Syndrome of acute-onset furunculosis

Community-acquired skin infections, particularly folliculitis (hot tub colliculitis) or painful nodules on the hands and feet(hot hand-foot syndrome), are well documented in humans as the result exposure to contaminated swimming pools, hot tubs, whirlpool baths, and saunas. Infections are generally associated with ubiquitous gram-negative bacteria such as Pseudomonas aeruginosa, and common-source exposure may result in outbreaks of several individuals.

A similar syndrome of acute-onset furunculosis following water immersion or grooming has been described in dogs. Furunculosis has been proposed as a sequel to follicular trauma from vigorous manipulation of the skin and coat (ie, brushing or coat-stripping), followed by bathing with contaminated shampoos or conditioners, particularly bulk formulations that are diluted for use in commercial grooming facilities. Pseudomonas aeruginosa and other gram-negative bacteria have been isolated most commonly from skin lesions of affected dogs. Gross and Crow reported 2 cases of acute, dorsally located furunculosis in dogs following use of grooming products. In one dog, P aeruginosa was isolated from skin lesions and diluted conditioner; in the other dog, Serratia marcescens was isolated from skin lesions and undiluted shampoo, supporting bacterial contamination of grooming products as the infection source for these dogs.

Although this clinical syndrome is a recognized entity in dogs, reports of acute-onset, dorsally located furuncolosis following water exposure are primarily anecdotal at this time. To our knowledge, no published case series has specifically described furunculosis in dogs with a recent history of grooming on water immersion. The purpose of the study reported here was to determine the clinical, histopathologic, and microbiological features as well as treatment of dogs with compatible clinical lesions of furunculosis and a recent history of water immersion or exposure to grooming products.

Materials and Methods

This study was designed as a retrospective analysis of canine patients with a histopathologic or clinical diagnosis of acute furunculosis following water immersion or exposure to grooming products. Computer searches of the University of Pennsylvania Laboratory of Pathology and Toxicology biopsy database and the matthew J. Ryan Veterinary Hospital of the University of Pennsylvania patient hospital discharge system were performed for medical records of dogs with a morphological or clinical diagnosis of furunculosis from January 1, 2005, to January 31, 2013. Inclusion criteria consisted of acute onset of skin lesions consistent with furunculosis (papules, pustules, plaques, nodules; with or without erosions, ulcers, and crusts) and a history of water immersion or grooming within 7 days prior to onset of skin lesions.

Medical records review – Medical records were reviewed for the following information: patient signalment, month of onset of clinical signs, location and description of skin lesions, time of lesion onset in days following water immersion or grooming, location of bathing or grooming (home vs commercial grooming facility), shampoo type if used (over the counter vs prescription; medicated vs nonmedicated), history of brushing prior to lesion onset, associated clinical, signs, clinical diagnostic tests performed and any abnormal results, results of bacteriologic culture of the skin samples (if performed), histopathologic features (if performed), treatment, and treatment response, For specimens of affected dogs submitted to the University of Pennsylvania Laboratory of Pathology and Toxicology by outside veterinarians, submitting veterianarians were contacted by email, fax, or telephone for additional follow- up information.

Results

Twenty-two dogs met the inclusion criteria. Nine (41%) dogs were castrated males, 3 (14%) were sexually intact males, 9 (41%) were spayed females, and 1 (4%) was a sexually intact female. The median age was 4 years (range, 0.75 to 13 years). Ten breeds were represented, with 4 (18%) German Shepherd Dogs, 4 (18%) Labrador Retrievers, 3 (14%) Golden Retrievers, and 3 (14%) Welsh Corgis. There were 3 mixed-breed dogs. The remainder of the patient population consisted of 1 each of the following breeds: Beagle, Bloodhound, Weimaraner, Jack Russel Terrier and Rottweiler. Three of 4 German Shepherd Dogs and 1 of 4 Labrador Retrievers were working police dogs.

Onset of clinical signs war perennial, with all months represented except for February and June. The most common month for diagnosis was September (6/22 [27%]), followed by August (3/22[14%]) and December (3/22 [14%]).

Skin lesion distribution and description – Skin lesions were dorsally distributed on the neck and trunk in all dogs; I dog was also affected on the dorsal aspect of the tail. In addition to dorsally located skin lesions, 2 dogs had lesions involving the inguinal region and hind limbs, I had lesion on the head and lateral aspect of the abdomen, I had lesions on the flanks and lateral aspect of the thorax, and I had lesions on the cranial aspect of the thorax.

The most commonly reported skin lesions were hemorrhagic crusts (15/22 [68%]), followed by papules and pustules (10/22 [45%]), plaques (8/22[36%]), pinpoint ulcers or draining tracts (6/22 [27%]), and nodules (3/22[14%]) or hemorrhagic furuncles (3/22 [14%]). For 4 dogs, oozing of hemorrhagic to purulent exudate from hair follicle ostia was specifically noted in the medical records. Intense macular erythema surrounded skin lesions along the dorsum of 2 dogs (Figure 1).

Grooming history – Water immersion or exposure to grooming products occurred a median of 2 days prior to onset of clinical sigs (range, 1 to 7 days). Of the 22 dogs, 10 (45%) were bathed at home (Figure 1), 9 (41%) at commercial grooming facilities, and 1 (4,5%) while boarding at a veterinary hospital; I dog was immersed in a underwater treadmill 1 day prior to onset of clinical signs, and 1 dog had hair clipped from the dorsal aspect of its coat and its skin scrubbed in preparation for hemilaminectomy 2 days prior to onset of clinical signs. In this dog, lesions were only found on the dorsal portion of the back where hair was clipped surrounding the surgical incision.

The shampoo type was unknown for 12 of 22 (55%) dogs. For the remaining 10 dogs, 5 were bathed with over-the-counter nonmedicated shampoos, and I each was bathed with an over-the-counter flea and tick shampoo, a prescription nonmedicated cleasing shampoo, and a prescription antiseborrheic shampoo. One dog was scrubbed with chlorhexidine-based surgical scrub prior to hemilaminectomy. The remaining dog developed lesions after physical therapy on an underwater treadmill and was towel-dried only (no products used). For the dog bathed with a prescription nonmedicated cleasing shampoo, the shampoo was known to be within the manufacturer’s recommended use-by date. It is unknown whether the other shampoos were expired or within recommended use-by dates. It is also unknown whether shampoo concentrates were diluted prior to use.