Two adult rottweiler dogs were evaluated for slowly progressive ataxia and paresis of all four limbs of over seven months duration. On neurologic examination, signs referable to a lesion in the cervical spinal cord affecting motor and sensory white matter tracts were found. Both dogs were necropsied and were found to have demyelinating lesions in the spinal cord, brain stem, and deep cerebellar white matter. Primary morphologic alterations were intact naked axons and thinly myelinated axons accompanied by reactive astrogliosis. The spinal cord lesions tended to have bilateral symmetry and were found in the lateral funiculi and occasionally in the dorsal funiculi. The cause and pathogenesis of the lesion were not determined.

A diagnostic test for feline infectious peritonitis virus (FIPV) infection based on a nested PCR (nPCR) assay was developed and tested with FIPV, feline enteric coronavirus (FECV), canine coronavirus (CCV), and transmissible gastroenteritis virus (TGEV) and clinical fluid samples from cats with effusive feline infectious peritonitis (FIP). The target sequence for the assay is in the S1 region of the peplomer protein E2 gene. A vaccine strain of FIPV and two wild-type FIPV strains tested positive, but FECV, TGEV, and CCV tested negative. Preliminary tests with 12 cats with clinical evidence of effusive FIP and 11 cats with an illness associated with effusions, but attributed to other causes, were performed. Eleven of the 12 cats with effusive FIP tested positive, while 1 was negative. Ten of the 11 cats ill from other causes tested negative, while 1 was positive. On the basis of clinical laboratory and histopathologic criteria, the preliminary sensitivity and specificity of the assay were 91.6 and 94%, respectively.

We evaluated serum T4 and T3 concentrations before and after administration of thyrotropin releasing hormone (TRH) in 35 cats with mild to moderate hyperthyroidism, 15 cats with nonthyroidal disease, and 31 clinically normal cats. The TRH stimulation test was performed by collecting blood for serum T4 and T3 determinations before and 4 houmafter IV administration of 0.1 mg/kg TRH. Mean basal serum thyroid hormone concentrations in hyperthymid cats were significantly (P i .05) higher than concentrations in normal cats and in those with nonthyroidal disease, but there was considerable overlap among the 3 groups. After administration of TRH, mean serum T4 concentrations increased significantly in all groups of cats, whereas mean T3 concentrations increased significantly in normal cats and in those with nonthyroidal disease, but not in cats with hyperthyroidism. The absolute difference between mean basal and TRH-stimulated serum concentrations of T4 in cats with hyperthyroidism (1 0.7 nmol/L) was significantly lower than the difference in the cats with nonthyroidal disease (20.0 nmol/L) and in clinically normal cats (28.3 nmol/L), but there was considerable overlap in values among groups. The mean value for relative change in serum T4 concentration after TRH was significantly lower in he diagnosis of hyperthyroidism in cats includes assess-T ment of the history, clinical signs, and physical examination findings, the most important of which is presence of apalpable thyroid gland. The disease is usually easy to confirm by finding high serum concentrations ofthyroxine (T4), triiodothyronine (T3), or both.',' Recent studies have shown, however, that some cats with early or mild hyperthyroidism have serum T4 and T3 concentrations within the normal range.3*4 In cats with mild hyperthyroidism and normal serum T4 concentrations, confirmation of the disease may require several T4 determinations over a period of weeks to months.We recently developed a protocol for a T3 suppression test in cats, and found the test to be useful in diagnosing mild hyperthyr~idism.~ Serum thyroid hormone concentrations were determined before and 3 days after administration of multiple oral doses of a T3 preparation (liothyronine brand [Cytomel; Smith Mine & French Laboratories, Philadelphia, PA]). Many cats with mild hyperthyroidism had highnormal or only slightly high basal serum T4 concentrations but displayed little, if any, suppression of serum T4 concentrations after administration of liothyronine. In contrast, liothyronine caused serum T4 concentrations to decrease to a great extent both in clinically normal cats and in those with nonthyroidal disease. The disadvantages of the T3 suppression test are that it is a relatively long test (3 days), multiple doses of liothyronine must be administered by the owner or veterinarian, and failure of a cat to swallow the liothyronine could result in a false positive diagnosis of hyperthyroidism ina normal cat or one with nonthyroidal d i~e a s e .~'~ In humans, the T3 suppression test has generally bee...

BackgroundNaturally occurring hypothyroidism in adult cats is rare, with only 4 cases reported.ObjectivesTo describe the historical, clinical, laboratory, and scintigraphic features of adult cats with spontaneous hypothyroidism.AnimalsSeven adult cats referred for suspected hypothyroidism.MethodsProspective case series. We collected data on cats’ signalment, clinical signs, results of physical examination, routine laboratory and thyroid hormone testing, and thyroid imaging (thyroid scintigraphy or ultrasound). We subsequently treated cats with levothyroxine and evaluated their response to treatment.ResultsCats ranged from 3.5 to 11 years, with no apparent breed predilection; 6/7 cats were male. Only 2/7 cats were initially tested because of signs of hypothyroidism (hair‐coat changes, lethargy, obesity); others were tested for routine thyroid monitoring or palpable thyroid nodules. Four were azotemic (serum creatinine, 2.2‐3.4 mg/dL). Six of the cats had low serum thyroxine (T4) and free T4 (fT4) concentrations, whereas all 7 cats had high thyroid‐stimulating hormone (TSH) concentrations. In 6/7 cats, thyroid scintigraphy revealed bilateral goiter with intense radionuclide uptake; imaging showed no visible thyroid tissue in the other. After levothyroxine treatment, serum concentrations of T4 and fT4 increased and TSH fell; high serum creatinine normalized in azotemic cats; and repeat imaging showed reduction in goiter size.Conclusions and Clinical ImportancePrimary hypothyroidism develops in adult cats, with a higher prevalence than previously thought. Most cats appear to develop a goitrous form of hypothyroidism associated with thyroid hyperplasia, whereas thyroid atrophy appears to be less common. With levothyroxine replacement, clinical and laboratory abnormalities improve or resolve.