Endocrine Diseases and the Skin

Question 1

Pars Intermedia Adenomas overview (predisposed, two types, CS)

Answer 1

Commonly seen in older horses, non-brachycephalic dog breeds and females
may be INACTIVE due to hypopituitarism or DI, or ACTIVE tumours that secrete ACTH, leading to adrenal cortical hyperplasia and increased cortisol release.

CS : PU/PD, polyphagia, muscle weakness, abnormal fat distribution, pyrexia, somnolence, hyperhidrosis, hirsutism, laminitis, hypertrichosis (winter coat is not shed due to hair getting stuck in anagen)

Question 2

How does Primary Hypothyroidism affect the hair follicle ?

Answer 2

TH stimulates anagen, the active phase of hair growth
a reduction in TH leads to a decrease in anagen and hence, an increase in telogen. The growth enters a rest phase where they are easily dislodged
this leads to alopecia, especially around the nose, neck, pinnae, flanks, ventrum and tail

Question 3

Describe some dermal diseases associated with hypothyroidism

Answer 3

keratinisation disorders = a reduction in thyroid hormones, altering lipogenesis and sebum production, altering skin levels (seborrhoea), leading to hyperkeratosis
- thickened waxy skin of the ear
- flakey scales of skin

haircoat abnormalities
delayed wound healing (altered collagen synthesis)
myxoedema
secondary infections

Question 4

Cs of Hyperthyroidism in cats

Answer 4

poor grooming
over grooming
increased claw growth
excessive shedding
thin skin
thin cat but increased appetite
heat seeking behaviour

Question 5

Dermal diseases associated with Hyperadrenocorticism

Answer 5

keratinisation disorders = comedones, seborrhea, sicca
hair coat abnormalities = inhibition of anagen, bilaterally symmetrical low rate of hair growth and alopecia
dermal atrophy = atrophy of epidermis and pilocebaceous apparatus, loss of collagen and elastin fibres in epidermis and subcutis, hyperpigmentation
calcinosis cutis = long standing cases, dermal deposition of calcium along the dorsal midline, ventral abdomen and inguinal region

Question 6

Describe skin fragility syndrome in cats with hyperadrenocorticism

Answer 6

thin skin
alopecia
unkept haircoat
recurrent abscesses, comedones, seborrhoea and hyperpigmentation

Question 7

Describe early castration in ferrets with hyperadrenocorticism

Answer 7

neutering –> lack of testosterone and oestradiol negative feedback on hypothalamus –> increase in GnRH –> increase in LH –> stimulated adrenal cortex –> hyperplasia and androgen production –> adenoma/adenocarcinoma

these tumours lead to bilateral, symmetrical alopecia on the ventral abdomen and medial aspect of rear legs and other characteristic lesions

Question 8

Describe dermal lesions associated with hyperoestrogenism

Answer 8

symmetrical alopecia
hyperpigmentation
enlarged nipples, vulva and mammary gland

(seen commonly in guinea pigs due to cystic ovarian diseases)