Foal Care

Janice Sojka VMD, MS

Diplomat ACVIM

Purdue University

General Information Regarding Foals

Foals have unique metabolic demands and challenges

  • Rapidly growing
  • Immunologically naive
  • every situation is new and thus stressful
  • difficult to handle

Key points

  • First two weeks - lay the groundwork by ensuring adequate colostrum
  • have a preventative health program in place before foaling
  • appropriate nutrition for mare to assure good nutrition for foal in first 2-3 months
  • treating problems rapidly when they arise. No time for a "wait and see" attitude; foals get very sick very quickly

Protecting the foal against disease

Passive Immunity -- Colostrum

  • Mare’s antibodies ingested with colostrum -- Passive Transfer
  • Act of ingesting mare’s antibodies from colostrum and absorbing them whole into blood stream is termed PASSIVE TRANSFER of antibodies
  • Successful passive transfer depends on precise sequence of events
    • Antibodies must be present in colostrum
    • GI tract must absorb the large proteins whole - "pinocytosis"
  • If adequate passive transfer occurs there will be over 400-800 mg/dl IgG in foal’s blood stream
  • It takes about 12 hours for all antibodies ingested in colostrum to show up in the blood
  • Can test at 12-24 hours of age for adequate passive transfer

  • Potential Problems with passive transfer of antibodies

    • FPT- Failure of passive transfer
      • No mare antibody in foal’s blood
      • 0 - 200 mg/dl IgG in blood 12-24 hours after suckling
      • Foal has no protection against disease
      • Tends to get severely ill or die in first days and weeks of life unless environment extremely clean
        •
    • PFPT- Partial failure of passive transfer
      • Not enough antibody present to completely protect against disease
      • 200-600 mg/dl IgG in blood 12-24 hours after suckling
      • Foal has some protection
      • Whether or not foal will get sick depends a large amount on environment and exposure to infectious agents
      •
  • Concentration of colostral antibodies is highest during the first week of life, then gradually declines as the antibodies are metabolized
  • Colostral antibodies gone by 4-5 months of life; varies with each infectious agent and degree of transfer of colostral antibodies

Active Immunity

  • Foal’s immune system is able to mount antibody response before birth, but because the uterus is normally sterile there is no stimulus to do so
  • Foal-produced antibodies first appear in blood stream at about 3 weeks of age; review notes on host immune defense (humeral immune response takes 7-10 days to completely kick in, but antibody levels are not yet detectible)
  • Normal adult levels of foal produced antibodies present in body by 4-5 months of age; depends upon exposure/vaccination status of foal

Window of Vulnerability to Infections -- 3-5 months of age in all foals

  • Colostral antibodies declining
  • Foal produced antibodies not yet at adult levels
  • Largest potential for problem exists if foal did not get adequate colostral antibody amounts during the first 2 days of life

  • Chances of Foal Acquiring Infectious Disease -- Factors involved

    • IMMUNITY- combination of colostral and foal produced antibodies and foal’s immunocompetence

    • ENVIRONMENT

 

Common Foal Problems

  • Internal parasites (see previous lecture)
  • Respiratory diseases
  • Gastrointestinal diseases
  • Skeletal system
  • Other

Respiratory Tract Diseases

G.I. Diseases

  • Parasites
  • Gastric Ulcers
  • Diarrhea
    • Viral
    • Bacterial
    • Nutritional

Skeletal System

  • Flexural deformities
    • "contracted tendons"
  • Physitis
  • Acquired angular limb deformities
  • OCD
  • Infected joints
    • "navel ill"

Other Problems

  • Hernia
  • Cryptorchid
  • Vit. E/ Se deficiency
  • Botulism
    • "shaker foal"

 

Other Common Diseases of Horses

Lameness

  • Because horses are athletes, it is important that they be SOUND in order to be used.
  • Just like human athletes they are prone to tendon, ligament, and muscle injury
  • Injury to joints may result in temporary loss of use or permanate arthritis

Common Reasons for Lameness

Neurologic Disease

  • Viral Infection
  • Vertebral instability in the neck
    • "Wobbler"

  • Equine Protozoal Myelitis (Hoof Prints - Equine Vol.5 No. 1 Page 3)(Equine Veterinary Network)

    • Caused by a protozoal parasite-Sarcocystis faculata

      • Parasite of opossum and birds

      • Horses are accidentally infected and are dead end hosts
      • Parasite reproduces in the central nervous system and causes Neurologic disease
  • Signs- Depend on location of parasites, but usually horse loses ability to place legs in correct position and appears "drunk" or "wobbly"
  • Diagnosis- Spinal tap to look for antibodies against parasite in CSF
    • High number of false positive tests

  • Treatment

    • Pyramethamine and sulfa drugs currently recommended treatment

    • Need to treat for long periods of time (up to 6 months) and response only 80%
  • Many experimental drugs are under investigation. Results have not yet been reported in scientific journals

Equine Infectious Anemia (Equine Veterinary Network)

  • Retrovirus- similar to AIDS virus
  • Once infected a horse will have the virus for life and will remain a source of infection to other horses
  • Antibodies are not protective
  • Reportable disease. The Coggin’s Test looks for EIA antibodies

  • Signs

    • Horse develops high fever, leg swelling, depression, and will not eat. Horse may die
    • Repeated bouts of high fever which get less and less severe over time and eventually go away
    • Anemia and other immune-mediated problems
  • There is no treatment for EIA.
  • Horse needs to be put to sleep or stabled in approved housing at least 100 yards from other horses
  • Passes through placenta and colostrum from mares to foals (not 100% of the time)

 

Preventative Health Programs

  • Parasite control program (see previous lecture)
  • Vaccination program

     

    • Tetanus
      • all horses should be vaccinated
      • horses are extremely sensitive to the tetanus toxin -- it is a fatal disease in >90% of infected horses
      • the causative agent is present in the soil and when a wound creates an anaerobic environment, the deadly toxin is produced
      • toxoid vaccines cause animals to develop neutralizing antibodies to the toxin, while administration of antitoxin in an unvaccinated animal who receives a would will provide "passive immunity" to the immediate threat of disease.
    • EEE, WEE (Eastern and Western Equine Encephalitis)
      • highly fatal neurologic diseases
      • spread by mosquitoes
      • horses are "dead end hosts"
      • VEE-Venezuelan Equine Encephalitis is a foreign animal disease and horses are not dead end hosts for this virus (it can multiply within the horse and spread to other animals and people through biting insects).  Horses that may be exposed to this virus through exportation, etc. can be vaccinated.

       

    • Influenza and Rhinopneumonitis
      • both cause upper respiratory tract infections with cough, fever and runny nose
      • horses recover in 3 weeks or less 
      • biggest problem is in young horses - race or show -
      • can cause abortion if a pregnant mare becomes infected

       

    • Potomac Horse Fever
      • causes severe diarrhea and laminitis and is often fatal
      • horses eat snails carrying the Erlichia organism
      • this is an example of an infectious disease that is not contagious
      • vaccination in the spring will protect horses during times of heaviest exposure grazing pastures where snails may be eaten.  The vaccines are bacterins which are not long lasting so yearly boosters are needed and areas where exposures may be year round (snails not killed by cold winter temperatures) twice-yearly vaccinations may be indicated.

       

    • Strangles
      • caused by Streptococcus equi 
      • causes an upper respiratory tract infection and abcessed lymph nodes in the head and neck.  When the abscesses rupture and drain, the organism is spread in the environment and can infect other exposed horses. 
      • Bastard strangles is a variant of this disease where abscess form in other parts of the body (lung, liver, intestine) and can cause major problems. 
      • An intranasal vaccine is available to prevent strangles.

       

    • Rabies -- although horses are not commonly vaccinated against rabies and state and federal laws do not require it, many owners will vaccinate horses kept in areas where rabies is highly endemic and the risk of being bitten by a rabid animal is great.

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