for years and infect animals grazing in contaminated areas.
• Feed and water: Shared troughs and contaminated feed spread many diseases, which is why watering points are high-risk places during an outbreak.

Factors that favour outbreaks in Kenya:

• Animal movement: Along stock routes and to markets, which mixes animals from many herds.
• Shared grazing and watering points: Particularly in dry seasons when animals concentrate.
• Contact with wildlife: Wildlife maintains FMD and other diseases in the environment.
• Rainfall patterns: Vectors multiply after rain and Rift Valley fever follows flooding.
• Low vaccination coverage: Long distances to veterinary services make this worse.
• Introduction of untested new stock: New animals brought into a clean herd can carry disease with them.

4.1.2.1 Bacterial diseases

Bacterial diseases are caused by bacteria that enter the animal through the mouth, nose, teat canal, wounds or the genital tract. Some, such as anthrax and blackquarter, form spores that live in the soil for years, while others, such as brucellosis and mastitis, spread within the herd. Several are also dangerous to people who handle milk, meat and aborted material.

Anthrax:

• Cause: Bacillus anthracis, a bacterium that forms spores surviving in soil for decades.
• Animals affected: Cattle, sheep, goats and camels, and people.
• Signs: Usually sudden death with no warning. Where signs are seen: very high fever, staggering, difficult breathing, and dark, tarry blood that fails to clot oozing from the nose, mouth, anus and vulva of the dead animal. The carcass bloats quickly and does not stiffen normally.
• Transmission: Grazing on contaminated pasture, particularly where soil has been disturbed or after flooding, and through contaminated bone meal.

A carcass suspected of anthrax must never be opened. Cutting it exposes the bacteria to air, which lets them form spores and contaminate the ground permanently. Do not skin it, do not butcher it, and do not let dogs or scavengers reach it. Report the death to the veterinary officer at once. The carcass is burned or buried deep with lime, under veterinary direction, on the spot where it lies.

• Human risk: People catch anthrax by handling infected carcasses, hides and meat, or by eating meat from an infected animal. The skin form causes a black ulcer, and the forms from eating or inhaling spores are frequently fatal. Butchers, herders and hide handlers are most at risk.
• Control: Annual vaccination in areas where anthrax occurs, correct disposal of carcasses, no slaughter of sick animals, and reporting every sudden unexplained death.

Brucellosis:

• Cause: Brucella abortus in cattle and Brucella melitensis in goats and sheep.
• Animals affected: Cattle, goats, sheep and camels, and people.
• Signs: Abortion in the last third of pregnancy, retained afterbirth, weak calves, infertility and repeat breeding. In bulls, swollen testicles. Many infected animals show no signs at all and remain carriers for life.
• Transmission: Contact with aborted foetuses, afterbirth and uterine discharges, contaminated feed and water, licking of newborn calves, infected semen and natural service, and from dam to offspring.
• Human risk: Brucellosis in people is undulant fever, causing recurring fever, heavy sweating, joint and muscle pain and lasting weakness. People are infected by drinking raw milk, eating unpasteurised cheese or soured milk, or handling aborted material with bare hands. It is an important zoonosis in pastoral areas and is often mistaken for malaria or typhoid.
• Control: There is no practical cure in animals. Infected animals are culled. Vaccinate heifers with S19 or RB51, and goats with Rev-1, as advised by the veterinary officer. Test new stock before introducing them. Handle afterbirth with gloves and bury or burn it. Boil or pasteurise all milk.

Contagious bovine pleuropneumonia (CBPP):

• Cause: Mycoplasma mycoides.
• Animals affected: Cattle.
• Signs: Fever, painful cough that worsens with exercise, difficult breathing with the elbows held out and the neck extended, nasal discharge, and grunting. Recovered animals may remain carriers with walled-off lung lesions.
• Transmission: Inhaling droplets from close contact, especially in crowded night bomas and at watering points. Spreads along stock movement routes.
• Control: Vaccination, quarantine of new animals, movement control, and treatment under veterinary direction. Notifiable.

Contagious caprine pleuropneumonia (CCPP):

The equivalent disease in goats, causing severe pneumonia and high mortality in arid and semi-arid areas. Controlled by vaccination and movement control.

Blackquarter (blackleg):

• Cause: Clostridium chauvoei, a spore-forming bacterium that persists in soil.
• Animals affected: Mainly young, well-conditioned cattle between six months and two years.
• Signs: Sudden lameness, hot painful swelling of the heavy muscles of the hindquarters or shoulder which later becomes cold and crackles under the hand because of gas, high fever, and death within one to two days.
• Transmission: Spores taken in with pasture, entering through wounds or the gut.
• Control: Annual vaccination in known areas. Treatment rarely succeeds once signs appear. Burn or bury carcasses deeply.

Mastitis:

• Cause: Mainly bacteria entering through the teat canal: streptococci, staphylococci and coliforms.
• Animals affected: Dairy cattle, goats and sheep.
• Signs: Hot, swollen, painful quarter, clots, flakes or blood in the milk, watery milk, and a drop in yield. Sub-clinical mastitis shows no visible change but raises the cell count and reduces yield.
• Transmission: Dirty milking, wet bedding, injured teats, and spread from cow to cow on the milker's hands and cloths.
• Control: Clean dry bedding, washing and drying each udder with a separate cloth, milking clean cows first and infected cows last, full milking out, post-milking teat dipping, dry cow therapy, and culling chronic cases. Use the California Mastitis Test to find sub-clinical cases.

4.1.2.2 Fungal diseases

Fungal diseases of ruminants are caused by moulds and yeasts that either grow on the skin or grow in stored feed and release toxins. They seldom kill animals quickly, but they reduce growth, lower hide value and, in the case of mouldy feed, can damage the liver and contaminate milk. A calf shed that is damp and crowded is a typical place for ringworm to spread.

Ringworm:

• Cause: Skin fungi, mainly Trichophyton verrucosum in cattle.
• Animals affected: Cattle, especially calves and young stock, and also goats and sheep. It passes to people.
• Signs: Round, grey-white, crusty patches with hair loss, usually on the head, around the eyes, on the neck and on the flanks. Itching is mild, and the patches may join into large scaly areas.
• Transmission: Direct contact, and indirectly through rubbing posts, walls, brushes and feeding troughs that carry spores. It spreads fastest in damp, crowded, poorly lit housing and in animals on poor diets.
• Effects: Reduced growth, a poor appearance and damaged hides that sell for less.
• Control: Isolate affected animals, brush off crusts with gloves on, and apply a topical antifungal as advised by the veterinary officer. Disinfect rubbing posts and pens, improve ventilation and light, and wash hands after handling affected animals.

Mycotoxicosis (mouldy feed poisoning):

• Cause: Toxins produced by moulds such as Aspergillus flavus growing on damp maize, groundnut cake, hay and silage. These are known as aflatoxins.
• Animals affected: All ruminants, but dairy cows and young animals are most affected.
• Signs: Reduced feed intake, poor growth, falling milk yield, rough coat and liver damage in severe cases. Toxin can pass into the milk.
• Control: Dry feed properly before storage, store on raised pallets in a ventilated store, discard any mouldy feed and never feed it to dairy animals.

4.1.2.3 Protozoan diseases

Protozoan diseases are caused by single-celled parasites that live in the blood, lymph nodes or gut of the animal. In Kenya the most important ones are carried by ticks and tsetse flies, so control of the vector is as important as treatment. A dairy farmer whose crossbred cows are not dipped regularly risks losing animals to East Coast fever within days of the first signs.

East Coast fever (ECF):

• Cause: Theileria parva, a protozoan parasite.
• Animals affected: Cattle, especially exotic and crossbred animals and calves.
• Signs: High fever, greatly swollen lymph nodes particularly in front of the shoulder and below the ear, laboured breathing with frothy discharge from the nostrils as the lungs fill, loss of appetite and rapid death.
• Transmission: The brown ear tick, Rhipicephalus appendiculatus.
• Control: Regular dipping or spraying against ticks, the infection and treatment method of immunisation, and prompt treatment with buparvaquone. Tick control is the mainstay: it is cheaper than treatment and protects against several diseases at once.

Babesiosis (redwater):

• Cause: Babesia species, protozoa that live inside the red blood cells.
• Animals affected: Cattle mainly, and also sheep and goats.
• Signs: Fever, anaemia, weakness and red to brown urine, which gives the disease its name.
• Transmission: Bites of infected ticks.
• Control: Tick control and treatment with specific drugs under veterinary advice. Calves raised in tick areas often build natural immunity.

Trypanosomiasis (nagana):

• Cause: Trypanosoma species, protozoan parasites.
• Animals affected: Cattle, goats, sheep and camels.
• Signs: Intermittent fever, progressive anaemia with pale membranes, rough coat, loss of condition despite feeding, swollen lymph nodes, watery eyes, abortion and eventual death.
• Transmission: The tsetse fly, present in parts of western Kenya, the coast and some rangelands.
• Control: Tsetse control through traps, targets and insecticide, bush clearing, trypanocidal drugs, and keeping trypanotolerant breeds such as the Orma Boran in affected areas.

The name sleeping sickness properly refers to the human form of the disease. The animal disease in Kenya is nagana, and the two should not be confused.

Coccidiosis:

• Cause: Eimeria species, protozoa that damage the lining of the gut.
• Animals affected: Mainly calves, kids and lambs.
• Signs: Diarrhoea that is often bloody, straining, dullness, loss of weight and dehydration.
• Transmission: Swallowing oocysts passed in dung, which build up in wet, dirty and overcrowded pens and at shared feeding troughs.
• Control: Clean, dry bedding, avoiding overcrowding, keeping feed and water free of dung, and treatment with a coccidiostat as advised by the veterinary officer.

4.1.2.4 Rickettsial diseases

Rickettsial diseases are caused by tiny bacteria-like organisms that live inside the animal's cells. In ruminants they are spread mainly by ticks, so they occur wherever tick control is poor. Because they respond to antibiotics of the tetracycline group when treated early, quick recognition by the farmer makes a real difference.

Heartwater:

• Cause: Ehrlichia ruminantium, a rickettsial organism.
• Animals affected: Cattle, sheep and goats. Goats and exotic breeds often die quickly.
• Signs: High fever, loss of appetite, nervous signs such as circling, high-stepping gait, muscle twitching, chewing movements and convulsions, and sometimes sudden death. Fluid collects around the heart and in the lungs.
• Transmission: The bont tick, Amblyomma variegatum.
• Control: Tick control, and early treatment with oxytetracycline under veterinary advice. Treatment is much less successful once nervous signs have appeared.

Anaplasmosis (gall sickness):

• Cause: Anaplasma marginale, which infects the red blood cells.
• Animals affected: Cattle mainly. Adults are more severely affected than calves.
• Signs: Fever, progressive anaemia, pale and yellow (jaundiced) membranes, loss of appetite, weakness and constipation with hard dark dung.
• Transmission: Bites of ticks, and also biting flies and needles or instruments contaminated with infected blood.
• Control: Tick and fly control, using a clean needle for every animal, and treatment with tetracycline-group drugs under veterinary advice. Recovered animals may remain carriers.

4.1.2.5 Nutritional diseases

Nutritional diseases arise when the ration lacks or has too much of an energy source, protein, mineral or vitamin, or when feeding changes too suddenly. They are not contagious, but they can affect many animals at once because the whole herd eats the same ration. They are prevented by balanced feeding, mineral supplementation and careful management at critical times such as calving.

Milk fever (hypocalcaemia):

Occurs in high-yielding dairy cows within days of calving. The cow becomes unsteady, goes down, turns the head into the flank, and dies if untreated. Treated with calcium borogluconate by a veterinary officer. Prevented by correct mineral feeding before calving.

Bloat:

Gas trapped in the rumen distends the left flank, and the animal becomes distressed and can die quickly. It follows grazing of lush young legumes or wet pasture. Prevented by filling animals with dry roughage before turning them onto lush pasture.

Ketosis:

Occurs in early lactation when energy intake falls short of output. The cow loses appetite, drops in milk yield, and the breath smells sweet like acetone. Corrected by improving the energy in the ration.

Mineral deficiencies:

• Copper deficiency: Causes poor growth, a faded coat and enzootic ataxia, in which lambs are born weak or develop a staggering gait. It is prevented by mineral supplementation where soils or pastures are low in copper.
• Phosphorus deficiency: Causes pica, an abnormal appetite in which animals chew bones, soil and wood, together with poor growth and weak fertility. It is common on phosphorus-poor pastures in the dry season and is corrected with a mineral lick.
• Calcium and magnesium imbalance: Lush, fast-growing pasture can be low in magnesium and cause grass tetany, with nervousness, staggering and convulsions. Animals can be protected by mineral supplements before turning them onto lush pasture.
• Salt deficiency: Causes licking of objects, reduced appetite and poor production. Provide salt freely at all times.

Pregnancy toxaemia:

Occurs in ewes and does in late pregnancy, especially when carrying twins, when energy intake cannot meet the needs of the growing foetuses. Affected animals become dull, stop eating, stand apart from the flock and may become blind and die. It is prevented by good feeding in the last weeks of pregnancy.

Chapter Summary

This chapter provides a comprehensive overview of ruminant diseases, detailing major categories such as bacterial, fungal, protozoan, rickettsial, and nutritional diseases that affect livestock health. It explains how to recognize the signs and symptoms that indicate the presence of these diseases, enabling timely diagnosis. The chapter emphasizes the importance of implementing effective disease control measures to prevent outbreaks and maintain herd productivity. It also covers the systematic preparation and maintenance of disease control records, which are essential for monitoring animal health and evaluating intervention success. Managing disease control waste is addressed to ensure environmental safety and reduce the risk of disease spread. Practical steps for identifying diseases in ruminant animals are outlined, equipping learners with the skills needed for accurate field diagnosis. The chapter concludes with guidance on applying various disease control methods and managing waste generated from these activities, promoting sustainable and responsible livestock management.