Perianal and pedal skin disease Flashcards
What is the role of anal sacs?
Scent marking
Describe the anatomy of anal sacs
- 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’
What are the clinical signs of anal sac impaction?
- Pruritus (scooting, rubbing and biting – local and more widespread)
- Pain and depression
- Often recurrent
- Distended sacs at 4 and 8 o’clock
- Malodour
What are some primary causes of anal sac impaction?
- Abnormal character and volume of secretion
- Change in muscle tone
- Faecal form – diarrhoea or constipation
- Plugging of the ducts
What are some secondary causes of anal sac impaction?
- Bacterial infection and possible abscessation
* Very rarely Malassezia
What are 3 differential diagnosis for anal sac impaction?
- Abscessation
- Palpable glands
- Anal pruritis
What are some diagnostic methods for anal sac impaction?
- Palpation & Expression of sacs: nature of exudate, check for masses
- Cytology
- Bacteriology: useful for infected glands and abscesses
How can anal sac impaction be treated?
- Expression
- Addition of fibre to food to improve faecal consistency
- Flush and pack
- Anal sacculectomy (removal of anal glands)
Describe the steps of ‘flush and pack’ in anal gland impaction treatment
- Sedation /anaesthesia - using lacrimal catheter to flush the AGs with warmed saline
- Pack with a suitable ear cream (e.g. Aurizon, Easotic)
How is abscessation of the anal sacstreated?
Combined local cleaning: chlorhexidine shampoo / scrub, iodine
- Systemic antibiotics
- Warm soaks
- Analgesia
A tumour in the wall of the anal sac is most commonly?
An anal sac adenocarcinoma
What are the effects of a patient having an anal sac adenocarcinoma
- Paraneoplastic disease often cause of concern
- Metastasis is common e.g. sublumbar and iliac lymph nodes
- Median survival time of 18 months
How is an anal sac adenocarcinoma treated?
Surgery, chemotherapy and radiation therapy are used
What is anal furunculosis?
- Poorly understood immune mediated skin disease of dogs
- Considered to represent an inappropriate response to bacteria around the anus
Which breed is predisposed to anal furunculosis?
German shepherd
What are the signs of anal furunculosis?
- Tissue destruction and sinus formation
- Moderate to severe pain – care in examining
- Difficulty in passing faeces and faecal incontinence
How is anal furunculosis diagnosed?
Cytology: Pyogranulomatous inflammation and bacteria present (low sensitivity in this form of inflammation?)
What are the treatment options for anal furunculosis?
- Prednisolone (steroid)
- Ciclosporin
- Excellent skin hygiene: daily wipes or washes, chlorhexidine
- Food trial to address a possible intolerance
- Surgery
Interdigital folliculitis/furunculosis +/- interdigital cysts or nodules is also known as?
Sterile pyogranulomatous pododermatitis
Describe the pathogenesis of Sterile pyogranulomatous pododermatitis
- 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
Which breeds are predisposed to Sterile pyogranulomatous pododermatitis?
Most commonly in smooth, short-coated breeds e.g., English bulldogs, Staffies and Labradors
How do lesions form in sterile pyogranulomatous pododermatitis?
- 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
Describe the pathology of sterile pyogranulomatous pododermatitis
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
Describe the lesions and signs of sterile pyogranulomatous pododermatitis
- 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
How is sterile pyogranulomatous pododermatitis diagnosed?
- History and clinical exam
- Body condition score
- Orthopaedic disease
- Cytology
- Histopathology
What differentials of sterile pyogranulomatous pododermatitis should be considered before diagnosis?
Demodicosis, primary infections e.g. atypical bacterial or fungal
What will the cytology of sterile pyogranulomatous pododermatitis show?
Cytology from unruptured cysts is sterile pyogranulomatous = neutrophils and macrophages
How are interdigital follicular cysts treated?
- 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
