Big Head Disease (BHD) - 40%

Question 1

What is Big Head Disease (BHD)- equine

Answer 1

Nutritional 2nd Hyperparathyroidism (aka osteomalacia)

Question 2

BHD - causes- equine

Answer 2

horse’s feed has an improper calcium to phosphorus ratio causing high phosphorus levels in the horse’s blood- (low Ca, High Ph, low Vit D). Diets too high in grain (high Ph, low Ca) or oxalates in grass of feed prevents calcium absorption from GIT.

Question 3

BHD - pathophysiology- equine

Answer 3

Mineral imbalance> parathyroid gland release excessive PTH to aid in Ca absorption> increase osteoclastic activity> calcium is absorbed from the bone, it is replaced by fibrous tissue that exceeds the amount of bone resorbed= subchondral bone microfractures (rads show subperiosteal cortical bone resorption, bowing deformities, long bone folding fractures) > Since the bones of the skull are affected, the head enlarges and causes the big head appearance

Question 4

BDH treatment- equine

Answer 4

2:1 Ca: Ph ratio in diet required- changing the feed to one with a correct calcium to phosphorus ratio.
Alfalfa is a good choice as it has a high calcium level. You can also add limestone to the alfalfa to increase the amount of calcium.
It will usually take up to a year for these horses to improve, if they survive. Restrict activity for 3-4 weeks.

Question 5

BHD- small ruminants - etiology

Answer 5

Acute infection from Clostridium- C. novyi, C. sordelli, C. chauvoei (rare)

Question 6

BHD- small ruminants - clinical signs

Answer 6

non-gaseous, non-hemorrhagic, edematous swelling of the head, face, neck (common in rams from head butting and wounds incurred)

Question 7

BHD- small ruminants - treatment

Answer 7

broad spectrum antibiotics- penicillin