Perianal and pedal skin disease

Question 1

What is the role of anal sacs?

Answer 1

Scent marking

Question 2

Describe the anatomy of anal sacs

Answer 2

• Paired invaginations of the skin located between the internal and external anal sphincters
• The walls of the sacs contain large sebaceous glands and the fundic portion shows numerous epitrichial glands
• Duct 3-10mm long: opening at the mucocutaneous junction in the dog at about ‘4:30’ and ‘7:30’

Question 3

What are the clinical signs of anal sac impaction?

Answer 3

• Pruritus (scooting, rubbing and biting – local and more widespread)
• Pain and depression
• Often recurrent
• Distended sacs at 4 and 8 o’clock
• Malodour

Question 4

What are some primary causes of anal sac impaction?

Answer 4

• Abnormal character and volume of secretion
• Change in muscle tone
• Faecal form – diarrhoea or constipation
• Plugging of the ducts

Question 5

What are some secondary causes of anal sac impaction?

Answer 5

• Bacterial infection and possible abscessation

* Very rarely Malassezia

Question 6

What are 3 differential diagnosis for anal sac impaction?

Answer 6

• Abscessation
• Palpable glands
• Anal pruritis

Question 7

What are some diagnostic methods for anal sac impaction?

Answer 7

• Palpation & Expression of sacs: nature of exudate, check for masses
• Cytology
• Bacteriology: useful for infected glands and abscesses

Question 8

How can anal sac impaction be treated?

Answer 8

• Expression
• Addition of fibre to food to improve faecal consistency
• Flush and pack
• Anal sacculectomy (removal of anal glands)

Question 9

Describe the steps of ‘flush and pack’ in anal gland impaction treatment

Answer 9

• Sedation /anaesthesia - using lacrimal catheter to flush the AGs with warmed saline
• Pack with a suitable ear cream (e.g. Aurizon, Easotic)

Question 10

How is abscessation of the anal sacstreated?

Answer 10

Combined local cleaning: chlorhexidine shampoo / scrub, iodine

• Systemic antibiotics
• Warm soaks
• Analgesia

Question 11

A tumour in the wall of the anal sac is most commonly?

Answer 11

An anal sac adenocarcinoma

Question 12

What are the effects of a patient having an anal sac adenocarcinoma

Answer 12

• Paraneoplastic disease often cause of concern
• Metastasis is common e.g. sublumbar and iliac lymph nodes
• Median survival time of 18 months

Question 13

How is an anal sac adenocarcinoma treated?

Answer 13

Surgery, chemotherapy and radiation therapy are used

Question 14

What is anal furunculosis?

Answer 14

• Poorly understood immune mediated skin disease of dogs

- Considered to represent an inappropriate response to bacteria around the anus

Question 15

Which breed is predisposed to anal furunculosis?

Answer 15

German shepherd

Question 16

What are the signs of anal furunculosis?

Answer 16

• Tissue destruction and sinus formation
• Moderate to severe pain – care in examining
• Difficulty in passing faeces and faecal incontinence

Question 17

How is anal furunculosis diagnosed?

Answer 17

Cytology: Pyogranulomatous inflammation and bacteria present (low sensitivity in this form of inflammation?)

Question 18

What are the treatment options for anal furunculosis?

Answer 18

• Prednisolone (steroid)
• Ciclosporin
• Excellent skin hygiene: daily wipes or washes, chlorhexidine
• Food trial to address a possible intolerance
• Surgery

Question 19

Interdigital folliculitis/furunculosis +/- interdigital cysts or nodules is also known as?

Answer 19

Sterile pyogranulomatous pododermatitis

Question 20

Describe the pathogenesis of Sterile pyogranulomatous pododermatitis

Answer 20

• Trauma from the environment +/- self-induced e.g. atopic dermatitis
• Front feet take more weight and are more prone to trauma
• Usually between digits 3 and 4, and 4 and 5

Question 21

Which breeds are predisposed to Sterile pyogranulomatous pododermatitis?

Answer 21

Most commonly in smooth, short-coated breeds e.g., English bulldogs, Staffies and Labradors

Question 22

How do lesions form in sterile pyogranulomatous pododermatitis?

Answer 22

• Chronic weight bearing and friction on haired skin leads to follicular obstruction, damage and rupture
• Lesions start sterile: rupturing of cysts +/- self-trauma quickly results in secondary infection
• Recurrent bouts lead to increased scar tissue and disease perpetuation

Question 23

Describe the pathology of sterile pyogranulomatous pododermatitis

Answer 23

The ventral interdigital skin becomes hyperkeratotic (thickened) and acanthotic, and primary and secondary follicles become dilated with keratin.
Hairs on this surface are lost as the lesions become more severe, and the interdigital skin thickens.
Follicles can rupture causing an inflammatory response and the development of draining tracts that migrate dorsally and open within the dorsal interdigital space

Question 24

Describe the lesions and signs of sterile pyogranulomatous pododermatitis

Answer 24

• Lesions form on ventral interdigital surface, but rupture onto dorsal surfaces
• Conforming pads (pseudo-pads) -> weight-bearing on haired skin
• Erythema, oedema, comedones, nodules, pustules, ulcers, haemorrhagic bullae, haemorrhagic draining tracts, pyogranulomas and callus formation
• Scar tissue from recurrent episodes

Question 25

How is sterile pyogranulomatous pododermatitis diagnosed?

Answer 25

• History and clinical exam
• Body condition score
• Orthopaedic disease
• Cytology
• Histopathology

Question 26

What differentials of sterile pyogranulomatous pododermatitis should be considered before diagnosis?

Answer 26

Demodicosis, primary infections e.g. atypical bacterial or fungal

Question 27

What will the cytology of sterile pyogranulomatous pododermatitis show?

Answer 27

Cytology from unruptured cysts is sterile pyogranulomatous = neutrophils and macrophages

Question 28

How are interdigital follicular cysts treated?

Answer 28

• Treat aggressively early on to prevent scarring and perpetuation
• Immune-modulation
• Topical antiseptics
• Restrict activity to smooth surfaces
• Protect paw from trauma
• Surgery
• Weight loss if needed