SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* MPM BIOVENTURES V, L.P. (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol ARATANA THERAPEUTICS, INC. [ PETX ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 03/03/2014
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	03/03/2014		J(1)		1,000,000(2)	D	$0.00	3,351,048	I	See Footnote(3)
Common Stock	03/03/2014		J(1)		20,876	A	$0.00	26,713	I	By Ansbert Gadicke
Common Stock	03/03/2014		J(1)		20,876	A	$0.00	38,386	I	By Luke Evnin
Common Stock	03/03/2014		J(1)		20,876	A	$0.00	22,767	I	By James Paul Scopa
Common Stock	03/03/2014		J(1)		15,310	A	$0.00	17,937	I	By Vaughn Kailian(4)
Common Stock	03/03/2014		J(1)		12,247	A	$0.00	12,393	I	By The Todd Foley Trust
Common Stock	03/03/2014		J(1)		37,117	A	$0.00	37,117	I	By MPM Capital LLC(5)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person* MPM BIOVENTURES V, L.P. (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Scopa James Paul (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 601 GATEWAY BOULEVARD, SUITE 350 (Street) SOUTH SAN FRANCISCO CA 94080 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* EVNIN LUKE (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Foley Todd (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* GADICKE ANSBERT (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* KAILIAN VAUGHN M (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* MPM ASSET MANAGEMENT INVESTORS BV5 LLC (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* MPM BIOVENTURES V GP LLC (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* MPM BIOVENTURES V LLC (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. Pro-rata distribution of partnership interests.

2. The shares were distributed as follows: 962,533 by MPM BioVentures V, L.P. ("BV V") and 37,467 by MPM Asset Management Investors BV5 LLC ("AM BV5"). MPM BioVentures V GP LLC and MPM BioVentures V LLC ("BV LLC") are the direct and indirect general partners of BV V and BV LLC is the manager of AM BV5. Ansbert Gadicke, Luke Evnin, Vaughn M. Kailian, James Paul Scopa and Todd Foley are the members of BV LLC. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its respective pecuniary interest therein.

3. The shares are held as follows: 3,225,494 by BV V and 125,554 by AM BV5. Each Reporting Person disclaims beneficial ownership of the securities except to the extent of his or its respective pecuniary interest therein.

4. Includes 2,627 shares held by The Vaughn and Patricia Kailian Revocable Trust u/a/dtd 12/18/1992, of which the Reporting Person is trustee.

5. MPM Founders LLC ("MPM Founders") is the managing member of MPM Capital LLC, and Messrs. Evnin and Gadicke are members of MPM Founders. Messrs. Evnin and Gadicke disclaim beneficial ownership of the shares held by MPM Capital LLC except to the extent of their respective pecuniary interests therein.

Remarks:

	By Ansbert Gadicke, member of MPM BioVentures V LLC, the managing member of MPM BioVentures V GP LLC, the general partner of MPM BioVentures V, L.P. /s/ Ansbert Gadicke	03/05/2014
	/s/ James Paul Scopa	03/05/2014
	/s/ Luke Evnin	03/05/2014
	/s/ Todd Foley	03/05/2014
	/s/ Ansbert Gadicke	03/05/2014
	/s/ Vaughn Kailian	03/05/2014
	By Ansbert Gadicke, member of MPM BioVentures V LLC, the manager of MPM Asset Management Investors BV5 LLC /s/ Ansbert Gadicke	03/05/2014
	By Ansbert Gadicke, member of MPM BioVentures V LLC, the managing member of MPM BioVentures V GP LLC /s/ Ansbert Gadicke	03/05/2014
	By Ansbert Gadicke, member of MPM BioVentures V LLC /s/ Ansbert Gadicke	03/05/2014
	** Signature of Reporting Person	Date
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* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
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