Dermatology cases make up a huge part of patient caseload in general practice and can be very frustrating for everyone involved. Many different dermatologic conditions can present with a similar clinical appearance, making it difficult to get a diagnosis in a timely manner. So how are you to figure out what’s what? You have to piece together the big picture, and veterinary technicians can be the key to success.
In a busy practice, the technician is usually the main contact for clients and usually the first health team member to examine the patient and gather the all-important patient profile and case history. The technician is usually the one to call clients with test results, usually the one to call clients for case follow-up, and usually the first team member to triage any client questions (and there are lots of questions with derm patients!)
Patient profile can immediately point toward differential diagnosis; breed, sex, age, coat color—all have disease predilections—history; appropriate diagnostics—cytology!
Certain conditions more common in certain breeds; i.e., atopy (allergic dermatitis) in golden retrievers, tumors in boxers, seborrhea in cocker spaniels, and hypothyroidism in Dobermans.
Some conditions more common at certain ages. Young animals may present with congenital or hereditary problems, like Ehlers Danlos syndrome. Young animals may present with conditions that are prevalent in patients with an immature immune system. Allergies tend to occur in more mature animals because of repeated exposure to allergens is necessary before becoming sensitized or allergic to an allergen. Hormonal problems or neoplasia tend to occur in older animals.
Some conditions more common in one gender, such as Sertoli cell tumor of the testicle in male dogs. Anal adenomas are more common in males than females.
Some inherited alopecia problems like color dilution alopecia in diluted coat colours like blue and fawn. White cats have higher incidence of solar dermatitis and squamous cell carcinoma.
When did problem first start? Age of onset? Rate of progression?
Are there lesion predilection sites (i.e., sarcoptic mange will affect edge of pinna, elbows, and hocks)? How do lesions look now? Have they changed?
Degree of Pruritus (Itching)
Are they pruritic? Where on body? How often are they scratching? Allergic dogs may itch at the face, feet, and ventrum. Some conditions develop pruritus over time but are not pruritic at first. Scratching, rubbing, licking, and biting may all indicate pruritus.
What’s been used? What was the dose given and how long of a course? Any effect? It’s important to note whether the drug worked or not. A good response to low-dose courses of corticosteroids will suggest an environmental allergy. Partial or total response to antibiotic therapy suggests that a bacterial infection is at least part of the problem. Find out when the last treatment was given as it may affect the clinical presentation.
Is this a recurrent problem at the same time of year? Insect problems are frequently an issue during summer months, while house dust mite allergy may affect an individual all year round.
What are they eating? Any changes to diet? What are previous diets given?
Food allergies in older animals are typically seen when the animal has been fed the same diet for years. Be specific—was a diet trial strict? Any treat or snacks? Any other vehicles for pilling? Any supplements being given? Flavoured toothpaste? Flavoured medications? Licking plates?
How much time spent indoors vs. outdoors? Where does pet sleep? What type of bedding is used? What type of flooring is in the environment? Any potted plants?
Is there any history of fleas or other parasites causing a problem? Are they on a preventative program? Contagion or zoonosis—is any other animal or person in the home affected? If suspicious of Sarcoptes, the magic words to the owner are “You don’t have to show me, but do any people in the house have any skin lesions?” Pay attention to diet, or any dietary indiscretions.
Other Clinical Signs
Sneezing, coughing, wheezing and conjunctivitis may accompany environmental allergies. Diarrhea may be associated with adverse food reactions. For dermatology cases, a client questionnaire filled out prior to seeing the patient is a very useful tool.
A brief general exam to look for any medical problems, followed by a more specific exam of the skin. Pay attention to skin temperature, quality of hair coat, and odor. Examine ears, eyes, mouth, mucous membranes, nail beds, interdigital spaces (including between foot pads), nail beds, axillary and inguinal regions, ventral neck and under the collar, perineum, the vulva or prepuce, the perianal region, and the entire dorsum.
Consider whether problem is localized or generalized. Localized problems may be due to infectious organisms that penetrated the skin at that point, while generalized conditions suggest hypersensitivity disorder, endocrine problem, or immune-mediated disease.
Symmetric lesions suggest an internal disease process (endocrine, immune-mediated), while asymmetric lesions suggest infection or parasites Look for evidence of itching or self-inflicted trauma. Try to incite the animal to itch. Gauge the level of pruritus on a scale from 1 to 10. Check how your estimation fits with the client’s own impression.
Lesions to look for: alopecia, hypotrichosis, erythema, edema, macule, wheal, vesicle, pustule, papule, epidermal collarettes, nodule, mass, cyst, scale, hyperkeratosis, crust, ulcer, erosion, excoriation, lichenification, hyperpigmentation.
- Loss of hair. Pay attention to any patterns. Symmetric hair loss is seen with endocrine diseases like Cushing’s or hypothyroidism. Consider breed predispositions: Boxers with recurrent seasonal flank alopecia, Greyhounds with bald thigh syndrome, Chihuahuas with pattern baldness.
- Erythema is redness, inflammation. Look for any patterns. Erythema of the elbow flexure surfaces is classic for environmental allergies, while perianal erythema is most often seen with food allergies.
- Edema is swelling. Hypothyroidism can result in facial myxedema known as a “tragic expression” +/- myxedema at the tail base.
- Macule is a circumscribed flat spot characterized by a change in colour of the skin (freckle). When >1 cm, a macule is called a patch. Can be footprints left behind from a previous skin condition but can also be natural markings.
- A wheal is a sharply circumscribed, raised lesion consisting of edema (a.k.a. hives, as in urticaria). Most often seen during an allergic reaction.
- A sharply circumscribed elevation of the skin up to 1 cm in diameter, filled with clear fluid. Uncommon—may indicate an immune-mediated disease. Large vesicles (blisters) are called a bulla.
- A small circumscribed elevation of the skin filled with pus—intraepidermal or follicular. Usually associated with bacterial infection. If a pustule incorporates more than one hair follicle, it may indicate an immune-mediated disease vs. a single affected follicle with pyoderma.
- A small circumscribed elevation of the skin up to 1 cm in diameter. A larger flat-topped elevation is called a plaque. A “rash” is a group of popular eruptions. Distribution patterns can be helpful to distinguish between environmental and food allergic patients: environmental most often have papules on the ventrum, while food-allergic most often have papules over the dorsum.
- Epidermal collarette
- A circular lesion with a torn appearance to outer edge. Usually the footprint of bacterial infection.
- Life span of a pustule
- It starts as a papule (erythema, irritation in a follicle); inflammation results in pus; body clears the infection and removes dead cells and debris, leaving a crust or epidermal collarette, as a footprint.
- A circumscribed, raised, solid lesion, no more than 1 cm in diameter that usually extends into the deep layers of the skin. Possible indication of neoplasia.
- A circumscribed, raised, solid lesion, larger than 1 cm in diameter, may extend into dermis or deeper; often neoplasia.
- A fluctuant mass usually filled with fluid; often seen in allergic patients on dorsal and palmar aspects of interdigital spaces.
- An accumulation of loose fragments of the stratum corneum (dander); may indicate nutritional deficits. If accompanied by pruritus, consider parasitism (Cheyletiella spp. or D. injai).
- Increased stratum corneum on nasal planum or foot pad. Some hyperkeratosis can be normal with aging, but it can also be seen with canine distemper, leishmaniasis, pemphigus, zinc responsive dermatosis, and hepatocutaneous syndrome.
- A dried lesional exudate on the skin surface. If yellow crusting present (along with pruritus) consider sarcoptic mange. Gold crusts also seen with pemphigus.
- An exposure of the underlying dermis—can be seen with deep pyoderma; infections with rod bacteria; some dermatophytes (Trichophyton mentagrophytes).
- Shallow ulcer of epidermis.
- Thickening of skin characterized by exaggeration of the superficial skin markings—result of chronic inflammation; often associated with Malassezia (yeast) infection.
- Darkening of the skin—footprint lesion from inflammation.
With a list of differentials, the next step is doing some diagnostics. Only by confirming with cytology, can you know what the appropriate treatment for secondary infections should be. I have been surprised on many occasions after doing cytology!
The vast majority of dermatology patients require lifelong management. This means lifelong relationships with your clients. You can keep these clients in your clinic, just by using the information outlined here.
There is a wide range of potential components of an antimicrobial stewardship program (Table 1). The feasibility and potential benefits of these vary, with some representing rather easy-to-implement and potentially high-yield measures, and others that can be categorized as useful to more complex and lower-priority measures.
Antibiogram data collection and use
Automatic stop orders
Cascading microbiology susceptibility reporting
Checklists (e.g., surgical)
Computerized decision support systems
De-escalation and streaming
Disease-specific treatment guidelines
Surgical prophylaxis guidelines
Formulary restriction with pre-authorization
Formulary restriction with authorization
Computer-based identification of inappropriate pathogen/drug combinations
Improved antimicrobial documentation
IV to oral conversion
User (owner) education
Prevention of treatment of non-infectious conditions
Promotion of timely and appropriate microbiological sampling
Prospective audit with feedback (clinician/service/facility)
Scheduled antimicrobial re-assessments (antibiotic time-outs)
Strategic microbiology results reporting
Targeted review for redundant therapy/therapeutic duplication
Therapeutic drug monitoring
Implementation of an Antimicrobial Stewardship Program
The approach to an ASP will vary greatly between facilities, based on a range of factors such as the nature of the caseload, the prevalence of resistant pathogens, the current state of antimicrobial use, access to specialists, access to a pharmacist, clinician motivation, management motivation and level of understanding of the issues.
Yet, any practice can implement some components of an effective ASP with little effort, time, cost, or access to other personnel. Often, starting with some easy measures (low-hanging fruit) is useful to facilitate acceptance of change (with addition of new measures over time as people realize the potential benefits) and has increased awareness and understand that an ASP is meant to help, not hamper, patient care.
While clinical antimicrobial stewardship is still in its infancy in veterinary medicine, a variety of resources are available. These include general position statements,4,6-8 disease-specific diagnosis and treatment guidelines,5,9-12 human healthcare ASP resources, and ASP program websites (Table 2). There are also national broad treatment guidelines, such as those from the Australian Infectious Disease Advisory Panel (http://www.ava.com.au/sites/default/files/AVA_website/pdfs/AIDAP%20prescribing%20guidelines.pdf) and Danish Small Animal Veterinary Association (http://www.fecava.org/sites/default/files/files/DSAVA_AntibioticGuide-lines%20-%20v1-1_3(1).pdf). These can provide the foundation for a facility-specific ASP in any veterinary practice, although more specific and practical guidance for veterinary facilities will hopefully be increasingly available in the near future.
Table 2. Examples of antimicrobial stewardship program resources
1. Bronzwaer S, Lonnroth A, Haigh R. The European Community strategy against antimicrobial resistance. Euro Surveill. 2004;9(1):1–3.
2. McEwen SA, Fedorka-Cray PJ. Antimicrobial use and resistance in animals. Clin Infect Dis. 2002;34(Suppl 3):S93–S106.
3. Prescott JF. Antimicrobial use in food and companion animals. Animal Health Research Reviews/Conference of Research Workers in Animal Diseases. 2008;9(2):127–133.
4. Page S, Prescott J, Weese S. The 5Rs approach to antimicrobial stewardship. Veterinary Record. 2014;175(8):207–208.
5. Weese JS, Blondeau J, Boothe D, et al. Antimicrobial use guidelines for treatment of urinary tract infections in dogs and cats: antimicrobial guidelines working group of the International Society for Companion Animal Infectious Diseases. Vet Med Int. 2011;4:1–9.
6. Weese J, Giguère S, Guardabassi L, et al. ACVIM consensus statement on therapeutic antimicrobial use in animals and antimicrobial resistance. J Vet Int Med. 2015;29:487–498.
7. American Veterinary Medical Association. Judicious therapeutic use of antimicrobials. http://www.avma.org/scienact/jtua/jtua98.asp. 2004. Accessed April 11, 2005.
8. Morley PS, Apley MD, Besser TE, et al. Antimicrobial drug use in veterinary medicine. J Vet Intern Med. 2005;19(4):617–629.
9. Hillier A, Lloyd DH, Weese JS, et al. Guidelines for the diagnosis and antimicrobial therapy of canine superficial bacterial folliculitis. Vet Dermatol. 2014;25(3):163–e43.
10. Lappin MR, Blondeau J, Booth D, et al. Anti-microbial use guidelines for treatment of respiratory tract disease in dogs and cats: Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases. J Vet Intern Med. 2017;31:279–294.
11. Beco L, Guaguere E, Lorente Méndez C, et al. Suggested guidelines for using systemic antimicrobials in bacterial skin infections. part 1. Vet Rec. 2013:1–11.
12. Beco L, Guaguere E, Lorente Méndez C, Noli C, Nuttall T, Vroom M. Suggested guidelines for using systemic antimicrobials in bacterial skin infections: part 2. Vet Rec. 2013;172(6):156–160.