Primary Hyperparathyroidism Associated With Atypical Headshaking Behavior in a Warmblood Gelding

A 14-year-old Zweibrücker Warmblood gelding was presented for evaluation of lethargy and headshaking. The horse had a history of bouts of lameness in different limbs and back problems. It also had many mild colic episodes in the past. Results of repeat laboratory tests had shown persistent hypercalcemia (4.8 mmol/L; reference interval [RI]: 2.0–3.2 mmol/L) for 1.5 years and later on hypophosphatemia (0.4 mmol/L; RI: 0.5–1.3 mmol/L) and mild hypermagnesemia (1.0 mmol/L; RI: 0.5–0.9 mmol/L). Parathyroid hormone (PTH) concentration was within the RI. Other causes of hypercalcemia, such as renal failure, vitamin D toxicosis, and granulomatous disease, and nutritional secondary hyperparathyroidism were ruled out. Furthermore, there was no evidence of neoplastic disease. Parathyroid hormone–related protein was measured but inconclusive. A diagnosis of primary hyperparathyroidism was established on the basis of hypercalcemia, hypophosphatemia, low fractional excretion of calcium, and high fractional excretion of phosphorus in combination with a PTH secretion refractory to high calcium levels. Because of the bad prognosis, the owner decided to euthanize the horse. Results of postmortem examination were unremarkable. Hypercalcemia should always be considered abnormal, and further examinations need to be performed to proof hypercalcemia and subsequently find the cause. The main differential diagnoses are renal insufficiency and humoral hypercalcemia of malignancy, but also rare diseases, such as hyperparathyroidism, have to be taken into account.     

Presumptive Iatrogenic Microcystin‐Associated Liver Failure and Encephalopathy in a Holsteiner Gelding

An 8‐year‐old Holsteiner gelding was presented for evaluation of anorexia, obtundation, icterus, and mild colic signs of 48 hours duration. History, physical examination, and initial diagnostics were suggestive of hepatic disease and encephalopathy. Microcystin toxicosis was suspected based on historical administration of a cyanobacteria supplement, associated serum biochemistry abnormalities, and characteristic histopathological changes. Microcystin contamination was confirmed in both supplement containers fed to the horse. Fulminant hepatic failure and encephalopathy progressed resulting in euthanasia. Necropsy findings were consistent with microcystin induced liver failure.     

Factors Associated with Failure of Passive Transfer of Colostral Antibodies in Standardbred Foals

The records of 361 Standardbred mares and their 1986 or 1987 foals were evaluated to identify factors associated with failure of passive transfer (FPT) of colostral antibodies in equine neonates. Sixty-five foals (18%) were classified as FPT based on a serum immunoglobulin concentration of less than 400 mg/dl at 24 to 36 hours of age, determined by the glutaraldehyde coagulation test. The potential association of mare- and foal-related factors with FPT were assessed by reviewing a series of multiple logistic regression models. The season in which the mare foaled and foal exam score, a subjective assessment of foal vigor, maturity, and general health, were the primary factors associated with the development of FPT. Foals with FPT were more likely (odds ratio = 3.50; 95% confidence interval = 1.81-6.68) than normal foals to require medical therapy during the first 3 months after parturition.     

Systemic Granulomatous Disease in a Hungarian Warmblood Gelding

An 8-year-old Hungarian warmblood gelding used for show jumping was evaluated because of poor performance and chronic weight loss. On admission, oral and gastroesophageal ulcerations and malabsorption were detected. Results of thoracic radiography, ultrasonography, bronchoalveolar lavage cytology, and positive polymerase chain reaction for equine herpesvirus 5 raised the possible diagnosis of equine multinodular pulmonary fibrosis. However, abdominal ultrasonography revealed inhomogeneous spleen with many different sized well-demarcated hypoechoic areas, which suggested further differential diagnoses such as tuberculosis, neoplasias, immune mediated diseases, systemic granulomatous disease (SGD), or toxicoses. The horse was euthanized at the owner's request because of the poor condition and possible grave prognosis. Histopathology findings were characteristic of SGD, which is a rare disorder of horses characterized by skin lesions, weight loss, and granulomatous inflammation of multiple organ systems. The lack of skin lesions in this case is an unusual finding. Systemic granulomatous disease is hypothesized to be induced by multiple conventional antigens that are not cleared from affected tissues. Equine herpesvirus 5 might have triggered the granulomatous reactions in this particular case.     

Life Threatening Complication Associated with Anesthesia in a Dog with Masticatory Muscle Myositis

Objective— To report a serious complication in a dog with masticatory muscle myositis (MMM) that occurred during general anesthesia for diagnostic testing.
Study Design— Case report.
Animals— A 2-year-old male Pug.
Methods— MMM was diagnosed in a Pug with a 2-week history of trismus by electrodiagnostics, histopathology, and 2M antibody test. During anesthesia tongue protrusion occurred and because of trismus, an inability to reposition the tongue resulted in venous congestion and severe swelling. Forceful physical attempts and subsequent removal of the rostral digastricus and masseter muscle attachments from the mandible did not increase jaw mobility. Mandibular symphysiotomy was necessary to resolve lingual venous congestion and to reposition the tongue into the oral cavity.
Results— Tongue swelling rapidly subsided after symphysiotomy allowing the tongue to be repositioned into the oral cavity. After treatment of MMM with corticosteroids, jaw range of motion improved and at 6 months was ∼70% normal.
Conclusions— Trismus could not be overcome by detachment of the masseter and digastricus muscle insertions from the mandible, and symphysiotomy was required to reposition the tongue in the oral cavity.  

Clinical Relevance—

In dogs with MMM, tongue position should be monitored during anesthesia to avoid inadvertent protrusion and swelling from venous congestion. Use of anesthetic monitoring equipment on the tongue, such as a pulse oximeter probe, should be avoided in these patients.     

Unilateral periorchitis with a secondary peritonitis in a Standardbred stallion

A 6‐year‐old Standardbred stallion presented for evaluation of progressive diffuse scrotal swelling of 5 days' duration. Physical examination was within normal limits apart from pitting ventral oedema and severely enlarged fluid filled scrotum. Rectal examination did not reveal any abnormalities in the palpable intestinal tract, spleen, kidneys or internal inguinal rings. Testicular ultrasound examination showed evidence of abnormal right testicular parenchyma that was displaced proximally by a heteroechoic region of possible abscessation. The left testis was surrounded by a large amount of hypoechoic fluid. Abdominocentesis was performed and was indicative of peritonitis. Broad‐spectrum antimicrobials and analgesics were administered preoperatively and a bilateral open orchidectomy with closure of the external inguinal ring in addition to scrotal ablation was performed. Post operative peritoneal lavage was performed once a day for 3 days. There were no complications associated with recovery or within the immediate post operative period. The horse was released to the care of his owners 5 days following surgery and has returned to his previous racing performance level.     

Conservative Management of a Cervical Vertebral Fracture in a Gelding

The presentation, diagnostic evaluation, treatment, and 5 years follow-up of a 12-year-old Arabian-Saddlebred cross gelding with neck pain and stiffness, attributable to a fracture of the third cervical vertebrae (C3), is described. Initial cervical spinal radiographs revealed a concave defect in the ventral aspect of the cranial end plate of C3. However, both this finding and ultrasonographic imaging of the area were inconclusive for a fracture. Nuclear scintigraphy revealed that the lesion was metabolically active, prompting computed tomographic imaging that revealed a fracture of C3. Sequential radiographs documented progressive fusion of C2-C3 and no neurological deficits developed over the 5 years after the injury. Cervical vertebral injuries in horses can lead to various clinical signs including ataxia, weakness, and neck stiffness or pain. Diagnosis with cervical radiographs alone can be challenging and, in some cases as the horse in this report, multiple imaging modalities may be required to establish a definitive diagnosis. Horses without neurological signs may recover successfully with conservative medical management, which was performed in this case.