Dexter Cattle Breeding: Small-Scale Herd Management and Genetics

Dexter cattle offer small-scale farmers a compact, dual-purpose breed suited to limited acreage, but successful breeding requires deliberate goal setting, careful genetic selection, and disciplined record keeping. This article provides a practical framework for establishing breeding objectives, managing genetic diversity, and avoiding inherited disorders that are known to affect the breed. The content is directed at farmers, farm employees, veterinarians, advisers, students, and farm planners who work with small herds and need concrete management guidance.

At a Glance

Breed Context and Historical Background

The Dexter breed originated in Ireland and carries a complex demographic history that influences its current genetic structure. Modern representatives of two proposed ancestral populations, the Devon and Kerry, have been analyzed alongside different Dexter subpopulations that experienced distinct demographic events. Research using microsatellite markers found comparatively high levels of genetic variability in most breed units, with expected heterozygosity values ranging from 0.63 to 0.68. However, three small, isolated Dexter populations showed much lower diversity, with expected heterozygosity values from 0.52 to 0.55, and higher differentiation values above 0.13. One of these isolated populations, where strong selection had occurred, also showed evidence of a demographic bottleneck. These findings indicate that the breed is not genetically uniform and that some subpopulations carry less diversity than others. For the small-scale breeder, this means that pedigree knowledge and genetic testing matter more than breed registration alone.

The Dexter breed standard emphasizes a small, hardy animal with a broad body and short legs. The breed is known for producing a high-quality carcass relative to its size and for providing milk suitable for family use. However, the breed also carries a documented history of inherited skeletal disorders, which makes genetic management a central part of responsible breeding.

Setting Breeding Goals for a Small Herd

Defining the Primary Purpose

Before selecting breeding stock, decide what the herd must deliver. Common goals for small-scale Dexter operations include milk production for home use, beef production for direct sale, or a combination of both. Some keepers prioritize show conformation, while others focus on low-input grazing ability or temperament for family handling. These goals are not mutually exclusive, but they require different selection priorities.

A breeding goal worksheet should list each trait in order of importance and assign a relative weight. For example, a herd focused on homestead milk production might weight milk yield at 40 percent, temperament at 25 percent, fertility at 20 percent, and conformation at 15 percent. A beef-focused herd might weight carcass quality at 35 percent, growth rate at 25 percent, fertility at 20 percent, and calving ease at 20 percent. Write the worksheet before purchasing a bull or retaining heifers, and revisit it annually to confirm that the goals still match the farm situation.

Size and Frame Considerations

Dexter cattle are small by design, but size variation exists within the breed. Some lines produce animals at the upper end of the breed standard, while others are notably smaller. Frame size affects feed requirements, calving ease, and market value. A cow that is too large for the available pasture will increase feed costs, while a cow that is too small may produce calves with lower market value.

When evaluating frame size, use body condition scoring alongside weight records. A mature Dexter cow typically maintains condition on less feed than larger breeds, but individual variation is significant. Track mature cow weights and body condition scores at calving, breeding, and weaning to establish a baseline for your herd. Use this data to identify cows that consistently lose excessive condition during lactation or that require more feed than the herd average to maintain adequate body condition.

Milk Production and Maternal Ability

Dexter cows are capable of producing enough milk for a calf and modest household use, but milk yield varies considerably between lines. Selection for milk production should balance calf growth against the cow's ability to maintain body condition and rebreed. A cow that produces excessive milk may wean a heavy calf but fail to conceive on schedule because of negative energy balance.

Record calf birth weights and weaning weights to estimate maternal milk production indirectly. A calf that grows steadily from birth to weaning without supplemental feed indicates adequate milk production. Compare calf performance across cows within the same management group to identify superior mothers. Also observe udder conformation at calving and during lactation. A well-attached udder with small teats is easier to milk by hand or machine and is less prone to injury.

Temperament and Handling Traits

Temperament is a heritable trait that affects daily handling, safety, and the overall enjoyment of keeping cattle. Dexter cattle are generally docile, but individual animals vary. Select replacements from cows that are calm during handling, milking, and calf processing. Avoid retaining offspring from animals that are consistently aggressive, flighty, or difficult to restrain.

Temperament evaluation should be systematic. Score each animal during routine handling using a simple scale, such as 1 for calm and easy to handle, 2 for slightly restless but manageable, and 3 for agitated or dangerous. Record these scores in the herd book and use them when making culling decisions. A single incident of aggressive behavior may be situational, but a pattern of difficult handling warrants culling from the breeding herd.

Genetic Diversity and Population Management

Understanding Breed Subdivision

The Dexter breed is subdivided into populations with different demographic histories, and these subdivisions affect genetic diversity. Research has shown that some Dexter subpopulations carry higher diversity than others and that isolated populations have experienced genetic drift. For the small-scale breeder, this means that the genetic value of a potential breeding animal depends on its pedigree and population background, beyond its registration papers.

When selecting a bull or purchasing replacement heifers, ask about the animal's population background and pedigree depth. Animals from small, isolated populations may carry less diversity and may be more closely related to your existing herd than expected. Use pedigree analysis to identify common ancestors within five generations and calculate the inbreeding coefficient for potential matings.

Linebreeding and Its Risks

Linebreeding is a form of inbreeding that concentrates the genetics of a particular ancestor while attempting to limit the overall increase in homozygosity. Some Dexter breeders use linebreeding to fix desirable traits such as small size, coat color, or milk production. However, linebreeding also increases the risk of exposing recessive genetic disorders.

The Dexter breed carries several known recessive mutations, including those associated with bulldog dwarfism and pulmonary hypoplasia with anasarca syndrome. Research has confirmed that mutations in the aggrecan-1 gene are associated with bulldog-type dwarfism in Dexter cattle. A study of miniature Scottish Highland cattle also confirmed that both the sire and dam were carriers of an aggrecan-1 gene mutation previously associated with dwarfism and bulldog calf malformations in Dexter cattle, demonstrating that this mutation is found in breeds beyond Dexter. Pulmonary hypoplasia and anasarca syndrome, characterized by extreme subcutaneous edema and underdeveloped lungs, has been reported in Australian Dexter cattle and other breeds. A case report from Slovenian Cika cattle described affected calves from a mating where the sire was the same bull, the dams were paternal half-sisters, and one calf resulted from a dam-son mating. These cases illustrate the danger of close matings when recessive mutations are present in the herd.

Linebreeding is not inherently wrong, but it requires genetic testing and careful pedigree analysis. If you choose to linebreed, test all breeding stock for known recessive mutations and avoid mating carriers to carriers. Track the coefficient of inbreeding for each calf and set a maximum threshold for your herd. When the coefficient approaches your threshold, introduce unrelated genetics.

Coat Color Genetics

Coat color in Dexter cattle is influenced by known genetic pathways. Research has identified that the tyrosinase related protein 1 gene, which is involved in the coat color pathway, is associated with dun coat color in Dexter cattle. In a study of Dexter cattle, all 25 animals with a dun brown coat color were homozygous for a specific amino acid change in this gene. None of the 70 black or red Dexter cattle examined were homozygous for this change, and the mutation was not found in any of the 121 cattle of other breeds that were examined. One Dexter that was homozygous for the change appeared red because of its genotype at another coat color gene, which led to the production of only one type of pigment.

For breeders, this means that coat color can be managed predictably if the genetics of the breeding stock are known. Black and red are common colors in the breed, and dun is a dilute color that requires the specific genetic change. If coat color is a breeding goal, test potential parents to understand their color genotypes and predict the range of colors expected in offspring.

Inherited Disorders and Genetic Testing

Bulldog Dwarfism

Bulldog dwarfism is a lethal condition in Dexter cattle caused by a mutation in the aggrecan-1 gene. Calves affected with this condition are typically aborted or stillborn and have severe skeletal abnormalities, including a shortened vertebral column and abnormal limb development. The condition is inherited in a recessive manner, meaning that carriers do not show symptoms but can produce affected calves when bred to another carrier.

Research on skeletal disorders in cattle has identified that mutations in the aggrecan gene are associated with bulldog-type dwarfism in Dexter cattle. A review of the molecular genetic basis of dwarfism in livestock noted that several mutations in the aggrecan gene are associated with bulldog-type dwarfism in Dexter cattle and dwarfism in American miniature horses. The same review described how dwarfism can be categorized as proportionate, an overall size reduction without changes in body proportions, or disproportionate, a size reduction in one or more limbs with changes in body proportions. Many forms of dwarfism are inherited and result from structural disruptions or disrupted signaling pathways.

Testing for the aggrecan-1 mutation is essential for any Dexter breeding program. DNA tests are available through commercial laboratories, and the results are reported as either free, carrier, or affected. A carrier animal has one copy of the mutation and one normal copy. When two carriers are mated, each calf has a 25 percent chance of being affected, a 50 percent chance of being a carrier, and a 25 percent chance of being free of the mutation. The only way to eliminate the risk of affected calves is to avoid mating carriers to carriers.

Pulmonary Hypoplasia and Anasarca Syndrome

Pulmonary hypoplasia and anasarca syndrome is a rare congenital abnormality in cattle characterized by hydrops fetalis, including extreme subcutaneous edema and underdeveloped or poorly formed lungs. The condition has been reported in Australian Dexter cattle, Belted Galloway, Maine-Anjou, and Shorthorn breeds. A case report from Slovenian Cika cattle described two affected calves, one aborted in the seventh month of pregnancy and one delivered by cesarean section at term. Both calves showed severe anasarca, fluid accumulation in the chest and abdominal cavities, hypoplastic lungs, and an enlarged heart. The pedigree analysis showed that the calves were sired by the same bull, the dams were paternal half-sisters, and one calf resulted from a dam-son mating.

The occurrence of this syndrome in closely related matings highlights the importance of avoiding excessive inbreeding. While the genetic basis of the condition is not fully characterized, the pattern of occurrence in related animals suggests a genetic component. Breeders should report any suspected cases to their veterinarian and to breed associations to support ongoing research.

Other Skeletal Disorders

Beyond the well-characterized bulldog dwarfism, Dexter cattle can be affected by other skeletal disorders. A case report described the first reported occurrence of polydactyly in Dexter cattle in the United States or abroad. A three-year-old Dexter cow and her yearling heifer calf exhibited extra digits on their front limbs. Neither animal was linebred within five generations, and the cow produced a second calf from a different sire that did not appear polydactylous. The affected animals remained in the breeding herd for further study because they did not suffer from limited mobility or require hoof treatments.

This case illustrates that not all skeletal abnormalities in Dexter cattle are caused by known mutations. Some conditions appear spontaneously, and their genetic basis may be complex. Breeders should document any congenital abnormalities in their herds and report them to their veterinarian and breed association.

Genetic Testing Protocols

Establish a genetic testing protocol for your herd and follow it consistently. Test all potential breeding stock for known recessive mutations before their first mating. Retest animals when new tests become available for conditions that affect the breed. Keep copies of all test results in the herd record book and share them with potential buyers of breeding stock.

When purchasing a bull, request his genetic test results and those of his parents. If the bull is a carrier for a recessive mutation, you can still use him, but you must test all replacement heifers and avoid retaining carrier daughters for breeding. Alternatively, choose a bull that is free of known mutations to simplify genetic management.

Practical Breeding Workflow

Step 1: Complete the Breeding Goal Worksheet

Write a one-page worksheet that lists your primary breeding goals, the relative weight of each goal, and the traits you will measure to track progress. Include a section for genetic testing requirements and a maximum acceptable inbreeding coefficient. Review the worksheet with your veterinarian or an experienced Dexter breeder before implementing it.

Step 2: Evaluate the Current Herd

Score each animal in the herd for conformation, temperament, body condition, and hair shedding. Record birth weights, weaning weights, and mature weights. Review the pedigree of each animal and calculate the coefficient of inbreeding for potential matings. Identify animals that carry known recessive mutations and mark their records clearly.

Step 3: Select Breeding Stock

Use the breeding goal worksheet to select bulls and replacement heifers. Prioritize animals that are free of known recessive mutations, that come from diverse genetic backgrounds, and that excel in the traits you have weighted most heavily. Avoid selecting animals solely on appearance without considering their genetic test results and pedigree relationships to the rest of the herd.

Step 4: Plan Matings

For each breeding season, plan matings that avoid carrier-to-carrier pairings and that keep the coefficient of inbreeding below your threshold. If you use natural service, confirm that the bull is not closely related to the cows he will serve. If you use artificial insemination, review the sire's pedigree and genetic test results before purchasing semen.

Step 5: Monitor Calving and Calf Performance

Record calving ease scores, birth weights, and any congenital abnormalities. Weigh calves at birth and at weaning to assess maternal milk production and calf growth. Investigate any calf that is stillborn, aborted, or malformed to determine the cause and to identify potential genetic problems in the herd.

Step 6: Review and Adjust

At the end of each breeding cycle, review the records and compare the results to the breeding goal worksheet. Identify traits that improved, traits that did not respond to selection, and any genetic problems that appeared. Adjust the breeding plan accordingly and update the worksheet if the farm situation has changed.

Records and Measurements

Essential Records for Breeding Decisions

Maintain a herd record book that includes the following information for each animal: identification number, birth date, sire and dam, genetic test results, birth weight, weaning weight, mature weight, body condition scores, calving dates, calving ease scores, and temperament scores. Record any health problems, especially those that might have a genetic basis.

Use a spreadsheet or paper forms to track the data consistently. The records are only useful if they are complete and accurate, so establish a routine for recording information at each handling event. Weigh calves at birth and at weaning, score body condition at calving and breeding, and note any abnormalities immediately.

Calculating Inbreeding Coefficients

The coefficient of inbreeding estimates the probability that an animal has two identical copies of a gene inherited from a common ancestor. Pedigree analysis software can calculate this value from the pedigree, or you can use a manual method with a five-generation pedigree. For small herds, a simple approach is to identify common ancestors within five generations and estimate the relationship between the sire and dam.

Set a maximum acceptable inbreeding coefficient for your herd. Many breeders use a threshold of 5 to 10 percent for individual matings, but the appropriate threshold depends on the genetic diversity of your herd and your tolerance for risk. If the coefficient approaches your threshold, introduce unrelated genetics through a new bull or purchased heifers.

Hair Shedding Scores

Hair shedding is a practical trait for herds in warm climates. Research on Dexter cattle evaluated the relationship of hair shedding with fertility and maternal performance in 72 cows. Cows were classified as high or low hair shedders based on scoring dates in May, June, and July. The study found that hair shedding levels were lower for two-year-old cows than for cows seven years and older on the first three scoring dates, and lower for lactating cows than for dry cows on the first two dates. Cow fertility was higher for high-shedding cows than for low-shedding cows for the July classification, and when records from cows that were dry in 2019 were excluded, fertility was higher for high-shedding cows at all four scoring dates. The associations of hair shedding with preweaning calf performance were minimal.

For herds in hot climates, score hair shedding on a scale from 1 for a completely shed winter coat to 5 for a full winter coat retained into summer. Record the scores at the same dates each year and use them to select cows that shed earlier and maintain fertility during summer breeding.

Common Failure Patterns in Dexter Breeding Programs

Failure to Test for Recessive Mutations

The most serious failure pattern is breeding carrier animals without testing. A single carrier-to-carrier mating can produce an affected calf, which is a welfare concern and a financial loss. The risk increases when linebreeding is practiced without genetic testing. Test all breeding stock and document the results before any mating occurs.

Excessive Inbreeding Without Pedigree Analysis

Some breeders linebreed aggressively to fix desirable traits, but this increases the risk of exposing recessive disorders and reduces fertility. Research on the genetic structure of the Dexter breed found that small, isolated populations showed much lower diversity and higher differentiation, with evidence of a demographic bottleneck in one population. These findings demonstrate that inbreeding has real consequences for the breed. Use pedigree analysis and inbreeding coefficients to guide mating decisions.

Selecting for Size Without Considering Health

Selecting for extremely small animals can inadvertently select for skeletal disorders. Dwarfism in livestock can be proportionate or disproportionate, and many forms are inherited. A review of dwarfism in livestock noted that impairment of bone growth at a young age leads to dwarfism in adulthood and that many forms result from structural disruptions or disrupted signaling pathways. Avoid selecting animals with disproportionate growth or obvious skeletal defects, and investigate any calf with abnormal body proportions.

Ignoring Maternal Traits

A cow that produces a heavy calf but loses excessive condition and fails to rebreed is not a productive herd member. Milk production must be balanced against fertility and body condition maintenance. Record calf weaning weights and cow body condition scores to identify cows that achieve this balance.

Neglecting Temperament

Temperament problems are difficult to correct and can make herd management unsafe. A single difficult animal can disrupt handling routines and increase the risk of injury to people and other cattle. Cull animals with persistent behavioral problems and select replacements from calm dams.

Welfare and Safety Considerations

Calving Management

Dexter cattle are generally easy calvers because of their small size, but dystocia can occur. Research on dystocia in nine British breeds of cattle examined the relationship between dystocia and the dimensions of the dam and calf. While the specific findings are not summarized here, the general principle is that calf size relative to the dam's pelvic dimensions influences calving difficulty. Monitor all calvings and intervene when labor does not progress normally. Have a calving kit ready and know when to call a veterinarian.

Handling Facilities

Small herds still require safe handling facilities. A well-designed chute or head gate allows you to examine, treat, and test animals without excessive stress. Train all handlers in low-stress cattle handling techniques and establish protocols for moving cattle through the facilities. Never work cattle alone in a confined space with an aggressive animal.

Biosecurity

Biosecurity is important for small herds because the introduction of a single infected animal can have serious consequences. Quarantine new animals for at least 30 days before introducing them to the herd. Monitor the herd for signs of disease and report unusual illness to your veterinarian. The USDA National Agricultural Library provides resources on animal health and welfare that can help you develop a biosecurity plan. The World Organisation for Animal Health also publishes standards and guidance on animal health and welfare that are relevant to livestock producers.

Food Safety

If you sell milk or meat from your Dexter herd, follow applicable food safety regulations. The U.S. Food and Drug Administration provides animal and veterinary resources that include information on food safety for livestock producers. Consult your local agricultural extension office for guidance on regulations that apply to your operation.

Professional Escalation Criteria

When to Call a Veterinarian

Call a veterinarian immediately if a cow is in labor and has not made progress within a reasonable time, if a calf is presented abnormally, or if a cow shows signs of illness such as fever, depression, or loss of appetite. Also call a veterinarian if a calf is born with obvious congenital abnormalities, if a cow aborts, or if a calf dies unexpectedly. These situations require professional assessment to protect the health of the animal and to identify potential herd problems.

When to Consult a Geneticist

Consult a geneticist or a veterinarian with expertise in cattle genetics if you are planning a linebreeding program, if you have produced a calf with a suspected genetic disorder, or if you are uncertain about the genetic relationships in your herd. A geneticist can help you interpret test results, calculate inbreeding coefficients, and design a mating plan that balances genetic progress with risk management.

When to Report to a Breed Association

Report any congenital abnormalities to your breed association, even if the cause is unknown. Breed associations rely on member reports to identify emerging genetic problems and to support research. The case report on polydactyly in Dexter cattle noted that the affected animals were the first reported occurrence of this condition in the breed in the United States or abroad, which demonstrates the value of reporting unusual cases.

Limitations of Current Knowledge

The genetic basis of some conditions in Dexter cattle is not fully characterized. While the aggrecan-1 mutation associated with bulldog dwarfism is well established, other skeletal disorders may involve multiple genes or complex inheritance patterns. A recent study that proposed a nosology of genetic skeletal disorders in cattle and sheep identified 43 different disorders associated with 45 different genes, but the study also noted that for eight cases affected by six disorders, no variant could be identified. This finding indicates that the genetic basis of some skeletal disorders remains unknown.

Similarly, the genetic basis of pulmonary hypoplasia and anasarca syndrome is not fully understood. The condition has been reported in several breeds, but the mode of inheritance has not been confirmed. Breeders should be cautious about assuming that a negative test result for known mutations eliminates the risk of congenital disorders.

Frequently Asked Questions

What is the most important genetic test for Dexter cattle?

The most important genetic test is for the aggrecan-1 mutation associated with bulldog dwarfism. This mutation is well documented in Dexter cattle and causes a lethal condition in affected calves. Test all breeding stock before mating and avoid carrier-to-carrier pairings.

Can I linebreed Dexter cattle safely?

Linebreeding can be safe if you test for known recessive mutations, analyze pedigrees, and keep inbreeding coefficients below your threshold. The risk is that linebreeding concentrates recessive mutations and reduces genetic diversity. Research on the Dexter breed has shown that small, isolated populations have lower diversity and higher differentiation, so linebreeding should be approached with caution.

How do I know if my cow is a good milk producer?

Record calf birth weights and weaning weights to estimate maternal milk production indirectly. A calf that grows steadily without supplemental feed indicates adequate milk production. Compare calf performance across cows within the same management group and observe udder conformation at calving and during lactation.

What should I do if my cow produces a calf with a congenital abnormality?

Call your veterinarian immediately to assess the calf and the cow. Document the abnormality with photographs and written records. Report the case to your breed association and consider genetic testing of the parents to determine whether the condition has a known genetic basis.

How can I improve fertility in my Dexter herd?

Maintain cows in adequate body condition at breeding, avoid excessive inbreeding, and select for traits associated with fertility. Research on Dexter cattle found that cows with higher hair shedding levels in spring and summer expressed higher summer fertility, so hair shedding scores may be a useful selection tool in warm climates.

What is the difference between proportionate and disproportionate dwarfism?

Proportionate dwarfism is an overall size reduction without changes in body proportions, while disproportionate dwarfism is a size reduction in one or more limbs with changes in body proportions. Many forms of dwarfism in livestock are inherited and result from structural disruptions or disrupted signaling pathways.

How often should I test my breeding stock for genetic disorders?

Test all potential breeding stock before their first mating and retest when new tests become available for conditions that affect the breed. Keep copies of all test results in the herd record book and share them with potential buyers of breeding stock.

What records should I keep for breeding decisions?

Maintain a herd record book with identification numbers, birth dates, parentage, genetic test results, birth weights, weaning weights, mature weights, body condition scores, calving dates, calving ease scores, and temperament scores. Record any health problems and congenital abnormalities. Use these records to evaluate the progress of your breeding program against your goals.

Related Farming Guides

• Camel Breeding Management: Genetics, Reproduction, and Herd Improvement
• Cervid Breeding Management: Genetics, Reproduction, and Herd Improvement
• Goat Genetics and Breeding: Selection for Production and Health Traits
• Poultry Genetics and Breeding: Selection Strategies for Production Traits
• Sheep Genetics and Breeding: Selection for Meat, Milk, and Wool Traits

References and Further Reading

• FAO Animal Production and Health. Food and Agriculture Organization of the United Nations.
• Animal Health and Welfare. USDA National Agricultural Library.
• Animal and Veterinary Resources. U.S. Food and Drug Administration.
• Animal Health and Welfare. World Organisation for Animal Health.
• Animal Production and Protection. USDA Agricultural Research Service.
• TYRP1 is associated with dun coat colour in Dexter cattle or how now brown cow?. Animal genetics, 2003.
• Current insights into the molecular genetic basis of dwarfism in livestock.. Veterinary journal (London, England : 1997), 2017.
• Familial chondrodysplasia in Holstein calves.. Journal of veterinary diagnostic investigation : official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc, 2004.
• Spontaneous Appearance and Transmission of Polydactyly in Dexter Cattle.. Case reports in veterinary medicine, 2020.
• Hydrops associated with chondrodysplasia of the fetus in a miniature Scottish Highland cow.. Journal of the American Veterinary Medical Association, 2016.
• Pulmonary hypoplasia and anasarca syndrome in Cika cattle.. Acta veterinaria Scandinavica, 2016.
• The population genetic effects of ancestry and admixture in a subdivided cattle breed.. Animal genetics, 2009.
• Pruritus is a common feature in sheep infected with the BSE agent.. BMC veterinary research, 2008.
• Histopathological characterisation of omphalitis in piglets.. 2025.
• 143 Retrospective Look at Cow-Calf Performance in Spring-Calving Dexter Cattle Scored for Winter Hair Shedding Level. 2023.
• 144 Assessment of Backgrounding Management on Growth Performance and Health in Southeastern Beef Calves. 2023.
• Associations between Ultrasonographically Diagnosed Lung Lesions, Clinical Parameters and Treatment Frequency in Veal Calves in an Austrian Fattening Farm.. 2024.
• Foraging behavior of Highland cattle in silvopastoral systems in the Alps.. 2024.
• Exploring skeletal disorders in cattle and sheep: a WGS-based framework for diagnosis and classification.. 2025.
• Association of Hair Shedding Level with Cow-Calf Performance in Summer-Bred Dexter Cattle. Ruminants, 2026.
• Dystocia in nine British breeds of cattle and its relationship to the dimensions of the dam and calf.. Veterinary Record, 1989.

This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.