I wanted to post this in case anyone's dog has experienced this particular reaction to rabies vaccination and they wondered what was happening.


Ischemic Dermatopathy / Cutaneous vasculitis

A little known and often misdiagnosed reaction to the rabies vaccine in dogs, this problem may develop near or over the vaccine administration site and around the vaccine material that was injected, or as a more widespread reaction. Symptoms include ulcers, scabs, darkening of the skin, lumps at the vaccine site, and scarring with loss of hair. In addition to the vaccination site, lesions most often develop on the ear flaps (pinnae), on the elbows and hocks, in the center of the footpads and on the face. Scarring may be permanent. Dogs do not usually seem ill, but may develop fever. Symptoms may show up within weeks of vaccination, or may take months to develop noticeably.

Dogs with active lesion development and / or widespread disease may be treated with pentoxyfylline, a drug that is useful in small vessel vasculitis, or tacrolimus, an ointment that will help suppress the inflammation in the affected areas.

Owners and veterinarians of dogs who have developed this type of reaction should review the vaccination protocol critically and try to reduce future vaccinations to the extent medically and legally possible. At the very least, vaccines from the same manufacturer should be avoided. It is also recommended that the location in which future vaccinations are administered should be changed to the rear leg, as far down on the leg as possible and should be given in the muscle rather than under the skin.


A retrospective study of canine and feline cutaneous vasculitis
Patrick R. Nichols**Animal Allergy and Dermatology Center of Central Texas, 4434 Frontier Trail, Austin, Texas 78745, USA
Daniel O. Morris††Department of Clinical Studies, Veterinary Hospital, University of Pennsylvania, 3850 Spruce St., Philadelphia, Pennsylvania 19104, USA and
Karin M. Beale‡‡Gulf Coast Veterinary Dermatology and Allergy, 1111 West Loop South, Suite 120, Houston, Texas 77027, USA
*Animal Allergy and Dermatology Center of Central Texas, 4434 Frontier Trail, Austin, Texas 78745, USA †Department of Clinical Studies, Veterinary Hospital, University of Pennsylvania, 3850 Spruce St., Philadelphia, Pennsylvania 19104, USA ‡Gulf Coast Veterinary Dermatology and Allergy, 1111 West Loop South, Suite 120, Houston, Texas 77027, USA
Correspondence: Daniel O. Morris, Department of Clinical Studies, Veterinary Hospital, University of Pennsylvania, 3850 Spruce St., Philadelphia, PA 19104, USA. E-mail:[email protected]

Twenty-one cases of cutaneous vasculitis in small animals (dogs and cats) were reviewed, and cases were divided by clinical signs into five groups. An attempt was made to correlate clinical types of vasculitis with histological inflammatory patterns, response to therapeutic drugs and prognosis. Greater than 50% of the cases were idiopathic, whereas five were induced by rabies vaccine, two were associated with hypersensitivity to beef, one was associated with lymphosarcoma and two were associated with the administration of oral drugs (ivermectin and itraconazole). Only the cases of rabies vaccine-induced vasculitis in dogs had a consistent histological inflammatory pattern (mononuclear/nonleukocytoclastic) and were responsive to combination therapy with prednisone and pentoxifylline, or to prednisone alone. Most cases with neutrophilic or neutrophilic/eosinophilic inflammatory patterns histologically did not respond to pentoxifylline, but responded to sulfone/sulfonamide drugs, prednisone, or a combination of the two.

Vitale, Gross, Magro (1999)
Vaccine-induced ischemic dermatopathy in the dog
Veterinary Dermatology 10 (2), 131–142.

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Full Article
Vaccine-induced ischemic dermatopathy in the dog
Gross &
1Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California 95616, USA, 2IDDEX Veterinary Services, California Dermatopathology Service, 2825 KOVR Drive, West Sacramento, California 95605, USA, 3Department of Pathology, Beth Israel Hospital, Harvard Medical School, Pathology Services, Inc., 640 Memorial Drive, Cambridge, Massuchusetts 02139, USA
Correspondence to: Carlo B. Vitale
Present address: Encina Veterinary Hospital, 2803 Ygnacio Valley Road, Walnut Creek, California 94598, USA.
Post-rabies vaccination alopecia associated with concurrent multifocal ischemic dermatopathy was identified in three unrelated dogs. All dogs received subcutaneous rabies vaccine dorsally between the scapulae several months prior to observation of the initial area of alopecia at the vaccination site. All three dogs developed multifocal cutaneous disease within 1–5 months after the appearance of the initial skin lesion. Cutaneous lesions were characterized clinically by variable alopecia, crusting, hyperpigmentation, erosions, and ulcers on the pinnal margins, periocular areas, skin overlying boney prominences, tip of the tail, and paw pads. Lingual erosions and ulcers were observed in two dogs. Histopathologic examination of the skin revealed moderate to severe follicular atrophy, hyalinization of collagen, vasculopathy, and cell-poor interface dermatitis and mural folliculitis. Hypovascularity was demonstrated by diminished Factor VIII staining of blood vessels. Nodular accumulations of lymphocytes, plasma cells, and histiocytes in the deep dermis and panniculus also were noted at the rabies vaccination site. An atrophic, ischemic myopathy paralleling the onset of skin disease was identified in two dogs. Histological examination of muscle biopsy specimens demonstrated perifascicular atrophy, perimysial fibrosis, and complement (C) 5b-9 (membrane attack complex) deposition in the microvasculature of both dogs with myopathy. Marked improvement of the skin disease was obtained with oral pentoxifylline and vitamin E.


The Armed Forces Institute of Pathology
Department of Veterinary Pathology

26 February 2003

Conference Moderator:
Dr. Michael Goldschmidt, MSc, BVMS, MRCVS Diplomate, ACVP
Professor, School of Veterinary Medicine
University of Pennsylvania
Philadelphia, PA 19104-6051

CASE II - 2513-02 (AFIP 2839301)

Signalment: 5-year-old, male, castrated, canine, Chihuahua
History: One by three cm lesion on the dorso-lateral neck
Gross Pathology: None
03WSC19 - 2 -
Laboratory Results: None

Contributor’s Morphologic Diagnosis: Post-rabies vaccination alopecia with injection site granuloma and panniculitis

Contributor’s Comment: The hair follicles are markedly atretic and their lower portions are replaced by an eosinophilic, hyaline stroma. The deeper dermis also has a cleft or seroma pocket that is partially lined by a thin layer of foamy macrophages and multinucleated giant cells with more peripheral lymphoid nodules with many scattered dermal macrophages, lymphocytes and plasma cells. Scattered melanin-laden macrophages (positive with Fontana-Masson melanin stain and negative for hemosiderin with a Prussian blue stain) are in the hyalinized lengths of the hair follicles with a few beneath the epidermal basement membrane (pigmentary incontinence).

This is post-rabies vaccination alopecia with an underlying injection site granuloma. Post-rabies vaccination alopecia is most commonly seen in toy or small breeds, especially Poodles, but Chihuahua cases have been reported. The lesion usually develops three to six months after vaccination.

Other reports describe mild to severe lymphocytic inflammation with macrophages in the superficial or deep dermis or scattered around hair follicle remnants. The dermis may have smudging of the collagen, especially around the hair follicles. Rabies vaccine antigen has been found in the hair follicle epithelium and in the walls of vessels in the area. One report of focal alopecia developing in all twelve of twelve inbred miniature Poodles injected with a killed rabies vaccine two months earlier suggest that there may be a familial predisposition to this apparently idiosyncratic, hypersensitivity reaction to the antigen.