The use of intrarenal injection of sodium pentobarbital for euthanasia in cats.

OBJECTIVE: To determine whether intrarenal injection of sodium pentobarbital is a viable method for euthanasia in anesthetized client-owned cats and assess potential factors associated with time to cardiopulmonary arrest (TCPA) for such treated cats. ANIMALS: 131 client-owned cats. PROCEDURES: In this retrospective study, client-owned cats presented for euthanasia between March 1, 2009, and January 15, 2010, were evaluated by veterinarians to determine suitability of intrarenal injection versus other methods of euthanasia. Cats included were anesthetized and then received 6 mL of sodium pentobarbital (390 mg/mL) by intrarenal injection. Results for TCPA were compared for cats grouped on the basis of variables of interest. RESULTS: 131 cats were included, of which 74 (79%) had a TCPA < 1 minute and 28 (21%) had a TCPA between 1.5 and 8 minutes after intrarenal injection. Most (124/131 [95%]) cats had no observable reaction to the intrarenal injection other than cardiopulmonary arrest. Median TCPA was longer for cats without (1 min; 25/131 [19%]) versus with (0 min; 106/131 [81%]) palpable kidney swelling upon injection. CLINICAL RELEVANCE: The effects of intrarenal injection of sodium pentobarbital in cats of the present study were similar to those typically observed with IV administration of euthanasia solution. When this intrarenal injection method is used, cardiopulmonary arrest with few agonal reactions can be expected to occur quickly in most patients. The intrarenal injection method is suited for euthanasia of anesthetized cats with easily located kidneys when IV access may be difficult.

Identification, characterization and deduced amino acid sequence of the dominant protease from Kudoa paniformis and K. thyrsites: a unique cytoplasmic cysteine protease.

Kudoa paniformis and Kudoa thyrsites (Myxozoa: Myxosporea) infections are associated with severe proteolysis of host muscle tissue post-mortem. The present study was undertaken to identify and characterize the protease responsible for myoliquefaction and determine mechanisms controlling protease function in vivo. N-terminal sequence analysis of partially purified protease from hake muscle infected with K. paniformis and K. thyrsites revealed a 23 amino acid sequence that aligned with cysteine proteases. Enzyme inhibition assays confirmed the presence of an essential active site cysteine residue. Using the above K. paniformis amino acid sequence data, a corresponding cDNA sequence from K. thyrsites plasmodia was elucidated revealing a cathepsin L proenzyme (Kth-CL). The translated amino acid sequence lacked a signal sequence characteristic of lysosomal and secreted proteins suggesting a unique cytoplasmic location. Only the proenzyme form of Kth-CL was present in Atlantic salmon muscle anti-mortem but this form became processed in vivo when infected muscle was stored at 4 degrees C. The proenzyme of Kth-CL showed uninhibited activity at pH 6.0, negligible activity at pH 6.5 and no measurable activity at pH 7.0 whilst the processed protease showed stability and function over a broad pH range (pH 4.5-8.8). The pH dependent processing and function of Kth-CL was consistent with histidine residues in the proregion playing a critical role in the regulation of Kth-CL.