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Ask Dr. Michael Salkin Your Own Question
Dr. Michael Salkin
Dr. Michael Salkin, Veterinarian
Category: Dog Veterinary
Satisfied Customers: 27438
Experience:  University of California at Davis graduate veterinarian with 44 years of experience
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I have a 2 year old Black Lab who is having pain. If she

Customer Question

I have a 2 year old Black Lab who is having facial pain. If she bumps her face or hits it going out the door (she's excitable), she will yelp, cry, paw at her face, and then go hide. She won't let anyone touch her. I have had her to three different vets and they can find nothing wrong. They've done complete skull, dental and spine x-rays, have sedated her and done a full exam of her ears, eyes and teeth, have done blood work nothing. One thought it might be nerve pain, so he put her on pain medication that actually stops the brain from feeling pain. That didn't work either, and it is getting worse. Now her whole body is affected. Just the other day, even her leg trembled violently when she had an episode. Any thoughts?
JA: Thanks. Can you give me any more details about your issue?
Customer: Oh, all the vets also prodded at her face and got no reaction. It did manifest itself on its own, though, with two of the vets when she bumped her face.
JA: OK got it. Last thing — Dog Veterinarians generally expect a deposit of about $19 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 1 year ago.
Category: Dog Veterinary
Customer: replied 1 year ago.
I've been told that the only other option is to take her to a specialist for a cat scan, which could cost upwards of $1000.
Expert:  Dr. Michael Salkin replied 1 year ago.

I'm sorry to hear of this with your Lab. My primary differential diagnosis would be idiopathic (unknown cause) polymyositis which can initially manifest about the jaws and eyes and then generalize to the rest of the body. This is considerated to be an autoimmune disorder (her immune system would be attacking her own muscles). Here is a synopsis of this disease for you:

Definition

An autoimmune inflammatory disease of unknown pathogenesis that primarily affects appendicular musculature

Epidemiology

Species, Age, Sex

Although any breed or age of dog can be affected, the majority of reported cases are middle-aged, large breeds. There is no apparent sex predilection.

Genetics and Breed Predisposition

Newfoundlands and boxers appear to be overrepresented. Newfoundlands tend to develop the disease at a younger age than other breeds. A substantial number of boxers with polymyositis may develop the disorder as a preneoplastic condition. A breed-specific suspected autoimmune polymyositis has recently been described in Hungarian Vizsla dogs. This latter disorder appears to primarily affect masticatory and pharyngeal muscles clinically, though other muscles are affected.

Associated Disorders

Uncommonly, dogs with autoimmune polymyositis may have concurrent masticatory myositis (which would cause her facial pain). This combination is referred to as overlap syndrome. Another uncommon associated condition in dogs with autoimmune polymyositis is thymoma.

Clinical Presentation

History, Chief Complaint

Clinical signs may be acute or chronic. The animal's medical history or clinical complaints may include any combination of generalized weakness (often worsened by exercise), stiff gait, generalized muscle atrophy, dysphonia, myalgia, dysphagia, regurgitation (megaesophagus may be present), fever, and muscle swelling.

Physical Exam Findings

Physical examination findings typically concur with the animal's medical history and clinical complaints.

Etiology and Pathophysiology

This is an idiopathic autoimmune disorder.

 Diagnosis

Diagnostic Overview

The diagnosis is suspected in a dog with signs of regional or diffuse muscle weakness and pain. Elevation of muscle enzymes on routine serum biochemistry panels is common. A definitive clinical diagnosis is achieved with muscle biopsy results in combination with normal (negative) serologic titers for potential infectious causes.

Differential Diagnosis

  • Infectious polymyositis (e.g., toxoplasmosis, neosporosis)
  • Overlap syndrome
  • Preneoplastic myositis
  • Myasthenia gravis

Initial Database

  • CBC, serum chemistry profile, urinalysis: elevated aspartate aminotransferase (AST) possible
  • Serum creatine kinase: usually elevated, often markedly so
  • Serologic titers for infectious diseases (e.g., toxoplasmosis, neosporosis)

Advanced or Confirmatory Testing

  • Electrodiagnostics: electromyogram (EMG) is usually abnormal.
  • Muscle biopsy: a nonsuppurative inflammatory infiltrate is typically evident. Immunohistochemical staining of muscle tissue can verify immunoglobulin localization to the sarcolemma.

 Treatment

Treatment Overview

The goal of therapy is to achieve clinical remission of myopathic signs.

Acute General Treatment

Immunosuppressive doses of prednisone (e.g., 1-2 mg/kg PO q 24h) are generally used as initial therapy.

Chronic Treatment

  • Once clinical remission of signs is achieved, the dosage of prednisone is slowly tapered over several months and is discontinued if possible.
  • If prednisone cannot be effectively tapered or discontinued, alternative immunosuppressive drugs can be instituted (e.g., azathioprine 2 mg/kg PO q 24h for 5 days, then q 48h; or mycophenolate mofetil 5-10 mg/kg PO q 12h).

Possible Complications

  • Either inadequate or excessive immunosuppression
  • Drug side effects or complications, including polyuria and polydipsia (PU/PD), polyphagia, weight gain, iatrogenic hyperadrenocorticism (glucocorticoids), bone marrow effects (azathioprine), and others

 Prognosis & Outcome

The prognosis is favorable in approximately 80% of cases. Relapses may occur with tapering or discontinuation of immunosuppressive drugs.

 Pearls & Considerations

Comments

When tapering prednisone in cases of autoimmune polymyositis, dose reductions should not be made more frequently than every 4 weeks.

I don't believe that a CT would be of value but referral to a specialist veterinary internist (please see here: www.acvim.org) is indicated once such extensive diagnostics have been performed which haven't clarified the diagnosis.

Please respond with further questions or concerns if you wish.

Expert:  Dr. Michael Salkin replied 1 year ago.
Hi,
I'm just following up on our conversation about your pet. How is everything going?
Dr. Michael Salkin