Myofasciitis in the Domestic Ferret

Neurologic Assessment and Critical Care of Exotic Animals: Approach to the Neurologic Exam, Species Differences, Prognostic Scales, Commonly Encountered Conditions, Ancillary Diagnostic Tests, and Caring for Neurologically Impaired Patients

Many disorders of other body systems have been well characterized in exotic species; however, data regarding neurologic conditions is limited. Across some of these species, correlates between feline and canine neurology can be made, but variations in the nervous system anatomy make evaluation more challenging. With accurate neurolocalization a focused list of differential diagnoses can be created. Performing the neurologic examination should be methodical for all patients, and the order and extent of examination may depend upon the patient's clinical condition and cooperation. Applications of objective scale measures (such as coma scales), and ancillary diagnostics (electrodiagnostics, advanced imaging, biopsy techniques, and BAER testing) complement physical assessment and clinicopathologic assessment in these neurologic patients. Once a neurolocalization, likely diagnosis, and prognosis have been established, specific considerations for hospitalization and care of neurologic patients can be implemented while treatment is instituted.

Ferret Dermatology

Skin diseases commonly affect pet ferrets, with neoplastic, endocrine, and parasitic diseases being the most common. This review includes clinical presentation, diagnostic workup, and treatment of diseases with a dermatologic presentation in ferrets.

Musculoskeletal and Neurologic Diseases

Ferrets may exhibit neurologic signs as a result of various conditions that may be of nervous or muscular origin. Neurologic examination follows the same principles as in small animal medicine. One of the main defect that may be screened during clinical examination is deafness. Congenital deafness in ferrets is associated with coat color patterns such as white markings and premature graying.In this species, paresis is a common presentation and may reflect a generalized weakness. Spinal disorder, intervertebral disk disease, and neoplasia are among the differential diagnosis. Diagnostic exams usually include advance diagnostic imaging such as CT-scan associated with myelography. Seizure is usually associated with hypoglycemia and insulinoma, but other causes such as hypocalcemia or intracranial disorders have been described. Ferrets are sensitive to various neurotropic infectious disease such as rabies, distemper, aleutian disease, or systemic coronavirus. Finally, muscular disorder such as disseminated idiopathic myofasciitis and myasthenia gravis have been recently described, and potential treatments have been intended.

Gonadotrophin-Releasing Hormone Agonists and Other Contraceptive Medications in Exotic Companion Animals

The use of a gonadotrophin-releasing hormone agonist slow-release implant (GnRH A-SRI) has become increasingly popular as an alternative for surgical contraception in many species. Although these implants have proven to be very effective in some species (eg, ferrets, rats, chicken, psittacines, and iguanas), they have been found less effective in other species (eg, male guinea pigs and rabbits, veiled chameleons, slider turtles, and leopard geckos). This review provides an overview of the available literature on the effects of GnRH A-SRIs in companion exotic animals.

Histological and immunohistochemical features of histiocytic sarcoma in four domestic ferrets (Mustela putorius furo)

Four cases of histiocytic sarcoma in domestic ferrets (Mustela putorius furo) are described in the present study. Tumor samples obtained from the abdominal viscera, including the spleen, were submitted for histologic examination. Microscopically, poorly demarcated masses contained numerous round- to pleomorphic-shaped cells with coarsely vacuolated and eosinophilic cytoplasm. Bizarre, binucleated tumor cells and multinucleated giant tumor cells with low phagocytic activity were commonly observed. Immunohistochemically, tumor cells in all of the cases were positive for vimentin, human leukocyte antigen-DR, ionized calcium-binding adapter molecule-1, and lysozyme, but some of them lacked cluster of differentiation (CD)163 or CD208 expression. The survival time after surgical resection was 9 days to 5 months. Histiocytic sarcoma in the ferret is a rare, but highly aggressive, tumor commonly found in the spleen.

Utility of two modified-live virus canine distemper vaccines in wild-caught fishers (Martes pennanti)

BACKGROUND

Canine distemper virus (CDV) infects families in the order Carnivora. As a preventive measure, vaccinations against CDV are frequently given to mustelids in captive environments.

OBJECTIVES

Our objectives were to compare the utility between two modified-live virus canine distemper vaccines (MLV CDV's), Fervac-D® (no longer manufactured) and Galaxy-D® (now manufactured by MSD Animal Health as part of a multivalent vaccine), in developing an immune response in wild-caught fishers.

ANIMALS AND METHODS

The Pennsylvania Fisher Reintroduction Project (PFRP) used 14 wild-caught fishers during one year of the project to evaluate the utility of vaccinations against CDV as part of any reintroduction project. Fishers were injected subcutaneously in the nape of the neck with their designated vaccine.

RESULTS

Fervac-D® did not effectively stimulate development of a serologic antibody response, whereas Galaxy-D® had adequate seroconversion or rise of titer levels to suggest that the general use of MLV CDV may be suitable in fishers pending further studies.

CONCLUSION

We recommend that future studies be conducted, evaluating the use of currently produced vaccines in fishers. Future research should also focus on the length of days required between administration of primary and booster vaccines to achieve sufficient immune response.

CLINICAL IMPORTANCE

If only primary doses are required, then hard-release reintroduction projects for fishers could be recommended. If primary and booster vaccines are required then soft-release reintroduction projects should be recommended that include captive management periods, allowing for appropriate vaccination intervals needed to maximize the probability of protection against CDV.

Flexible Gastrointestinal Endoscopy in Ferrets (Mustela putorius furo)

Gastrointestinal disease is a common complaint in ferrets (Mustela putorius furo). Their relatively simple and short gastrointestinal tract makes them good candidates for flexible endoscopy. However, apart from a few references in biomedical research articles, there is little information on the use of flexible endoscopy in ferrets. This review describes patient preparation, equipment, and select gastrointestinal endoscopy techniques in ferrets, including esophagoscopy, gastroscopy, duodenoscopy, percutaneous endoscopic gastrostomy, jejunoileoscopy, colonoscopy, and biopsy.

Necrotizing and eosinophilic masticatory myositis in farmed mink: a preliminary description

This report describes necrotizing and eosinophilic myositis affecting the masticatory muscles of a group of mink. Affected animals demonstrated sudden death with marked subcutaneous oedema over the dorsal head. The temporalis and masseter muscles were pale, swollen and friable. Histologic changes consisted of varying degrees of myodegeneration, myonecrosis and inflammation. Eosinophils were prominent in the inflammatory infiltrate. Similar to dogs, masticatory muscles in mink were found to contain unique type 2M fibres, suggesting a possible target for an immune response. Aerobic and anaerobic tissue cultures of the affected musculature revealed no significant pathogens. Histological and nutritional analyses were not typical of vitamin E/selenium deficiency. This case series supports the existence of a novel disease entity in mink with some features comparable with masticatory muscle myositis in dogs.

Diagnosis of liver disease in domestic ferrets (Mustela putorius)

Liver disease in ferrets is often subclinical and underdiagnosed. Clinical pathology and diagnostic imaging are needed to guide clinicians but definite diagnosis is based on histopathologic lesions. Inflammatory digestive conditions can lead to ascending tract infection and hepatobiliary inflammation. Ferrets have a specific sensitivity to hepatic lipidosis. Incidence of hepatic neoplasia is high in ferrets. After a summary of anatomy and physiology of the ferret liver, hepatic diseases known in ferret species are reviewed with their subsequent diagnostic procedures.

Disseminated idiopathic myofasciitis in ferrets

First described in 2003, disseminated idiopathic myofasciitis (DIM) has emerged as a new disease in young, domestic ferrets. DIM is a severe inflammatory condition that affects primarily muscles and surrounding connective tissues. The disease is characterized by rapid onset of clinical signs, high fever, neutrophilic leukocytosis, and general lack of response to therapeutic intervention. Until recently DIM was considered fatal, but a few surviving ferrets indicate there may be an effective treatment protocol. DIM is suspected to be an immune-mediated disease, but the etiopathogenesis is not known. This article reviews clinical and pathologic findings in DIM patients, covers recommended diagnostic procedures and clinical management of ferrets with DIM, and discusses potential etiologies for this newly recognized disease in ferrets.

Emerging Ferret Diseases

There are a number of newly described and emerging disease syndromes affecting the domestic ferret, and the purpose of this article is to make veterinarians aware of these diseases. A recently described systemic coronavirus infection appears to be a variant of the ferret enteric coronavirus and is currently termed “ferret infectious peritonitis.” Disseminated immunopathologic myositis, aplastic anemia/bone marrow aplasia, acute hemorrhagic syndrome, and oral ulcerations are also described, although the exact etiologies for these diseases have yet to be determined. There appears to be at least 2 important amino acid metabolism deficiencies in ferrets: hindlimb weakness in older ferrets (L-carnitine) and cysteine urolithiasis. Ferrets have recently been found to be susceptible to H1N1 influenza, so knowledge regarding this zoonotic disease is essential for veterinarians working with these animals. A novel Mycoplasma spp. has also recently been identified in ferrets with chronic respiratory problems that originated from one breeding colony. Because these diseases are still being investigated, practitioners who treat a ferret patient exhibiting clinical signs consistent with any of the conditions mentioned are encouraged to contact people who are knowledgeable of that particular illness.

Autoimmune myasthenia gravis in a ferret

CASE DESCRIPTION

A 7-month-old neutered male ferret was evaluated for episodic pelvic limb weakness of 2 weeks' duration.

CLINICAL FINDINGS

Neurologic examination revealed flaccid tetraparesis with decreased spinal reflexes suggestive of a neuromuscular disease. Results of hematologic and CSF analyses, thoracic radiography, and abdominal ultrasonography were unremarkable. Electrodiagnostic testing revealed subtle spontaneous activity localized to pelvic limb interosseous muscles, unremarkable motor nerve conduction velocities, and lower than typical compound muscle action potential (CMAP) amplitude for tibial nerve stimulation only. A severe decremental response of the CMAP was detected with repetitive nerve stimulation (45.5% at the third ulnar nerve). An esophagogram revealed mild megaesophagus. Intravenous neostigmine methylsulfate administration resulted in immediate resolution of muscle weakness. Cross-reacting anti-acetylcholine receptor (AChR) antibodies were detected in serum (0.35 nmol/L) by use of a canine- and feline-specific muscle extract. Clinical signs and ancillary test results were diagnostic of acquired myasthenia gravis.

TREATMENT AND OUTCOME

Pyridostigmine bromide was administered (1 mg/kg [0.45 mg/lb], PO, q 8 h), resulting in complete remission of clinical signs. However, 1 month after the diagnosis, the ferret was euthanized because of recurrence of weakness despite anticholinesterase treatment.

CLINICAL RELEVANCE

To the authors' knowledge, this is the first report of acquired myasthenia gravis in a ferret and the first identification of anti-AChR antibodies in this species. Autoimmune myasthenia gravis should be considered in ferrets when weakness and flaccid paresis suggest a neuromuscular disease. Electrodiagnostic testing, anticholinesterase challenge, and AChR antibody titer determination were helpful for diagnosis of this condition.

Electrodiagnostic Examination of the Tibial Nerve in Clinically Normal Ferrets

Tibial nerves of 10 normal domestic ferrets (Mustela putorius furo) were evaluated by means of electrodiagnostic tests: motor nerve conduction studies (MNCSs), supramaximal repetitive nerve stimulation (SRNS), F waves, and cord dorsum potentials (CDPs). Values of conduction velocity, proximal and distal compound muscular action potentials, and amplitudes of MNCS were, respectively, 63.25 ± 7.56 m/sec, 10.79 ± 2.75 mV, and 13.02 ± 3.41 mV. Mean decrements in amplitude and area of compound muscular action potentials of wave 9 with low frequency SRNS were 0.3 ± 3.83% and 0.1 ± 3.51%. The minimum latency of the F waves and the F ratio were, respectively, 8.49 ± 0.65 ms and 1.92 ± 0.17. Onset latency of CDP was 1.99 ± 0.03 ms. These tests may help in diagnosing neuromuscular disorders and in better characterizing the hindlimb paresis reported in many ferrets with systemic illnesses.

Clinicopathologic features of a systemic coronavirus-associated disease resembling feline infectious peritonitis in the domestic ferret (Mustela putorius)

From 2002 to 2007, 23 ferrets from Europe and the United States were diagnosed with systemic pyogranulomatous inflammation resembling feline infectious peritonitis (FIP). The average age at the time of diagnosis was 11 months. The disease was progressive in all cases, and average duration of clinical illness was 67 days. Common clinical findings were anorexia, weight loss, diarrhea, and large, palpable intra-abdominal masses; less frequent findings included hind limb paresis, central nervous system signs, vomiting, and dyspnea. Frequent hematologic findings were mild anemia, thrombocytopenia, and hypergammaglobulinemia. Grossly, whitish nodules were found in numerous tissues, most frequently the mesenteric adipose tissue and lymph nodes, visceral peritoneum, liver, kidneys, spleen, and lungs. One ferret had a serous abdominal effusion. Microscopically, pyogranulomatous inflammation involved especially the visceral peritoneum, mesenteric adipose tissue, liver, lungs, kidneys, lymph nodes, spleen, pancreas, adrenal glands, and/or blood vessels. Immunohistochemically, all cases were positive for coronavirus antigen using monoclonal antibody FIPV3-70. Electron microscopic examination of inflammatory lesions identified particles with coronavirus morphology in the cytoplasm of macrophages. Partial sequencing of the coronavirus spike gene obtained from frozen tissue indicates that the virus is related to ferret enteric coronavirus.