Theriogenology Medications

Question 1

Obj: Which Medications/Hormones are commonly used in Equine Reproduction

Question 2

Obj: Understand indications and contraindications for Equine Therio medications

• What do you want to accomplish?
• What good can the drug do?
• What harm can the drug do?
  
  • horse or human!

Question 3

Obj: Understand the mechanism of action of Equine Therio drugs

Question 4

Obj: Recognize common reproductive procedures (and which drugs are used for said procedures)

Question 5

What are the most common pharmaceuticals used in Equine Reproduction?

Question 6

What drugs could be used for standing sedations during a rectal palpation in a mare?

Answer 6

• Xylazine (0.3 - 0.6mg/kg)
• Detomidine (0.006 - 0.02 mg/kg)
• Butorphanol (0.01 - 0.02 mg/kg)
• Acepromazine (0.02 - 0.06 mg/kg)
• Romifidine (0.04 - 0.12 mg/kg)

Question 7

What drugs could be used to prevent rectal straining during a rectal palpation in a mare?

Answer 7

• Rectal infusion of lidocaine
• Buscopan (0.08 - 0.12 mg/kg)

Question 8

How does Buscopan work to prevent rectal straining?

Answer 8

• Antispasmodic and Anticholinergic

Question 9

Is Buscopan for rectal straining during a rectal palpation on or off label?

Answer 9

• Off-label
• Labeled: For Control of colic associated with spasmodic, gas, and simple impactions

Question 10

What are the risks of using Buscopan for rectal palpations?

Answer 10

• Side Effects:
  
  • tachycardia
  • Decreased GI sounds
• Contraindications:
  
  • Pregnant mares

Question 11

What drugs can be used to advance the equine breeding season?

Answer 11

• Progestins
  
  • Altrenogest (Regumate^®/Altresyn^®
• GnRH
  
  • Deslorelin
  • Buserelin
  • Historelin
• Dopamine D₂ antagonists
  
  • Domperidone
  • Sulpiride

Question 12

How do progestins advance the breeding season in mares?

Answer 12

• Maintaining progesterone concentrations suppresses LH surge and estrous behavior
• Progesterone may prime hypothalamic center for estrous expression and LH surge

Question 13

What are the indications for use for Altrenogest?

Answer 13

• 0.044 mg/kg PO SID 14-18days
• Used in:
  
  • Late transition
  • Follicles 20-25 mm

Question 14

How does GnRH advance the breeding season in mares?

Answer 14

• Stimulate FSH secretion ⇢ Follicular development

Question 15

When is GnRH indicated for use?

Answer 15

• Deslorelin (FDA) or Buserelin/Historelin (compounded)
• Use in:
  
  • Late transition
  • Follicles ≥25mm

Question 16

How do Dopamine D₂ Antagonists advance the breeding season?

Answer 16

• Dopamine decreases prolactin
  
  • Prolactin is thought to increase the number of LH and FSH responsive receptors within follicles
    
    • ⇡ responsiveness to LH and FSH
• D₂ antagonists ⇡ prolactin

Question 17

How is Domperidone/Sulpiride used?

Answer 17

• Domperidone - 1.1 mg/kg PO SID
• Sulpiride - 0.5 - 1.0 mg/kg IM SID
• Use:
  
  • until ovulation occurs
  • in conjunction with artificial lights to speed up ovulation in transitional mares
    
    • 3 weeks of lights before treatment

Question 18

How many days of artificial light does it take to get a mare to estrus and ovulation?

Answer 18

on average 70 days

Question 19

What are the medical options for Prostaglandin F_2α (PGF_2α)?

Answer 19

• Lutalyse^® (dinoprost) : 5-10 mg IM
  
  • Off-label
• Estrumate^® (cloprostenol) : 250 μg IM
  
  • Off-label

Question 20

How do PGF_2α work to induce estrus?

Answer 20

• Functional and morphological regression of the CL → Luteolysis
• Shortens diestrus and interovulatory interval
  
  • Requires a mature CL
• Estrus occurs 2-5 days after dossage

Question 21

What are the possible side effects of PGF_2α

Answer 21

• Sweating and abdominal discomfort
• Increased heart rate and/or respiratory rate
• incoordination, lying down
• Not to be administered in post-ovulation period after breeding

Question 22

What are the risks of PGF_2α to humans?

Answer 22

• Can cause abortion and bronchospasm
• Is readily absorbed through the skin
• Caution for: Women, asthmatics, people w/ respiratory problems

Question 23

What drugs can be used to induce ovulation in mares?

Answer 23

• Human Chorionic Gonadotropin (HCG)
• Deslorelin acetate (SucroMate^™ Equine)

Question 24

How does Human Chorionic Gonadotropin induce ovulation in mares?

Answer 24

• 2500 IU IV (2.5mls)
  
  • range of 1500 - 3000
• Ovulation 36hrs after injection (80%)
  
  • range of 24 - 48hrs
  • 85-95% ovulate w/in 48hrs

Question 25

How does Deslorelin acetate induce ovulation

Question 26

What pharmaceuticals/therapeutics can be used for post-mating induced endometritis?

Answer 26

• Ecbolic Hormones:
  
  • Oxytocin
  • PGF_2α
  • Uterine lavage

Question 27

How does Oxytocin work for treatment for Post-mating induced endometritis?

Answer 27

• Direct action on uterine smooth muscles inducing rhythmic contraction
• 10 - 20 IU IM/SQ/IV q 4 - 6hrs or as needed
  
  • T_½ 7 minutes
  • Contractions for 30-45 minutes

Question 28

How does PGF_2α work for Post-mating induced endometritis?

Answer 28

• Promotes myometrial contractions
• Dinoprost 5-10 mg IM
• Closprostenol 250 μg IM (off-label)
• T_½ 2-3hrs
  
  • less vigorous contractions for 4-5 hours

Question 29

What harm can result from oxytocin use to treat post-mating induced endometritis

Question 30

What harm can result from PGF_2α use to treat Post-mating induced endometritis?