Misc (Derm, Ophtho, Repro etc)

Question 1

Superficial necrolytic dermatitis - 2 ddx in dogs? Skin lesion distribution?
What 2 endocrinopathies are commonly associated?
What nutritional deficiency is associated?

Answer 1

Hepatocutaneous syndrome, glucagonoma (classic sign in people, rare in dogs)
HAC, DM
Hypoaminoacidemia. (In glucagonoma –> increased gluconeogenesis so increased AA turnover)

Question 2

What disease is cutaneous phlebectasia associated with in dogs? Does it resolve with treatment?

Answer 2

HyperA (iatrogenic or spontaneous), reported in up to 40% dogs with spontaneous HAC.
No.

Question 3

Summarize the pathogenesis of BPH.

Answer 3

With age:
- Increased testosterone converted within prostatic epithelial cells by 5-alpha reductase enzyme to dihydrotestosterone (DHT). DHT = main mediator of prostatic stromal/glandular growth (less estradiol-17-beta, other local GFs)
- Decr testosterone but no change in E2 > altered androgen: oestrogen ratio contributes to increased no. & sensitivity of DHT-R > prostatic glandular (cystic) hyperplasia & hypertrophy
- Predisposes to prostatic cyst formation, chronic bacterial prostatitis (cystitis, orchitis, epididymitis)

Question 4

What treatments (and associated AE) are recommended for benign prostatic hyperplasia?

Answer 4

Castration 1st
Anti-androgen tx (not all approved in USA)
- Megestrol acetate: single SQ inj. AE: E2-mediated (squamous metaplasia of prostatic epithelium, myelosuppression, mammary neoplasia) & P4-mediated (insulin & glucose dysregulation)
- Osaterone acetate (Ypozane): structurally related to P4, inhibits 5-alpha reductase (conversion of testosterone to DHT). AE - adrenal suppression (mostly PB-4 metabolite), some P4 activity.
- Finasteride: 5-alpha reductase inhibitor > causes atrophy of prostatic glandular and stromal tissues w/o changing testosterone [ ]
- Flutamide = anti-androgen, binds to DHT-R in prostate

Deslorelin acetate (Suprelorin implant): GnRH analogue, chronic use desensitizes AP gonadotropes, decr LH & FSH

Question 5

Describe the origin & roles of
- LH
- FSH

Answer 5

GnRH (hypothalamus) stimulates LH & FSH release from AP

LH: pulsatile release
- Stimulates Leydig cells in interstitium of testicles > testosterone production & release

FSH: constant release
- Stimulates Sertoli cells in seminiferous tubules of testicles
- Assists in spermatogenesis
- Assists in formation of E2 from testosterone
- Produces inhibin > neg feedback on AP

Question 6

Serum concentrations of what enzyme correlates with histologic evidence of BPH?

Answer 6

Canine prostate-specific arginine esterase - ELISA assay.
May be used if other diagnostics are inconclusive or unavailable. Also useful to screen for preclinical cases of BPH for proactive preventative treatment options.