Cats can be affected by autoimmune diseases in which their own immune system plays tricks on them. Pemphigus is characterized by the formation of primary lesions consisting of vesicles or blisters in various locations, depending on the type of pemphigus. While they are more frequent in the oral cavity or in the mucocutaneous folds in pemphigus vulgaris, in pemphigus foliaceus they usually affect the skin exclusively; the erythematosus is restricted only to the face of the feline and the paraneoplastic is rare and occurs as a consequence of an underlying tumor. Of these, the most common in small cats is pemphigus foliaceus.
Pemphigus treatment should be based on immunosuppressive therapy to stop the immune system responsible for the process. Keep reading this article on our site where we explain what is pemphigus in cats, its symptoms and treatment
What is feline pemphigus?
Feline pemphigus is an autoimmune disease in which the cat's immune system does not recognize part of its body as its own and creates a immune reaction against it. It consists of skin or mucocutaneous disorders due to a type II hypersensitivity reaction that begins with the participation of immunoglobulins G and M, which bind to target cells and activate complement, inducing phagocytosis. This leads to the production of autoantibodies against certain components of the epidermis.
This is a dermatological disease characterized by acantholysis or detachment of each cell of the epidermis that creates vesicles within it. These vesicles can be infiltrated with eosinophils or neutrophils and transform into pustules.
What types of pemphigus are there in cats?
In cats, depending on the distribution of the lesions and their pathological characteristics, they can be classified into four types:
- Pemphigus vulgaris: consists of the formation of vesicles or blisters in the oral cavity, skin and mucocutaneous junctions, such as the axilla and the Region inguinal. These lesions, due to their fragility, evolve into collarettes, erosions, ulcers and scabs.
- Pemphigus foliaceus: Autoantibodies are produced against proteins of the stratum spinosum of the epidermis. It is characterized by the formation of vesicles, blisters or, less frequently, subcorneal pustules that affect follicles and interfollicular skin. Secondary lesions are erythema, exudation, crusting, alopecia, and collaretes. These are generally distributed symmetrically on the face, snout, ears to the extremities and abdomen. The lesions occur on the skin, without affecting the oral cavity or mucocutaneous junctions.
- Pemphigus erythematosus: It is considered an intermediate form between lupus erythematosus and pemphigus or as the benign form of pemphigus foliaceus. Vesicles and blisters and pustular lesions form on the ears and head. It is important to consider that solar radiation can aggravate the pathology.
- Paraneoplastic pemphigus: Vesicles and blisters occur on multiple organs other than the skin. It is a disease associated with an underlying cancer, usually of lymphoproliferative origin.
Symptoms of pemphigus in cats
Cats with pemphigus present, in addition to the lesions described above depending on the type they develop, nonspecific signs such as:
- Fever.
- Anorexy.
- Lethargy.
- Apathy.
- Pain.
- Lymphadenopathy.
In cats, pemphigus foliaceus is the most common autoimmune disease More so than subcorneal pustules, which are more common in dogs, in cats with pemphigus foliaceus are seen more frequently yellowish crusts A characteristic lesion of this pemphigus in cats is paronychia (inflammation of the skin around the nail) and pruritus (itching).
Feline pemphigus diagnosis
Due to the pruritus produced by pemphigus foliaceus in cats, a differential diagnosismust be made among other diseases that cause itching in this species such as allergies and parasitic diseases. In addition, the following tests will be performed:
- Blood test: in the case of this type of injury in a cat, you should start with a blood test, which can be normal or abnormal. have an increased count of neutrophils and eosinophils. Blood biochemistry is normal if there is no concurrent disease.
- Cytology: Cytology of lesions may aid diagnosis if neutrophils and acanthocytes are seen. It is also useful to assess whether there is a bacterial infection. In that case the cat would be treated with antibiotics before taking and sending the biopsy to the laboratory.
- Histopathological examination: However, the definitive diagnosis is achieved by histopathological examination. To do this, biopsies of recent primary lesions must be collected, and it is important that the cat has not received immunomodulatory or immunosuppressive treatment in the previous days, as this may alter the results. Biopsy will find subcorneal pustules with neutrophils and a variable number of acanthocytes and eosinophils. If these are not seen, a presumptive diagnosis can be made if serocellular crusts with acanthocytes and neutrophils are seen.
As a curiosity, oral lesions are detected in 90% of pemphigus vulgaris diagnoses. Paronychia would be seen in 30% of pemphigus foliaceus and itching in 80%.
Treatment of pemphigus in cats
The treatment should contain immunosuppressive drugs such as prednisolone at doses of 2-8 mg/kg every 24 h orally. Immunosuppressive doses should be reduced when remission of clinical signs begins, to the lowest dose that maintains disease resolution.
If the clinical signs are not reduced one month after the start of immunosuppressive treatment, it is recommended to switch to dexamethadone or methylprednisolone, decreasing until the minimum effective dose.
If no response is observed with these treatments or secondary effects appear such as polyphagia, polyuria-polydipsia, apathy, diarrhoea, diabetes or urinary tract infections, add chlorambucil(0.1-0.2 mg/kg every 24-48 h). In some cases, corticosteroids can be withdrawn and continued only with chlorambucil twice a week or every other day. The beneficial effects of this drug may take weeks to appear. It must be taken into account that chlorambucil is a cytotoxic drug, so periodic blood tests should be performed every 2-4 weeks for the first 3 months, until every 6 months thereafter.
On the other hand, it has been determined that the use of cyclosporine at doses of 4.4 to 7.4 mg/kg each 24 hours can be effective for feline pemphigus, even being able to suppress corticosteroids and with efficacy similar to chlorambucil.
In addition, drugs for cats with pemphigus may also contain immunomodulators such as mycophenolic acid and leflunomide.
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