Dairy Cow Health Guide: Common Diseases, Milk Quality, Transition Period & Preventive Care
By FarmVetGuide Editorial Team · Published April 2026 · Updated March 2026 · Based on verified data from our directory of 9,500+ practices
Dairy cattle are among the most intensively managed animals in American agriculture, and for good reason: a high-producing Holstein cow is a physiological marvel, converting feed into 60, 80, or even 100 pounds of milk per day at peak lactation. Sustaining that level of production requires meticulous attention to health, nutrition, and cow comfort across an entire lactation cycle and into the critical transition period that precedes it. When management falls short, the consequences show up immediately — in the bulk tank, in the vet bill, and eventually in the culling rate and herd longevity.
This guide is written for dairy producers across the US — whether you manage a 50-cow family operation in Vermont, a 200-cow herd in Wisconsin, or a 1,000-cow operation in California's Central Valley. The diseases, management challenges, and prevention principles are universal. The goal is to give you a practical, comprehensive reference for maintaining cow health, protecting milk quality, and navigating the transition period, which remains the highest-risk phase of the dairy cow's production cycle.
The Dairy Cow Production Cycle: A Framework for Health Management
Understanding health in dairy cattle requires understanding the production cycle. A dairy cow's life is organized around a repeating series of phases, each with its own nutritional requirements, physiological stresses, and disease risks.
The Standard Lactation Cycle
| Phase | Duration | Key Characteristics | Primary Health Risks |
|---|---|---|---|
| Early dry period | Day 1–21 of dry-off | Involution of mammary gland; declining milk secretion | Mastitis at dry-off; teat canal vulnerability |
| Late dry / close-up period | Day 22–42 of dry-off (last 3 weeks) | Preparation for calving; colostrum development | Hypocalcemia risk, displaced abomasum risk begins |
| Transition period | 3 weeks pre-calving to 3 weeks post-calving | Highest metabolic stress of the cycle | Hypocalcemia, ketosis, displaced abomasum, metritis, retained placenta |
| Early lactation | Week 1–16 post-calving | Rapidly increasing production; negative energy balance | Ketosis, LDA, mastitis; peak metabolic demand |
| Peak lactation | Week 6–10 post-calving | Maximum daily milk yield | Mastitis; feet and leg problems from production stress |
| Mid-lactation | Week 10–30 post-calving | Declining production; positive energy balance begins | Mastitis; reproduction (conception rate) |
| Late lactation / rebreeding | Week 30 to dry-off | Declining production; body condition recovery | Subclinical mastitis; lameness |
The transition period — roughly the final three weeks of gestation and the first three weeks of lactation — accounts for a disproportionate share of all dairy cow disease, veterinary expense, and involuntary culling. A cow that navigates the transition period successfully is set up for a productive and healthy lactation; one that struggles through a cascade of metabolic diseases may never fully recover that lactation.
The Transition Period: The Make-or-Break Phase of Dairy Health
Why the Transition Period Is So Difficult
The transition cow is simultaneously managing three massive physiological events: the end of gestation (and the associated demands of the rapidly growing near-term calf), the initiation of colostrum synthesis, and — within hours of calving — the explosive onset of lactation. At peak lactation, a high-producing Holstein may be secreting 80–100 pounds of milk per day. The nutrient demands of that production level are far beyond what feed intake alone can supply in the immediate postpartum period.
As a result, essentially all fresh cows enter what nutritionists call negative energy balance (NEB) — a state in which the cow is burning more energy than she is consuming. To compensate, she mobilizes fat reserves from her own body. This fat mobilization, measured as elevated non-esterified fatty acids (NEFAs) in the bloodstream, is normal in controlled amounts but becomes pathological when it overwhelms the liver's capacity to process lipids. Excessive fat mobilization leads to fatty liver (hepatic lipidosis), which then impairs the cow's ability to fight infection, maintain immune function, and handle the hormonal changes of the transition period.
Body Condition Score Management
Body condition score (BCS) at dry-off is one of the most powerful predictors of transition health outcomes. Cows that are overconditioned (BCS above 3.75 on the 1–5 scale) at dry-off lose excessive body condition after calving, mobilize more fat, have higher NEFA levels, and are at significantly greater risk for ketosis, displaced abomasum, and fatty liver. The target BCS at dry-off is 3.25–3.75.
BCS management guidelines:
- Score every cow at dry-off and flag those above 3.75 for management attention
- Do not attempt to aggressively reduce BCS in the final weeks of lactation — the goal is prevention during mid-lactation, not rapid correction pre-dry-off
- In the close-up period (final 3 weeks), ensure adequate feed intake — reducing feed in this period to "control BCS" is counterproductive and increases transition disease risk
- Target BCS 2.75–3.25 at 30 days in milk — excessive loss from calving to 30 DIM indicates inadequate transition management
The Major Metabolic Diseases of Dairy Cattle
Hypocalcemia (Milk Fever)
Milk fever is the most common metabolic disease of dairy cattle at calving, affecting an estimated 5–8% of all dairy cows in the US with clinical symptoms — but subclinical hypocalcemia (low blood calcium without overt signs) affects 25–50% or more of all cows in many herds. The disease occurs because the sudden onset of milk secretion at calving demands far more calcium than the cow can immediately mobilize from bone and intestinal absorption.
Clinical signs:
- Stage 1 (early): hypersensitivity, muscle tremors, mild weakness, reluctance to move — easily missed
- Stage 2 (classic): recumbency (cow is "down"), hind limbs tucked to the side, head turned to flank, cool extremities, decreased rumen motility, constipation
- Stage 3 (severe): complete lateral recumbency, inability to rise, coma — high mortality without treatment
Treatment and prevention:
- Treatment: IV calcium borogluconate (generally 500 mL of a 23% solution) administered slowly by a veterinarian. Additional subcutaneous calcium may be given. Response is usually dramatic within 30–60 minutes if treatment is timely.
- Prevention: Dietary cation-anion difference (DCAD) management in the close-up period is the most evidence-based prevention strategy. Feeding anionic salts (negatively charged mineral supplements) for the 3 weeks pre-calving reduces clinical milk fever incidence dramatically.
- Oral calcium drenches at calving and 12–24 hours post-calving are cost-effective supplements for high-risk cows (older cows, Jersey breed, cows with previous milk fever history).
- Jersey cattle are at significantly higher risk than Holsteins and should receive more aggressive prevention.
Ketosis (Acetonemia)
Ketosis results from the liver's incomplete oxidation of mobilized fat (non-esterified fatty acids, or NEFAs), producing ketone bodies — beta-hydroxybutyrate (BHB), acetoacetate, and acetone — that accumulate in the bloodstream. Elevated ketones depress appetite, which further reduces energy intake and perpetuates the cycle. Clinical ketosis is visible; subclinical ketosis is detected only by testing and is far more prevalent.
Clinical signs:
- Reduced milk production, often the first noticeable sign
- Depressed appetite, particularly for grain; may accept hay but not grain (inverse appetite)
- Weight loss, sunken-appearing paralumbar fossa
- Sweet or fruity odor on the breath, milk, and urine (acetone smell)
- Neurological form (nervous ketosis): licking and chewing behavior, hypersensitivity, aggression, bellowing — uncommon but dramatic
Subclinical ketosis testing:
| Test Method | Target Threshold | Timing | Cost per Test |
|---|---|---|---|
| Cow-side BHB meter (Precision Xtra) | BHB ≥ 1.4 mmol/L | Days 3–7 and 10–14 post-calving | $0.50–$1.00 per test |
| Milk BHB test strip | ≥ 0.10 mmol/L | First 2 weeks post-calving | $0.30–$0.60 per test |
| Urine ketone strip | Trace to moderate | Days 3–14 post-calving | $0.10–$0.20 per test |
Treatment:
- Propylene glycol oral drench: 300–500 mL twice daily for 3–5 days — provides a direct glucogenic precursor
- IV 50% dextrose: provides immediate blood glucose; effect is short-lived without follow-up treatment
- Glucocorticoids (dexamethasone or prednisolone): prescribed by veterinarians to stimulate gluconeogenesis in severe cases
- Prevention: ensure adequate dry matter intake in the close-up and fresh cow period; avoid overconditioned cows at dry-off; consider propylene glycol supplementation in feed for the final 2 weeks pre-calving
Left Displaced Abomasum (LDA)
The abomasum (true stomach) normally rests on the floor of the abdominal cavity. When gas accumulates and the rumen is not adequately filling the abdominal space (due to reduced feed intake around calving), the abomasum can float to the left side of the abdomen, where it becomes trapped. LDA is strongly associated with hypocalcemia, ketosis, and fresh cow disease generally — these conditions all reduce rumen fill and motility, creating the physical space for displacement to occur.
Signs of LDA:
- Sudden drop in milk production in the first 2–3 weeks post-calving
- Reduced appetite, particularly for grain
- Decreased manure output; manure may be pasty or scant
- High-pitched "ping" sound in the upper left paralumbar fossa on simultaneous auscultation and percussion — this is the diagnostic sign
Treatment: Surgical correction is standard. The two most common approaches are roll-and-toggle (a non-surgical procedure where the cow is rolled and a toggle suture is placed through the body wall) and surgical omentopexy (right flank or right paramedian approach). A veterinarian must be involved. LDA surgery costs typically range from $300–$600 in the field, and most cows recover fully if treated promptly. Delayed treatment results in a progressively thinner, debilitated cow and a much worse prognosis.
Retained Placenta
The placenta should be passed within 6–12 hours of calving. When it is not passed within 24 hours, it is considered retained. Retained placenta is more common after dystocia, twin births, premature or induced calving, hypocalcemia, and selenium/vitamin E deficiency. The immediate risk is uterine infection (metritis).
Management:
- Do not manually remove a retained placenta — the cotyledons are firmly attached and forced removal causes hemorrhage and increases metritis risk
- Allow natural separation; monitor for fever and systemic illness daily
- Cows with retained placenta that develop fever (above 103.5°F), reduced milk production, or foul-smelling discharge should receive prompt veterinary evaluation for metritis treatment
- Prevention: ensure adequate selenium and vitamin E status in the dry cow diet; minimize dystocia risk with appropriate sire selection and calving assistance protocols
Metritis
Metritis — uterine infection — is the most common infectious disease of the immediate postpartum period. It is strongly associated with retained placenta, dystocia, and twins, but occurs in cows without these predisposing factors as well. Clinical metritis is defined as an enlarged uterus with foul-smelling, watery red-brown discharge, accompanied by systemic signs (fever, depression, reduced milk, reduced appetite).
Treatment:
- Systemic antibiotic therapy (procaine penicillin G, ceftiofur, or oxytetracycline depending on culture results and withdrawal time considerations) — always with veterinary prescription
- Anti-inflammatory therapy (flunixin meglumine or meloxicam) to address fever and pain — improves feed intake and speeds recovery
- Intrauterine therapy is generally not recommended by current evidence-based guidelines for metritis (systemic antibiotics reach the uterus effectively)
- Severe cases with systemic toxemia may require IV fluids and intensive supportive care
Mastitis: The Disease That Costs American Dairy Farmers the Most
Mastitis — inflammation of the mammary gland, almost always caused by bacterial infection — is the most economically damaging disease in the US dairy industry, costing an estimated $2 billion annually when all costs are tallied: discarded milk, treatment costs, reduced production, premature culling, and labor. Understanding mastitis management is not optional for any dairy producer — it is central to the economics of the operation.
Contagious vs. Environmental Mastitis
| Category | Primary Pathogens | Primary Source | Primary Control Strategy |
|---|---|---|---|
| Contagious mastitis | Staphylococcus aureus, Streptococcus agalactiae, Mycoplasma bovis | Infected quarters → milking equipment → susceptible quarters | Milking hygiene, post-dip, dry cow therapy, cull chronic cows |
| Environmental mastitis | E. coli, Klebsiella, Streptococcus uberis, Streptococcus dysgalactiae | Bedding, soil, manure → teat orifice between milkings | Bedding management, pre-dip, teat end condition, lying time |
| Coagulase-negative Staph (CNS) | S. chromogenes, S. epidermidis, S. simulans | Skin of teat and udder | Teat sanitation; significance varies by species |
Somatic Cell Count: Your Real-Time Mastitis Indicator
Somatic cell count (SCC) is the number of white blood cells per milliliter of milk. An elevated SCC indicates the udder's immune response to infection. SCC is measured monthly (or more frequently in problem herds) via Dairy Herd Improvement (DHI) testing and is reported on the bulk tank by milk processors.
| SCC Level (cells/mL) | Interpretation | Action Required |
|---|---|---|
| Below 100,000 | Excellent udder health | Maintain current practices |
| 100,000–200,000 | Good — industry benchmark | Monitor; investigate any upward trend |
| 200,000–400,000 | Elevated — subclinical mastitis present | Review milking hygiene; identify chronic cows |
| 400,000–750,000 | High — significant economic impact | Comprehensive mastitis control review; culture program |
| Above 750,000 | Crisis — regulatory risk; major production loss | Emergency veterinary consultation; culture all cows |
US federal milk quality standards require bulk tank SCC below 750,000 cells/mL for Grade A milk. EU standards are stricter at 400,000. Many premium milk contracts require below 200,000. Every 100,000 cell increase above 50,000 is associated with approximately a 1.5% reduction in milk production.
Clinical Mastitis: Identification and Treatment
Clinical mastitis is visible — the cow shows signs of infection in one or more quarters. Severity ranges from mild (only milk is abnormal) to severe (systemic illness, fever, depression, quarter swelling). Strip milk from all four quarters at the start of every milking and examine carefully for clots, flakes, watery appearance, or discoloration.
Clinical mastitis treatment decision framework:
- Mild/moderate (milk abnormal, no systemic signs): culture the affected quarter; consider intramammary antibiotic therapy based on culture results and pathogen identity — not all mastitis requires antibiotics (E. coli mastitis often resolves with supportive care and frequent stripping)
- Severe (fever, depression, swollen quarter, toxic cow): requires systemic antibiotics, anti-inflammatory therapy, and possibly IV fluids — call your veterinarian
- Do not treat without an established milk and meat withdrawal protocol
- Chronic, recurrent cases (especially S. aureus): culling is frequently the most economically sound decision — S. aureus mastitis has very low cure rates with antibiotic treatment
The Five-Point Mastitis Control Program
The International Dairy Federation's five-point program has been the foundation of mastitis control for decades and remains evidence-based:
- Post-milking teat dipping: Apply an effective germicidal teat dip (iodine 0.5–1.0%, or chlorhexidine-based products) immediately after every milking. This is the single highest-impact intervention for contagious mastitis control.
- Prompt treatment of clinical cases: Identify, record, and treat clinical cases quickly. Delay allows infection to progress and increases the risk of spread.
- Dry cow therapy: At dry-off, treat all quarters with an intramammary antibiotic preparation (blanket dry cow therapy) or selectively treat quarters with elevated SCC (selective dry cow therapy — increasingly used in low-SCC herds). Internal teat sealants (bismuth subnitrate) protect teat canals during the dry period.
- Cull chronic cows: Cows with repeatedly elevated SCC or chronic clinical mastitis (particularly S. aureus) are reservoirs for herd spread. Identifying and culling or segregating these cows is essential for herd-level control.
- Maintain milking equipment: Proper vacuum levels, pulsation ratios, liner condition, and cluster alignment are critical. Have your milking system tested annually by a qualified technician.
Lameness: The Silent Profitability Killer
After mastitis, lameness is the second most economically significant disease of US dairy cattle. Lame cows produce less milk, cycle less reliably, have lower conception rates, and are culled earlier. The economic cost per lame cow per lactation has been estimated at $215–$500 when all costs are included. In the typical US dairy herd, 15–25% of cows are lame at any given time — most with subclinical or moderate lameness that producers may not readily notice.
Common Causes of Lameness in Dairy Cattle
| Condition | Description | Primary Risk Factors | Veterinary Treatment |
|---|---|---|---|
| White line disease | Separation of the white line junction at the abaxial hoof wall | Transition period metabolic disease, high grain diet, hard concrete | Hoof trimming, block on sound claw |
| Sole ulcer | Focal necrosis of the sole corium, typically at the typical site | Same as white line disease; most common in 2nd lactation peak cows | Functional hoof trimming, block, anti-inflammatory |
| Digital dermatitis (Mortellaro's) | Painful, moist, proliferative skin lesion at heel/interdigital area | Wet conditions, contaminated hoof baths, contagious spread | Oxytetracycline topical spray, hoof bath programs |
| Foot rot (interdigital necrobacillosis) | Acute infection between claws; characteristic foul odor | Puncture wounds, wet conditions, soil exposure | Systemic antibiotics, cleaning; often self-limiting with treatment |
| Laminitis | Subclinical diffuse inflammation of the corium; secondary to acidosis | High-grain diets, SARA, transition period stress | Nutritional management, hoof trimming, buffering |
Locomotion Scoring: Seeing Lameness Before It Worsens
Locomotion scoring (LS) on a 1–5 scale is the standard method for identifying lame cows early. Observe cows while they are walking on a level, non-slip surface:
- LS 1: Normal — walks with a level back, free-moving gait
- LS 2: Mildly lame — slightly arched back while walking; all four limbs bear weight
- LS 3: Moderately lame — arched back while standing and walking; favors one limb
- LS 4: Lame — pronounced arching; reluctance to bear weight on affected limb
- LS 5: Severely lame — unable or barely able to bear weight; may not be able to walk
Cows at LS 3 or above should receive prompt attention. LS 2 cows should be flagged and monitored. Target a herd locomotion score distribution where fewer than 10–15% of cows are LS 2 or above.
Milk Quality: From Farm to Processor
Keeping Bulk Tank Quality High
Bulk tank milk quality is measured on multiple dimensions: somatic cell count (udder health), standard plate count (bacterial contamination), preliminary incubation count (psychrotrophic bacteria from biofilm or cooling failure), coliform count (environmental contamination), and presence of antibiotic residues.
Temperature management: Milk must be cooled to 45°F or below within 2 hours of milking and maintained at that temperature. Every degree of warmer milk temperature accelerates bacterial growth exponentially. Ensure your plate cooler, bulk tank refrigeration, and agitator are functioning correctly.
Antibiotic residues: This is a zero-tolerance issue. A single positive antibiotic test on a bulk tank load results in rejection of the entire load and penalties that can reach tens of thousands of dollars. Implement rigorous withhold protocols: clearly identify treated cows, use colored leg bands, maintain treatment records, test milk with a cow-side test before releasing from the withhold, and have two people verify before releasing treated cows to the milking string.
Milking Hygiene Protocols
Every milking should follow a consistent, timed protocol. Variation in prep time is one of the most common and costly milking management errors:
- Apply pre-dip and let contact for 30 seconds minimum
- Wipe teats dry with individual paper towels (one towel per cow — no shared cloths)
- Forestrip two to three squirts from each teat — examine for clots, flakes, or abnormality
- Attach milking unit within 60–120 seconds of stimulation beginning (lag time is critical for milk letdown)
- Remove unit promptly at milk-out — unit-on time beyond milk-out damages teat ends
- Post-dip immediately after unit removal
Preventive Health Programs: Building Your Veterinary Protocol
Vaccination Programs for Dairy Cattle
| Vaccine Type | Target | Timing | Notes |
|---|---|---|---|
| IBR/BVD/PI3/BRSV (modified live or killed) | Respiratory/reproductive viruses | Annually; 2x in naive heifers | Use killed products in pregnant cows unless labeled for use in pregnancy |
| Leptospirosis (5-way) | Leptospira serovars | Annually; 2x for naive heifers | Critical for reproductive disease prevention |
| Clostridial (8-way) | Blackleg, enterotoxemia, malignant edema, etc. | Annually; 2x for naive animals | Inexpensive, highly effective — no excuse for skipping |
| J5 E. coli bacterin | Gram-negative mastitis (E. coli, Klebsiella) | Twice in close-up period; annually | Reduces severity of coliform mastitis — especially valuable in herds with E. coli mastitis history |
| Salmonella | Salmonella dublin and S. typhimurium | Per label protocol | Consider in herds with Salmonella history or high-risk geography |
| Bovine rotavirus/coronavirus | Neonatal calf scours pathogens | Pre-calving (passes to colostrum) | Essential for calf health programs |
Parasite Control
Internal parasite burden in dairy cattle varies significantly by region and management system. Pastured dairy cows — common on organic operations and smaller farms — face higher parasite pressure than cows in confinement. Key parasites of concern include:
- Liver fluke (Fasciola hepatica): Found in wet, marshy pastures across the Gulf Coast, Pacific Northwest, and mountainous regions. Subclinical infection reduces milk production and immune function; severe infection causes acute hepatitis. Diagnosis by fecal fluke egg count or ELISA; treatment with clorsulon (Curatrem) or albendazole.
- Gastrointestinal nematodes: Primarily Ostertagia ostertagi (brown stomach worm), the most economically important parasite of pastured dairy cattle in North America. Subclinical type II ostertagiosis (larval emergence in spring) reduces milk production and feed efficiency significantly.
- External parasites (horn flies, stable flies, lice): Horn fly populations above the economic threshold of 200 flies per animal reduce weight gain in beef cattle; in dairy cattle, they cause reduced milk production, increased mastitis risk (from fly-irritated behavior), and teat damage. Control with ear tags, pour-ons, or insecticide sprays per label directions.
Reproduction Management
Reproductive performance is among the most important economic drivers in the dairy industry. The standard reproductive efficiency metric is the 21-day pregnancy rate — the percentage of eligible cows that become pregnant in any given 21-day cycle. Industry average is approximately 18–22%; well-managed herds achieve 25–30% or higher.
Key reproductive management practices:
- Voluntary waiting period (VWP): Most US dairies set the VWP at 50–70 days post-calving to allow adequate uterine involution and resumption of normal cyclicity. Starting AI before this risks conception failure and early embryo loss.
- Estrus detection: Automated activity monitors (neck or leg-mounted accelerometers) have dramatically improved estrus detection efficiency over observation alone. Detection rates of 90%+ are achievable vs. 50–60% with twice-daily visual observation.
- Ovsynch and synchronization programs: First-service Ovsynch (GnRH → 7 days → PGF2α → 2 days → GnRH → timed AI) achieves conception rates of 30–40% in well-managed herds without dependency on estrus detection. Pre-synchronization programs (Presynch, Double-Ovsynch) improve first-service conception rates further.
- Pregnancy diagnosis: Ultrasound at 28–35 days post-AI allows early identification of non-pregnant cows for rebreeding. This shortens the interval from calving to confirmed pregnancy and is cost-effective in all herd sizes.
Regional Considerations for US Dairy Producers
Northeast and Great Lakes
Herds in Vermont, New York, Pennsylvania, Wisconsin, and Michigan face cold stress challenges in winter that can suppress immune function and increase mastitis and respiratory disease risk. Bedding management (deep pack barns, sand-bedded free stalls) and draft prevention are priorities. Johne's disease (paratuberculosis) is widespread in these regions and is a significant cause of chronic weight loss and diarrhea in older cows — testing programs and biosecurity measures to reduce spread to calves are important.
Southeast and Gulf Coast
Heat stress management dominates the economic calculus of dairy operations in Florida, Georgia, Texas, and surrounding states. These operations typically invest heavily in soaker and fan systems, utilize Bos indicus-influenced genetics for heat tolerance, and adjust reproduction programs to account for reduced summer conception rates. Digital dermatitis and foot rot are more prevalent in wet, humid conditions.
Western US (California, Idaho, New Mexico)
Large-scale operations dominate the West. California produces approximately 20% of US milk output. Dry climate in the Central Valley favors evaporative cooling effectiveness for heat stress. Valley fever (Coccidioidomycosis) is a concern for cattle in arid regions of California, Arizona, and New Mexico — typically a subclinical respiratory infection but occasionally severe. Water quality issues (high mineral content, salinity) can affect milk production and reproductive performance and should be monitored.
Calf Health: Protecting Your Future Herd
Dairy heifer calves are the future of the herd, and mortality and morbidity in the first two months of life set the trajectory for lifetime productivity. US dairy calf pre-weaning mortality averages approximately 5–6% nationally, but excellent herds achieve below 2%.
The Critical First Hours: Colostrum Management
The single most important management intervention in calf health is timely, adequate colostrum delivery. Newborn calves are born with essentially no circulating immunoglobulins (antibodies) — they are immunologically naive and entirely dependent on immunoglobulin G (IgG) absorbed from colostrum to establish passive immunity. Gut closure — the end of IgG absorption through intestinal cells — occurs within 24 hours of birth, with efficiency declining rapidly after 6–8 hours.
Colostrum management rules:
- Feed colostrum within the first 2 hours of birth — the earlier, the better
- Feed at least 10% of body weight (4 liters for a 90-lb Holstein calf)
- Use a Brix refractometer to test colostrum quality: Brix ≥ 22% indicates IgG ≥ 50 g/L — the threshold for high-quality colostrum. Colostrum below this threshold should be supplemented with a commercial colostrum replacer.
- Test passive transfer success with a Brix reading on calf serum at 24–48 hours: ≥ 8.5% Brix indicates successful transfer (IgG ≥ 10 g/L); below this threshold indicates failure of passive transfer and significantly increased disease risk
- Store excess colostrum: refrigerate for up to 1 week or freeze for up to 1 year. Pasteurized colostrum (60°C for 60 minutes) reduces Johne's disease, Salmonella, and Mycoplasma transmission without significantly reducing IgG content.
When to Call Your Large Animal Vet: Dairy Cattle
Knowing when a situation requires veterinary involvement is as important as any other management skill. The following situations always require professional veterinary evaluation:
- Any cow down (recumbent and unable to rise) — hypocalcemia, LDA, severe ketosis, and musculoskeletal injury are common causes, all requiring different treatments
- Clinical mastitis in a cow that is systemically ill (fever above 103.5°F, depression, reduced milk) — this is a veterinary emergency that can progress to septicemia
- Any case of suspected Salmonella (bloody, profuse diarrhea with fever in adult cows) — requires culture confirmation, appropriate antibiotics, and biosecurity measures
- Dystocia — prolonged calving with the calf not presenting or presenting abnormally after 30 minutes of active labor
- Suspected LDA — do not delay; abomasal displacement worsens the longer it is untreated
- Any neurological signs (circling, star-gazing, blindness, convulsions) in adult cows — polioencephalomalacia, listeriosis, and other serious conditions require diagnosis
- Bulk tank SCC above 600,000 — this is a herd-level crisis requiring a structured investigation, culture program, and management review with your veterinarian
- Any disease affecting more than 5–10% of a group within a short timeframe — this suggests a management or infectious disease problem that needs systematic investigation
Find a Large Animal Vet Near You
A productive relationship with a knowledgeable large animal veterinarian is one of the highest-value investments a dairy producer can make. Your herd health veterinarian is not just a resource for sick cows — they are your partner in reproductive program design, vaccination protocol optimization, mastitis culture interpretation, nutrition consultation, and regulatory compliance. The cost of regular herd health visits is consistently outweighed by the production and reproduction improvements they facilitate.
FarmVetGuide is the most comprehensive directory of large animal and dairy veterinarians in the United States. Search by state and county to find bovine veterinarians who serve your area — including practitioners who specialize in dairy cattle medicine, reproduction, and udder health. Filter for mobile/farm-call availability, emergency services, and USDA accreditation. Find a dairy cattle vet near you at FarmVetGuide.com.
Frequently Asked Questions About Dairy Cow Health
How many days in milk does ketosis risk peak for dairy cows?
Ketosis risk is highest in the first 2–3 weeks post-calving, with the peak incidence typically occurring between days 3 and 14. This is when the gap between energy demand (rapidly increasing milk production) and energy intake (voluntary dry matter intake still recovering post-calving) is widest. Subclinical ketosis — detectable by cow-side BHB testing but without obvious clinical signs — affects 40–60% of cows in some herds during this period. Routine BHB monitoring of all fresh cows in the first 2 weeks of lactation is a cost-effective herd health practice.
What is the difference between clinical and subclinical mastitis?
Clinical mastitis produces visible signs — abnormal milk (clots, flakes, watery milk, discoloration), and often swelling, heat, and pain in the affected quarter. Severe clinical cases include systemic signs: fever, depression, and reduced milk production. Subclinical mastitis has no visible signs in the cow or milk — the only indicator is an elevated somatic cell count (SCC) on individual cow testing. Subclinical mastitis is far more prevalent than clinical mastitis and causes the majority of the industry's SCC-related production losses.
How long should the dry period be for optimal production in the next lactation?
The traditional dry period length is 60 days. Research over the past two decades has examined shorter dry periods (30–45 days) and found that while shorter dry periods increase energy balance in the transition period (and may reduce metabolic disease), they can compromise milk production and udder health in the subsequent lactation, particularly for high-producing cows. The current evidence supports a 45–60 day dry period as the optimal range for most cows, with individual cow adjustments based on condition score and production level at dry-off.
What causes digital dermatitis (Mortellaro's disease) and how do I control it?
Digital dermatitis is caused by a spirochete bacteria, Treponema species, acting in combination with other anaerobic bacteria. It is highly contagious, spread primarily through contaminated hoof baths and contaminated equipment. Once established in a herd, it is very difficult to eliminate. Control requires: (1) regular hoof bath programs using copper sulfate (5%), formalin (2–4%, with biosafety precautions), or commercial footbath products; (2) prompt topical treatment of active lesions with oxytetracycline spray; (3) regular hoof trimming for early identification; (4) strict biosecurity around introduced cattle. A herd vaccination program (autogenous vaccine) can be considered in herds with severe, persistent outbreaks.
What is Johne's disease and why does it matter for dairy herds?
Johne's disease (paratuberculosis) is a chronic, progressive, ultimately fatal bacterial disease of the small intestine caused by Mycobacterium avium subspecies paratuberculosis (MAP). Cattle are infected in the first months of life (most commonly through contaminated colostrum or milk), remain subclinically infected for years, and eventually develop clinical disease characterized by profuse, watery, non-odorous diarrhea and progressive weight loss despite normal appetite — typically at 3–5 years of age. There is no effective treatment; culling is the only option for clinical cases. The economic impact comes from premature culling, reduced milk production in subclinical animals, and difficulty marketing affected cattle. Control programs involve testing (fecal PCR, ELISA serology), management to minimize calf exposure to adult feces, and pasteurization of colostrum.
When is blanket dry cow therapy justified versus selective dry cow therapy?
Blanket dry cow therapy (treating all quarters of all cows at dry-off with intramammary antibiotics) was the standard for decades and remains appropriate in herds with elevated SCC (bulk tank SCC above 200,000), herds with significant contagious mastitis pathogen burden (S. aureus, S. agalactiae), or herds without a reliable individual cow SCC testing program. Selective dry cow therapy (treating only cows or quarters with elevated SCC or recent clinical mastitis history at dry-off) is appropriate in herds with excellent udder health (bulk tank SCC consistently below 200,000), robust individual cow SCC records, and minimal contagious mastitis pathogen presence on culture. All cows, regardless of dry cow therapy approach, should receive an internal teat sealant (bismuth subnitrate) to provide physical protection during the dry period. The decision should be made in consultation with your herd health veterinarian.