Aug 24, 2026·DairyLogs Team
The 12 dairy cattle diseases that cost farmers the most, from mastitis to BVD and milk fever, with early signs, causes, and practical prevention tips.
A sick cow does not just cost you a vet bill. It costs you milk, breeding time, and sometimes the animal itself. Across dairy farms worldwide, a small group of dairy cattle diseases cause most of the yearly losses on any herd — and the good news is that most of them are preventable once you know what to watch for.
This guide covers the 12 dairy cow diseases that matter most, wherever you farm: what causes them, the early signs to look for, and what actually reduces your risk. We have grouped them into infectious diseases (spread by bacteria, viruses, or parasites) and metabolic diseases (caused by the strain of calving and high milk output). This is educational information, not a substitute for a veterinarian — always confirm diagnosis and treatment with a vet, especially for anything involving antibiotics or a suspected outbreak.
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Use this table as a quick reference, then read the detailed section for each disease below.
Disease | Type | Key cow signs | Main prevention |
|---|---|---|---|
Mastitis | Bacterial | Swollen udder, clots in milk, falling yield | Milking hygiene, teat dipping, dry bedding |
Lumpy skin disease | Viral (insect-borne) | Skin nodules, fever, sharp milk drop | Vaccination, insect control, quarantine |
Foot and mouth disease | Viral | Mouth and foot blisters, drooling, lameness | Vaccination where present, strict biosecurity |
Brucellosis | Bacterial, spreads to people | Late abortion, retained placenta | Testing, vaccination, pasteurised milk |
Bovine respiratory disease | Viral and bacterial | Cough, nasal discharge, fast breathing | Ventilation, colostrum, vaccination |
BVD | Viral | Abortion, poor fertility, sickly calves | Testing for PI animals, vaccination |
Johne's disease | Bacterial | Chronic diarrhoea, weight loss | Clean calving area, test and cull |
Tick-borne diseases | Blood parasites | Fever, anaemia, red urine | Tick control, careful cattle movement |
Milk fever | Metabolic | Weakness, cold ears, unable to stand | Close-up dry cow mineral balance |
Ketosis | Metabolic | Low appetite, weight loss, sweet breath | Transition diet, avoid over-fat cows |
Retained placenta and metritis | Reproductive | Hanging membranes, foul discharge, fever | Clean calving, good dry cow nutrition |
Lameness and foot rot | Bacterial and management | Limping, swelling between the claws | Dry floors, hoof trimming, foot baths |
Infectious diseases pass from animal to animal, or arrive through equipment, insects, ticks, or contaminated feed and water. They are the reason biosecurity — controlling what comes onto your farm and how sick animals are handled — matters so much.
Photo: Muhammad Mahdi Karim, GFDL 1.2, via Wikimedia Commons
Ask any dairy farmer, anywhere in the world, and mastitis is usually the first disease they mention. It is widely recognized as the most prevalent and economically damaging disease in dairy herds globally, and it comes in two forms: clinical cases you can see, and "subclinical" cases that hide inside a quietly falling milk yield.
What it is: An infection of the udder, usually caused by bacteria entering through the teat.
Signs to watch for: A swollen, warm, or painful udder; watery milk or milk with clots; and, in subclinical cases, a drop in milk output and a rising somatic cell count with no obvious visible symptom at all.
What causes it: Dirty milking equipment, poor teat hygiene, wet or dirty bedding, and stress during the dry period all raise the risk, according to Boehringer Ingelheim's animal health guidance.
Prevention: Clean milking equipment, proper teat cleaning before and after milking, dry bedding, and good nutrition during the dry period. If you're managing the transition into the dry period, our guide on drying off a cow at 7 months pregnant covers feeding changes that also lower mastitis risk during that window. For treatment options and culture testing, read our full guide to mastitis in cows.
Photo: Pavanaja, CC BY-SA 4.0, via Wikimedia Commons
Lumpy skin disease was once mostly confined to Africa, but it has spread rapidly across Asia, the Middle East, and parts of Europe over the past several years, causing major economic losses wherever it arrives.
What it is: A viral disease caused by the lumpy skin disease virus and spread mainly by biting insects such as mosquitoes and flies, and by ticks.
Signs to watch for: Firm, round skin nodules on the head, neck, udder, and legs; high fever; swollen lymph nodes; reduced appetite; and a sharp drop in milk yield. Veterinary sources note that lactating cows and Bos taurus-type breeds (like Holstein Friesian) tend to show more severe clinical signs than zebu-type cattle.
What causes it: The virus spreads mainly through insect bites, and also through contaminated feed, water, and direct contact with infected animals.
Prevention: Vaccination where available, insect and tick control around the shed, and quarantining any new or sick animals before mixing them with the herd. There is no direct cure for LSD since it's viral — treatment is supportive care to manage fever and prevent secondary infections like mastitis or pneumonia.
Photo: Izvora, CC BY-SA 3.0, via Wikimedia Commons
FMD spreads fast and remains one of the most economically damaging diseases for any cloven-hoofed animal, including cattle and buffalo, in countries where it is still present.
Signs to watch for: Blisters on the mouth, tongue, teats, and feet; drooling; fever; a sudden fall in milk; and lameness.
What causes it: A highly contagious virus that spreads through direct contact, contaminated equipment, vehicles and people, and even air over short distances.
Prevention: Vaccination on a regular schedule where the disease is present, strict biosecurity (disinfecting equipment, boots, and vehicles), and quarantining new animals before they join the herd. Since FMD is viral, there is no direct cure — treatment is supportive only, which is exactly why prevention matters more than treatment here. In FMD-free countries such as Australia, it is a notifiable emergency disease: if you ever suspect it, call your vet or the government animal disease hotline straight away.
Brucellosis deserves special attention because it is zoonotic, meaning it can pass from animals to humans, usually through unpasteurized milk or contact with an infected animal during calving or abortion. Some countries, including Australia, have eradicated bovine brucellosis, but it remains a concern in many dairy regions of Asia, Africa, the Middle East, and Latin America.
Signs to watch for: Abortion in late pregnancy, retained placenta, weak calves, and reduced fertility. Many infected animals show no obvious signs at all.
What causes it: The bacterium Brucella abortus, which is shed in huge numbers in aborted calves, afterbirth, and uterine fluids, and also in milk.
Prevention: Vaccination of young heifers where it is permitted, testing new animals before adding them to the herd, safe disposal of aborted material, and always pasteurizing or boiling milk before drinking it, especially from animals with unknown health status.
Bovine respiratory disease (BRD), usually just called pneumonia, is one of the most common causes of illness and death in dairy calves and young heifers. It rarely has a single cause: it typically starts with stress and a virus, and then bacteria move in and do the real damage to the lungs.
Signs to watch for: Fever (above about 39.5 °C / 103 °F), nasal discharge, coughing, fast or laboured breathing, droopy ears, dull eyes, and a calf that leaves its milk or feed.
What causes it: Viruses such as IBR, BRSV, and PI3 weaken the airways, and bacteria such as Mannheimia haemolytica and Pasteurella multocida then cause pneumonia. Weaning, transport, mixing groups, overcrowding, poor ventilation, and too little colostrum at birth all raise the risk.
Prevention: Feed every calf enough good-quality colostrum within the first few hours of life, house calves in well-ventilated but draught-free pens, avoid overcrowding, and follow a respiratory vaccination programme agreed with your vet. Sick calves recover far better when they are treated early, so check young stock daily.
Despite its name, BVD is mostly a fertility and immunity problem rather than a diarrhoea problem. It quietly drags down conception rates and leaves animals more vulnerable to every other disease on this list.
Signs to watch for: Repeat breeders and early embryo loss, abortions, weak or deformed calves, diarrhoea, and a general rise in sickness — especially pneumonia and scours in calves.
What causes it: A virus that spreads through nasal secretions, saliva, manure, and semen. The biggest source is "persistently infected" (PI) animals: calves infected in the womb during roughly the first four months of pregnancy can be born carrying the virus for life. They often look normal, but shed huge amounts of virus every day.
Prevention: Test the herd to find and remove PI animals (ear-notch tissue tests on calves or bulk milk testing are common), test bought-in cattle, and vaccinate breeding females before mating. Remember that a pregnant cow can test negative yet carry a PI calf, so test calves born to any purchased cow.
Johne's disease (pronounced "yo-knees") is a slow, chronic bowel infection. Calves usually pick it up in their first months of life, but signs often do not appear until the cow is several years old — by which time she may have been spreading it for a long time.
Signs to watch for: Steady weight loss despite a good appetite, watery diarrhoea without fever, and a falling milk yield in adult cows. Many infected cows show nothing at all while still shedding bacteria.
What causes it: The bacterium Mycobacterium avium subspecies paratuberculosis (MAP), spread mainly when young calves swallow manure from infected cows — on dirty teats, in colostrum and milk, or in contaminated feed and water.
Prevention: There is no cure, so prevention is everything. Keep the calving area clean and dry, separate calves from cows quickly after birth, feed colostrum from low-risk cows or pasteurised colostrum, keep manure out of feed and water troughs, and test the herd regularly so infected cows can be managed or culled.
Free tool: When a cow keeps getting sick, let the numbers guide you. Compare what she earns with what she costs before you keep or cull her. Open the Culling Decision Calculator →
In warm and tropical regions, ticks spread blood parasites that can kill cattle quickly. These diseases are often grouped together as "tick fever", and high-producing Holstein Friesian and other Bos taurus cows are usually hit harder than zebu-type cattle.
Signs to watch for: Babesiosis (redwater) causes high fever, red or brown urine, and anaemia. Anaplasmosis causes anaemia, pale or yellow gums, weakness, and weight loss, mostly in adult cattle. Theileriosis causes fever, swollen lymph nodes, and anaemia. All three can cause a sudden drop in milk and, in severe cases, death.
What causes it: Parasites carried in tick saliva and passed to cattle when the tick feeds. Anaplasmosis can also spread through biting flies and reused needles.
Prevention: A year-round tick control programme (acaricide treatments, pasture management, and checking animals regularly), vaccination where a tick fever vaccine is available, and extra care when moving cattle from tick-free areas into tick areas, because animals with no previous exposure are the most vulnerable. Treatment needs a vet quickly.
Metabolic diseases are not contagious. They happen when a cow's body cannot keep up with the demands of calving and early lactation, which is why most of them strike in the "transition period" — roughly three weeks before to three weeks after calving. They also come in clusters: a cow with milk fever is more likely to go on to develop a retained placenta, ketosis, or mastitis.
Milk fever hits hardest right around calving, and it affects high-producing herds everywhere, not any one region.
What it is: A sudden drop in blood calcium levels, usually within 24–48 hours of calving, when the cow's body cannot keep up with the calcium demand of starting a new lactation.
Signs to watch for: Weakness, cold ears, muscle tremors, a wobbly walk, and in severe cases the cow lying with her head turned into her flank, unable to stand.
What causes it: High-producing dairy breeds like Holstein Friesian are more prone to milk fever, especially older cows in their third lactation or later.
Prevention: Proper mineral balance in the close-up dry cow diet, and monitoring body condition so cows aren't overconditioned at calving. Tracking body condition score through late pregnancy is one of the simplest ways to catch cows at higher risk before calving. A downer cow is an emergency: your vet will usually give calcium into the vein, which must be given slowly and only under veterinary guidance because it affects the heart.
Ketosis usually shows up in the weeks just after calving, when a cow's energy demand for milk production outpaces what she can eat — a common problem on high-output dairy farms worldwide.
Signs to watch for: Reduced appetite (often refusing concentrates first), weight loss, a drop in milk yield, and in some cases a sweet or acetone-like smell on the breath.
What causes it: A negative energy balance — the cow's body is producing more milk than her feed intake can support, so it starts breaking down body fat for energy, which produces ketones.
Prevention: A well-balanced transition diet in the weeks before and after calving, and avoiding cows becoming overconditioned during the dry period. Cow-side milk or blood ketone test strips let you check fresh cows in about a minute, which catches subclinical cases before they turn into a sick cow or a displaced abomasum.
A retained placenta (retained "cleanings") is when the cow fails to pass her afterbirth within about 24 hours of calving. It often leads to metritis, an infection of the uterus in the first three weeks after calving.
Signs to watch for: Membranes hanging from the vulva a day after calving; later, a foul-smelling, watery, reddish-brown discharge, fever, dullness, and a drop in feed intake and milk.
What causes it: Twins, difficult or assisted calvings, abortion or early calving, milk fever, and poor dry cow nutrition (including low selenium and vitamin E) all raise the risk. A dirty calving area and unhygienic calving assistance invite infection.
Prevention: Keep calving pens clean, assist only when needed and with clean gloves, feed a balanced transition diet, and take the temperature of fresh cows daily for the first 10 days. Never pull a retained placenta by force. Both problems delay the return to heat, which is why they show up later as a longer calving interval.
Photo: Flominator, CC BY-SA 3.0, via Wikimedia Commons
Foot problems don't always get the same attention as visible disease, but they quietly cost farmers a lot in reduced milk yield, poor fertility, and lost body condition, regardless of climate or region.
Signs to watch for: Limping, an arched back when walking, swelling between the claws, a foul smell from the foot, and reluctance to walk or stand for milking.
What causes it: Foot rot is caused by bacteria entering through wet, damaged skin between the claws — common in muddy or poorly drained sheds and paddocks. Other common causes of lameness include digital dermatitis (painful, raw lesions on the heel that spread between cows) and sole ulcers linked to long standing times on hard floors.
Prevention: Keeping walking and standing areas dry, regular hoof trimming, routine foot baths, comfortable lying areas, and prompt treatment of any early limping before it worsens.
Most of the diseases above share the same handful of prevention habits. Build these into your routine and you lower the risk of almost every disease at once:
Quarantine new animals for three to four weeks and test them (for BVD, brucellosis, and Johne's, for example) before they join the herd.
Follow a vaccination calendar agreed with your vet. Depending on your country, it may cover FMD, LSD, BVD, IBR, clostridial diseases, and brucellosis.
Manage the transition period — the three weeks either side of calving — with the right minerals, energy, and body condition.
Keep calving and milking areas clean and dry to cut mastitis, metritis, Johne's, and foot problems.
Control ticks, flies, and mosquitoes around sheds and pastures.
Feed calves enough colostrum, fast — within the first few hours of life — to protect them against scours and pneumonia.
Check fresh cows daily for appetite, temperature, discharge, udder health, and milk yield.
Record everything — treatments, vaccinations, and withdrawal dates — so patterns and repeat cases stand out.
Photo: 1st Lt. Rock Stevens, U.S. Army, public domain, via Wikimedia Commons
Every disease above has one thing in common: the earlier you catch it, the cheaper and easier it is to manage. A cow with subclinical mastitis or the first signs of ketosis often shows no obvious symptom except a small, easy-to-miss drop in her daily milk yield.
This is exactly the gap that proper animal tracking closes. When you record milk yield per animal, per session, small drops that would be invisible in daily totals become visible early — before the disease is severe enough to be obvious by eye. DairyLogs' health records feature is built for exactly this: it lets you log every disease, cow by cow, along with treatments, vaccinations, and health events, with medicine withdrawal periods tracked so a treated cow's milk isn't accidentally sold or mixed into the tank. To get started, see our guide to logging health treatments, and for treatment timing rules, our guide to tracking milk withdrawal breaks that down further.
Suspect FMD or lumpy skin disease? Isolate the animals and call your vet before anything else. Both are notifiable in many countries, and fast reporting protects every farm around you.
Some signs should never wait until tomorrow. Call your vet straight away if you see:
A cow that is down and cannot get up, especially around calving
Blisters in the mouth or on the feet, or several animals with skin nodules — possible FMD or LSD, which are notifiable in many countries
Abortions, especially more than one in a short period
A high fever with fast breathing, red urine, or yellow gums
A sudden, severe drop in milk yield across several cows
Any sick cow that does not improve within a day or two of treatment
Mastitis. It is the most common and most costly disease in dairy herds worldwide, and subclinical cases — with no visible signs, just lower milk and a higher somatic cell count — are far more common than clinical ones.
Watch for a cow that eats less, gives less milk, stands apart from the herd, has droopy ears or dull eyes, runs a fever, passes unusual manure, or is reluctant to walk. A drop in her individual milk yield is often the very first sign, which is why recording milk per cow is so useful.
Brucellosis, bovine tuberculosis, leptospirosis, ringworm, and diarrhoea-causing bacteria such as salmonella and E. coli can all pass from cattle to people. Pasteurise or boil milk, wear gloves when handling calvings and abortions, and wash your hands after working with sick animals.
Viral diseases such as FMD, LSD, and BVD have no direct cure — treatment only supports the animal while its immune system fights the virus. Johne's disease is also incurable. For these, vaccination, biosecurity, and testing are your main defences.
The DairyLogs health overview: animals that need attention, vaccinations due and deworming in one place.
Most dairy cattle diseases — from mastitis, LSD, and FMD to BVD, milk fever, ketosis, and lameness — are manageable when caught early and largely preventable with the right hygiene, nutrition, and vaccination routine, no matter where your farm is located. The hardest part is rarely the treatment itself; it's noticing the problem before it becomes serious.
If your farm still relies on memory or scattered notes to track vaccination dates and health events, you can start a free DairyLogs account for up to 10 animals and keep every treatment, vaccination, and milk record in one place — so nothing slips through unnoticed.
Fast detection starts with good records. DairyLogs helps you see problems while they are still cheap to fix.
Record every illness, treatment and vaccination per animal
Get reminders for vaccinations, deworming and follow-up checks
Spot cows with falling milk or repeat health problems early
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