Hemithyroidectomy in a horse with confirmed hyperthyroidism.

A 23-year-old Quarter Horse gelding was admitted to the hospital because of cachexia and hyperactive behavior of 1 year's duration. At admission the horse was severely emaciated, tachycardic with a grade V/VI diastolic murmur, pyrexic, polydipsic, enophthalmic, and alopecic. The right lobe of the thyroid gland was noticeably larger than typical. The horse was also hyperexcitable and had a ravenous appetite. A presumptive diagnosis of hyperthyroidism was made on the basis of clinical signs and high plasma thyroid hormone concentrations. Confirmation of the diagnosis was made on the basis of results of a triiodothyronine-suppression test. Following endocrine testing, the affected portion of the thyroid gland was removed and identified histologically as an adenoma. Return or plasma thyroid hormone concentrations to reference range values and resolution of the clinical signs of disease following hemithyroidectomy provided further conformation of the diagnosis. On the basis of finding in this horse, it appears that horses with hyperthyroidism may be successfully treated by hemithyroidectomy.

Use of 99mTc-mercaptoacetyltriglycine to evaluate renal function in horses.

Ten healthy horses were injected intravenously with 99mTc-MAG3 and the disappearance of radioactivity from the blood was measured. The total body clearance (Cl(B)) and elimination half-life (t1/2(beta)) were 7.9 +/- 1.5 ml/kg/minute and 32.8 +/- 4.1 minutes, respectively. The disappearance of 99mTc-MAG3 from the blood of 2 horses with compromised renal function was also measured. The data suggest that 99mTc-MAG3 is a useful and clinically applicable radiopharmaceutical for measurement of effective renal blood flow in the horse.

Internal diseases that have skin lesions.

Skin lesions can be associated with many internal diseases. Most organ systems seem to have conditions in which skin lesions can develop. Treatment of the skin lesions in such a situation is palliative. The underlying internal disease must be addressed for resolution of the skin lesions to occur. It is important to view the skin as an integral communicating part of the body and not just as the skin.

Neuronal ceroid lipofuscinosis in Rambouillet sheep: characterization of the clinical disease.

A chronic progressive, neurodegenerative disease has been identified in 4 closely related flocks of purebred Rambouillet sheep. Blindness, circling, proprioceptive deficits, reduced cognition, and poor body condition are the main clinical signs. Prominent lesions include markedly decreased cerebral size and weight, enlarged cerebral ventricles, and intraneuronal accumulations of autofluorescent pigment. Affected sheep usually die between 1 and 2 years of age. The clinical signs and postmortem findings are consistent with neuronal ceroid-lipofuscinosis.

Granulomatous enteritis and cutaneous arteritis in a horse.

A 5-year-old Quarter Horse mare was examined because of weight loss of 2 months' duration. The horse was anemic and in poor body condition, and had several areas of cutaneous ulceration, including areas on the muzzle and distal portion of the limbs. Histologic examination of a rectal mucosa biopsy specimen revealed a lymphoplasmacytic infiltrate in the lamina propria mucosa. Results of a glucose absorption test were suggestive of malabsorption. Histologic examination of a biopsy specimen from the cutaneous lesions revealed pronounced arteritis, and weak, patchy immunofluorescent staining for immunoglobulins at the basement membrane. The horse was treated with prednisone, but did not improve, so the horse was humanely destroyed. Necropsy revealed granulomatous enteritis. This case identified an unusual combination of clinical problems and suggests further evidence for similarities between equine granulomatous enteritis and regional enteritis in human beings.

Acute myelomonocytic leukemia in a calf.

In a 2-month-old crossbred calf with paraplegia, results of neurologic evaluation were suggestive of a spinal cord lesion caudal to L3. The calf bled from the blood sampling site for an extended period after venipuncture. Leukocytosis, anemia, and thrombocytopenia were observed. The leukocytes were predominantly atypical blast cells. Postmortem examination revealed petechial hemorrhages throughout the internal organs. Bone marrow was pale tan, with no red marrow seen. Atypical leukocytes were diffusely distributed throughout the body, with penetration of the spinal cord and spinal roots, particularly in the lumbar region. Atypical leukocytes stained positively for alpha-naphthyl acetate esterase and chloracetate esterase, and stained with Sudan black B. Atypical leukocytes expressed class-1 and class-2 major histocompatability antigens, but did not express specific T-, B-, or null-cell surface antigens. The final diagnosis was myelomonocytic leukemia. Differential diagnosis of leukemia in calves should include myelogenous leukemia, and requires use of various techniques to make a definitive diagnosis.

Metastatic renal adenocarcinoma in a mule.

A 15-year-old mare mule was presented with a 2-month history of weight loss, lethargy, and anorexia. Clinicopathologic abnormalities were consistent with liver disease. Repeated urinalysis revealed hyposthenuria, but water intake and a water deprivation test were normal, suggesting adequate renal function. Ultrasonography revealed pulmonary, hepatic, and renal masses. Cytologic and histologic examination of pulmonary aspirates and hepatic biopsies, respectively, revealed polygonal neoplastic cells with many mitotic figures, the cells having the characteristics of adenocarcinoma. Necropsy confirmed a primary renal adenocarcinoma with metastasis to liver, lung, lymph nodes and the opposite kidney.

Bleeding disorder (von Willebrand disease) in a quarter horse.

Bleeding diathesis in a Quarter Horse filly was caused by von Willebrand disease. Hemorrhage occurred mainly from mucosal surfaces and after trauma. Quantitative and qualitative measurements of plasma von Willebrand factor (vWF) documented a specific deficiency of vWF high molecular weight multimers, and concurrently greater than expected deficiency of vWF activity relative to vWF concentration. These findings are characteristic of type-II von Willebrand disease in human beings. Application of vWF assays used in human and small animal medicine now permits evaluation of vWF and diagnosis of von Willebrand disease in horses with bleeding disorders.