Horse Breeding

Why Breed Horses?

• breeds with greater endurance so they can be ridden longer distances
• breeds that run faster, for racing
• breeds with greater strength to be used for heavier work

Lesson Structure

There are 8 lessons in this course:

1. Breeding Horses
2. The Broodmare
3. The Stallion
4. Breeding Management
5. The Pregnant Mare
6. Parturition and Foaling
7. Care of the New-born Foal
8. Infertility in the Mare and Stallion

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.

Aims

• Understand the process of selecting mares and stallions for successful breeding purposes.
• Identify and understand the anatomy and physiology of the mare’s reproductive tract and the physical characteristics, which are preferable for a successful brood mare.
• Identify and understand the anatomy and physiology of the stallion’s reproductive tract and the physical characteristics, which are preferable for a successful breeding stallion.
• Explain and compare different ways of breeding horses.
• Identify and explain the appropriate management of a pregnant mare.
• Understand and explain the foaling process.
• Describe the important care of a newborn foal.
• Discuss common fertility problems that can occur in a mare and stallion.

What You Will Do

• Lesson 1
  • Why breed horses?
  • An understanding of heritability is fundamental
  • Meiosis
  • The Work of Gregor Mendel
  • Chromsomes and Genetics in Breeding
  • Selecting the mare and the stallion
  • Quantitative and Qualitative Inheritance
  • Inbreeding and Linebreeding
  • The Genetic Effect of Inbreeding
  • Line Breeding
  • Advantages of Inbreeding
  • Stallion and Mare Complementation
  • The Industry
• Lesson 2
  • Mare Anatomy
  • The Reproductive Cycle of the Mare
  • Hormonal Control
  • Abnormal Oestrus
  • Breeding Fitness
  • General Broodmare Care
  • Nutrition and Feeding
  • Rations
  • Carbohydrates
  • Fat
  • Protein
  • Vitamins
  • Roughage
  • Hay
  • Pre-Season Care
• Lesson 3
  • Stallion Anatomy
  • Sperm Production
  • Semen Release
  • Reproductive Cycle of the Stallion
  • Breeding Fitness
  • General Stallion Care
  • Handling
  • Pre-Season Care
  • Stallion Management for Reproduction
  • Training the young stallion
  • Steps in training a novice stallion onto the phantom
  • Common clinical problems with stallions
  • Castration (Gelding)
• Lesson 4
  • Managing the Arrival and Departure of the horse at the stud
  • Semen from the stallion
  • Collection and Processing
  • Evaluating the Quality of Sperm
  • Breeding methods
  • Natural Breeding
  • Live cover – In-hand or Pasture
  • Artificial insemination
  • Handling Frozen Semen
  • Embryo transfer
  • When to breed
  • Detection of Oestrus
  • Teasers
  • Visual Signs
  • A plan for when things go wrong
  • Sexually Transmitted Infections
• Lesson 5
  • Pre-natal growth
  • Conception of twins
  • Gestation and Methods and Detecting Pregnancy
  • Methods of Diagnosis
  • Palpation
  • Pregnancy Tests
  • Ultrasound
  • Post-Natal Growth
• Lesson 6
  • Care of the Pregnant Mare
  • Nutritional Requirements
  • Caslicked Mares
  • Preparation for foaling
  • Exercise Needs
  • Worming
  • A deworming program for mares
  • Preparation of the foaling environment
  • Preparation for if things go wrong
  • The Physical Environment - Bedding
  • Common Bedding in the Foaling Environment
  • Straw
  • Wood Shavings
  • Wood Pellets
  • Rubber Matting
  • The Parturition Process
  • Stages of Labour
  • Common Foaling Problems
  • Dystokia
  • Abnormal Presentations
  • Health Problems of the post-partum mare
  • Retained placenta
  • Haemorrhage
  • Post-Partum Metritis
  • Rejection of the Foal
  • Prolapsed Uterus
  • Lactation (Udder edema)
  • Lactation (reduced milk supply)
  • Foal and foaling reports
  • Example Foaling Record
  • Example Foal Report
• Lesson 7
  • General newborn care
  • Stabling and safe environment for newborn foals
  • Lactation and suckling
  • Premature Foals
  • Orphan foals
  • Common health problems in newborn foals
  • Infections, Constipation and Diarrhoea
  • Septicaemia
  • Meconium Impaction
  • Diarrhoea
  • Congenital disorders
  • Neonatal Isoerythrolysis (NI)
  • Angular Limb Deformities
  • Flexor and Extensor Tendon Abnormalities
  • Delayed Ossification of the Cuboidal Bones
  • Heart Murmurs
  • Congenital Papilloma (Warts)
  • Entropion
  • Neurological disorders
  • Neonatal Maladjustment Syndrome (NMS)
  • Head Tilt
  • Structural abnormalities
  • Uroperitoneum
  • Umbilical Hernias
  • Training a foal in the earliest stages
• Lesson 8
  • Introduction to Fertility
  • Understanding Fertility in Mares
  • Understanding Fertility in Stallions
  • Handling and Management in Stallions
  • Age
  • Overuse
  • Nutrition
  • Illness and Injury
  • Other Abnormalities
  • Semen problems
  • Haemospermia
  • Urospermia
  • Oligospermia
  • Structural disorders of the reproductive tract (mares)
  • Pneumovagina
  • 'Maiden Cervix' or Cervical Incompetence
  • Vesicovaginal Reflux or Urine Pooling
  • Structural disroders of the reproductive tract (stallions)
  • Cryptorchidism
  • Testicle Conformation
  • Testicular Torsion
  • Testicular Tumours
  • Scrotal Hernia
  • Venereal diseases (mares)
  • Endometritis
  • Bacterial Endometritis
  • Fungal Endometritis
  • Mating Induced Endometritis
  • Contagious Equine Metritis (CEM)
  • Equine Viral Arteritis (EVA)
  • Pyometra
  • Abnormal Oestrus Cycles
  • Silent Heat and Post-Partum Anoestrus
  • Persistant Oestrus
  • Vernal Transition
  • Ovarian Tumours
  • Persistant Corpus Luteum
  • Haemorrhagic Follicles
  • Abortion
  • Venereal diseases (stallions)
  • Bacterial Infections
  • Equine Viral Arteritis (EVA)
  • Equine Coital Exanthema
  • Dourine
  • Contagious Equine Metritis (CEM)
  • Infectious causes of abortion (mares)
  • Viral Abortion
  • Bacterial Abortion
  • Leptospirosis
  • Non-infectious causes of abortion (mares)
  • Congenital Defects
  • Twinning
  • Umbilical Cord Torsion
  • Progesterone Deficiency

The Mare Must be Fertile

Peak fertility in horses occurs at approximately 6 – 7 years of age.  Fertility begins to decline around 15 years of age, when often mare’s become more difficult to get into foal and experience more instances of pregnancy losses.

A young, healthy mare has an approximately 50-60% chance of getting pregnant during a given oestrus cycle, when mated with a fertile stallion. You can see that even if the mare is young and healthy and without any anatomical or pathological problems, the chance of a positive mating that ends in a live birth, is still relatively low.

There are many reasons why a mare may not conceive, and cause her to be classed as sub-fertile or infertile.  Many of these problems are treatable once they have been successfully diagnosed.

As mentioned in previous lessons, a thorough breeding soundness examination is recommended to ensure that any possible fertility problems are identified and treated before excessive amounts of time and finance are used up trying to get her to conceive. It is vitally important that a mare which has undesirable or poor general conformation of the body, legs, feet or mouth should be seriously considered for breeding at all.

Poor vulvar conformation can result in a condition called pneumovagina, in which air is pulled into the vagina, along with bacterial contaminants. Poor vulvar conformation can also result in faecal bacteria getting into the vaginal area and causing a problem. Bacterial infections can then set in and can render the mare practically infertile. The most common treatment is to give the mare antibiotics to treat the infection and to prevent further reinfection by means of corrective surgery- a procedure known as a Caslick’s. In a Caslick’s procedure, the level of the mare’s pelvic floor is ascertained by inserting a hand into the reproductive tract.  The external vulvar lips are then anaesthetized and stitched from just under the anus down to the pelvic floor level, leaving only a small opening that urine can escape from.  This effectively seals the vagina and prevents it from becoming contaminated.  Depending on the size of the stallion, the stitches may need to be removed when the mare is subsequently mated and will definitely need to be removed when foaling is imminent. 

'Maiden Cervix' or Cervical Incompetence

A maiden mare (one that has not been bred before) may suffer from cervical incompetence or ‘maiden cervix’.  After mating, the cervix is so tightly closed that any excess seminal fluid cannot drain away properly. The retained fluid causes an inflammatory reaction and if untreated, creates an overly acidic environment which soon evolves into a full blown infection. Mares with the condition are commonly treated with antibiotics when they are mated and a uterine lavage (internal cleanse) is also administered post mating to try to prevent the infection setting in. The vet may also administer Oxytocin, a hormone which promotes uterine contractions, which helps the mare's body clear the problematic foreign material.

Vesicovaginal Reflux or Urine Pooling

A poorly conformed reproductive tract or structural changes to the tract caused by loss of muscle tone after multiple foaling’s can result in retention of urine in the vagina. This condition can result in reduced conception rates due to an overly acidic environment, formation of scar tissue in the vagina and/or inflammation. Treatment of this condition will depend very much on the underlying cause.  If the problem is mild and caught early enough the urine can be removed and the mare’s body condition improved, which will in turn help to increase muscle tone and prevent the condition occurring in the future. In other cases, uterine lavage may be necessary and the use of drugs to improve the muscle tone may also be required.

Diseases

Bacterial Endometritis

Infectious endometritis can occur when the external physical barriers to the uterus are compromised, which may break down over time as part of the natural ageing process or as a result of repeated infections. The most common bacteria that cause a problem are Strep. equi zooepidemicus (the most common), E. coli, Pseudomonas aeruginosa, and Klebsiella pneumonia. Infection causes scarring of the uterine lining and adhesions to form, which prevents conception and will cause eventual infertility. This condition is treated with appropriate antibiotics both before and after mating. One of the drawbacks of regular antibiotic use is the fact that the antibiotic will kill both good and bad bacteria, leaving the mare without any natural protection against further bacterial or fungal infection.

Fungal Endometritis

The most common fungi that cause fungal endometritis include the Candida (yeast) family and the Aspergillus (mould) family.  Both of these fungi proliferate when the mare’s immune system has been weakened after prolonged antibiotic use. Fungal endometritis can be passed between stallions and mares, and unfortunately there is no specific cure. Management of fungal endometritis relies primarily on reducing the numbers of fungi via uterine lavage with appropriate anti-fungal agents.

Mating Induced Endometritis

Some mares may suffer inflammation and subsequent bacterial/fungal infection as a direct result of mating. There are management issues that can help prevent breeding induced endometritis; mares that are bred on their foal heat are more likely to develop subsequent infection, perhaps due to the stress and strain of the recent foaling.  Multiple attempts at breeding in a single oestrus period are also known to increase the chances of endometritis. This condition is treated in a similar way to ‘Maiden Cervix’, as fluid retention is generally thought to be the main cause of the problem.

Contagious Equine Metritis (CEM)

This type of sexually transmitted metritis is caused by the organism Taylorella equigenitalis, which can survive on the stallions external genitalia and in the vagina and clitoris of the mare for extended periods of time. Transmission is via direct sexual contact or via infected semen that is used for AI. Infected stallions often do not present any clinical signs of infection.  Mares are likely to suffer from a thick vaginal discharge and inflammation of the reproductive tract approximately a week after infection.  Their oestrus cycles may also be adversely affected.  In many countries CEM is a notifiable disease and the appropriate authorities must be informed of any suspected or confirmed outbreaks. Infection is confirmed by swabbing the mare and then appropriate treatment can be given. Infected mares should not be used for breeding until the infection has been treated and successfully cleared up.

Equine Viral Arteritis (EVA)

EVA is an acute, contagious viral disease caused by the Equine Arteritis virus. Infection with the virus is not life threatening but it can cause spontaneous abortions in pregnant mares and sometimes death of new born foals.  Other clinical signs include depression, lethargy, fever, oedema of the limbs and genitals, conjunctivitis and a nasal discharge.  The virus is transmitted via the respiratory route as well as through sexual contact with infected mares/stallions. Stallions can carry the virus and appear to be free of clinical signs, but still pass the virus on when covering or teasing mares.  These stallions are known as ‘shedder’ stallions.  Diagnosis of infection is via a positive blood test.  Stallions and mares should be routinely tested for infection and not used for breeding if positive blood test results are obtained. Similarly to CEM, in many countries EVA is a notifiable disease and the appropriate authorities must be informed of any suspected or confirmed outbreaks. Vaccination against infection is available in some countries and is carried out as part of the normal breeding routine.

Pyometra