Equine Therapeutics

Question 1

Regu-mate (altrenogest)

Answer 1

• Suppresses oestrus in mares
• Synthetic P4 analogue
• Promoting uterine quiescence - placentitis - inhibits receptor formation, prevents prostaglandin-induced abortion

Question 2

TMPS / Gentamicin (+ Penicillin) / Ceftiofur

Answer 2

• Antimicrobials that cross placental barrier
• Placentitis; RFM; metritis; uterine laceration
• TMPS - shown alone to improve pregnancy outcome in placentitis
• Ceftiofur - distributes more widely in foal to get to same level as plasma (foals, sepsis)

Question 3

Flunixin meglumine / Phenylbutazone / Pentoxifylline

Answer 3

• Reduce inflammation in placenta, inhibit action of prostaglandins which may promote abortion
• Placentitis; metritis

Question 4

Aspirin / Pentoxifylline

Answer 4

• Maintain uteroplacental perfusion
• Aspirin - prevents microthrombi formation
• Placentitis

Question 5

Firocoxib

Answer 5

• NSAID
• Coxib (COX-2 inhibitor)

Question 6

Oxytocin

Answer 6

• After parturition (large animals)
• Contracts uterus + occludes small blood vv
• Post-partum haemorrhage - promotes uterine involution; persistent mating-induced endometritis (PMIE); metritis; hypogalactia/agalactia
• Uterine prolapse once replaced -> inc uterine tone / dystocia - post-calving for uterus involution
• Retained foetal membranes (low dose IM hourly)
• Milk letdown
• Toxic mastitis - cleans udder, milk let-down
• Maternal bonding

Question 7

Clenbuterol

Answer 7

• AKA Planipart
• Beta-2 receptor agonist = smooth muscle relaxant
• Dystocia - relaxes uterus for prepping birth canal in heifers + opens up uterus, aid to obstetrical manoeuvres; caesarean section (can find incision made); replacement of prolapsed uterus; uterine torsion

Question 8

Oxytocin / calcium

Answer 8

• Uterotonics -> uterine contraction
• Dystocia
• Following Clenbuterol use - reverses effects
• Control of post-partum haemorrhage
• Management of uterine prolapse (after replacement)
• Has short half-life - give 1 mL q 30 - 60 min

Question 9

Bismuth subsalicyclate (Peptobismol)

Answer 9

• Intestinal protectants
• Binds bacterial toxins, stimulates intestinal absorption
• Mild infectious D+ - e.g. due to Rotavirus
• Foal

Question 10

‘Biosponge’ - Di, tri, octahedral smecite

Answer 10

• Intestinal protectant
• Binds to clostridial exotoxins
• Mild infectious D+
• Foal

Question 11

Ranitidine

Answer 11

• Antacid
• Infectious D+ (6.6 mg/kg PO TID) - GI ulceration prevention
• Foal

Question 12

Omeprazole

Answer 12

• Acid blocker, go-to drug - highly effective
• Horses, only licensed treatment for EGUS
• Suppresses stomach acid secretion
• Infectious D+, ulceration prevention, 1 - 2 mL/kg PO SID

Question 13

Moxidectin

Answer 13

• Macrocyclic lactone
• Endoparasite Tx
• Only effective Tx in killing larval stages of cyathostomes

Question 14

Praziquantel

Answer 14

• Tapeworm
• Single annual Tx at end of risk period (autumn/spring)

Question 15

Diazepam (Valium)

Answer 15

• Benzodiazepine
• Sedative
• If foal seizing w/ neonatal maladjustment syndrome (NMS)

Question 16

Butorphanol

Answer 16

• Kappa receptor agonist and mu receptor competitive antagonist
• High dose -> sedation in seizing foals

Question 17

Flumazenil

Answer 17

• Benzodiazepine reversal

Question 18

IV Oxytetracycline (not used for antimicrobial)

Answer 18

• 2 - 3 g diluted in 250 mL saline, slow IV
• Interferes w/ collagen matrix -> extends out -> muscle relaxation, prevents hyperflexion of joint
• For tendon contracture (flexural limb deformities)

Question 19

Erythromycin, Azithromycin and Clarithromycin, Rifampicin

Answer 19

• Macrolide AB
• Infectious D+/ill thrift - proliferative enteropathy (Lawsonia intracellularis); Rhodococcus equi (pneumonia) - resistance seen w/ Rifampicin, so Erythromycin
• G- bacteria
• Foals - don’t use in adults > 230 kg, inc risk of colitis

Question 20

Oxytetracycline, doxytetracycline, minocycline

Answer 20

• Tetracycline - inhibit protein synthesis in susceptible bacteria - bacteriostatic, time-dependent
• Broad spectrum activity - gram +ive + gram -ive bacteria - Pasteurella, Bordetella bronchiseptica, Staphylococcus aureus (+ other staph spp.) + streptococcus spp.
• Good lung penetration
• Lawsonia. intracellularis

Question 21

Heparin

Answer 21

• Glycosaminoglycans present in mast cells
• Extracted from beef/pig
• Inhibit coagulation by increasing affinity of antithrombin III to thrombin + other protease enzymes in coagulation cascade
• Heparin IV/SC (not IM - causes hematomas)
• LMWHs SC
• Promotion of anticoagulation: maintenance of IV catheter placement (heparin), prevention of 2y thromboembolic disease, disseminated intravascular coagulation (DIC) (controversial)
• AE: haemorrhage (stop, give antagonist for heparin = protamin sulfate); heparin-induced thrombocytopenia; interacts w/ other drugs affecting coagulation e.g. aspirin/NSAIDs; may antagonise corticosteroids/insulin -> may inc diazepam levels
• PLE - Tx of reduced antithrombin levels, L. intraceullularis

Question 22

Clopidogrel

Answer 22

• Antiplatelet
• Prodrug - inhibits P2Y12 (an ADP-activated GPCR on platelets)
• Can be given w/ aspirin
• AE: Caution in hepatic + renal disease, has bad taste
• Dec risk of thromboembolism
• PLE - dec antithrombin levels in L. intracellularis infection

Question 23

Phenylbutazone

Answer 23

• Oral NSAID
• Physitis