Zubair Khalid

Virologist/Molecular Biologist | Veterinarian | Bioinformatician

Conventional & Molecular Virology • Vaccine Development • Computational Biology

Dr. Zubair Khalid is a veterinarian and virologist specializing in conventional and molecular virology, vaccine development, and computational biology. Dedicated to advancing animal health through innovative research and multi-omics approaches.

Dr. Zubair Khalid - Veterinarian, Virologist, and Vaccine Development Researcher specializing in Computational Biology, Multi-omics, Animal Health, and Infectious Disease Research

Category: Blog

Lagomorphs: Rabbits, Hares, and Pikas Explained

The order Lagomorpha contains about 90 living species divided into two families: the pikas (Ochotonidae) and the rabbits, hares, and jackrabbits (Leporidae). Lagomorphs are native to all continents except Antarctica and occur from the equator to the Arctic, spanning a wide range of environmental conditions. They are important economically and scientifically as major human food resources, valued game species, pests of agricultural significance, model laboratory animals, and key elements in food webs. A quarter of lagomorph species are listed as threatened. This article explains the defining characteristics of lagomorphs, their evolutionary history, and how they differ from rodents, with practical relevance for farmers, researchers, and wildlife professionals who work with these animals.

At a Glance

The table below summarizes the key distinctions between the two lagomorph families and the closely related rodent order.

Feature Family Leporidae (Rabbits and Hares) Family Ochotonidae (Pikas) Order Rodentia (Rodents)
Representative species European rabbit, cottontails, jackrabbits American pika, plateau pika Mice, rats, squirrels, beavers
Dentition Two pairs of upper incisors (one large pair behind a smaller pair) Two pairs of upper incisors One pair of upper incisors
Birth condition Altricial in rabbits, precocial in hares Altricial Varies by species
Habitat range All continents except Antarctica Cool mountainous and steppe regions All continents
Economic role Meat, fur, game, laboratory models, pests Wild herbivores, prey species Pests, laboratory models, pets
Conservation status Several species threatened Several species threatened Varies widely

Defining Characteristics of Lagomorphs

Lagomorphs share a set of anatomical and physiological features that distinguish them from other mammalian orders. The most recognizable trait is their dentition. Unlike rodents, which have a single pair of upper incisors, lagomorphs possess two pairs. The second pair, called peg teeth, sits directly behind the first pair and is smaller. This dental arrangement is a primary diagnostic feature used in field identification and taxonomic classification.

The digestive system of lagomorphs is adapted for processing fibrous plant material through coprophagy, the consumption of soft fecal pellets that undergo a second pass through the digestive tract. This behavior allows efficient extraction of nutrients from grasses, forbs, and woody vegetation. Farmers raising rabbits for meat or fiber should understand that this digestive strategy requires access to high-fiber feed and that disruption of normal cecotrophy can lead to digestive disorders.

Lagomorphs have large eyes positioned laterally on the skull, providing a wide field of vision suited to detecting predators. Their ears vary considerably between species, from the short rounded ears of pikas to the long ears of hares and jackrabbits. The hind limbs are elongated in hares and jackrabbits, enabling rapid escape locomotion, while rabbits have more compact builds suited to burrowing.

Evolutionary History and Taxonomy

The order Lagomorpha has a deep evolutionary history that places it within the clade Glires, which also includes rodents. Molecular and morphological evidence supports a close relationship between lagomorphs and rodents, but the two orders diverged tens of millions of years ago and have followed distinct evolutionary trajectories. Conserved protein sequence signatures reliably demarcate different clades of rodents and Glires species, confirming their evolutionary relationships while also highlighting the genetic distance between the groups.

The Lagomorph Genomics Consortium (LaGomiCs) was established as an international collaborative effort to sequence the genomes of all extant and selected extinct lagomorph species. At the time of the consortium's founding, only two lagomorph genomes had been sequenced and assembled: the European rabbit and the American pika. The order has notable taxonomic problems presenting significant difficulties for defining species due to broad phenotypic variation, overlap of morphological characteristics, and relatively recent speciation events. This means that field identification of lagomorph species can be challenging, and wildlife managers should rely on multiple characteristics instead of a single trait.

Recent genomic research has revealed unusual evolutionary dynamics in lagomorphs. Independent duplications of the immunoglobulin kappa constant gene occurred in both Ochotonidae and Leporidae, giving rise to rabbit IGKC1 and IGKC2. Selection analyses revealed pervasive purifying selection interspersed with codons under positive selection, indicating a balance between structural conservation and lineage-specific functional diversification. These findings have implications for understanding immune function in domestic rabbits and wild lagomorph populations.

Rabbits: The Leporidae Family

The family Leporidae includes rabbits, hares, and jackrabbits. Rabbits are generally smaller than hares, have shorter ears, and give birth to altricial young that are born hairless and blind. Hares are typically larger, have longer ears and hind legs, and give birth to precocial young that are furred with open eyes shortly after birth.

The European rabbit is the most economically significant lagomorph species. Domestication of the rabbit has led to a multi-purpose species that includes many breeds and lines with broad phenotypic diversity, mainly for external traits such as coat colors and patterns, fur structure, and morphometric traits valued by fancy rabbit breeders. Genomic studies of Italian commercial meat rabbit breeds and fancy rabbit breeds identified 309 genomic regions containing signatures of selection, including genes known to affect coat color, coat structure, and body size. These findings demonstrate that human-driven selection has left distinct signatures in the rabbit genome.

For farmers, understanding breed differences matters for production decisions. Meat breeds have been selected for growth rate and carcass traits, while fancy breeds carry genes for specific coat colors and body conformations. The genetic markers identified in recent research may eventually support selection decisions, but producers should currently rely on established breed standards and performance records.

Hares and Jackrabbits

Hares and jackrabbits belong to the genus Lepus and are adapted to open habitats where speed is the primary defense against predators. They do not burrow but instead use shallow depressions called forms. Their young are born fully furred with open eyes and can move within hours of birth.

Hares are important game species across their range and serve as prey for many predators. In Mediterranean ecosystems, hares and rabbits coexist and share some pathogens. Emerging lagoviruses, particularly rabbit hemorrhagic disease virus 2 (RHDV2/GI.2), have caused substantial mortality in European rabbits and, sporadically, hares. Viral dynamics of recombinant strains in wild populations show that different recombinant lineages have replaced each other over time. In northeastern Spain, four distinct recombinant strains were detected in European brown hares, while rabbits were infected by only three of these strains. The findings suggest that recombinant strains may have been progressively replaced over time in leporid species from northeastern Iberia.

Wildlife managers and farmers in areas where RHDV2 is present should monitor local lagomorph populations for signs of disease and report unusual mortality events to veterinary authorities. The presence of multiple recombinant strains complicates disease management because immunity to one strain may not protect against another.

Pikas: The Ochotonidae Family

Pikas are small lagomorphs in the family Ochotonidae, distinguished from leporids by their short rounded ears, lack of visible tail, and compact body shape. They inhabit cool mountainous and steppe regions across Asia and North America. Pikas are diurnal and often conspicuous as they gather vegetation into haypiles for winter food storage.

The American pika has been the subject of considerable research attention because of its sensitivity to warm temperatures. Pikas are adapted to cold environments and can die from heat exposure when temperatures exceed their thermal tolerance. Climate change poses a direct threat to pika populations in lower elevation habitats.

Recent virological surveys detected a putative novel gammaherpesvirus in pikas with approximately 80 percent similarity to known gammaherpesviruses. This finding expands knowledge of herpesvirus diversity in lagomorphs and raises questions about the health impacts of these viruses on wild populations. Given their potential role in immunosuppression and disease interactions, further research is needed to assess their impact on host health and population dynamics.

Lagomorphs Versus Rodents

The distinction between lagomorphs and rodents is a common source of confusion. Both groups belong to the clade Glires, but they differ in several fundamental characteristics.

The most reliable distinguishing feature is dentition. Rodents have a single pair of upper incisors, while lagomorphs have two pairs. The second pair of upper incisors in lagomorphs is small and sits directly behind the first pair. This difference is visible in skull specimens and can be used for species identification.

Reproductive strategies also differ. Many rodents have large litters and rapid reproductive cycles, while lagomorphs generally have smaller litters with longer gestation periods. Rabbits are induced ovulators, meaning that ovulation occurs in response to mating instead of on a regular estrous cycle. This has practical implications for rabbit breeders who must manage breeding timing carefully.

Digestive physiology differs as well. Both groups practice coprophagy, but lagomorphs produce two distinct types of feces: hard fecal pellets and soft cecotropes that are reingested. Rodents do not produce cecotropes in the same manner. Farmers switching from rodent husbandry to rabbit production should understand these digestive differences to avoid feeding errors.

Lagomorphs as Model Organisms in Research

Lagomorphs, particularly rabbits, serve as important model organisms in biomedical research. The New Zealand white rabbit has been used to study adult mammalian neurogenesis, with unexpected features of structural plasticity found in the rabbit cerebrum and cerebellum despite the relative closeness of the orders Lagomorpha and Rodentia. This research has implications for understanding brain repair and regeneration.

Rabbits are also used in cardiovascular research. Studies of recombinant factor VIIa effects on anastomotic patency of vascular grafts used a rabbit model, and research on hypertrophic cardiomyopathy versus athlete's heart has relevance to understanding cardiac adaptation. The rabbit heart has electrophysiological properties that differ from rodents, making it a valuable model for studying cardiac arrhythmias and drug effects.

Muscle physiology research has used rabbits alongside mice and rats to characterize the force-velocity relationship in mammalian muscle. Studies spanning three orders of magnitude in body mass demonstrated that rates of relative force development were consistent across species during eccentric lengthening, supporting hypotheses about cross-bridge and titin activation. This research informs understanding of muscle function relevant to livestock production and veterinary medicine.

Burn research has used mouse, rat, and pig models, with each species offering distinct advantages and limitations for translational applications. While rabbits are not the primary model for burn research, they are used in other areas of wound healing and tissue repair research.

Practical Management Considerations for Rabbit Farmers

Rabbit production requires attention to several management areas that directly affect animal health and productivity. The following considerations apply to commercial meat rabbit operations and small-scale production systems.

Housing systems must provide adequate space, ventilation, and protection from predators and extreme weather. Rabbits are sensitive to heat stress, and temperatures above their thermal comfort zone can reduce feed intake, fertility, and growth rates. Producers in hot climates should provide shade, ventilation, and cooling measures during warm periods.

Nutrition is critical for rabbit health and productivity. Rabbits require high-fiber diets to maintain normal digestive function. The practice of cecotrophy means that rabbits reingest soft fecal pellets to extract additional nutrients, particularly B vitamins and microbial protein. Disruption of this process through dietary changes, stress, or illness can lead to nutritional deficiencies and digestive disorders.

Breeding management should account for the reproductive physiology of rabbits. Does are induced ovulators, and successful mating depends on proper timing and management. Record keeping is essential for tracking breeding dates, litter sizes, and individual animal performance.

Biosecurity measures protect rabbit operations from infectious diseases. Rabbit hemorrhagic disease virus and myxomatosis are significant threats in many regions. Producers should implement quarantine procedures for new animals, control visitor access, and work with veterinarians to develop vaccination protocols appropriate for their region.

Records and Measurements for Lagomorph Operations

Maintaining accurate records is essential for successful lagomorph management, whether for commercial production, research colonies, or conservation programs. The following measurements and records support informed decision making.

Body weight should be recorded at regular intervals for growing animals and breeding stock. Growth rates vary by breed and production system, and deviations from expected growth patterns may indicate health problems or management issues. Feed intake records help identify changes in appetite that may signal illness.

Reproductive records should include breeding dates, kindling dates, litter sizes, and weaning weights. These records support evaluation of doe productivity and identification of animals that should be culled or retained for breeding. Mortality records should document causes of death when known, as patterns of mortality may indicate disease outbreaks or management problems.

Health records should document vaccinations, treatments, and observations of illness. These records support veterinary consultations and help identify recurring health issues. For research colonies, additional records may be required to document experimental procedures and animal welfare monitoring.

Common Failure Patterns in Lagomorph Management

Several recurring problems affect lagomorph operations. Recognizing these patterns early allows corrective action before losses become severe.

Digestive disorders are common in rabbits and often result from dietary errors. Sudden changes in feed, inadequate fiber, or excessive carbohydrate intake can disrupt the cecal microbial population and lead to enteritis. Producers should introduce dietary changes gradually and maintain consistent feed quality.

Respiratory disease is a frequent problem in rabbit operations, particularly in facilities with poor ventilation. High ammonia levels from urine accumulation irritate the respiratory tract and increase susceptibility to bacterial infections. Adequate ventilation and regular cleaning reduce respiratory disease risk.

Reproductive failure can result from multiple factors including heat stress, poor nutrition, and inadequate breeding management. Does that fail to conceive or produce small litters should be evaluated for health problems and management issues. Body condition scoring helps identify does that are too thin or too fat for optimal reproductive performance.

Heat stress is a particular concern in warm climates. Rabbits have limited ability to dissipate heat and are more sensitive to high temperatures than many other livestock species. Signs of heat stress include panting, drooling, and reduced feed intake. Emergency measures include providing cool water, improving ventilation, and moving animals to cooler areas.

Welfare and Safety Considerations

Lagomorph welfare is a growing concern for producers, researchers, and consumers. Understanding the behavioral and physiological needs of these animals supports better management and compliance with welfare standards.

Rabbits are prey species with strong flight responses. Handling should be calm and confident to avoid causing fear and stress. Improper handling can cause injury to both the animal and the handler. Rabbits have fragile spines and can be seriously injured by rough handling or improper restraint.

Social housing considerations vary by species and production system. Rabbits are social animals that benefit from companionship, but males may fight when housed together. Does with litters require privacy and protection from disturbances. Pikas are territorial and should be housed individually in captivity.

Environmental enrichment supports normal behavior and reduces stress-related problems. Providing materials for digging, hiding, and chewing allows rabbits to express natural behaviors. Barren environments are associated with stereotypic behaviors such as bar biting and overgrooming.

Safety considerations for handlers include zoonotic disease risks and physical injury from bites and scratches. Proper hygiene practices, including hand washing after animal contact, reduce disease transmission risks. Protective equipment such as gloves may be appropriate for certain tasks.

Disease Surveillance and Biosecurity

Disease surveillance is critical for protecting lagomorph populations, whether domestic or wild. Recent research has expanded knowledge of pathogens affecting lagomorphs, including herpesviruses and lagoviruses.

Gammaherpesviruses co-evolve with their hosts, resulting in species-specific associations and restricted host tropism. In lagomorphs, six herpesviruses have been identified, with one associated with mortality in European rabbits while others cause asymptomatic infections. Another herpesvirus has been hypothesized to contribute to high morbidity and mortality in Iberian hares when in the presence of concomitant infections such as myxomatosis. Large-scale screening of over 1,000 DNA samples from lagomorph species detected herpesviruses in 7.24 percent of samples, revealing a putative novel virus in pikas and showing circulation of a known herpesvirus in European and mountain hares for the first time.

Rabbit hemorrhagic disease virus 2 has caused substantial mortality in European rabbits and hares. Recombination is common among RNA viruses, including lagoviruses, and shapes their evolution, influencing pathogenicity, epidemiology, and host range. Producers and wildlife managers should be aware of the disease status in their region and report unusual mortality events to veterinary authorities.

Biosecurity measures for rabbit operations include controlling visitor access, quarantining new animals, and preventing contact between domestic rabbits and wild lagomorphs. Wild rabbits and hares can serve as reservoirs for diseases that affect domestic stock.

Professional Escalation Criteria

Certain situations require professional veterinary involvement. Producers and managers should seek veterinary assistance when they observe signs of serious disease, unexplained mortality, or conditions that do not respond to standard management interventions.

Sudden death in multiple animals warrants immediate veterinary investigation. Diseases such as rabbit hemorrhagic disease can cause rapid mortality with few warning signs. Early diagnosis supports implementation of control measures and reduces further losses.

Reproductive problems that persist despite management corrections should be evaluated by a veterinarian. Causes may include infectious disease, nutritional deficiencies, or genetic factors that require professional diagnosis.

Digestive disorders that do not respond to dietary adjustment may indicate infectious causes or other conditions requiring veterinary treatment. Prolonged anorexia, diarrhea, or abdominal distension are signs that warrant professional evaluation.

Respiratory disease that spreads through a herd despite improved ventilation and hygiene should be investigated to identify the causative organism and guide treatment decisions. Chronic respiratory disease can cause substantial production losses if not properly managed.

Frequently Asked Questions

What is the difference between a rabbit and a hare?

Rabbits and hares are both members of the family Leporidae but differ in several characteristics. Rabbits are generally smaller, have shorter ears, and give birth to altricial young that are born hairless and blind. Hares are typically larger, have longer ears and hind legs, and give birth to precocial young that are furred with open eyes shortly after birth. Rabbits often burrow, while hares use shallow depressions called forms.

How can I tell a lagomorph from a rodent?

The most reliable distinguishing feature is dentition. Lagomorphs have two pairs of upper incisors, with a small second pair behind the first pair. Rodents have only one pair of upper incisors. This difference is visible in skull specimens and can be used for species identification.

What do lagomorphs eat?

Lagomorphs are herbivores that consume a variety of plant material including grasses, forbs, and woody vegetation. They practice coprophagy, reingesting soft fecal pellets to extract additional nutrients. Domestic rabbits require high-fiber diets to maintain normal digestive function.

Are pikas related to rabbits?

Pikas are in the same order as rabbits and hares, Lagomorpha, but belong to a different family, Ochotonidae. They share the characteristic lagomorph dentition and digestive physiology but differ in appearance, with short rounded ears and compact bodies adapted to cool mountainous habitats.

Why are rabbits used in research?

Rabbits are used as model organisms in biomedical research because their physiology in some areas more closely resembles humans than rodents. They have been used to study neurogenesis, cardiovascular function, muscle physiology, and other topics. The New Zealand white rabbit is a common research breed.

What diseases affect lagomorphs?

Lagomorphs are affected by several significant diseases including rabbit hemorrhagic disease, myxomatosis, and herpesvirus infections. Rabbit hemorrhagic disease virus 2 has caused substantial mortality in European rabbits and hares. Gammaherpesviruses have been detected in multiple lagomorph species, with some associated with disease.

How many species of lagomorphs exist?

The order Lagomorpha comprises about 90 living species divided into two families. The family Ochotonidae contains the pikas, and the family Leporidae contains the rabbits, hares, and jackrabbits. A quarter of lagomorph species are listed as threatened.

What should I do if I find a sick or dead wild lagomorph?

Do not handle sick or dead wild lagomorphs without protection. Report unusual mortality events to local wildlife authorities or veterinary authorities. Diseases such as rabbit hemorrhagic disease can spread rapidly and may affect domestic rabbit populations.

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References and Further Reading

This article is educational and does not replace institutional policy, professional advice, or applicable safety and regulatory requirements.