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Diagnosing puppy strangles

This rare condition has an autoimmune cause and usually affects one puppy in an otherwise healthy litter

13 March 2020, at 9:00am
Puppy's face
FIGURE (1) The puppy showed periorbital alopecia and swollen skin mimicking Demodex

Puppy strangles, or juvenile cellulitis, is another rare condition and the focus of this month’s feature. It usually turns up in one puppy in an otherwise healthy litter. The puppy I saw was on a course of antibiotics and corticosteroids and at first glance appeared to have periorbital alopecia (Figure 1) which looked just like demodicosis, the “spectacles” of bare skin around the eyes. Otherwise he was lively and eating well. I continued his course of treatment and advised re-examination in two weeks.

The condition gets its name from the swollen submandibular lymph nodes which are the presenting sign of strangles in horses. Equine strangles is a primary bacterial syndrome which is caused by Streptococcus equi. It is highly infectious and highly prevalent.

Puppy strangles on the other hand is rare, usually affects one individual in a litter and has an autoimmune cause with a hereditary component. Pointers, Golden Retrievers, Dachshunds, Gordon Setters and Beagles are the breeds in which it is most likely to occur. Puppies are usually affected between three weeks and four months of age.

The first signs are swelling of the face (Figure 2A), chin (Figure 2B), eyelids, muzzle and lips with papules and then pustules developing in the first 24 to 48 hours. These become crusted and may bleed or discharge pus. The lesions are painful, the ears may discharge and the draining lymph nodes will be swollen and tender and may discharge serum or pus. Multiple joints can be affected with non-erosive arthritis and the puppy is depressed, pyrexic and anorexic. Sometimes there are nodular lesions on the back, or, as in the case that I saw, swollen eyelids which were followed by alopecia.

Skin scrapings for external parasites will be negative and any bacteria found will be secondary invaders. Impression smears will show a neutrophilic exudate which may include bacteria. Histopathology shows granulomas and pyogranulomas which can be discrete or conjoined. These are made up of cores of neutrophils surrounded by large epithelioid macrophages. The apocrine sweat glands and sebaceous glands may be obscured. In severe established cases, the hair follicles in the superficial dermis may be ruptured with suppurative changes in both dermis and underlying panniculus. In the referral situation, Andrew Jagoe has found that, very occasionally, puppy strangles shows up in a severe adult-onset version and sometimes it is missed in a diagnosis of deep fulminant pyoderma.

Treatment is primarily immune-suppressive doses of steroid, for example prednisolone at 2mg/kg per 24 hours or dexamethasone at 0.2mg/kg per 24 hours. This may need to be reinforced by antibacterials to control the secondary infection. Recovery is usually achieved in a few weeks, although more time is needed for hair regrowth which should be complete unless treatment has been delayed. If so, scarring and alopecia can be permanent.

The lesions of puppy strangles are highly characteristic in appearance and taken with the age of onset and the fact that most of the litter are unaffected give a strong index of suspicion. As Peter J Ihrke of the University of California said “The clinical presentation of some of these lesions comes very close to being pathognomonic. These clinical clues can be used to prioritise our index of suspicion when generating differential diagnoses and this allows us to take short cuts when considering the most appropriate clinical and laboratory diagnostic procedures” (Ihrke 2008).

Although puppy strangles shows up at the same time as the primary vaccination course is being given there appears to be no causal relationship and recovered dogs can have a normal pattern of vaccination through life without relapse of strangles.

References
Author Year Title
Ihrke, P. 2008 Clinical markers of selected dermatoses: visual clues. In: 33rd World Small Animal Veterinary Association World Congress Proceedings. Dublin, Ireland: Veterinary Information Network

Marion McCullagh, MVB, MRCVS, worked in mixed practice, with intervals working for the Donkey Sanctuary and MAFF. She had her own practice for five years, did some acupuncture, has always written articles and now does small animal locums.

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