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VETERINARY PRACTICE JANUARY 2016 DERMATOLOGY 31 Anal sacs: a new approach to an old problem? THERE are numerous reasons why dogs will “scoot” on their bottoms but the most common of these is an attempt for them to empty their anal sacs. Whilst we are uncertain what opportunities veterinary undergraduates get to hone their anal sac emptying skills before they qualify, there is no doubt that the frequent requests from dog owners to perform the ritual emptying during routine small animal consultations means that it doesn’t take long for them to become highly adept at the art of anal sac evacuation once they do get their coveted MRCVS. What are anal sacs and why do they fill up? Anal sacs, sometimes mistakenly referred to as anal glands, are two small structures located between the internal and external sphincter muscles. Each sac is lined with both sebaceous and apocrine glands whose combined secretions produce a semi-oil foul smelling brown liquid. As the anal sphincter muscles expand, as defaecation occurs, pressure on the sacs leads to the expulsion of their contents over the faeces. Problems arise when this emptying process does not occur and the secretions build up in the sac, causing obvious discomfort to the dog. There is very little high-quality information as to why anal sacs “overfill”. Suggested reasons include change in the character of the secretion, excessive secretions, soft faeces or diarrhoea, poor muscle tone and obesity. Poodles, Chihuahuas and Lhasa apsos are said to be at increased risk of developing anal sac disease although most of this information is anecdotal. The more difficult question to answer is how often should anal sacs be emptied and when if ever should they be packed or removed? When anal sacs are emptied it is important this is done per rectum. Briefly, a gloved, lubricated finger Sue Paterson, MA, VetMB, DVD, DipECVD, MRCVS, RCVS and European Specialist in Veterinary Dermatology, is at Rutland House Veterinary Hospital, St Helens, Merseyside. Stephen Steen, MSc, FIBMS, CHS (ABHI), is laboratory manager and microbiology adviser at CAPL/NWL Knutton, Staffs. should be inserted into the anus. Gentle pressure should be applied against a juxtaposed thumb. The discharge should be collected onto clean cotton wool. A bacteriology swab or cytology can be taken from the cotton wool. The empty sac should be palpated to check for swelling and to assess the anal sac cytology from normal and diseased sac. Studies by Lake (2004) and Robson (2003) suggest neutrophils and erythrocytes are rarely found in normal anal sac cytology. Lake’s paper also suggests the characteristics of the discharge can be very variable in normal animals and that the colour, consistency and quantity of secretions can give little SUE PATERSON and clue as to the STEPHEN STEEN review this status of the common problem, including gland. how often they should be A more recent emptied, and discuss some study by James of the misconceptions about (2010) also antibiotics to use for infections showed that dogs with anal thickness of the walls. The perianal sac disease do have more neutrophils area should be cleaned with dilute on cytology than normal dogs; antiseptic and the procedure should however, the increased frequency of be repeated on the other side. neutrophils in affected dogs was not When the walls of a normal anal found to be statistically significant. gland are palpated between finger and That same study suggested there was thumb they should feel smooth and no cytological difference between anal the thickness of a balloon. Where sac cytology from normal dogs and there is chronic hyperplastic change in those with anal sac disease. However, the wall or there is neoplasia they feel many of the dogs in this study needed thickened and leathery. their anal glands emptying (evidenced One possible progression of the by a return to “bottom scooting”) after disease process is outlined in the flow only seven days, suggesting that their chart – Figure 1. perianal pruritus may have been caused Clinical decisions as to when by other factors. over-full anal sacs progress to anal Where relief of pruritus is so impaction, anal sacculitis, and then short-lived, perianal allergy must be a anal sac infection and abscessation, significant alternative reason for the are challenging and must rely on “bottom scooting” (Maina, 2014). history, clinical examination, cytology Important factors in the history that and where necessary culture. suggest the problem is related to anal In Hedlund and Fossum’s Small sac disease are summarised in Table 2. Animal Surgery they suggest that anal Whilst the authors would accept that sacculitis is diagnosed when moderate the presence of bacteria, erythrocytes or severe pain is elicited on palpation and neutrophils on cytology could and secretions are liquid yellow, blood be suggestive of anal sac disease, a tinged or purulent. Cytology, they diagnosis should only be made when suggest, reveals cellular debris, large other criteria are included. The authors numbers of leukocytes and numerous would suggest at least three out of four bacteria. of the criteria in Table 2 should be Several studies have compared present to suggest anal sac disease. Figure 2. Cytology from anal gland showing inflammatory infiltrate with rods and cocci. Figure 3. Cytology from anal gland showing rods and cocci but no inflammatory infiltrate. Figure 4. Anal sacs may be flushed and then packed with an antibiotic solution. Where dogs are re-presented on a regular basis to have their anal sacs emptied, and where abnormalities are detected, then it is often beneficial to flush and pack the sacs. Where such a procedure fails to resolve the problem then anal sac removal may be necessary. There are many misconceptions as to the best antibiotics to use for anal sac infections. The authors examined the Full anal sacs discharge from 20 normal anal sacs of 10 dogs considered not to be diseased Impaction – sacs need to be emptied monthly or more frequently (based on the criteria in Table 2) and Impacted anal sacs 20 anal sacs from 20 dogs with disease Inflammation within the sac initially without infection but identified by palpation of sac (either anal sac infection or anal sac abscessation) to identify the bacterial Anal sacculitis flora present and their antibiogram. The Infection and chronic change in the sac identified on palpation and by presence data are contained in Tables 3 and 4 infiltrate on cytology of an inflammatory (see overleaf). Anal sac infection and abscess The bacteria found in normal anal sacs and infected sacs are very similar, Figure 1. Possible progression of anal sac disease. which is why culture results alone should not be used to make a diagnosis of anal sac disease. Interestingly, the profile of the anal Table 1. Suggested reasons why anal sacs fill up. Table 2. Factors suggesting anal gland disease. sac organisms 32 DERMATOLOGY VETERINARY PRACTICE JANUARY 2016 and culture, to flush the sac using an antiseptic solution such as chlorhexidine and triz EDTA, and then pack it with a topical antibiotic (Figure 4). Although off-license use of bovine intramammary preparations containing clavamox and prednisolone is useful, the author (SP) Table 5. Antibiotic sensitivity pattern of would prefer to use a Enterococcus faecalis (y axis antibiotic, x axis product with an anti-yeast percentage). component. Key to antibiotics: Fusid – fusidic acid, Poly – polymyxin, Fram – framycetin, Gent – gentamicin, Dox – doxycycline, Pra Ear preparations – pradofloxacin, Orb – orbifloxacin, Enr – enrofloxacin, Mar containing aminoglycosides – marbofloxacin, Cvn – cefovecin, Ceph- cephalexin, Amc – clavamox, Ery – erythromycin, Clind – clindamycin. such as framycetin and gentamicin would seem good first choices. Fluoroquinolones should be used as a second choice antibiotic. Where possible, the author (SP) would choose a preparation that is oilbased rather than propylene glycol-based to avoid any potential irritant reactions Table 6. Antibiotic sensitivity pattern of Proteus to the latter. Where anal sacs have formed an abscess mirabilis (y axis antibiotic, x axis percentage). and ruptured, systemic a fluoroquinolone as a second line antibiotics are important. option, the data showing no significant Useful choices in these situations, difference between enrofloxacin, based on Table 8, would be marbofloxacin and pradofloxacin. clavamox as a first line choice and Whilst the authors are aware smell associated with anal sac secretions. Whilst Enterococcus faecalis is capable of growing at a wide range of different temperatures, Proteus mirabilis and E. coli grow best at mammalian body temperatures, the optimum growth temperature for Proteus Table 3. Bacteria and yeast identified from mirabilis being slightly higher at normal anal sacs. 40ºC than E. coli (37ºC), which might explain why inflammation within an infected sac may lead to a switch in the two populations of bacteria. The second stage of this study, undertaken by the authors, was to assess antibiotic sensitivity for a range of topical and systemic antibiotics. Table 4. Bacteria and yeast identified from Although antibiotic sensitivity infected anal sacs. was performed for all of the organisms identified on culture, only from normal sacs does not mirror that the results for the most “significant” of either canine skin or faeces. organisms – Enterococcus faecalis, E. coli The most significant change in and Proteus mirabilis – are reported in pathogen profile between these two Tables 5, 6, 7 and 8. small studies is the increased numbers Antibiotic sensitivity becomes of Proteus mirabilis in the group of dogs important when anal sac infections with infection. require therapy. Where there is anal Proteus mirabilis (like E. coli) sacculitis and infection within an intact is a Gram-negative facultative anal sac, the authors would generally anaerobic rod-shaped bacterium. select a topical antibiotic. It characteristically produces a very A suitable protocol might include, distinct “fishy odour” which probably after sampling the sac for cytology accounts for a large part of the Professional Expertise & SUPPORT Our 6 UK based diagnostic laboratories offer over 1200 tests and profiles across the 4 key animal groups, companion, equine, farm and exotics. 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Trust us. www.nwlabs.co.uk NationWide Laboratories is a trading business of National Veterinary Services Ltd VETERINARY PRACTICE JANUARY 2016 antibiotics listed, notably fuscidic acid, erythromycin and clindamycin, and enterococci are innately resistant to clindamycin and the cephalosporins, this is not something that clinicians are familiar with and likely explains the very high incidence with which clindamcyin is prescribed in Table 7. Antibiotic sensitivity pattern of E. coli anal sac disease. Where disease is recurrent (y axis antibiotic, x axis percentage). or where palpation of the that Gram-negative rods display sac suggests the potential presence of innate resistance to certain of the neoplasia, anal sac removal is preferable. DERMATOLOGY 33 References and further reading James, D. J., Griffin, C. E., Polissar, N. L. and Neradilek, M. B. (2011) Comparison of anal sac cytological findings and behaviour in clinically normal dogs and those with anal sac disease. Vet Derm 22 (1): 80-87. Lake, A. M., Scott, D. W., Miller, W. H. and Erb, H. N. (2004) Gross and cytological characteristics of normal canine anal sac secretions. JAVMA 51: 249-253. Maina, E., Galzerano, M. and Noli, C. (2014) Perianal pruritus in dogs with skin disease. Vet Derm 25 (3): 204-208. Pappalardo, E., Martino, P. A. and Noli, C. (2002) Macroscopic, cytological and bacteriological evaluation of anal sac content in normal dogs and dogs with selected dermatological disease. Vet Derm 13 (6): 315-322. Robson, D. C., Burton, G. G. and Lorimer, M. F. (2003) Cytological examination and physical characteristics of the anal sacs in 17 clinically normal dogs. Aust Vet Jour 81: 37-41. Table 8. Selected systemic and topical antibiotics with sensitivity patterns against common anal sac pathogens [Proteus mirabilis (PM), E. coli (EC), Enterococcus faecalis (EF)] (y axis antibiotic, x axis percentage). CANINE HEPATOCUTANEOUS SYNDROME (superficial necrolytic dermatitis, necrolytic migratory erythema, metabolic epidermal necrosis, diabetic dermatopathy) Hepatocutaneous syndrome is an and perinasal areas (Figures 1 and 2) uncommon disease in dogs and very and mucocutaneous junctions. There rare in cats. is usually marked hyperkeratosis of The majority of the footpads with DAVID GRANT cases are associated ulceration and continues the series of with chronic liver fissures (Figure dermatology briefs disease with a much 3). These lesions smaller number are painful and being caused by a glucagon secreting are often the trigger for requesting pancreatic neoplasm. In a survey of veterinary advice. 75 cases in the veterinary literature only six were caused by a pancreatic Differential diagnosis neoplasm (Miller, Griffin and (from Hnilica, 2011) Campbell, 2013). Cutaneous epitheliotropic The pathogenesis is incompletely lymphoma understood. In the case of pancreatic Pemphigus foliaceus neoplasia, increased gluconeogenesis Pemphigus vulgaris may be caused by hyperglucagonaemia. Systemic lupus erythematosus With liver disease there may be Drug eruption increased catabolism of amino acids. Pedal pyoderma with an underlying With both diseases the end result is cause (dermatophytosis, demodicosis) low plasma amino acid concentrations Zinc-responsive dermatosis and depletion of epidermal protein, which is thought to be the cause of Diagnosis skin lesions. Blood samples may reveal a nonregenerative anaemia and in the case of Clinical features an underlying hepatopathy there will Signs of ill health may be apparent usually be an increase in serum alkaline at initial presentation or a few months phosphatase, alanine aminotransferase, after the skin lesions. total bilirubin and bile acids. Polydipsia. Hyperglycaemia is also possible. Polyuria. The most useful diagnostic tests in Concurrent diabetes mellitus may practice are abdominal ultrasonography be present with the above signs. and skin biopsy. With liver disease Skin lesions are variable and there are hypoechoic regions include crusting, erosions and ulcers surrounded by hyperechoic areas giving commonly occurring in the periocular rise to a honeycomb pattern which is very suggestive. Pancreatic neoplasia David Grant, MBE, BVetMed, may also be detected either in situ or as CertSAD, FRCVS, graduated liver metastases. from the RVC in Skin biopsy, particularly if 1968 and received performed early, is diagnostic in many his FRCVS by cases. There is parakeratosis, oedema examination in 1978. in the stratum spinosum caused by He was hospital vacuolated keratinocytes and a deeply director at RSPCA basophilic basal layer. This gives rise Harmsworth for 25 to a “red, white and blue pattern” years until his retirement from sometimes called the “French flag”. the RSPCA and is currently Liver biopsy will identify the type engaged in writing and lecturing of hepatopathy. internationally, mainly in Glucagon concentrations will veterinary dermatology. be elevated in pancreatic neoplasia cases but may or may not be elevated with hepatopathy. Plasma amino acid concentrations are markedly decreased. Treatment three to six raw egg yolks per day together with zinc and essential fatty acid supplementation. As the hepatopathy is usually irreversible, the prognosis is very poor with survival time after the onset of skin lesions a few months only in the majority of cases. There is, however, a recent report of prolonged survival in a dog (Bach and Glasser, 2013). This case was managed for 24 months with a combination of oral fatty acid and protein supplements, intravenous amino acid infusion and intravenous lipid infusion. The authors suggest that the addition of lipid to the treatment regime was highly beneficial and to the best of their knowledge had been reported previously in the veterinary literature. Rarely, in the case of a benign pancreatic tumour such as Figure 1. Erythematous glucagonoma, surgical periocular lesions with resection of the tumour early ulceration laterally is curative. in a 10-year-old male With chronic neutered Jack Russell hepatic disease an terrier. attempt should be made to identify an underlying cause, such as mycotoxins or anticonvulsant drug hepatotoxicity. Most cases do not have an identifiable underlying Figure 2. Perinasal and cause and in these upper lip lesions in the symptomatic hepatic same dog. supportive treatment may prolong survival with drugs such as S-adenosylmethionine (sAME) or Ursodiol. Parenteral amino acid supplementation References and is the treatment of suggested reading choice for improving Figure 3. Severe 1. Bach, J. A. and Glasser, skin lesions in animals pododermatitis in the S. A. (2013) A case of with an underlying same dog. There is necrolytic migratory hepatopathy (Hnilica, erythema managed for 24 paronychia, ulceration 2011). 10% crystalline months with intravenous and hyperkeratosis of amino acid solution, or amino acid and lipid the pads and secondary 3% amino electrolyte infusions. Can Vet J. 54 (9): infection. Lesions are also solution, both at 873-875. visible on the pressure a dose of 25mL/ 2. Hnilica, K. A. (2011) points of the hocks. Hepatocutaneous kg intravenously are The feet were painful, syndrome. In: Small Animal administered over eight which was the reason for Dermatology. A Color Atlas hours. This treatment presentation. and Therapeutic Guide, 3rd is repeated every seven edition, 387-385. Elsevier. to 10 days with improvement in skin 3. Miller, W. H., Griffin, C. E. and lesions to be expected within one to Campbell, K. L. (2013) Necrolytic three weeks. Migratory Erythema. In: Muller and Kirk’s A less effective alternative (Hnilica, Small Animal Dermatology, 7th edition, 540542. Elsevier. 2011) is oral supplementation with